JP2005244174A - Piezoelectric element, manufacturing method thereof, and ink jet head and ink jet recording apparatus using the piezoelectric element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain a highly reliable piezoelectric element which does not cause a decrease in insulation even when driven at a high voltage in a high humidity environment.
SOLUTION: The amount of lead contained in a piezoelectric thin film 3 of a piezoelectric element 20 is made smaller than the stoichiometric composition. That is, the piezoelectric thin film 3 is made of lead zirconate titanate represented by Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ (0 <s <1), or A is a perovskite crystal. and additional metal ions that enters the a site structure, as an additive metal ions entering the B to B site of the perovskite-type crystal _{structure, (Pb (1-xy)} a y) (Zr (1-st) Ti s B t) O ₃ It is composed of a lead zirconate titanate oxide represented by (0 <s <1, 0 <t <1-s), and the value of x indicating the Pb composition deficiency exceeds 0 and is 0.15 or less. To do.
[Selection] Figure 1

Description

  The present invention belongs to a technical field related to a piezoelectric element exhibiting an electromechanical conversion function, a manufacturing method thereof, an ink jet head using the piezoelectric element, and an ink jet recording apparatus.

In general, a piezoelectric element includes a laminated body in which a piezoelectric body is sandwiched between two electrodes in the thickness direction. Here, the piezoelectric material is a material that converts mechanical energy into electrical energy, or converts electrical energy into mechanical energy. Typical examples of the piezoelectric material include lead zirconate titanate (Pb (Zr, Ti) O ₃ ) (PZT), which is an oxide having a perovskite crystal structure, and magnesium, manganese, nickel, niobium, and PZT. Etc. to which etc. were added.

  In particular, in the case of PZT having a perovskite-type tetragonal crystal structure, the largest piezoelectric displacement is obtained in the <001> axial direction (c-axis direction). However, many piezoelectric materials are polycrystalline bodies composed of aggregates of crystal grains, and the crystal axes of the crystal grains are in random directions. For this reason, the spontaneous polarization Ps is also randomly arranged, but in the case of a piezoelectric element, the sum of these vectors is made to be in a direction parallel to the electric field. And, in a piezoelectric actuator which is one form of this piezoelectric element (a diaphragm is provided on the laminate), when a voltage is applied between both electrodes, a mechanical displacement proportional to the magnitude of the voltage can be obtained. .

  However, when a high voltage is applied to the piezoelectric element exposed to a high humidity atmosphere for a long time, the electrical insulation of the piezoelectric element deteriorates and dielectric breakdown occurs. It has been regarded as one of the big problems.

  Therefore, various ideas have been made for the purpose of preventing the occurrence of such a phenomenon. In particular, in order to prevent the migration of the electrode material, which is most closely related to the dielectric breakdown, it was considered to select gold or platinum, which hardly causes migration, as the electrode material.

  However, it has been clarified that the insulation resistance of the piezoelectric body is lowered even if the electrode material is prevented from migration by using gold or platinum as the electrode material. That is, the cause of the decrease in the insulation resistance is that moisture directly attacks the piezoelectric material, and as a method for preventing this decrease, for example, in a metal sealed container containing a desiccant inside. It has been proved that if the entire piezoelectric element is accommodated and the container is completely sealed, the piezoelectric body does not deteriorate in insulation (for example, see Patent Document 1).

  By the way, with the recent miniaturization of electronic devices, there has been a strong demand for miniaturization of piezoelectric elements. In order to satisfy this requirement, piezoelectric elements are being used in the form of thin films that have a significantly smaller volume than sintered bodies that have been widely used in the past. Research and development has become popular. For example, as a method for forming a PZT film, there are a sputtering method, a CVD method, a sol-gel method, and the like, and high-performance piezoelectric thin films have been obtained by adjusting the oxygen concentration and devising heat treatment conditions, respectively. .

  In order to reduce the size, the piezoelectric element is required to be used in an exposed state without being placed in a metal sealed container as described above. The device has been devised so that it will not deteriorate even if it is used. For example, a method has been proposed in which a heat generating film is provided beside the piezoelectric layer constituting the piezoelectric element, and the piezoelectric layer is actively heated by this heat generating film, thereby preventing moisture absorption into the piezoelectric layer. (For example, refer to Patent Document 2).

Here, a piezoelectric body containing a lead compound such as PZT is synthesized at a high temperature. This is the same even in the form of a thin film, and since the vapor pressure of lead at a high temperature is high, for example, in the case of a PZT thin film, the stoichiometric composition PZT (chemical composition formula is Pb (Zr _1-x Ti _x ) O ₃ (0 <x <1) and chemical composition ratio Pb: Zr + Ti: O = 1: 1: 3) It is normal to make the composition somewhat more lead (for example, patent Reference 3).
JP-A-4-349675 (2nd page) JP 2000-43259 A JP 10-290033 A (page 3)

  The present inventors have investigated the cause of dielectric breakdown when a high voltage is applied in a high humidity environment in the piezoelectric element using the lead-excess piezoelectric thin film, and as a result, the following mechanism has been proposed. I found it. That is, the piezoelectric thin film is often composed of an aggregate composed of a plurality of columnar crystal particles oriented from one side to the other in the thickness direction of the piezoelectric thin film prepared by sputtering, for example. The boundary part between grains exists as a grain boundary. Moreover, even if it does not show the form of the aggregate of columnar crystals, it has many crystal grain boundaries. Excess lead exists in the form of oxides at the crystal grain boundaries of this piezoelectric body, and lead oxides present at these crystal grain boundaries cause an electrochemical reaction with moisture absorbed as moisture. The cause of the dielectric breakdown in the conventional piezoelectric element is that water penetrates into the crystal grain boundary of the piezoelectric thin film through the pinhole of the electrode film and exists in the crystal grain boundary. It was thought that the lead oxide was transformed into lead dioxide having conductivity through lead hydroxide due to its moisture.

  From this concept, it is only necessary to eliminate a direct attack due to moisture on a piezoelectric material containing a lead compound such as PZT. As a method for this, when manufacturing a piezoelectric element, the piezoelectric body and the first electrode After the laminate of the first electrode and the second electrode is prepared, either one of the first electrode and the second electrode is exposed to a chemical substance such as zirconium alkoxide, zirconium acetylacetonate, zirconium carboxylate, and the chemical substance. Is absorbed by the piezoelectric thin film from the electrode, and lead oxide and lead hydroxide present at the crystal grain boundary of the piezoelectric thin film are coated with electrochemically stable zirconium oxide, so that the leakage current is crystallized. A method of preventing the flow through the grain boundary is conceivable. Since the crystal grain boundaries are thus covered with the insulating film made of zirconium oxide, the electrochemical properties of the crystal grain boundaries are governed by the zirconium oxide present at the crystal grain boundaries. Therefore, since the crystal grain boundary can be brought into an electrochemically stable state, it is possible to prevent the occurrence of dielectric breakdown in which a leak current flows through the crystal grain boundary. This can prevent dielectric breakdown even under high humidity.

  However, in the above method, it is necessary to perform a zirconia treatment or the like after the laminate is manufactured, and there is a problem that the manufacturing process becomes complicated.

  The present invention has been made in view of such points, and an object of the present invention is to provide a highly reliable piezoelectric body that does not cause a decrease in insulation even when driven at a high voltage in a high humidity environment. It is to make it easy to obtain an element.

  In order to achieve the above object, in the present invention, the amount of lead contained in the piezoelectric thin film is made smaller than the stoichiometric composition.

  Specifically, the invention of claim 1 is directed to a piezoelectric element including a laminate in which a first electrode film, a piezoelectric thin film, and a second electrode film are laminated in this order.

The piezoelectric thin film is an oxide having a perovskite crystal structure, and the chemical composition formula is Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ (0 <s <1). As described above, lead zirconate titanate or A as an additive metal ion entering the A site of the perovskite crystal structure, and B as an additive metal ion entering the B site of the perovskite crystal structure (Pb _(1-xy) A _y ) (Zr _(1-st) Ti _s B _t ) O ₃ (0 <s <1, 0 <t <1-s) In the chemical composition formulas of lead zirconate titanate and lead zirconate titanate-based oxides, the value of x indicating the amount of Pb composition deficiency from the stoichiometric composition exceeds 0 and is 0.15 or less.

  With the above configuration, the lead thin film contained in the piezoelectric thin film constituting the piezoelectric element has a smaller amount than the stoichiometric composition, and the lead oxide that causes a chemical reaction due to moisture in the atmosphere is the crystal of the piezoelectric thin film. As a result, even if driving is performed by applying a voltage in a high-humidity environment, deterioration due to a decrease in insulation does not occur. Moreover, such a piezoelectric thin film having a low lead composition can be easily obtained only by appropriately setting the sputtering conditions (see claims 7 and 8), and does not require zirconia treatment or the like. Therefore, a highly reliable piezoelectric element can be easily obtained.

  In the invention of claim 2, in the invention of claim 1, A in the chemical composition formula of the lead zirconate titanate oxide is lanthanum (La), strontium (Sr), bismuth (Bi), and calcium (Ca). At least one metal ion selected from the group consisting of: B in the chemical composition formula is a group of niobium (Nb), magnesium (Mg), nickel (Ni), manganese (Mn) and iron (Fe) And at least one metal ion selected from

  As a result, piezoelectric thin films having various properties can be obtained, and piezoelectric elements having characteristic piezoelectric characteristics can be realized.

  In the invention of claim 3, in the invention of claim 1, the thickness of the piezoelectric thin film is 2 μm or more and 6 μm or less.

  Thus, a piezoelectric thin film having stable displacement and reliability can be easily obtained in normal use.

  In the invention of claim 4, in the invention of claim 1, the piezoelectric thin film is preferentially oriented in the (001) plane.

  By doing so, the polarization directions of the crystal grains of the piezoelectric thin film are aligned in one direction, so that stable displacement is exhibited with respect to voltage application.

  According to a fifth aspect of the present invention, in the first aspect of the present invention, a diaphragm is disposed on the surface on one side in the stacking direction of the stacked body.

  According to a sixth aspect of the invention, in the fifth aspect of the invention, the diaphragm is made of at least one selected from the group consisting of silicon, glass, a ceramic material, and a metal material.

  According to the fifth and sixth aspects of the present invention, a highly reliable piezoelectric element (piezoelectric actuator) that is displaced in the stacking direction of the stacked body by applying a voltage between the first and second electrode films can be easily obtained.

  The invention according to claim 7 includes a step of forming a first electrode film on a substrate, a step of forming a piezoelectric thin film on the first electrode film by a sputtering method, And a step of forming a second electrode film.

In the present invention, the piezoelectric thin film is an oxide having a perovskite crystal structure, and has a chemical composition formula of Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ (0 <s <1) Lead titanate zirconate or A as an additive metal ion entering the A site of the perovskite crystal structure and B as an additive metal ion entering the B site of the perovskite crystal structure (Pb ₍ consisted _{1-xy) A y) (} Zr (1-st) Ti s B t) O 3 (0 <s <1,0 <t <1-s) of lead zirconate titanate is expressed by based oxide The value of x indicating the Pb composition deficiency from the stoichiometric composition in the chemical composition formula of the above lead zirconate titanate and lead zirconate titanate-based oxides exceeds 0 and is 0.15 or less, In the step of forming the piezoelectric thin film, the substrate on which the first electrode film is formed is grounded. It assumed to be a step of forming a piezoelectric thin film by the sputtering conditions and the electrically only One sputtering gas pressure in a potential state of floated 0.05Pa or 0.15Pa or less from.

  That is, in the piezoelectric thin film formation process, in order to form a piezoelectric thin film with a low lead composition, during the sputtering film formation, among the constituent element particles that are ejected from the target by the sputtering gas and fly to the substrate, vapor The present inventors have found that it is only necessary to lower the deposition rate of lead element particles having a high pressure, and for this purpose, it is effective to apply ion bombardment to strike the sputtered particles on the substrate. As a specific method, when the substrate is in a potential state that is electrically floating from the ground potential (that is, the substrate is not grounded and is not electrically connected to the other), sputter deposition is performed. A method of applying ion bombardment to a substrate by increasing the degree of vacuum (lowering the sputtering gas pressure) and reducing the probability that sputtered particles collide with gas molecules existing in the space between the substrate and the target. Alternatively, there is a method in which ion bombardment is applied to the substrate by electrically attracting sputtered particles to the substrate by setting the substrate potential to the negative potential state that is the same as or lower than the ground potential. In the invention of claim 7, by setting the sputtering gas pressure as low as 0.15 Pa or less, ion bombardment can be applied to the substrate, thereby easily forming a piezoelectric thin film having a small lead composition. it can. Therefore, the piezoelectric element having high reliability according to the invention of claim 1 can be easily mass-produced. The reason why the sputtering gas pressure is set to 0.05 Pa or more is that when it is less than 0.05 Pa, it is difficult to generate plasma when forming a film with a sputtering apparatus.

  In the invention of claim 8, a step of forming a first electrode film on a substrate, a step of forming a piezoelectric thin film on the first electrode film by a sputtering method, and on the piezoelectric thin film, A method of manufacturing a piezoelectric element including a step of forming a second electrode film.

The piezoelectric thin film is an oxide having a perovskite crystal structure, and the chemical composition formula is Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ (0 <s <1). Lead Zirconate titanate or A as an additive metal ion entering the A site of the perovskite crystal structure and B as an additive metal ion entering the B site of the perovskite crystal structure (Pb _(1-xy) A _y ) (Zr _(1-st) Ti _s B _t ) O ₃ (0 <s <1, 0 <t <1-s) In the chemical composition formulas of lead zirconate titanate and lead zirconate titanate-based oxides, the value of x indicating the Pb composition deficiency from the stoichiometric composition is more than 0 and 0.15 or less, and the piezoelectric thin film Forming the first electrode film on the substrate on which the first electrode film is formed; Flip or assumed to be a step of forming a piezoelectric thin film by sputtering condition of applying a bias voltage so that the low negative potential state than the ground potential.

  Thus, ion bombardment can be applied to the substrate by electrically attracting the sputtered particles to the substrate, and as described above, a piezoelectric thin film having a small lead composition can be formed. In particular, if the substrate is in a negative potential state lower than the ground potential, the sputtered particles can be more strongly attracted to the substrate. As a result, a considerably large ion bombardment can be applied to the substrate, and the lead composition is low. The piezoelectric thin film can be more reliably and easily formed. Therefore, similarly to the seventh aspect of the invention, a piezoelectric element having high reliability can be easily mass-produced.

  The invention according to claim 9 is a laminate in which a first electrode film, a piezoelectric thin film, and a second electrode film are laminated in this order, and a diaphragm disposed on one side in the lamination direction of the laminate. A piezoelectric chamber having a pressure chamber containing ink, and a nozzle communicating with the pressure chamber, and the diaphragm is displaced in the thickness direction by the piezoelectric effect of the piezoelectric thin film of the piezoelectric device. It is an invention of an ink jet head configured to eject ink in a room from the nozzle.

In the present invention, the piezoelectric thin film of the piezoelectric element is an oxide having a perovskite crystal structure, and the chemical composition formula is Pb _(1-x) (Zr _(1-s) Ti _s ) O _3. Lead zirconate titanate represented by (0 <s <1) or A as an additive metal ion entering the A site of the perovskite crystal structure and B as an additive metal ion entering the B site of the perovskite crystal structure _{, (Pb (1-xy)} A y) (Zr (1-st) Ti s B t) O 3 (0 <s <1,0 <t <1-s) lead zirconate titanate which is expressed in The value of x indicating the amount of Pb composition deficiency from the stoichiometric composition in the chemical composition formula of the above lead zirconate titanate and lead zirconate titanate oxides exceeds 0 and is 0.15. Assume that:

  According to the present invention, an ink jet head having extremely good reliability and durability can be easily obtained.

  The invention of claim 10 is an invention of an ink jet recording apparatus. In this invention, the ink jet head according to claim 9 and a relative moving means for relatively moving the ink jet head and the recording medium are provided. It is assumed that when the inkjet head is moved relative to the recording medium by the means, recording is performed by discharging ink in a pressure chamber from the nozzle of the inkjet head to the recording medium.

  According to the present invention, it is possible to easily obtain an ink jet recording apparatus with little variation in ejection performance and high reliability.

  According to an eleventh aspect of the invention, in the tenth aspect of the invention, the relative movement means includes a head transfer means for reciprocating the inkjet head in a predetermined direction, and a recording medium for transferring the recording medium in a direction substantially perpendicular to the predetermined direction. And when the ink jet head is moved in the predetermined direction by the head moving means of the relative moving means, the ink in the pressure chamber is ejected from the nozzles of the ink jet head onto the recording medium for recording. Assume that it is configured to do.

  Thus, an ink jet type recording apparatus in which the ink jet head reciprocates can be easily obtained.

  According to a twelfth aspect of the invention, in the tenth aspect of the invention, the plurality of inkjet heads are connected to each other in a state of being aligned in a predetermined direction, and the relative movement means transfers the recording medium in a direction substantially perpendicular to the predetermined direction. Thus, the inkjet head and the recording medium are configured to move relative to each other.

  Thus, a line head type ink jet recording apparatus can be easily obtained.

  As described above, according to the present invention, since the lead composition contained in the piezoelectric thin film is made smaller than the stoichiometric composition, the deterioration due to the lowering of the insulating property occurs due to the influence of moisture in the atmosphere. Thus, a highly reliable piezoelectric element, ink jet head, and ink jet recording apparatus can be easily obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a perspective view showing a piezoelectric element according to an embodiment of the present invention. As shown in FIG. 1, a piezoelectric element 20 according to the present embodiment includes a substrate 1 made of silicon (Si) having a rectangular plate shape having a length of 11.0 mm, a width of 3.0 mm, and a thickness of 0.30 mm, and the substrate. 1 and a laminated body 10 disposed on the substrate 1. This piezoelectric element 20 has a length of 10. mm extending in a direction perpendicular to the piezoelectric element 20 (Y-axis direction of the coordinate axis shown in FIG. 1) by the epoxy adhesive 6 at a portion from one end to 3.0 mm. The piezoelectric element 20 is supported in a cantilever shape by a stainless support substrate 5 having a thickness of 0 mm, a width of 3.0 mm, and a thickness of 1.0 mm.

  The laminated body 10 includes a first electrode film 2, a piezoelectric thin film 3, and a second electrode film 4 laminated in this order, and the first electrode film 2 and the piezoelectric thin film are formed on the substrate 1. 3 and the second electrode film 4 are sequentially formed by sputtering and stacked. The first and second electrode films 2 and 4 may be formed by any method, such as a CVD method or a sol / gel method.

  The substrate 1 serves as a diaphragm disposed on the surface of the laminate 10 on one side in the stacking direction (first electrode film 2 side). That is, the piezoelectric thin film 3 expands and contracts in a direction perpendicular to the thickness direction due to the piezoelectric effect of the piezoelectric thin film 3 of the multilayer body 10, and the expansion and contraction of the substrate 1 as a diaphragm prevents the piezoelectric element. The tip end side (free end side) of 20 is displaced in the thickness direction (stacking direction of the stacked body 10). The substrate 1 is not limited to silicon, and may be made of glass, a ceramic material, a metal material, or the like.

  The first electrode film 2 is an iridium (Ir) alloy thin film having a film thickness of 0.10 μm and containing 6 mol% of cobalt (Co), and the entire surface on one side of the substrate 1 in the thickness direction. Is provided. The first electrode film 2 need not be made of such an iridium alloy containing Co, and may be made of any metal. However, the first electrode film 2 is formed on the first electrode film 2 as described later. Titanium (Ti), aluminum (Al), iron (Fe), cobalt (Co), nickel (in order to be able to satisfactorily control the crystal orientation of the piezoelectric thin film 3 when the piezoelectric thin film 3 is formed. Ni), manganese (Mn), copper (Cu), magnesium (Mg), calcium (Ca), strontium (St), barium (Ba) and at least one additive selected from the group of these oxides It is preferably made of an added noble metal.

The piezoelectric thin film 3 has an entire surface (that is, a width of 3.0 mm) excluding a portion from one end on the side (base end side) bonded to the stainless steel supporting substrate 5 on the first electrode film 2 to 3.0 mm. And is made of an oxide having a perovskite crystal structure. Specifically, the chemical composition formula is
Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ (0 <s <1)
As lead metal zirconate titanate (PZT) or an additive metal ion entering the A site of the perovskite crystal structure and B as an additive metal ion entering the B site of the perovskite crystal structure,
_{(Pb (1-xy) A} y) (Zr (1-st) Ti s B t) O 3 (0 <s <1,0 <t <1-s)
It consists of a lead zirconate titanate oxide (PZT oxide). In the chemical composition formulas of the lead zirconate titanate and lead zirconate titanate oxides, the value of x indicating the Pb composition deficiency from the stoichiometric composition exceeds 0 and is 0.15 or less. . Thus, the lead composition contained in the piezoelectric thin film 3 is smaller than the stoichiometric composition. Accordingly, lead oxide that causes a chemical reaction due to moisture in the atmosphere does not exist in the crystal grain boundary of the piezoelectric thin film 3. As a result, even if driving is performed by applying voltage in a high humidity environment, deterioration due to a decrease in insulation does not occur. Such an effect is more surely obtained as the lead composition contained in the piezoelectric thin film 3 is smaller (the larger the value of x), but when the value of x is larger than 0.15, the piezoelectric thin film is obtained. 3 is difficult to form, or even if the film can be formed, the piezoelectric characteristics are insufficient. The value of x is more preferably 0.03 or more and 0.15 or less.

  A in the chemical composition formula of the lead zirconate titanate oxide is at least one metal ion selected from the group consisting of lanthanum (La), strontium (Sr), bismuth (Bi), and calcium (Ca). Preferably, B in the chemical composition formula is at least one metal ion selected from the group consisting of niobium (Nb), magnesium (Mg), nickel (Ni), manganese (Mn), and iron (Fe). It is preferable that

  The piezoelectric thin film 3 is preferably preferentially oriented in the (001) plane, and the thickness of the piezoelectric thin film 3 is preferably 2 μm or more and 6 μm or less.

  The second electrode film 4 is a platinum (Pt) thin film having a film thickness of 0.25 μm, and is provided on the entire piezoelectric thin film 3, and the first electrode film 2 and the second electrode film 2 are provided. Lead wires 7 and 8 are connected to the electrode film 4, respectively. Note that the second electrode film 4 need not be made of platinum, and may be made of any metal.

When a voltage is applied between the first electrode film 2 and the second electrode film 4 of the piezoelectric element 20 via the lead wires 7 and 8, the piezoelectric thin film 3 has a coordinate axis shown in FIG. It extends in the X-axis direction (the length direction of the piezoelectric thin film 3). At this time, the change amount ΔL (m) of the elongation of the piezoelectric thin film 3 is the applied voltage E (V), the thickness of the piezoelectric thin film 3 is t (m), and the length of the piezoelectric thin film 3 is L (m). ), When the piezoelectric constant of the piezoelectric thin film 3 is d ₃₁ (pm / V),
ΔL = d ₃₁ × L × E / t
It becomes.

  Here, in the piezoelectric thin film 3, the upper part joined to the thin second electrode film 4 extends in the X-axis direction, but the lower part joined to the substrate 1 via the first electrode film 2. Is suppressed by the thick substrate 1. As a result, the distal end side of the piezoelectric element 20 located on the opposite side to the base end side (terminal side to which the lead wires 7 and 8 are connected) fixed to the stainless steel support substrate 5 is the Z of the coordinate axis shown in FIG. It is displaced to the negative side in the axial direction (lower side in FIG. 1). As a result, when voltage application and removal are alternately repeated at a constant frequency, the tip of the piezoelectric element 20 moves up and down with a predetermined displacement width. The displacement characteristics of the piezoelectric element 20 can be evaluated by measuring the relationship between the applied voltage and the displacement width of the tip of the piezoelectric element 20.

  Next, a method for manufacturing the piezoelectric element 20 will be described with reference to the process diagram of FIG.

  First, as shown in FIG. 2A, a substrate 1 having a 20 mm square whose surface is mirror-polished and having a thickness of 0.30 mm is prepared. On this substrate 1, a rectangle having a width of 5.0 mm and a length of 18.0 mm is prepared. The first electrode film 2 is formed by RF sputtering using a stainless steel mask (not shown) having a thickness of 0.2 mm.

  Subsequently, RF magnetron sputtering is accurately performed on the surface of the first electrode film 2 using a stainless steel mask (thickness: 0.2 mm) having a rectangular opening having a width of 5.0 mm and a length of 8.0 mm. By the method, the piezoelectric thin film 3 made of the PZT or PZT oxide is formed. At this time, a sintered body target of PZT or PZT-based oxide is used. Then, the substrate 1 on which the first electrode film 2 is formed is brought into a potential state that is electrically floated from the ground potential (that is, the substrate is not grounded and is not electrically connected to the other), and the sputtering gas pressure is set. The piezoelectric thin film 3 is formed under the sputtering conditions of 0.05 Pa or more and 0.15 Pa or less, or the substrate 1 is formed on the substrate 1 on which the first electrode film 2 is formed. The piezoelectric thin film 3 is formed under sputtering conditions in which a bias voltage is applied so as to be in a low negative potential state.

  By forming the piezoelectric thin film 3 under such sputtering conditions, ion bombardment can be applied to the substrate 1. That is, when the substrate is in a state that is electrically floating from the ground potential, the sputtering gas pressure is reduced to 0.15 Pa or less (however, plasma is generated so as to increase the degree of vacuum during sputtering film formation). In order to reduce the probability that the sputtered particles collide with gas molecules existing in the space between the substrate 1 and the target, or the potential of the substrate 1 is equal to the ground potential or By setting the negative potential lower than the ground potential to electrically attract the sputtered particles to the substrate 1, ion bombardment can be applied to the substrate 1. Thereby, at the time of sputtering film formation, among the particles of the constituent elements that are ejected from the target by the sputtering gas and fly to the substrate 1, the deposition rate of the particles of the lead element having a high vapor pressure can be lowered. The piezoelectric thin film 3 having a small lead composition as expressed by the above chemical composition formula can be easily formed.

  As described above, the first electrode film 2 is made of a noble metal to which an additive such as titanium is added (in this embodiment, iridium to which cobalt is added), whereby the piezoelectric thin film 3 is (001). ) It becomes easy to preferentially align the surface. That is, the additive is scattered in the form of islands on the surface portion of the first electrode film 2, and this additive such as titanium is easily oxidized and does not contain it in the form of an oxide. If oxygen is present when the piezoelectric thin film 3 is formed, the additive scattered on the surface becomes an oxide. Then, the piezoelectric thin film 3 grows crystals on the upper side with the additive (oxide) scattered in the island shape as a nucleus, and is thus easily oriented on the (001) plane on the additive. On the other hand, when a substrate such as silicon is used, the first electrode film 2 is normally (111) -oriented, and therefore, in the piezoelectric thin film 3 on the surface portion of the first electrode film 2. In the upper region of the portion where the additive is not present, it becomes a plane orientation other than the (001) plane (for example, (111) plane orientation) or becomes amorphous. However, such a region not having the (001) plane orientation exists only in the vicinity of the surface of the piezoelectric thin film 3 on the first electrode film 2 side (in the range from the surface to about 20 nm at most). That is, since the (001) -oriented region on the additive expands as the crystal grows, the area of the region in the cross section perpendicular to the film thickness direction changes from the first electrode film 2 side to the opposite side ( (The second electrode film 4 side) increases, and as a result, the region that is not in the (001) plane orientation is reduced, so that the entire thickness of the piezoelectric thin film 3 becomes approximately 20 nm. It becomes a region of (001) plane orientation.

  Next, the second electrode film 4 is formed on the surface of the piezoelectric thin film 3 by RF sputtering using a stainless steel mask having the same shape as the piezoelectric thin film 3 is formed. As a result, a structure 21 in which the laminated body 10 including the piezoelectric thin film 3 is provided on the substrate 1 as shown in FIG. 2B is obtained.

  Next, as shown in FIG. 2C, in a square portion having a width of 3.0 mm and a length of 11.0 mm, and one end of which is 3.0 mm wide and 3.0 mm long. The structure 21 is cut with a dicing saw so that a part of the first electrode film 2 is exposed. Thereby, the piezoelectric element structure component 22 in which the second electrode film 4 is exposed at the upper surface portion having the remaining width of 3.0 mm and the length of 8.0 mm is obtained.

  Subsequently, as shown in FIG. 2D, one end portion of the substrate 1 in the piezoelectric element structure component 22 is bonded to the stainless steel support substrate 5 using an epoxy adhesive 6.

  Next, as shown in FIG. 2 (e), a 0.1 mm gold lead is formed on the first electrode film 2 exposed in the piezoelectric element structure component 22 using a conductive adhesive (silver paste). The piezoelectric element 20 is completed by connecting the wire 7 and connecting the same lead wire 8 to the second electrode film 4 on the same one end side by wire bonding.

  Therefore, in the present embodiment, the lead composition contained in the piezoelectric thin film 3 is less than the stoichiometric composition, so that lead oxide that causes a chemical reaction due to moisture in the atmosphere exists in the crystal grain boundary of the piezoelectric thin film 3. As a result, even if driving is performed by applying a voltage in a high humidity environment, deterioration due to a decrease in insulation does not occur. Moreover, the piezoelectric thin film 3 having such a low lead composition can be easily obtained simply by setting the sputtering conditions appropriately as described above. Therefore, the piezoelectric element 20 having high reliability can be easily obtained.

  Here, a specific example will be described.

(Example 1)
The substrate 1 was a silicon substrate having the same shape as that of the above embodiment, and the first electrode film 2 was an iridium alloy thin film containing 6 mol% of 0.10 μm thick cobalt as in the above embodiment. In this iridium alloy thin film, an RF magnetron sputtering apparatus is used to heat and hold a silicon substrate in advance at a temperature of 400 ° C., and a mixed gas of argon and oxygen (gas volume ratio Ar: O ₂ = 15: 1) is used as a sputtering gas. Then, the total gas pressure was maintained at 0.25 Pa, an iridium plate containing 6 mol% of cobalt was used as a target of the sputtering apparatus, and 200 W of high frequency power was applied to form a film by sputtering for 16 minutes. During the film formation, the silicon substrate was held in a sputtering apparatus so as to be in a potential state that was electrically floated from the ground potential.

  The piezoelectric thin film 3 was a PZT thin film preferentially oriented in the (001) plane. This PZT thin film was formed using an RF magnetron sputtering apparatus. Specifically, a 6-inch diameter sintered compact target of PZT having a stoichiometric composition (composition molar ratio Pb: Zr: Ti = 1.00: 0.53: 0.47) was used as a target. Then, in the film forming chamber to which the PZT target is attached, the silicon substrate on which the iridium alloy thin film is formed is preliminarily heated to a temperature of 580 ° C., and a mixed gas of argon and oxygen is used as a sputtering gas. A PZT thin film was formed for 50 minutes at a mixing ratio of argon: oxygen = 79: 1, a flow rate of 40 ml / min, a sputtering gas pressure of 0.15 Pa, and a plasma generation power of 3 kW. During the film formation, the silicon substrate was held in a sputtering apparatus so as to be in a potential state that was electrically floated from the ground potential.

  Furthermore, the second electrode film 4 was formed by RF sputtering as a platinum thin film having the same thickness of 0.25 μm as in the above embodiment.

  In addition, in order to accurately obtain the thickness and crystal structure of the PZT thin film, a laminated film sample was formed at the same time after the PZT thin film was formed and the film forming process was terminated without forming the second electrode film 4. The sample was subjected to composition analysis by X-ray diffraction and an X-ray microanalyzer, and then the film thickness was also accurately measured by breaking it and observing the fracture surface with a scanning electron microscope.

  As a result of analyzing the above sample by X-ray diffraction, the PZT thin film was a film having a perovskite crystal structure with a preferential orientation on the (001) plane ((001) plane crystal orientation ratio of 96%) (<001> axis is A thin film that is oriented perpendicular to the film surface. Here, the (001) plane crystal orientation ratio is defined by the (001) plane, (100) plane, (010) plane, (110) plane, (011) plane, (101) plane, and (101) of the X-ray diffraction pattern of the thin film. This is the ratio (percentage) of the peak intensity of the (001) plane to the total peak intensity of the (111) plane.

Further, as a result of composition analysis using an X-ray microanalyzer, the composition of the PZT thin film was Pb: Zr: Ti = 0.99: 0.53: 0.47. That is, when expressed in the chemical composition formula, Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ notation, x = 0.01 (that is, Pb _0.99 (Zr _0.53 Ti _0.47 ) O ₃ ). It was found that the composition of Zr and Ti did not change compared to the target composition, and the Pb composition was lower than 1.00.

  Furthermore, as a result of observing the fracture surface of the sample with a scanning electron microscope, the film thickness of the PZT thin film was 3.5 μm.

  The piezoelectric element 20 produced as described above was evaluated. That is, a triangular wave voltage having a maximum voltage of 0 V and a minimum voltage of −25 V is applied between the first electrode film 2 and the second electrode film 4 of the piezoelectric element 20 via the lead wires 7 and 8, and laser Doppler is applied. The amount of vertical movement displacement in the Z-axis direction at the tip of the piezoelectric element 20 was measured using a vibration displacement measuring device.

  FIG. 3 shows the amount of vertical movement displacement in the Z-axis direction at the tip of the piezoelectric element 20 when a triangular wave voltage with a frequency of 2 kHz is applied. As shown in the figure, when the applied voltage changed from 0 V to −25 V, the tip of the piezoelectric element 20 was linearly displaced from 0 μm to −7.2 μm in proportion to the applied voltage.

  Further, the produced piezoelectric element 20 is placed in a constant temperature and high humidity container maintained at 35 ° C. in an atmosphere with a relative humidity of 80%, and 35 V is provided between the first electrode film 2 and the second electrode film 4. A 200-hour endurance test was conducted by applying a DC voltage of. Then, the elapsed time from the start of voltage application and the leakage current value at that time were measured.

  As a result of this endurance test, the leak current value was 0.3 nA at the start of measurement, 0.8 nA after 1 hour, 3 nA after 100 hours, 3 nA after 200 hours, and no leak current value exceeding 3 nA was observed. The reliability was found to be very good.

  Furthermore, when the appearance of the electrode film surface of the piezoelectric element 20 after the 200-hour durability test was observed with an optical microscope, changes such as cracks and coloring were not observed.

  Furthermore, when the piezoelectric element 20 after the 200-hour endurance test was driven by applying the same triangular wave voltage as before the endurance test and the relationship between the applied voltage and the displacement amount was confirmed, the same characteristics as before the endurance test were obtained. It was confirmed that there was no deterioration.

(Example 2)
In the present embodiment, the sputtering gas pressure of the film formation condition by sputtering when forming the piezoelectric thin film 3 (PZT thin film) is changed to 0.12 Pa, and the piezoelectric element 20 is formed in the same manner as in the first embodiment. Produced.

The PZT thin film of the piezoelectric element 20 thus obtained was a perovskite crystal structure film preferentially oriented to the (001) plane ((001) plane crystal orientation ratio of 96%) as a result of analysis by X-ray diffraction. . Further, as a result of the composition analysis by the X-ray microanalyzer, x = 0.03 (that is, Pb _0.97 (Zr _0.53 Ti _0.47 ) O in Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ notation. ₃ ). Further, as a result of observation with a scanning electron microscope, the thickness of the PZT thin film was 3.5 μm.

  Then, a triangular wave voltage having a maximum voltage of 0 V and a minimum voltage of −25 V is applied between the first electrode film 2 and the second electrode film 4 in the piezoelectric element 20 so that the top and bottom of the piezoelectric element 20 are When the displacement amount of the motion was measured, when the applied voltage changed from 0V to −25V, the tip of the piezoelectric element 20 was linearly displaced from 0 μm to −7.2 μm in proportion to the applied voltage.

  Further, as a result of performing an endurance test on the piezoelectric element 20 in a constant temperature and high humidity container having a temperature of 35 ° C. and a relative humidity of 80%, as in Example 1, the measurement was started, 1 hour later, 100 hours later. The leak current values after 200 hours and 0.3 nA were 0.3 nA, 0.8 nA, 3 nA, and 3 nA, respectively, and it was found that there was reliability equivalent to that of the piezoelectric element 20 of Example 1.

  Furthermore, when the appearance of the electrode film surface of the piezoelectric element 20 after the 200-hour durability test was observed with an optical microscope, changes such as cracks and coloring were not observed.

  Furthermore, when the piezoelectric element 20 after the 200-hour endurance test was driven by applying the same triangular wave voltage as before the endurance test and the relationship between the applied voltage and the displacement amount was confirmed, the same characteristics as before the endurance test were obtained. It was confirmed that there was no deterioration.

(Example 3)
In this example, the sputtering gas pressure of the film formation condition by sputtering at the time of forming the piezoelectric thin film 3 (PZT thin film) was changed to 0.09 Pa. Produced.

The PZT thin film of the piezoelectric thin film 3 thus obtained was a perovskite crystal structure film preferentially oriented to the (001) plane ((001) plane crystal orientation ratio of 96%) as a result of analysis by X-ray diffraction. . Further, as a result of the composition analysis by the X-ray microanalyzer, x = 0.04 (that is, Pb _0.96 (Zr _0.53 Ti _0.47 ) O in Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ notation. ₃ ). Furthermore, as a result of observation with a scanning electron microscope, the thickness of the PZT thin film was 3.7 μm.

  Then, a triangular wave voltage having a maximum voltage of 0 V and a minimum voltage of −25 V is applied between the first electrode film 2 and the second electrode film 4 in the piezoelectric element 20 so that the top and bottom of the piezoelectric element 20 are When the displacement amount of the movement was measured, when the applied voltage changed from 0V to −25V, the tip of the piezoelectric element 20 was linearly displaced from 0 μm to −7.0 μm in proportion to the applied voltage.

  Further, as a result of performing an endurance test on the piezoelectric element 20 in a constant temperature and high humidity container having a temperature of 35 ° C. and a relative humidity of 80%, as in Example 1, the measurement was started, 1 hour later, 100 hours later. The leakage current values after 200 hours and 0.4 nA were 0.4 nA, 0.8 nA, 3 nA, and 3 nA, respectively, and it was found that there was reliability equivalent to that of the piezoelectric element 20 of Example 1.

  Furthermore, when the appearance of the electrode film surface of the piezoelectric element 20 after the 200-hour durability test was observed with an optical microscope, changes such as cracks and coloring were not observed.

  Furthermore, when the piezoelectric element 20 after the 200-hour endurance test was driven by applying the same triangular wave voltage as before the endurance test and the relationship between the applied voltage and the displacement amount was confirmed, the same characteristics as before the endurance test were obtained. It was confirmed that there was no deterioration.

Example 4
In this embodiment, the sputtering gas pressure under the film forming conditions by sputtering when forming the piezoelectric thin film 3 (PZT thin film) is set to 0.07 Pa, which is a value close to the limit of stable plasma generation in the RF magnetron sputtering apparatus used. Otherwise, the piezoelectric element 20 was manufactured in the same manner as in Example 1 above.

The PZT thin film of the piezoelectric element 20 thus obtained was a perovskite crystal structure film preferentially oriented to the (001) plane ((001) plane crystal orientation ratio of 96%) as a result of analysis by X-ray diffraction. . Further, as a result of the composition analysis by the X-ray microanalyzer, x = 0.04 (that is, Pb _0.96 (Zr _0.53 Ti _0.47 ) O in Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ notation. ₃ ). Furthermore, as a result of observation with a scanning electron microscope, the thickness of the PZT thin film was 3.8 μm.

  Then, a triangular wave voltage having a maximum voltage of 0 V and a minimum voltage of −25 V is applied between the first electrode film 2 and the second electrode film 4 in the piezoelectric element 20 so that the top and bottom of the piezoelectric element 20 are When the displacement amount of the motion was measured, when the applied voltage changed from 0V to −25V, the tip of the piezoelectric element 20 was linearly displaced from 0 μm to −6.9 μm in proportion to the applied voltage.

  Further, as a result of performing an endurance test on the piezoelectric element 20 in a constant temperature and high humidity container having a temperature of 35 ° C. and a relative humidity of 80%, as in Example 1, the measurement was started, 1 hour later, 100 hours later. The leak current values after 200 hours and 0.3 nA were 0.3 nA, 0.8 nA, 3 nA, and 3 nA, respectively, and it was found that there was reliability equivalent to that of the piezoelectric element 20 of Example 1.

  Furthermore, when the appearance of the electrode film surface of the piezoelectric element 20 after the 200-hour durability test was observed with an optical microscope, changes such as cracks and coloring were not observed.

  Furthermore, when the piezoelectric element 20 after the 200-hour endurance test was driven by applying the same triangular wave voltage as before the endurance test and the relationship between the applied voltage and the displacement amount was confirmed, the same characteristics as before the endurance test were obtained. It was confirmed that there was no deterioration.

(Example 5)
In this example, the piezoelectric element 20 was manufactured in the same manner as in Example 1 except that the sputtering time in the film formation by sputtering of the piezoelectric thin film 3 (PZT thin film) was changed to 30 minutes.

The PZT thin film of the piezoelectric element 20 thus obtained was a perovskite type crystal structure film preferentially oriented to the (001) plane ((001) plane crystal orientation ratio 95%) as a result of analysis by X-ray diffraction. . Further, as a result of the composition analysis by the X-ray microanalyzer, x = 0.01 (that is, Pb _0.99 (Zr _0.53 Ti _0.47 ) O in Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ notation. ₃ ). Furthermore, as a result of scanning electron microscope observation, the thickness of the PZT thin film was 2.0 μm.

  Then, a triangular wave voltage having a maximum voltage of 0 V and a minimum voltage of −15 V is applied between the first electrode film 2 and the second electrode film 4 in the piezoelectric element 20, so When the displacement amount of the movement was measured, when the applied voltage changed from 0V to −15V, the tip of the piezoelectric element 20 was linearly displaced from 0 μm to −4.0 μm in proportion to the applied voltage.

  Further, as a result of performing an endurance test on the piezoelectric element 20 in a constant temperature and high humidity container having a temperature of 35 ° C. and a relative humidity of 80%, as in Example 1, the measurement was started, 1 hour later, 100 hours later. And the leakage current values after 200 hours were 0.5 nA, 2.2 nA, 5 nA and 5 nA, respectively, and it was found that the reliability was good.

  Furthermore, when the appearance of the electrode film surface of the piezoelectric element 20 after the 200-hour durability test was observed with an optical microscope, changes such as cracks and coloring were not observed.

  Furthermore, when the piezoelectric element 20 after the 200-hour endurance test was driven by applying the same triangular wave voltage as before the endurance test and the relationship between the applied voltage and the displacement amount was confirmed, the same characteristics as before the endurance test were obtained. It was confirmed that there was no deterioration.

(Example 6)
In this example, the piezoelectric element 20 was manufactured in the same manner as in Example 1 except that the sputtering time in the film formation by sputtering of the piezoelectric thin film 3 (PZT thin film) was changed to 85 minutes.

The PZT thin film of the piezoelectric element 20 thus obtained was a perovskite crystal structure film preferentially oriented to the (001) plane ((001) plane crystal orientation ratio of 96%) as a result of analysis by X-ray diffraction. . Further, as a result of the composition analysis by the X-ray microanalyzer, x = 0.01 (that is, Pb _0.99 (Zr _0.53 Ti _0.47 ) O in Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ notation. ₃ ). Furthermore, as a result of observation with a scanning electron microscope, the thickness of the PZT thin film was 6.0 μm.

  Then, a triangular wave voltage having a maximum voltage of 0 V and a minimum voltage of −40 V is applied between the first electrode film 2 and the second electrode film 4 in the piezoelectric element 20 so that the top and bottom of the piezoelectric element 20 are When the displacement amount of the motion was measured, when the applied voltage changed from 0V to −40V, the tip of the piezoelectric element 20 was linearly displaced from 0 μm to −11.6 μm in proportion to the applied voltage.

  Further, as a result of performing an endurance test on the piezoelectric element 20 in a constant temperature and high humidity container having a temperature of 35 ° C. and a relative humidity of 80%, as in Example 1, the measurement was started, 1 hour later, 100 hours later. And the leak current values after 200 hours were 0.3 nA, 1.0 nA, 3 nA and 3 nA, respectively, and it was found that the reliability was extremely good.

  Furthermore, when the appearance of the electrode film surface of the piezoelectric element 20 after the 200-hour durability test was observed with an optical microscope, changes such as cracks and coloring were not observed.

  Furthermore, when the piezoelectric element 20 after the 200-hour endurance test was driven by applying the same triangular wave voltage as before the endurance test and the relationship between the applied voltage and the displacement amount was confirmed, the same characteristics as before the endurance test were obtained. It was confirmed that there was no deterioration.

(Example 7)
In this example, the piezoelectric element 20 was fabricated in the same manner as in Example 1 except that the film formation method by sputtering of the piezoelectric thin film 3 (PZT thin film) was as follows.

  That is, in this embodiment, when forming a PZT thin film using an RF magnetron sputtering apparatus, a sintered body target (composition molar ratio Pb) composed of PZT having a 6-inch diameter and Pb excess than the stoichiometric composition is used as a target. : Zr: Ti = 1.20: 0.53: 0.47). Then, in the film forming chamber to which the PZT target is attached, the silicon substrate on which the first electrode film 2 (iridium alloy thin film) is formed is attached to the metal substrate holder, and the ground wire is attached to the substrate holder. To ground potential. As a result, the silicon substrate on which the PZT thin film was formed was brought into the same potential as the ground potential. Subsequently, the silicon substrate is heated and held in advance at a temperature of 560 ° C., a mixed gas of argon and oxygen is used as the sputtering gas, the mixing ratio is argon: oxygen = 79: 1, and the flow rate is 40 ml / min. A PZT thin film was formed for 50 minutes at a sputtering gas pressure of 0.30 Pa and a plasma generation power of 3 kW.

The PZT thin film of the piezoelectric element 20 thus fabricated is a perovskite crystal structure film preferentially oriented on the (001) plane ((001) plane crystal orientation ratio 90%) as a result of analysis by X-ray diffraction. there were. Further, as a result of the composition analysis by the X-ray microanalyzer, x = 0.08 (that is, Pb _0.92 (Zr _0.53 Ti _0.47 ) O in Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ notation. ₃ ). Furthermore, as a result of observation with a scanning electron microscope, the thickness of the PZT thin film was 3.2 μm.

  Then, a triangular wave voltage having a maximum voltage of 0 V and a minimum voltage of −25 V is applied between the first electrode film 2 and the second electrode film 4 in the piezoelectric element 20 so that the top and bottom of the piezoelectric element 20 are When the displacement amount of the movement was measured, when the applied voltage changed from 0V to −25V, the tip of the piezoelectric element 20 was linearly displaced from 0 μm to −6.5 μm in proportion to the applied voltage.

  Further, as a result of performing an endurance test on the piezoelectric element 20 in a constant temperature and high humidity container having a temperature of 35 ° C. and a relative humidity of 80%, as in Example 1, the measurement was started, 1 hour later, 100 hours later. And the leakage current values after 200 hours were 0.3 nA, 0.9 nA, 2 nA and 2 nA, respectively, and it was found that the reliability was extremely good.

  Furthermore, when the appearance of the electrode film surface of the piezoelectric element 20 after the 200-hour durability test was observed with an optical microscope, changes such as cracks and coloring were not observed.

  Furthermore, when the piezoelectric element 20 after the 200-hour endurance test was driven by applying the same triangular wave voltage as before the endurance test and the relationship between the applied voltage and the displacement amount was confirmed, the same characteristics as before the endurance test were obtained. It was confirmed that there was no deterioration.

(Example 8)
In this example, the substrate 1 was changed to a Pyrex glass substrate (Corning # 7059), and the others were produced in the same manner as in Example 7 described above.

The piezoelectric thin film 3 (PZT thin film) of the piezoelectric element 20 thus obtained is a perovskite type that is preferentially oriented to the (001) plane (92% (001) plane crystal orientation) as a result of analysis by X-ray diffraction. It was a crystal structure film. Further, as a result of the composition analysis by the X-ray microanalyzer, x = 0.08 (that is, Pb _0.92 (Zr _0.53 Ti _0.47 ) O in Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ notation. ₃ ). Furthermore, as a result of observation with a scanning electron microscope, the thickness of the PZT thin film was 3.3 μm.

  Then, a triangular wave voltage having a maximum voltage of 0 V and a minimum voltage of −25 V is applied between the first electrode film 2 and the second electrode film 4 in the piezoelectric element 20 so that the top and bottom of the piezoelectric element 20 are When the displacement amount of the motion was measured, when the applied voltage changed from 0V to −25V, the tip of the piezoelectric element 20 was linearly displaced from 0 μm to −9.3 μm in proportion to the applied voltage.

  Further, as a result of performing an endurance test on the piezoelectric element 20 in a constant temperature and high humidity container having a temperature of 35 ° C. and a relative humidity of 80%, as in Example 1, the measurement was started, 1 hour later, 100 hours later. And the leak current values after 200 hours were 0.3 nA, 0.8 nA, 2 nA and 2 nA, respectively, and it was found that the reliability was very good.

  Furthermore, when the appearance of the electrode film surface of the piezoelectric element 20 after the 200-hour durability test was observed with an optical microscope, changes such as cracks and coloring were not observed.

  Furthermore, when the piezoelectric element 20 after the 200-hour endurance test was driven by applying the same triangular wave voltage as before the endurance test and the relationship between the applied voltage and the displacement amount was confirmed, the same characteristics as before the endurance test were obtained. It was confirmed that there was no deterioration.

Example 9
In this example, the substrate 1 was changed to a mirror-polished alumina sintered body substrate made of a ceramic material, and the others were the same as in Example 7 to produce the piezoelectric element 20.

The piezoelectric thin film 3 (PZT thin film) of the piezoelectric element 20 thus obtained is a perovskite type that is preferentially oriented to the (001) plane (92% (001) plane crystal orientation) as a result of analysis by X-ray diffraction. It was a crystal structure film. Further, as a result of the composition analysis by the X-ray microanalyzer, x = 0.08 (that is, Pb _0.92 (Zr _0.53 Ti _0.47 ) O in Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ notation. ₃ ). Furthermore, as a result of observation with a scanning electron microscope, the thickness of the PZT thin film was 3.2 μm.

  Then, a triangular wave voltage having a maximum voltage of 0 V and a minimum voltage of −25 V is applied between the first electrode film 2 and the second electrode film 4 in the piezoelectric element 20 so that the top and bottom of the piezoelectric element 20 are When the displacement amount of the motion was measured, when the applied voltage changed from 0V to −25V, the tip of the piezoelectric element 20 was linearly displaced from 0 μm to −5.0 μm in proportion to the applied voltage.

  Further, as a result of performing an endurance test on the piezoelectric element 20 in a constant temperature and high humidity container having a temperature of 35 ° C. and a relative humidity of 80%, as in Example 1, the measurement was started, 1 hour later, 100 hours later. And the leak current values after 200 hours were 0.3 nA, 0.8 nA, 2 nA and 2 nA, respectively, and it was found that the reliability was very good.

  Furthermore, when the appearance of the electrode film surface of the piezoelectric element 20 after the 200-hour durability test was observed with an optical microscope, changes such as cracks and coloring were not observed.

  Furthermore, when the piezoelectric element 20 after the 200-hour endurance test was driven by applying the same triangular wave voltage as before the endurance test and the relationship between the applied voltage and the displacement amount was confirmed, the same characteristics as before the endurance test were obtained. It was confirmed that there was no deterioration.

(Example 10)
In this embodiment, the piezoelectric thin film 3 is a PZT-based oxide in which La, Sr, Mg, and Nb are added to PZT, and a Lat is used as a sputtering target when the piezoelectric thin film 3 (PZT-based oxide) is formed. A piezoelectric element 20 was fabricated in the same manner as in Example 2 except that a PZT oxide sintered body target (6 inch diameter) having a stoichiometric composition to which Sr, Mg, and Nb were added. . The target has a chemical composition of (Pb _0.94 La _0.01 Sr _0.05 ) (Zr _0.50 Ti _0.46 Mg _0.02 Nb _0.02 ) O ₃ .

The PZT-based oxide thin film of the piezoelectric element 20 obtained in this manner is a perovskite-type crystal structure film that is preferentially oriented on the (001) plane ((001) plane crystal orientation ratio 89%) as a result of analysis by the X-ray diffraction method. Met. In addition, as a result of compositional analysis by an X-ray microanalyzer, (Pb _(1-xy) A _y ) (Zr _(1-st) Ti _s B _t ) O ₃ notation (A is added to the A site of the perovskite crystal structure) It is a metal ion, B is an added metal ion that enters the B site of the perovskite crystal structure, and x = 0.03 (that is, (Pb _0.91 La _0.01 Sr _0.05 ) (Zr _0.50 Ti _0.46 Mg _0.02 Nb _0.02 ) O ₃ ). Furthermore, as a result of observation with a scanning electron microscope, the thickness of the PZT-based oxide thin film was 3.4 μm.

  Then, a triangular wave voltage having a maximum voltage of 0 V and a minimum voltage of −25 V is applied between the first electrode film 2 and the second electrode film 4 in the piezoelectric element 20, so When the displacement amount of the movement was measured, when the applied voltage changed from 0 V to −25 V, the tip of the piezoelectric element 20 was linearly displaced from 0 μm to −8.5 μm in proportion to the applied voltage.

  Further, as a result of performing an endurance test on the piezoelectric element 20 in a constant temperature and high humidity container having a temperature of 35 ° C. and a relative humidity of 80%, as in Example 1, the measurement was started, 1 hour later, 100 hours later. The leakage current values after 200 hours and 200 hours were 0.4 nA, 1.2 nA, 5 nA, and 5 nA, respectively, and it was found that the reliability was good.

  Furthermore, when the appearance of the electrode film surface of the piezoelectric element 20 after the 200-hour durability test was observed with an optical microscope, changes such as cracks and coloring were not observed.

  Furthermore, when the piezoelectric element 20 after the 200-hour endurance test was driven by applying the same triangular wave voltage as before the endurance test and the relationship between the applied voltage and the displacement amount was confirmed, the same characteristics as before the endurance test were obtained. It was confirmed that there was no deterioration.

(Example 11)
In this embodiment, the piezoelectric thin film 3 is a PZT-based oxide in which Ca, Ni, Mn and Nb are added to PZT, and the sputtering target when this piezoelectric thin film 3 (PZT-based oxide) is formed is Ca. A piezoelectric element 20 was fabricated in the same manner as in Example 2 except that a sintered target (6 inch diameter) of PZT oxide having a stoichiometric composition to which Ni, Mn, and Nb were added was used. . The target has a chemical composition of (Pb _0.98 Ca _0.02 ) (Zr _0.50 Ti _0.46 Ni _0.01 Mn _0.01 Nb _0.02 ) O ₃ .

The PZT-based oxide thin film of the piezoelectric element 20 obtained in this way is a perovskite type crystal structure film that is preferentially oriented on the (001) plane (85% (001) plane crystal orientation ratio) as a result of analysis by X-ray diffraction method. Met. In addition, as a result of compositional analysis by an X-ray microanalyzer, (Pb _(1-xy) A _y ) (Zr _(1-st) Ti _s B _t ) O ₃ notation (A is added to the A site of the perovskite crystal structure) It is a metal ion, B is an added metal ion that enters the B site of the perovskite crystal structure, and x = 0.02 (that is, (Pb _0.96 Ca _0.02 ) (Zr _0.50 Ti _0.46 Ni _0.01 Mn _0.01 Nb _0.02 )) O ₃ ). Furthermore, as a result of observation with a scanning electron microscope, the thickness of the PZT-based oxide thin film was 3.3 μm.

  Then, a triangular wave voltage having a maximum voltage of 0 V and a minimum voltage of −25 V is applied between the first electrode film 2 and the second electrode film 4 in the piezoelectric element 20 so that the top and bottom of the piezoelectric element 20 are When the displacement amount of the movement was measured, when the applied voltage changed from 0V to −25V, the tip of the piezoelectric element 20 was linearly displaced from 0 μm to −8.2 μm in proportion to the applied voltage.

  Further, as a result of performing an endurance test on the piezoelectric element 20 in a constant temperature and high humidity container having a temperature of 35 ° C. and a relative humidity of 80%, as in Example 1, the measurement was started, 1 hour later, 100 hours later. The leakage current values after 200 hours and 200 hours were 0.4 nA, 1.2 nA, 5 nA, and 5 nA, respectively, and it was found that the reliability was good.

  Furthermore, when the appearance of the electrode film surface of the piezoelectric element 20 after the 200-hour durability test was observed with an optical microscope, changes such as cracks and coloring were not observed.

  Furthermore, when the piezoelectric element 20 after the 200-hour endurance test was driven by applying the same triangular wave voltage as before the endurance test and the relationship between the applied voltage and the displacement amount was confirmed, the same characteristics as before the endurance test were obtained. It was confirmed that there was no deterioration.

(Example 12)
In this embodiment, the piezoelectric thin film 3 is a PZT-based oxide in which Bi, Fe, and Nb are added to PZT, and Bi, Fe are used as sputtering targets when the piezoelectric thin film 3 (PZT-based oxide) is formed. A piezoelectric element 20 was manufactured in the same manner as in Example 7 except that a PZT oxide sintered body target (6 inch diameter) having a stoichiometric composition to which Nb was added. The target has a chemical composition of (Pb _0.99 Bi _0.01 ) (Zr _0.50 Ti _0.46 Fe _0.02 Nb _0.02 ) O ₃ .

As a result of analysis by the X-ray diffraction method, the PZT-based oxide thin film of the piezoelectric element 20 obtained in this way has a perovskite crystal structure film preferentially oriented on the (001) plane ((001) plane crystal orientation ratio 93%). Met. In addition, as a result of compositional analysis by an X-ray microanalyzer, (Pb _(1-xy) A _y ) (Zr _(1-st) Ti _s B _t ) O ₃ notation (A is added to the A site of the perovskite crystal structure) It is a metal ion, B is an added metal ion that enters the B site of the perovskite crystal structure, and x = 0.08 (that is, (Pb _0.91 Bi _0.01 ) (Zr _0.50 Ti _0.46 Fe _0.02 Nb _0.02 ) O ₃ )Met. Furthermore, as a result of observation with a scanning electron microscope, the thickness of the PZT-based oxide thin film was 3.4 μm.

  Then, a triangular wave voltage having a maximum voltage of 0 V and a minimum voltage of −25 V is applied between the first electrode film 2 and the second electrode film 4 in the piezoelectric element 20 so that the top and bottom of the piezoelectric element 20 are When the displacement amount of the motion was measured, when the applied voltage changed from 0V to −25V, the tip of the piezoelectric element 20 was linearly displaced from 0 μm to −8.4 μm in proportion to the applied voltage.

  Further, as a result of performing an endurance test on the piezoelectric element 20 in a constant temperature and high humidity container having a temperature of 35 ° C. and a relative humidity of 80%, as in Example 1, the measurement was started, 1 hour later, 100 hours later. The leakage current values after 200 hours and 200 hours were 1.0 nA, 3.2 nA, 6 nA, and 6 nA, respectively, and it was found that the reliability was good.

  Furthermore, when the appearance of the electrode film surface of the piezoelectric element 20 after the 200-hour durability test was observed with an optical microscope, changes such as cracks and coloring were not observed.

  Furthermore, when the piezoelectric element 20 after the 200-hour endurance test was driven by applying the same triangular wave voltage as before the endurance test and the relationship between the applied voltage and the displacement amount was confirmed, the same characteristics as before the endurance test were obtained. It was confirmed that there was no deterioration.

(Example 13)
In this example, the piezoelectric element 20 was fabricated in the same manner as in Example 1 except that the film formation method by sputtering of the piezoelectric thin film 3 (PZT thin film) was as follows.

  That is, in this example, when a PZT thin film is formed using an RF magnetron sputtering apparatus, a 6-inch diameter sintered body target (composition molar ratio Pb) composed of PZT having a Pb excess over the stoichiometric composition as a target. : Zr: Ti = 1.20: 0.53: 0.47). In the film forming chamber to which the PZT target is attached, the silicon substrate on which the first electrode film 2 (iridium alloy thin film) is formed is attached to a metal substrate holder, and one end of a lead wire is attached to the substrate holder. The other end of the lead wire was connected to a DC power source, and a negative bias voltage of −200 V with respect to the ground potential was applied to the substrate holder (that is, the silicon substrate) by the DC power source. As a result, the silicon substrate on which the PZT thin film was formed was held at a potential state of −200 V with respect to the ground potential. Subsequently, the silicon substrate is heated and held in advance at a temperature of 560 ° C., a mixed gas of argon and oxygen is used as the sputtering gas, the mixing ratio is argon: oxygen = 79: 1, and the flow rate is 40 ml per minute, The sputtering gas pressure was 0.30 Pa, the plasma generation power was 3 kW, and a PZT thin film was formed for 50 minutes.

The PZT thin film of the piezoelectric element 20 thus fabricated is a perovskite type crystal structure film preferentially oriented on the (001) plane ((001) plane crystal orientation ratio of 96%) as a result of analysis by X-ray diffraction. there were. Further, as a result of the composition analysis by the X-ray microanalyzer, x = 0.13 (that is, Pb _0.87 (Zr _0.53 Ti _0.47 ) O in Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ notation. ₃ ). Furthermore, as a result of observation with a scanning electron microscope, the thickness of the PZT thin film was 3.1 μm.

  Then, a triangular wave voltage having a maximum voltage of 0 V and a minimum voltage of −25 V is applied between the first electrode film 2 and the second electrode film 4 in the piezoelectric element 20 so that the top and bottom of the piezoelectric element 20 are When the displacement amount of the movement was measured, when the applied voltage changed from 0 V to −25 V, the tip of the piezoelectric element 20 was linearly displaced from 0 μm to −6.2 μm in proportion to the applied voltage.

  Further, as a result of performing an endurance test on the piezoelectric element 20 in a constant temperature and high humidity container having a temperature of 35 ° C. and a relative humidity of 80%, as in Example 1, the measurement was started, 1 hour later, 100 hours later. And the leak current values after 200 hours were 0.3 nA, 0.8 nA, 2 nA and 2 nA, respectively, and it was found that the reliability was very good.

  Furthermore, when the appearance of the electrode film surface of the piezoelectric element 20 after the 200-hour durability test was observed with an optical microscope, changes such as cracks and coloring were not observed.

  Furthermore, when the piezoelectric element 20 after the 200-hour endurance test was driven by applying the same triangular wave voltage as before the endurance test and the relationship between the applied voltage and the displacement amount was confirmed, the same characteristics as before the endurance test were obtained. It was confirmed that there was no deterioration.

(Example 14)
In this embodiment, the piezoelectric body is the same as in Embodiment 13 except that the negative bias voltage applied to the substrate during sputtering film formation of the piezoelectric thin film 3 (PZT thin film) is changed to −300V. Element 20 was produced.

The PZT thin film of the piezoelectric element 20 thus fabricated is a perovskite type crystal structure film preferentially oriented to the (001) plane ((001) plane crystal orientation ratio 97%) as a result of analysis by X-ray diffraction. there were. Further, as a result of the composition analysis by the X-ray microanalyzer, x = 0.15 (that is, Pb _0.85 (Zr _0.53 Ti _0.47 ) O in Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ notation. ₃ ). Furthermore, as a result of observation with a scanning electron microscope, the thickness of the PZT thin film was 2.9 μm.

  Then, a triangular wave voltage having a maximum voltage of 0 V and a minimum voltage of −25 V is applied between the first electrode film 2 and the second electrode film 4 in the piezoelectric element 20 so that the top and bottom of the piezoelectric element 20 are When the displacement amount of the movement was measured, when the applied voltage changed from 0 V to −25 V, the tip of the piezoelectric element 20 was linearly displaced from 0 μm to −6.4 μm in proportion to the applied voltage.

  Further, as a result of performing an endurance test on the piezoelectric element 20 in a constant temperature and high humidity container having a temperature of 35 ° C. and a relative humidity of 80%, as in Example 1, the measurement was started, 1 hour later, 100 hours later. And the leak current values after 200 hours were 0.3 nA, 0.8 nA, 2 nA and 2 nA, respectively, and it was found that the reliability was very good.

  Furthermore, when the appearance of the electrode film surface of the piezoelectric element 20 after the 200-hour durability test was observed with an optical microscope, changes such as cracks and coloring were not observed.

  Furthermore, when the piezoelectric element 20 after the 200-hour endurance test was driven by applying the same triangular wave voltage as before the endurance test and the relationship between the applied voltage and the displacement amount was confirmed, the same characteristics as before the endurance test were obtained. It was confirmed that there was no deterioration.

(Comparative Example 1)
Here, for comparison, a piezoelectric element including a piezoelectric thin film made of PZT having a Pb composition in excess of the stoichiometric composition was produced. That is, a PZT sintered body target having a composition (Pb excess composition) in a molar ratio of Pb: Zr: Ti = 1.20: 0.53: 0.47 is used as a sputtering target when forming a piezoelectric thin film (PZT thin film). A piezoelectric element was fabricated in the same manner as in Example 1 except that sputtering time was 50 minutes.

The PZT thin film of the piezoelectric element thus obtained was a perovskite type crystal structure film preferentially oriented to the (001) plane ((001) plane crystal orientation ratio 99%) as a result of analysis by X-ray diffraction. Further, as a result of the composition analysis by the X-ray microanalyzer, x = −0.10 (that is, Pb _1.1 (Zr _0.53 Ti _0.47 )) in Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ notation. O ₃ ). Furthermore, as a result of observation with a scanning electron microscope, the thickness of the PZT thin film was 3.8 μm.

  Then, a triangular wave voltage having a maximum voltage of 0 V and a minimum voltage of −25 V is applied between the first electrode film and the second electrode film in the piezoelectric element, and the displacement amount of the vertical movement of the tip of the piezoelectric element. When the applied voltage was changed from 0 V to −25 V, the tip of the piezoelectric element was linearly displaced from 0 μm to −8.7 μm in proportion to the applied voltage.

  Further, as a result of performing an endurance test on the piezoelectric element in a constant temperature and high humidity container at a temperature of 35 ° C. and a relative humidity of 80% as in Example 1, the leak current value at the start of measurement was 0.5 nA. However, in the measurement after 1 hour, the leak current value was 10000 nA (= 10 mA), and after 100 hours, it showed 100 mA or more and the insulation was broken.

  Furthermore, when the appearance of the electrode film surface of the piezoelectric element after the 100-hour durability test was observed with an optical microscope, the entire surface was colored black, and numerous indentations were observed in the black colored portion. It was. Further, the piezoelectric element after the 100-hour endurance test could not be subjected to a driving test because of a large current leak as described above.

(Comparative Example 2)
In Comparative Example 2, a piezoelectric element was fabricated in the same manner as in Example 1 except that the sputtering gas pressure was changed to 0.2 Pa for the film forming conditions by sputtering when forming the piezoelectric thin film (PZT thin film). did.

The PZT thin film of the piezoelectric element thus obtained was a perovskite type crystal structure film preferentially oriented to the (001) plane ((001) plane crystal orientation ratio 97%) as a result of analysis by X-ray diffraction. Further, as a result of the composition analysis by the X-ray microanalyzer, x = 0.00 (that is, Pb _1.00 (Zr _0.53 Ti _0.47 ) O in Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ notation. ₃ ). Further, as a result of observation with a scanning electron microscope, the thickness of the PZT thin film was 3.5 μm.

  Then, a triangular wave voltage having a maximum voltage of 0 V and a minimum voltage of −25 V is applied between the first electrode film and the second electrode film in the piezoelectric element, and the displacement amount of the vertical movement of the tip of the piezoelectric element. When the applied voltage was changed from 0 V to −25 V, the tip of the piezoelectric element was linearly displaced from 0 μm to −7.6 μm in proportion to the applied voltage.

  Further, as a result of performing an endurance test on the piezoelectric element in a constant temperature and high humidity container at a temperature of 35 ° C. and a relative humidity of 80% as in Example 1, the leak current value at the start of measurement was 0.5 nA. However, in the measurement after 1 hour, the leakage current value was 10000 nA (= 10 mA), and after 100 hours, it showed 100 mA or more and the insulation was broken.

  Furthermore, when the appearance of the electrode film surface of the piezoelectric element after the 100-hour endurance test was observed with an optical microscope, the entire surface was colored black as in Comparative Example 1, and the black coloring was observed. Innumerable recesses were observed in the part. Further, the piezoelectric element after the 100-hour endurance test could not be subjected to a driving test because of a large current leak as described above.

  Therefore, the dielectric breakdown does not occur and high reliability is obtained by making the amount of lead of the piezoelectric thin film 3 smaller than the stoichiometric composition as in Examples 1 to 14 (0 <x ≦ 0.15). I understand that.

  In the present embodiment and examples, the substrate 1 is used as both a film formation substrate and a vibration plate. However, the film formation substrate and the vibration plate may be provided separately. In this case, the first electrode film 2 is formed on the substrate 1, the piezoelectric thin film 3 is formed on the first electrode film 2, and the second electrode film 4 is formed on the piezoelectric thin film 3. (The laminated body 10 is formed on the substrate 1), a vibration plate is formed on the second electrode film 4, and the substrate 1 is removed after all of these films are formed. Thus, the diaphragm is disposed on the surface of the laminate 10 on the second electrode film 4 side.

(Embodiment 2)
Next, an ink jet head using the laminated film configuration of the piezoelectric element of the present invention will be described.

  FIG. 4 is a schematic configuration diagram illustrating the inkjet head 201 according to the embodiment of the present invention. As shown in FIG. 4, the inkjet head 201 of the present embodiment includes a plurality of (10 in FIG. 10) ink ejection elements 202 having the same shape arranged in a line, and the ink ejection elements 202. And a driving power source element 203 such as an IC chip for driving the IC.

  FIG. 5 is an exploded perspective view, partly broken away, showing the configuration of each of the ink ejection elements 202 described above. In FIG. 5, A is a pressure chamber member made of glass, and a pressure chamber opening 31 is formed in the pressure chamber member A. B is an actuator portion arranged so as to cover the upper end opening surface of the pressure chamber opening 31 (size: an ellipse having a minor axis of 200 μm and a major axis of 400 μm), and C is the pressure chamber opening 31. It is an ink flow path member arranged so as to cover the lower end opening surface. That is, the pressure chamber opening 31 of the pressure chamber member A is partitioned by the actuator portion B and the ink flow path member C positioned above and below, thereby forming the pressure chamber 32 (depth 0.2 mm). Yes.

  The actuator part B has a first electrode film 33 (individual electrode) located almost directly above the pressure chamber 32. The ink flow path member C is connected to the common liquid chamber 35 shared between the pressure chambers 32 of the plurality of ink ejection elements 202 arranged in the ink supply direction, and the common liquid chamber 35 is communicated with the pressure chamber 32. A supply port 36 for supplying the ink in the common liquid chamber 35 to the pressure chamber 32 and an ink flow path 37 for discharging the ink in the pressure chamber 32 are formed. Further, D is a nozzle plate, and this nozzle plate D is provided with a nozzle 38 (nozzle hole having a diameter of 30 μm) communicating with the pressure chamber 32 via the ink flow path 37. Then, the pressure chamber member A, the actuator portion B, the ink flow path member C, and the nozzle plate D are bonded to each other with an adhesive to constitute the ink ejection element 202.

  In this embodiment, the pressure chamber member A, the actuator portion B (excluding the first electrode film 33 and the piezoelectric thin film 41 (see FIG. 6)), the ink flow path member C, and the nozzle plate D are all ejected from the ink. A portion formed integrally with the element 202 includes a pressure chamber 32 and a nozzle 38, a first electrode film 33, and a piezoelectric thin film 41 provided corresponding to the pressure chamber 32. The ink ejection element 202 is used. In addition, each ink discharge element 202 may be formed separately, and they may be combined and arranged. Further, the inkjet head 201 does not need to be composed of a plurality of ink ejection elements 202, and may be composed of a single ink ejection element 202.

  The drive power supply element 203 is connected to each first electrode film 33 of the actuator portion B of the plurality of ink ejection elements 202 via bonding wires, and the first electrode film 33 is connected from the drive power supply element 203 to each first electrode film 33. To supply voltage.

  Next, the configuration of the actuator part B will be described with reference to FIG. 6 is a cross-sectional view taken along line VI-VI of the actuator portion B of the ink ejection element 202 shown in FIG. As shown in FIG. 6, the actuator portion B includes a first electrode film 33 positioned substantially directly above each pressure chamber 32 as described above, and on each first electrode film 33 (in FIG. And the second electrode film 42 (provided on the piezoelectric thin film 41 (on the lower side) and common to all the piezoelectric thin films 41 (all ink ejection elements 202)). And a diaphragm 43 (in this embodiment, a diaphragm) that is provided over the second electrode film 42 (on the lower side thereof) and is displaced in the thickness direction by the piezoelectric effect of the piezoelectric thin film 41 and vibrates. Film). Similarly to the second electrode film 42, the vibration plate 43 is also shared between the pressure chambers 32 of the respective ink ejection elements 202 (is integrally formed over all the ink ejection elements 202).

  The first electrode film 33, the piezoelectric thin film 41, and the second electrode film 42 constitute a laminated body in which these are laminated in order, and this laminated body and one side in the laminating direction of the laminated body (second The vibration plate 43 disposed on the surface of the electrode film 42) constitutes a piezoelectric element (piezoelectric actuator).

  As in the first embodiment, the first electrode film 33 is an iridium alloy thin film having a thickness of 0.10 μm and containing 6 mol% of cobalt (Co). In the present embodiment as well, the first electrode film 33 may be made of any metal, but when the piezoelectric thin film 41 is formed on the first electrode film 33 as will be described later. In order to control the crystal orientation of the piezoelectric thin film 41 satisfactorily, titanium (Ti), aluminum (Al), iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), copper (Cu), magnesium (Mg), calcium (Ca), strontium (St), barium (Ba) and a noble metal to which at least one additive selected from the group of these oxides is added. Is preferred.

In the present embodiment, the piezoelectric thin film 41 is a PZT thin film represented by Pb _0.97 (Zr _0.53 Ti _0.47 ) O ₃ . As described in the first embodiment, the piezoelectric thin film 41 is an oxide having a perovskite crystal structure and has a chemical composition formula:
Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ (0 <s <1)
PZT represented by or
_{(Pb (1-xy) A} y) (Zr (1-st) Ti s B t) O 3 (0 <s <1,0 <t <1-s)
The value of x indicating the Pb composition deficiency from the stoichiometric composition in the chemical composition formula of the above lead zirconate titanate and lead zirconate titanate oxides. However, it should just be over 0 and 0.15 or less (preferably 0.03 or more and 0.15 or less).

  A in the chemical composition formula of the lead zirconate titanate-based oxide is at least one metal selected from the group consisting of lanthanum (La), strontium (Sr), bismuth (Bi), and calcium (Ca). Preferably, B in the chemical composition formula is at least one selected from the group consisting of niobium (Nb), magnesium (Mg), nickel (Ni), manganese (Mn), and iron (Fe). A metal ion is preferred.

  Furthermore, the piezoelectric thin film 41 is preferably preferentially oriented in the (001) plane (in this embodiment, the (001) plane crystal orientation ratio is 96%), and the thickness of the piezoelectric thin film 41 is 2 μm or more. It is preferably 6 μm or less (in this embodiment, 5 μm).

  The second electrode film 42 is a platinum thin film having a thickness of 0.15 μm. In the present embodiment, the second electrode film 42 may be made of any metal.

  In the present embodiment, the diaphragm 43 is made of a chromium (Cr) film having a thickness of 3.5 μm. The material of the diaphragm 43 is not limited to Cr, but may be a metal material such as nickel, silicon, or glass or a ceramic material.

  Around the first electrode film 33 and the piezoelectric thin film 41 on the second electrode film 42, an electrically insulating organic material made of polyimide resin so that the upper surface is substantially the same as the height of the first electrode film 33. A lead electrode-shaped gold thin film (film thickness: 0.1 μm) extending from the first electrode film 33 is formed on the upper surface of the electrically insulating organic film 44. .

  Next, a method for manufacturing the inkjet head 201 will be described with reference to FIG.

  That is, first, as shown in FIG. 7A, a silicon substrate 51 having a length of 20 mm, a width of 20 mm, and a thickness of 0.3 mm is used to form a silicon substrate 51 on the silicon substrate 51 in the same manner as in Example 3 of the first embodiment. The first electrode film 33, the piezoelectric thin film 41, and the second electrode film 42 are sequentially stacked to obtain a structure 54.

  Subsequently, as shown in FIG. 7B, a diaphragm 43 made of a chromium film is formed on the second electrode film 42 of the structure 54 by using an RF sputtering method at room temperature.

  Next, as shown in FIG. 7C, the structure 54 on which the diaphragm 43 is formed is joined to the pressure chamber member A using an adhesive (acrylic resin) 55. That is, the pressure chamber member A in which the pressure chamber opening 31 is formed in advance is bonded to the surface of the diaphragm 43 opposite to the second electrode film 42.

Thereafter, as shown in FIG. 7D, the silicon substrate 51 is removed by dry etching using SF ₆ gas using a plasma reaction etching apparatus.

  Next, as shown in FIG. 7E, in order to pattern the first electrode film 33 and the piezoelectric thin film 41 into an elliptical pattern (size: an elliptical shape having a minor axis of 180 μm and a major axis of 380 μm). A photoresist resin film 57 is applied to the non-etched portion on the first electrode film 33.

  Then, as shown in FIG. 7F, the first electrode film 33 and the piezoelectric thin film 41 are patterned by performing an etching process using dry etching of Ar gas and wet etching of weak hydrofluoric acid. After that, as shown in FIG. 7G, the photoresist resin film 57 is removed by processing with a resist stripping solution.

  Subsequently, as shown in FIG. 7 (h), an electrically insulating organic film 44 made of polyimide resin is formed on the second electrode film 42 exposed by the above patterning by a printing method. As shown in i), a lead wire-shaped lead electrode film 45 made of a gold thin film is formed on the upper surface of the electrically insulating organic film 44 by DC sputtering, whereby the actuator part B is completed.

  On the other hand, although not shown, the ink flow path member C in which the common liquid chamber 35, the supply port 36, and the ink flow path 37 are formed in advance and the nozzle plate D in which the nozzle holes 38 are formed in advance are bonded using an adhesive. Keep it. Then, alignment adjustment of the pressure chamber member A joined to the completed actuator part B and the ink flow path member C to which the nozzle plate D is bonded is performed, and both are bonded by an adhesive. Thus, the inkjet head 201 is completed.

  In the inkjet head 201 configured as described above, a voltage is supplied from the drive power supply element 203 to each of the first electrode films 33 of the plurality of ink ejection elements 202 via the bonding wires, and the piezoelectric effect of the piezoelectric thin film 41 is achieved. When the diaphragm 43 joined to the second electrode film 42, which is a common electrode, is displaced in the thickness direction and vibrates, the volume of the pressure chamber 32 increases or decreases, and when the volume of the pressure chamber 32 decreases, the pressure chamber While the ink in the liquid 32 is ejected from the nozzle 38 via the ink flow path 37, the ink in the common liquid chamber 35 is supplied to the pressure chamber 32 through the supply port 36 when the volume of the pressure chamber 32 increases. The In this case, in the inkjet head 201, the piezoelectric thin film 41 constituting the actuator portion B of the ink ejection element 202 has a lead amount smaller than the stoichiometric composition, so that even when a voltage is applied in a high humidity environment, Does not cause deterioration of electrical insulation. As a result, even when driven by applying a high voltage, failure due to deterioration of electrical insulation is unlikely to occur, and as a result, piezoelectric displacement is less likely to be reduced, and highly reliable and stable driving is possible. Since the amount of piezoelectric displacement directly affects the ink discharge capability, it is easily controlled by adjusting the power supply voltage so that the variation in discharge of individual ink liquids of the plurality of ink discharge elements 202 is reduced. be able to.

  Here, the inkjet head 201 having 30 ink ejection elements 202 having the same shape is actually manufactured by the above manufacturing method, and two electrodes sandwiching the piezoelectric thin film 41 in a high humidity environment of 35 ° C. and 80%. When the diaphragms 43 are vibrated 1 billion times by applying a sine waveform voltage (200 Hz) having a maximum voltage of 0 V and a minimum voltage of −25 V to the films 33 and 42, occurrence of defects is observed in all the ink ejection elements 202. I couldn't.

  In the present embodiment, the substrate 51 is used only as a film formation substrate and is removed after the film formation. However, the pressure chamber member A can also be used as the film formation substrate. In this case, the diaphragm 43, the first electrode film 33 (corresponding to the common electrode), the piezoelectric thin film 41, and the second electrode film 42 (on the pressure chamber member A in which the pressure chamber opening 31 is not formed) The pressure chamber openings 31 may be formed in the pressure chamber member A after the film formation. In this way, the diaphragm 43 is disposed on the surface of the laminated body on the first electrode film 33 side.

(Embodiment 3)
FIG. 8 shows an ink jet recording apparatus 81 according to an embodiment of the present invention, and the ink jet recording apparatus 81 includes the ink jet head 201 described in the second embodiment. In the inkjet head 201, recording is performed by ejecting ink in the pressure chamber 32 from a nozzle 38 provided to communicate with the pressure chamber 32 and landing on the recording medium 82 (recording paper or the like). ing.

  The inkjet head 201 is mounted on a carriage 84 that is slidably provided on a carriage shaft 83 that extends in the main scanning direction (the X direction shown in FIG. 8). The carriage 84 reciprocates along the carriage shaft 83. In response to this, it is configured to reciprocate in the main scanning direction X. Thus, the carriage 84 constitutes a relative movement unit that relatively moves the inkjet head 201 and the recording medium 82 and also constitutes a head transfer unit that reciprocates the inkjet head 201 in a predetermined direction (main scanning direction X). It will be.

  In addition, the ink jet recording apparatus 81 includes a plurality of rollers 85 that move the recording medium 82 in the sub scanning direction (Y direction shown in FIG. 8) substantially perpendicular to the main scanning direction X of the ink jet head 201. . Accordingly, the plurality of rollers 85 constitute a relative movement unit that relatively moves the inkjet head 201 and the recording medium 82, and transfers the recording medium 82 in a direction (sub-scanning direction Y) substantially perpendicular to the predetermined direction. The recording medium transporting means to be configured is configured. In FIG. 8, Z is the vertical direction.

  When the ink jet head 201 is moved in the main scanning direction X by the carriage 84, ink is ejected from the nozzles 38 of the ink jet head 201 to the recording medium 82. The recording medium 82 is moved by a predetermined amount to perform the next one-scan recording.

  As described above, the ink jet recording apparatus 81 uses the ink jet head 201 with high environmental reliability of the second embodiment that can easily control the ink discharge variation among the plurality of ink discharge elements 202. By configuring as described above, it is possible to reduce variations in recording on the recording medium 82 such as paper and to improve reliability.

(Embodiment 4)
FIG. 9 shows another ink jet recording apparatus 91 according to the embodiment of the present invention. The ink jet recording apparatus 91 includes a plurality of ink jet heads 201 (13 in this embodiment) described in the second embodiment. The plurality of inkjet heads 201 are connected to each other in a state in which they are arranged in a predetermined direction (X direction in FIG. 9) to form a line head 86 including an inkjet head group. The line head 86 is supported by the support member 87 extending in the predetermined direction, and is provided over substantially the entire width direction of the recording medium 82 so that ink can be simultaneously ejected to substantially the entire width direction of the recording medium 82. It has become.

  The ink jet recording apparatus 91 includes a plurality of rollers 85 that move the recording medium 82 in a direction substantially perpendicular to the predetermined direction (Y direction shown in FIG. 9). Thus, the plurality of rollers 85 constitute relative moving means for moving the inkjet head 201 and the recording medium 82 relative to each other by transferring the recording medium 82 in a direction substantially perpendicular to the predetermined direction. In FIG. 9, Z is the vertical direction.

  The ink jet recording apparatus 91 is configured to perform recording by ejecting ink from the nozzles 38 of the respective ink jet heads 201 to the recording medium 82 when the recording medium 82 is moved by the roller 85. .

  Accordingly, in this embodiment as well as the third embodiment, since the inkjet head 201 having the high environmental resistance of the second embodiment is used, a plurality of ink ejection elements 202 in each inkjet head 201 of the line head 86 are used. It is possible to easily control the ink discharge variation during this period, thereby reducing the recording variation on the recording medium 82 such as paper, and improving the reliability.

  The piezoelectric element of the present invention is useful for an inkjet head (inkjet recording apparatus), a gyro element, a MEMS (Micro Electro Mechanical System) device represented by an optical switch component, and the like.

1 is a perspective view showing a piezoelectric element according to an embodiment of the present invention. It is process drawing which shows the manufacturing method of the piezoelectric body element of FIG. FIG. 6 is a characteristic diagram showing the amount of displacement of the tip of the piezoelectric element when a triangular wave voltage is applied between the first electrode film and the second electrode film in the piezoelectric element of Example 1. It is the schematic which shows the inkjet head which concerns on embodiment of this invention. FIG. 5 is an exploded perspective view, partly broken away, showing an ink ejection element of the ink jet head of FIG. 4. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. It is process drawing which shows the manufacturing method of the inkjet head of FIG. 1 is a schematic perspective view showing an ink jet recording apparatus according to an embodiment of the present invention. It is a schematic perspective view which shows another inkjet recording device which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 1st electrode film 3 Piezoelectric thin film 4 2nd electrode film 10 Laminated body 20 Piezoelectric element 32 Pressure chamber 33 1st electrode film (individual electrode)
38 Nozzle 41 Piezoelectric thin film 42 Second electrode film (common electrode)
43 Diaphragm 81 Inkjet recording device 82 Recording medium 84 Carriage (relative movement means, head transfer means)
85 rollers (relative movement means, recording medium transfer means)
86 Line Head 201 Ink Jet Head

Claims (12)

A piezoelectric element including a laminate in which a first electrode film, a piezoelectric thin film, and a second electrode film are laminated in this order,
The piezoelectric thin film is an oxide having a perovskite crystal structure, and the chemical composition formula is
Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ (0 <s <1)
In the above, lead zirconate titanate or A is an additive metal ion entering the A site of the perovskite crystal structure, and B is an additive metal ion entering the B site of the perovskite crystal structure,
_{(Pb (1-xy) A} y) (Zr (1-st) Ti s B t) O 3 (0 <s <1,0 <t <1-s)
It consists of a lead zirconate titanate oxide represented by
In the chemical composition formula of the lead zirconate titanate and lead zirconate titanate oxides, the value of x indicating the Pb composition deficiency from the stoichiometric composition is more than 0 and 0.15 or less. Piezoelectric element. A in the chemical composition formula of the lead zirconate titanate oxide is at least one metal ion selected from the group consisting of lanthanum (La), strontium (Sr), bismuth (Bi), and calcium (Ca). ,
B in the above chemical composition formula is at least one metal ion selected from the group of niobium (Nb), magnesium (Mg), nickel (Ni), manganese (Mn) and iron (Fe). The piezoelectric element according to claim 1.   2. The piezoelectric element according to claim 1, wherein the thickness of the piezoelectric thin film is 2 μm or more and 6 μm or less.   2. The piezoelectric element according to claim 1, wherein the piezoelectric thin film is preferentially oriented in a (001) plane.   2. The piezoelectric element according to claim 1, wherein a vibration plate is disposed on a surface on one side in the stacking direction of the stack.   6. The piezoelectric element according to claim 5, wherein the diaphragm is made of at least one selected from the group consisting of silicon, glass, a ceramic material, and a metal material. Forming a first electrode film on the substrate; forming a piezoelectric thin film on the first electrode film by sputtering; forming a second electrode film on the piezoelectric thin film; A method of manufacturing a piezoelectric element including the step of:
The piezoelectric thin film is an oxide having a perovskite crystal structure, and the chemical composition formula is
Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ (0 <s <1)
In the above, lead zirconate titanate or A is an additive metal ion entering the A site of the perovskite crystal structure, and B is an additive metal ion entering the B site of the perovskite crystal structure,
_{(Pb (1-xy) A} y) (Zr (1-st) Ti s B t) O 3 (0 <s <1,0 <t <1-s)
It consists of a lead zirconate titanate oxide represented by
In the chemical composition formula of the lead zirconate titanate and lead zirconate titanate oxides, the value of x indicating the Pb composition deficiency amount from the stoichiometric composition is more than 0 and 0.15 or less,
The step of forming the piezoelectric thin film is performed under sputtering conditions in which the substrate on which the first electrode film is formed is brought into a potential state that is electrically floated from a ground potential and the sputtering gas pressure is set to 0.05 Pa or more and 0.15 Pa or less. A method of manufacturing a piezoelectric element, which is a step of forming a piezoelectric thin film. Forming a first electrode film on the substrate; forming a piezoelectric thin film on the first electrode film by sputtering; forming a second electrode film on the piezoelectric thin film; A method of manufacturing a piezoelectric element including the step of:
The piezoelectric thin film is an oxide having a perovskite crystal structure, and the chemical composition formula is
Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ (0 <s <1)
In the above, lead zirconate titanate or A is an additive metal ion entering the A site of the perovskite crystal structure, and B is an additive metal ion entering the B site of the perovskite crystal structure,
_{(Pb (1-xy) A} y) (Zr (1-st) Ti s B t) O 3 (0 <s <1,0 <t <1-s)
It consists of a lead zirconate titanate oxide represented by
In the chemical composition formula of the lead zirconate titanate and lead zirconate titanate oxides, the value of x indicating the Pb composition deficiency amount from the stoichiometric composition is more than 0 and 0.15 or less,
In the step of forming the piezoelectric thin film, sputtering is performed by applying a bias voltage to the substrate on which the first electrode film is formed so that the substrate is in a negative potential state that is the same as or lower than the ground potential. A method of manufacturing a piezoelectric element, characterized by being a step of forming a piezoelectric thin film under conditions. A piezoelectric element having a laminated body in which a first electrode film, a piezoelectric thin film, and a second electrode film are laminated in this order, and a vibration plate disposed on one surface in the laminating direction of the laminated body; A pressure chamber containing ink, and a nozzle communicating with the pressure chamber, and the diaphragm is displaced in the thickness direction by the piezoelectric effect of the piezoelectric thin film of the piezoelectric element, so that the ink in the pressure chamber is discharged from the nozzle. An inkjet head configured to be discharged,
The piezoelectric thin film of the piezoelectric element is an oxide having a perovskite crystal structure, and the chemical composition formula is
Pb _(1-x) (Zr _(1-s) Ti _s ) O ₃ (0 <s <1)
In the above, lead zirconate titanate or A is an additive metal ion entering the A site of the perovskite crystal structure, and B is an additive metal ion entering the B site of the perovskite crystal structure,
_{(Pb (1-xy) A} y) (Zr (1-st) Ti s B t) O 3 (0 <s <1,0 <t <1-s)
It consists of a lead zirconate titanate oxide represented by
In the chemical composition formula of the lead zirconate titanate and lead zirconate titanate oxides, the value of x indicating the Pb composition deficiency from the stoichiometric composition is more than 0 and 0.15 or less. Inkjet head. An inkjet head according to claim 9;
A relative movement means for relatively moving the inkjet head and the recording medium,
When the inkjet head is relatively moved with respect to the recording medium by the relative movement means, the recording is performed by discharging ink in a pressure chamber from the nozzle of the inkjet head to the recording medium. An ink jet recording apparatus. The relative movement means includes a head transfer means for reciprocating the inkjet head in a predetermined direction, and a recording medium transfer means for transferring the recording medium in a direction substantially perpendicular to the predetermined direction.
When the ink jet head is moved in the predetermined direction by the head moving means of the relative movement means, the ink in the pressure chamber is ejected from the nozzles of the ink jet head onto the recording medium to perform recording. The ink jet recording apparatus according to claim 10. A plurality of inkjet heads are connected to each other in a predetermined direction,
11. The inkjet according to claim 10, wherein the relative moving means is configured to move the inkjet head and the recording medium relative to each other by transferring the recording medium in a direction substantially perpendicular to the predetermined direction. Type recording device.

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