JP2006027155A - Substrate bonding method, droplet discharge head manufacturing method, droplet discharge head, and droplet discharge apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bond a substrate capable of positioning and bonding substrates constituting an actuator with high accuracy, a method of manufacturing a droplet discharge head using this bonding method, and a droplet discharge head manufactured using this manufacturing method And a droplet discharge device.
A concave portion 15 as a first alignment mark formed on a bonding surface of a glass substrate 1 having an electrode portion 8 and a second alignment formed on a silicon substrate 2 before a diaphragm portion is formed. The concave portion 16 as a mark is aligned while being observed from the back surface of the glass substrate 1 with an optical system having a visible light camera 50. Then, after the glass substrate 1 and the silicon substrate 2 are anodically bonded, a vibration plate portion is formed on the silicon substrate 2 by anisotropic etching with the recess 16 as a reference.
[Selection] Figure 7

Description

  The present invention relates to a method for bonding substrates, a method for manufacturing a droplet discharge head that discharges liquid using the bonding method as droplets, a droplet discharge head, and a droplet discharge apparatus.

  As a droplet discharge head for discharging the filled liquid as droplets, a plurality of nozzle holes, a plurality of independent discharge chambers communicating with each of the nozzle holes, and a diaphragm ( Diaphragm) and an individual electrode (electrode part) opposed to the diaphragm with a gap, applying a voltage between the diaphragm and the individual electrode to deform the diaphragm, so that ink droplets are ejected from the nozzle holes. An ink jet head for discharging is known. In this method of manufacturing an ink jet head as a droplet discharge head, the thickness of the first substrate is reduced after the first substrate that constitutes the diaphragm and the second substrate having the individual electrodes are joined. This is a method of forming at least a diaphragm (Patent Document 1).

  In addition, the inkjet head manufacturing method is arranged so as to face the electrostatic actuator (vibrating plate and this at a predetermined interval) as the number of nozzles is increased and the pitch is reduced corresponding to high-speed printing and high resolution of the inkjet recording apparatus. It is intended to improve the crosstalk between the electrostatic actuators caused by increasing the density (by the configuration with the electrode portion) by reducing the thickness of the first substrate.

Japanese Patent Laid-Open No. 11-993

  In such a droplet discharge head having such a conventional electrostatic actuator, the interval between adjacent discharge chambers has become very narrow due to higher density. For example, in a droplet discharge head having a nozzle pitch of 70 μm, the partition walls separating the discharge chambers have a thickness of 20 to 30 μm. Therefore, the first substrate that constitutes the diaphragm and the second substrate that includes the individual electrodes When joining the two, a highly accurate joining method on the order of microns is required. If there is a deviation in the joining, the diaphragm and the electrode portion disposed facing the diaphragm at a predetermined interval may be displaced in the plane direction, and the electrostatic actuator may not operate normally.

  The present invention has been made in consideration of the above problems, and a substrate bonding method capable of positioning and bonding substrates constituting an actuator with high accuracy, a method of manufacturing a droplet discharge head using this bonding method, It is an object of the present invention to provide a droplet discharge head and a droplet discharge device manufactured using this manufacturing method.

  The substrate bonding method of the present invention includes a first mark forming step of forming a first alignment mark on at least one surface of a first substrate, and a second alignment on at least one surface of a second substrate that is a silicon substrate. The second mark forming step for forming the mark, the alignment step for adjusting the position of the first substrate and the second substrate by aligning the first alignment mark and the second alignment mark, and the position adjustment And a bonding step of bonding the first substrate and the second substrate.

  According to this configuration, the first substrate and the second substrate are bonded using the first alignment mark formed in the first mark formation step and the second alignment mark formed in the second mark formation step. Since alignment is performed in the alignment step and bonding is performed, the first substrate and the second substrate can be bonded with high positional accuracy.

  In this case, the first substrate is a glass substrate, and the first substrate and the second substrate are anodically bonded. According to this, the first substrate that is a glass substrate and the second substrate that is a silicon substrate can be anodically bonded with high positional accuracy.

  In this case, in the second mark forming step, it is preferable to form a parallelogram or trapezoidal second alignment mark on the second substrate by anisotropic etching. According to this, since the second alignment mark is formed by anisotropic etching into a parallelogram or a trapezoidal shape on the second substrate which is a silicon substrate, the second alignment mark has a stable shape. Thus, the alignment accuracy can be improved.

  In this case, in the first mark forming step, it is preferable to form the first alignment mark at a position that is substantially point-symmetric with respect to the center of the first substrate. According to this, since the first alignment mark is formed at a substantially point-symmetrical position with respect to the center of the first substrate in the first mark forming step, the first substrate and the second substrate in the alignment step. Even if the substrate is displaced in the rotation direction, the displacement direction can be easily recognized and corrected.

  In this case, in the alignment step, each of the first alignment mark and the second alignment mark is imaged, one of the alignment marks is stored as an image, and the stored first alignment mark image and second alignment mark are stored. Alignment is performed by relatively moving the first substrate and the second substrate so as to overlap the image of the mark.

  According to this configuration, even when the first alignment mark and the second alignment mark cannot be recognized at the same time in the alignment step, each alignment mark is imaged and one alignment mark is stored as an image. By relatively moving the first substrate and the second substrate so that the images are superimposed, the first substrate and the second substrate can be accurately aligned.

  In this case, the alignment step is characterized in that the first alignment mark and the second alignment mark are aligned while being observed from the opposite surface side with respect to the bonding surface of the first substrate.

  According to this configuration, since the first substrate is a transparent glass substrate, in the alignment step, the first alignment mark and the second alignment mark are formed from the opposite side to the bonding surface of the first substrate. Can be aligned while observing through the first substrate. In the bonding step, the first substrate and the second substrate can be bonded with higher accuracy.

  The method for manufacturing a droplet discharge head according to the present invention includes at least a first substrate constituting an actuator, a second substrate having a flow path serving as a discharge chamber filled with liquid on at least one surface, and a discharge chamber. And a third substrate having a communicating nozzle, pressurizing the liquid filled in the discharge chamber by an actuator, and discharging the liquid from the nozzle as liquid droplets. The first substrate and the second substrate are bonded using a substrate bonding method.

  According to this configuration, the first substrate constituting the actuator and the second substrate having a flow path serving as a discharge chamber in which at least one surface is filled with the liquid are bonded using the substrate bonding method of the invention. Therefore, it is possible to manufacture a droplet discharge head in which the actuator and the flow path serving as the discharge chamber are aligned with high positional accuracy and bonded. Therefore, it is possible to improve the yield reduction due to the positional deviation between the actuator and the flow path, and to manufacture the droplet discharge head with a high yield.

  In another method of manufacturing a droplet discharge head according to the present invention, a first substrate having an electrode portion, a second substrate having a vibration plate portion constituting one surface of the discharge chamber, and a nozzle communicating with the discharge chamber are provided. The diaphragm portion is displaced by an actuator having an electromechanical conversion element composed of a diaphragm portion and an electrode portion arranged opposite to the diaphragm portion at a predetermined interval. A method of manufacturing a droplet discharge head that discharges liquid as droplets from a nozzle by changing the volume of a discharge chamber that contains a liquid, the first substrate and the first substrate using the substrate bonding method of the invention described above. It is characterized by joining two substrates.

  According to this configuration, since the first substrate having the electrode portion and the second substrate having the diaphragm portion are joined using the substrate joining method of the invention, the electrode portion and the diaphragm portion are A droplet discharge head that is aligned and bonded with high positional accuracy can be manufactured. Therefore, it is possible to improve the yield reduction due to the positional deviation between the electrode portion and the diaphragm portion, and to manufacture the droplet discharge head with a high yield.

  The droplet discharge head of the present invention includes a first substrate having an electrode portion, a second substrate having a vibration plate portion constituting one surface of the discharge chamber, and a third substrate having a nozzle communicating with the discharge chamber. Displacement of the diaphragm portion by an actuator having an electromechanical conversion element composed of the diaphragm portion and an electrode portion disposed opposite to the diaphragm portion at a predetermined interval, and containing liquid A droplet discharge head for discharging a liquid from a nozzle by changing a volume of a chamber, wherein a first alignment mark is formed on at least one surface of the first substrate, and a second substrate which is a silicon substrate. A second alignment mark is formed on at least one surface of the substrate.

  According to this configuration, the first alignment mark is formed on at least one surface of the first substrate constituting the droplet discharge head, and the second alignment mark is formed on at least one surface of the second substrate that is a silicon substrate. Therefore, if the first substrate and the second substrate are aligned and bonded using the first alignment mark and the second alignment mark, the electrode is densely formed. Even if the portion and the diaphragm portion are formed, a droplet discharge head having an actuator in which the electrode portion and the diaphragm portion are arranged to face each other with high positional accuracy can be obtained. Therefore, it is possible to obtain a liquid droplet ejection head having high reliability quality with less occurrence of actuator malfunction due to relative displacement between the electrode portion and the diaphragm portion.

  In this case, it is preferable that the first alignment mark is formed on the bonding surface of the first substrate that is bonded to the second substrate. According to this, since the first alignment mark of the first substrate having the electrode portion is formed on the bonding surface with the second substrate having the diaphragm portion, the first alignment mark and the second alignment mark If the first substrate and the second substrate are aligned and joined using the alignment mark, the electrode portion and the diaphragm portion can be arranged to face each other with higher positional accuracy.

  In this case, it is preferable that the first alignment mark is formed on the bonding surface with the second substrate at a position substantially point-symmetric with respect to the center of the first substrate. According to this, when aligning the first substrate and the second substrate using the first alignment mark and the second alignment mark, the first alignment mark is positioned at the center of the first substrate. Since it is formed on the joint surface with the second substrate at a substantially point-symmetrical position, even if the first substrate and the second substrate are displaced in the rotational direction, the displacement direction can be easily recognized. It can be corrected. Therefore, it is possible to obtain a droplet discharge head in which the electrode portion and the diaphragm portion are joined in a state where the deviation in the rotation direction is small.

  In this case, the second alignment mark is preferably formed on the bonding surface of the second substrate to be bonded to the first substrate. Since the second alignment mark of the second substrate having the vibration plate portion is formed on the bonding surface side with the first substrate having the electrode portion, the first alignment mark, the second alignment mark, If the first substrate and the second substrate are aligned and bonded using the electrode, the electrode portion and the diaphragm portion can be arranged to face each other with higher positional accuracy.

  In this case, the second alignment mark may be formed on the surface opposite to the bonding surface of the second substrate to be bonded to the first substrate. Moreover, you may form in the joint surface of the said 2nd board | substrate joined to a 1st board | substrate, and an opposite surface. According to this, the second alignment mark is formed on the surface opposite to the bonding surface of the second substrate to be bonded to the first substrate. Alternatively, since it is formed on both the bonding surface and the opposite surface of the second substrate to be bonded to the first substrate, the second substrate which is an opaque silicon substrate is bonded to the first substrate. The second alignment mark formed on the opposite surface can be easily recognized with visible light, and the first substrate and the second substrate can be accurately aligned and bonded.

  In this case, the second alignment mark is preferably formed on the second substrate by anisotropic etching so as to have a parallelogram shape or a trapezoidal shape. According to this, since the shape of the second alignment mark formed so as to be a parallelogram or trapezoid by anisotropic etching is stable, the first alignment mark is used by using the second alignment mark. If the substrate and the second substrate are aligned and bonded, a droplet discharge head in which the diaphragm portion of the second substrate and the electrode portion of the first substrate are bonded with high positional accuracy can be obtained.

  Further, in this case, it is preferable that the first alignment mark is formed outside the electrode portion formation region, and the second alignment mark is formed outside the diaphragm portion formation region. According to this, even if the electrode part and the diaphragm part are formed at a high density, the first alignment mark is outside the electrode part formation region, and the second alignment mark is outside the diaphragm part formation region. Since it is formed, each alignment mark can be easily found, recognized, and aligned.

  The liquid droplet ejection apparatus of the present invention is equipped with the liquid droplet ejection head of the above invention. According to this, even when the electrode part and the diaphragm part are formed with high density, the droplet discharge head having high reliability quality with less occurrence of malfunction of the actuator due to relative displacement between the electrode part and the diaphragm part. Therefore, a droplet discharge device having high quality characteristics can be provided.

  First, a droplet discharge head according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic exploded perspective view showing the structure of a droplet discharge head. FIG. 2 is a schematic cross-sectional view of a droplet discharge head in which the substrates of FIG. 1 are stacked. 2A is a schematic cross-sectional view of the whole, and FIG. 2B is a schematic cross-sectional view showing a junction state of equipotential points.

  As shown in FIG. 1, the droplet discharge head 10 of this embodiment includes a glass substrate 1 as a first substrate having an electrode portion 8 and a second substrate having a vibrating plate portion 4 constituting one surface of the discharge chamber 5. And a nozzle plate 3 as a third substrate having a nozzle 12 and a silicon substrate 2 as a three-layer structure.

  As shown in FIG. 2, the droplet discharge head 10 includes an electrostatic actuator 20 having an electromechanical conversion element 19 including a vibration plate portion 4 and an electrode portion 8 disposed to face the vibration plate portion 4 with a predetermined gap G. By displacing the vibration plate portion 4 by this, and changing the volume of the discharge chamber 5 containing the liquid (ink), the liquid (ink) is discharged from the nozzle 12 as droplets. Accordingly, the ink jet head 10 will be described below. As shown in FIG. 1, in the inkjet head 10, a plurality of discharge chambers 5 and electrostatic actuators 20 communicating with the nozzles 12 are formed on each substrate corresponding to the plurality of nozzles 12.

  The glass substrate 1 as the first substrate uses a borosilicate heat-resistant hard glass having a thickness of about 1 mm. As shown in FIG. 1, the glass substrate 1 has an electrode portion 8 constituting the electromechanical conversion element 19 and a terminal portion 11 connected to the electrode portion 8, and ITO (Indium Tin Oxide) is formed on the bottom surface of the concave portion 9 with a thickness of about 0. The film is formed to a thickness of 1 μm.

  Further, when anodically bonding the glass substrate 1 and the silicon substrate 2 later, the vibration plate portion 4 and the electrode portion 8 are bonded to prevent discharge from occurring between the vibration plate portion 4 and the electrode portion 8 made of ITO. An equipotential point 25 that is sometimes equipotential is formed in parallel with the electrode portion 8 on the bonding surface of the glass substrate 1 using the deposited ITO.

  The silicon substrate 2 as the second substrate is a single crystal silicon substrate having a plane orientation (110) of about 140 μm thickness. As shown in FIG. 1 or FIG. 2, the silicon substrate 2 includes a discharge chamber 5 having a diaphragm 4 as one component surface, and a reservoir 7 that is a common ink cavity for supplying ink (liquid) to the discharge chamber 5. Is formed by anisotropic etching.

  The reservoir 7 is partially perforated so as to communicate with an ink supply hole 13 provided in the glass substrate 1 for supplying ink from the outside.

  Then, as shown in FIG. 2, the glass substrate 1 and the silicon substrate 2 are joined together, and a part of the gap formed between the vibration plate portion 4 and the electrode portion 8 disposed to face the diaphragm portion 4 at a predetermined gap G. Is sealed with a sealant 26 to form the vibration chamber 18 in a sealed state. At this time, in order to spread the sealing agent 26 to each vibration chamber 18, the sealing groove 23 is anisotropically formed on the bonding surface of the silicon substrate 2 so as to communicate with the sealing agent injection hole 24 provided in the glass substrate 1. Formed by reactive etching.

  The nozzle plate 3 as the third substrate is a silicon thin plate having a thickness of about 180 μm. As shown in FIGS. 1 and 2, a plurality of nozzles 12 communicating with the discharge chamber 5 are formed in the nozzle plate 3. Further, a recess 6a for forming an orifice 6 which is a flow path for supplying ink from the reservoir 7 to the discharge chamber 5 is formed by anisotropic etching. The nozzle plate 3 can be made of a borosilicate hard glass, a steel plate such as stainless steel, a resin plate such as plastic, or the like as the first substrate.

In the inkjet head 10 of this embodiment, the boron dope layer 4a is formed in advance on the bonding surface side of the silicon substrate 2 so that the vibration plate portion 4 has a desired thickness. The boron doped layer 4a has a boron doped region with a high concentration (about 5 × 10 ¹⁹ atoms · cm ⁻³ or more). When the silicon substrate 2 is anisotropically etched with an alkaline aqueous solution, the etching is stopped at the boron doped layer 4a. To do. The diaphragm 4 is formed using this etching stop technique.

  In addition, an insulating film 14 is formed on the bonding surface of the silicon substrate 2 so that when the electrostatic actuator 20 is driven, the vibration plate portion 4 and the electrode portion 8 are in contact with each other and are not electrically short-circuited. The insulating film 14 is formed by depositing TEOS (Tetraethyl orthosilicate Tetraethoxysilane) to a thickness of about 0.1 μm by plasma CVD (Chemical Vapor Deposition).

  Therefore, in order to bring the equipotential point 25 described above into contact with the boron doped layer 4a and make it equipotential with the electrode portion 8, the electrode portion 8 and the equipotential point 25 are formed as shown in FIG. Before joining the glass substrate 1 and the silicon substrate 2 on which the vibration plate portion 4 is formed, the equipotential point 25 of the insulating film 14 formed on the bonding surface of the silicon substrate 2 can be in contact with the boron doped layer 4a. It is partially etched away.

  FIG. 3 is a schematic plan view of the first substrate of FIG. As shown in FIG. 3, the equipotential point 25 is formed on the joint surface so as to be in parallel with the electrode portion 8 of the glass substrate 1. The equipotential point 25 is connected to the right side of the dicing line 33 that is cut to take out one inkjet head 10 after the glass substrate 1, the silicon substrate 2, and the nozzle plate 3 are bonded to each other via the terminal portion 11. A plurality of electrode portions 8 are connected. Therefore, when the line is cut by the dicing line 33, the equipotential point 25 is divided from the plurality of electrode portions 8. The plurality of electrode portions 8 are also divided to form individual electrode portions 8.

  In the method of driving the ink jet head 10 as described above, the oscillation circuit 22 is connected between the terminal portion 11 of the electrode portion 8 and the common electrode 21 provided on the silicon substrate 2 as shown in FIG. . Then, a voltage pulse of a drive voltage of 30 V is applied from the oscillation circuit 22 between the electrode unit 8 and the common electrode 21 at 24 kHz, for example. Then, when the electrode portion 8 is positively charged, the diaphragm portion 4 facing the electrode portion 8 is negatively charged and the diaphragm portion 4 is attracted to the electrode portion 8 by electrostatic force. When the application of the voltage pulse is released and the stored charge is discharged, the diaphragm portion 4 returns to the original position. The volume of the discharge chamber 5 changes due to the displacement of the vibration plate portion 4 and the filled ink is pressurized and discharged as droplets from the nozzle 12.

  The ink used is prepared by dissolving or dispersing a surfactant such as ethylene glycol and a dye or pigment in a main solvent such as water or alcohol. Furthermore, if a heater or the like is attached to the inkjet head 10, hot melt type ink can also be used. The ink jet head 10 of the present embodiment is a face ink jet system, but may be an edge ink jet system in which nozzles 12 for ejecting ink are opened on the end surface of the silicon substrate 2 or the nozzle plate 3.

  Next, the manufacturing method of the inkjet head 10 is demonstrated based on FIGS. In the method of manufacturing the inkjet head 10 according to the present embodiment, a first mark is formed by forming a first alignment mark on at least one surface of a glass substrate 1 as a first substrate to be bonded to a silicon substrate 2 as a second substrate. And a second mark formation step of forming a second alignment mark on at least one surface of the silicon substrate 2 at a position corresponding to the first alignment mark formed in the first mark formation step. The glass substrate 1 and the silicon substrate 2 are aligned using a first alignment mark and a second alignment mark, and a bonding step of anodic bonding is provided. Further, the bonding step is an anodic bonding between the glass substrate 1 on which the electrode portion 8 is formed and the silicon substrate 2 before the vibration plate portion 4 is formed.

  FIG. 4 is a flowchart showing a method for manufacturing the inkjet head. FIG. 5 is a schematic cross-sectional view showing a processing state of each substrate corresponding to the flowchart of FIG. Specifically, FIG. 5.1 is a schematic sectional view from (a) to (f), FIG. 5.2 is a schematic sectional view from (g) to (k), and FIG. It is a schematic sectional drawing to p).

  Step S1 in FIG. 4 is a step of forming the electrode portion 8, the equipotential point 25, and the concave portion 15 as the first alignment mark on the glass substrate 1. As shown in FIG. 5.1 (a), the glass substrate 1 is first etched into a borosilicate hard glass having a thickness of 1 mm so that the recesses 9 and 15 have a depth of approximately 0.3 μm. The etching method is performed by masking the surface of the glass substrate 1 other than the etching surface with Cr—Au and immersing the glass substrate 1 in a mixed solution of ammonium fluoride and hydrogen peroxide at room temperature.

  Then, an ITO film serving as an electrode portion is formed on the bonding surface 1a where the recesses 9 and 15 are formed to a thickness of about 0.1 μm by sputtering, and the electrode portion 8 is formed on the bottom surface of the corresponding recess 9 by photolithography. At the same time, an equipotential point 25 is formed on the bonding surface 1a. The shape of the equipotential point 25 is linear in the present embodiment, but may be any shape as long as it can contact the boron doped layer 4a.

  Further, the glass substrate 1 is provided with the ink supply holes 13 and the sealant injection holes 24 by a cutting method using a diamond drill or the like from the bonding surface 1a side. However, the perforation is stopped at a position where the glass substrate 1 is not penetrated so that chemicals, foreign substances, and the like used in a processing step performed after the glass substrate 1 and the silicon substrate 2 are anodically bonded do not enter the vibration chamber 18. Then, the process proceeds to step S2.

  In step S2, the concave portion 16 as the second alignment mark is formed on the silicon substrate 2 at the bonding surface 2a with the glass substrate 1, and the concave portion 17 as the second alignment mark is formed on the bonding surface 2b opposite to the concave portion 16. It is the process of forming. As shown in FIG. 5.1 (b), the silicon substrate 2 was obtained by mirror-polishing both surfaces of a single crystal silicon substrate having a plane orientation (110) having a low oxygen concentration, and the thickness was about 525 μm. . By leaving this silicon substrate 2 in a steam atmosphere at a temperature of 1075 ° C. for 4 hours, a silicon oxide film 27 having a thickness of about 1 μm is formed on the surface.

  Then, a photoresist is applied to both surfaces, and the silicon oxide film 27 is immersed and etched in a hydrofluoric acid aqueous solution by a photolithography method to form a pattern corresponding to the recesses 16 and 17. Then, the process proceeds to step S3.

  In step S3, as shown in FIG. 5.1 (c), using the pattern of the silicon oxide film 27 formed on the silicon substrate 2 in step S2 as a mask, the recesses 16 and 17 as the second alignment marks are about 10 μm deep. This is a step of etching. As an etching method at this time, anisotropic etching is performed by immersing the silicon substrate 2 in a 35 wt% potassium hydroxide aqueous solution. Then, the process proceeds to step S4.

  Step S4 is a process of forming the sealing groove 23 on the bonding surface 2a of the silicon substrate 2 with the glass substrate 1 with reference to the recess 16 (or recess 17) as the second alignment mark formed in step S3. is there. As shown in FIG. 5.1 (d), in the sealing groove 23, a photoresist is applied to the bonding surface 2a, and the silicon oxide film 27 is first etched using a hydrofluoric acid aqueous solution by a photolithography method. Next, the silicon substrate 2 is immersed in a 35 wt% aqueous potassium hydroxide solution and anisotropically etched to a depth of about 100 μm. Then, the process proceeds to step S5.

  Step S5 is a process of removing the silicon oxide films 27 formed on both surfaces of the silicon substrate 2. As shown in FIG. 5.1 (e), the boron substrate 4a is formed on the silicon substrate 2 in the next step S6. If the silicon oxide film 27 is present on the surface at this time, boron is difficult to diffuse and is removed. Keep it. In this case, the silicon substrate 2 is immersed and removed in an aqueous hydrofluoric acid solution. Then, the process proceeds to step S6.

  Step S <b> 6 is a step of forming the boron doped layer 4 a on the silicon substrate 2. The silicon substrate 2 is first cleaned to remove and clean the minute foreign matter or metal adhering to the bonding surface 2a forming the boron doped layer 4a. In this case, cleaning with a mixed solution of ammonia water and hydrogen peroxide solution and cleaning with a mixed solution of hydrochloric acid and hydrogen peroxide solution are performed.

Next, the cleaned silicon substrate 2 is set in a diffusion furnace having a solid diffusion source mainly composed of B ₂ O _{3 so} that the bonding surface 2a faces the diffusion source, and the inside of the furnace is made a nitrogen atmosphere. Hold at a temperature of 1050 ° C. for 7 hours. As a result, boron is diffused into the bonding surface 2a of the silicon substrate 2 to form a boron doped layer 4a as shown in FIG. 5.1 (f).

In step S6, the temperature at which the silicon substrate 2 is put into the diffusion furnace and the temperature at which it is taken out is preferably 800 ° C. According to this, it is possible to prevent oxygen defects from being generated by quickly passing through a temperature range of 600 to 800 ° C. where oxygen defects are likely to occur in the silicon substrate 2. When an oxygen defect occurs, a hole may be formed in that part. In addition, when the silicon substrate 2 is anisotropically etched, an etching abnormality is likely to occur at the oxygen defect portion. Furthermore, it is preferable to remove the boron compound (SiB ₆ ) (not shown) formed on the surface of the boron doped layer 4a. According to this, it is known that this boron compound inhibits the adhesion of the insulating film 14 formed in the next step S7. Accordingly, the silicon substrate 2 is heated to 600 ° C. in an oxygen and water vapor atmosphere and left for one and a half hours to oxidize the boron compound, and it is removed as B ₂ O ₃ + SiO ₂ by etching with a hydrofluoric acid aqueous solution. Then, the process proceeds to step S7.

Step S7 is a step of forming the insulating film 14 on the surface of the boron doped layer 4a as shown in FIG. 5.2 (g). The insulating film 14 is formed by forming TEOS to a thickness of approximately 0.1 μm by plasma CVD. The film forming conditions in this case are, for example, a temperature of 360 ° C., a high frequency output of 250 W, a pressure of 66.7 Pa (0.5 Torr), a TEOS gas flow rate of 100 cm ³ / min (100 sccm), and an oxygen flow rate of 1000 cm ³ / min (1000 sccm). Then, the process proceeds to step S8.

  In step S8, a part of the insulating film 14 formed in the previous step S7 is formed in FIG. 5.2 (h) so that the equipotential point 25 formed on the glass substrate 1 in step S1 can be in contact with the boron doped layer 4a. This is a step of removing by etching as shown in FIG. A photoresist is applied to the surface of the insulating film 14, patterned, and etched with a hydrofluoric acid aqueous solution to form the opening 2c. Then, the process proceeds to step S9. FIG. 5.2 (h) is a schematic cross-sectional view of the silicon substrate 2 at a position corresponding to the equipotential point 25.

  Step S9 is a bonding process in which the glass substrate 1 and the silicon substrate 2 are anodic bonded. This bonding step includes an alignment step of adjusting the position of the glass substrate 1 and the silicon substrate 2 using the recess 15 as the first alignment mark and the recess 16 or the recess 17 as the second alignment mark. The alignment process will be described in detail later.

  In the anodic bonding method in step S9, the glass substrate 1 and the silicon substrate 2 that have been aligned in the alignment step are heated at a temperature of 360 ° C. for 30 minutes, and then the glass substrate 1 is used as a negative electrode and the silicon substrate 2 is used as a positive electrode. A voltage is applied for 5 minutes to bond. At this time, if the voltage boosting rate is too high, a large current flows through the equipotential point 25 and the ITO wiring may be damaged. Therefore, it is preferable to perform the bonding so that the current does not exceed 10 mA. Then, the process proceeds to step S10.

  Step S10 is a step of grinding the surface of the silicon substrate 2 so that the thickness of the silicon substrate 2 becomes approximately 150 μm as shown in FIG. 5.2 (j). Further, since a work-affected layer having a brittle composition appears on the surface of the silicon substrate 2 by grinding, the work-affected layer is etched by about 10 μm with a 32 wt% potassium hydroxide aqueous solution. As a result, the thickness of the silicon substrate 2 becomes approximately 140 μm. Then, the process proceeds to step S11.

Step S11 is a step of forming the TEOS film 28 on the surface of the silicon substrate 2 from which the work-affected layer has been removed as shown in FIG. 5.2 (k). The TEOS film 28 is used as an etching mask when the silicon substrate 2 is anisotropically etched in the next step S12. The film formation conditions of the TEOS film 28 are, for example, a temperature of 360 ° C., a high frequency output of 700 W, a pressure of 33.3 Pa (0.25 Torr), a TEOS gas flow rate of 100 cm ³ / min (100 sccm), and an oxygen flow rate of 1000 cm ³ / min (1000 sccm). . Thereby, a TEOS film 28 having a thickness of about 1.5 μm is formed. Then, the process proceeds to step S12.

  In step S12, as shown in FIG. 5.3 (l), the concave portion 29 constituting the vibration plate portion 4 and the discharge chamber 5 and the concave portion 30 constituting the reservoir 7 and the electrode outlet 32 (m in FIG. This is a step of forming the recess 31 for forming the reference) by anisotropic etching. In this case, it is called a cavity etching process.

  First, a resist pattern corresponding to each of the recesses 29, 30, 31 is formed on the surface of the TEOS film 28 by photolithography. Then, the TEOS film 28 is etched with a hydrofluoric acid aqueous solution to form an etching mask pattern. At this time, etching is performed so that the TEOS film 28 remains on the surface of the TEOS film 28 corresponding to the recess 30 with a thickness of about 0.3 μm.

  Next, the bonded glass substrate 1 and silicon substrate 2 are immersed in a 35 wt% potassium hydroxide aqueous solution, and anisotropic etching is performed so that the thickness of the bottom surface of the recess 29 becomes approximately 10 μm. Then, this is immersed in a 3 wt% potassium hydroxide aqueous solution, and anisotropic etching is performed until the etching is stopped at the boron doped layer 4a. By performing two-stage anisotropic etching with different concentrations as described above, the vibration plate portion 4 having an accuracy with a thickness of 0.8 ± 0.05 μm or less can be formed while suppressing etching surface roughness. In addition, since the TEOS film 28 is left by 0.3 μm, the recess 30 is formed with the thickness of about 40 μm remaining after the anisotropic etching starts late. By ensuring the thickness accuracy of the diaphragm 4, the characteristics as the electrostatic actuator 20 are stabilized. That is, the ink ejection characteristics of the inkjet head 10 can be stabilized. Then, the process proceeds to step S13.

  Step S13 is a step of forming an electrode outlet 32 in the silicon substrate 2 as shown in FIG. 5.3 (m). First, the bonded glass substrate 1 and silicon substrate 2 are immersed in a hydrofluoric acid aqueous solution, and the TEOS film 28 on the silicon substrate 2 is removed by etching. Next, portions other than the portion corresponding to the electrode outlet 32 are masked and opened by RIE dry etching. As dry etching conditions at this time, for example, etching is performed for 50 minutes at an RF power of 200 W, a pressure of 40 Pa (0.3 Torr), and a CF4 flow rate of 30 cm 3 / min (30 sccm). Then, the process proceeds to step S14.

  Step S14 is a step of hermetically sealing the vibration chamber 18 with the sealant 26 as shown in FIG. 5.3 (n). In addition, the common electrode 21 is formed on the silicon substrate 2. First, the ink supply hole 13 and the sealant injection hole 24 that are not penetrating from the opposite surface of the bonding surface 1a of the glass substrate 1 are penetrated by laser processing. Next, the sealing agent 26 is injected from the penetrating sealing agent injection hole 24, and the sealing agent 26 is filled into each vibration chamber 18 in which the vibration plate portion 4 and the electrode portion 8 are arranged to face each other through the sealing groove 23. To do. As a result, each vibration chamber 18 is sealed.

  Then, the cavity portion opened in the bonding surface 2b of the silicon substrate 2 is masked and chromium-gold (Cr-Au) or platinum (Pt) is formed by sputtering to form the common electrode 21. Then, the process proceeds to step S15.

  Step S15 is a joining step for joining the nozzle plate 3 to the joining surface 2b of the silicon substrate 2 as shown in FIG. 5.3 (o). In the nozzle plate 3, a plurality of nozzles 12 and a recess 6 a that constitutes the orifice 6 are formed in advance by anisotropic etching. The nozzle 12 and the recess 6a can also be formed by dry etching.

  Further, before joining the nozzle plate 3 to the silicon substrate 2, a hole communicating with the ink supply hole 13 is formed in the bottom surface of the recess 30 serving as the reservoir 7 by cutting or laser.

  The silicon substrate 2 and the nozzle plate 3 are bonded using a thermosetting resin such as an epoxy resin. Further, in this case, an alignment mark (not shown) is anisotropically provided on the opposite surface to the adhesive surface of the nozzle plate 3 corresponding to the recess 16 as the second alignment mark formed on the bonding surface 2a of the silicon substrate 2. The silicon substrate 2 and the nozzle plate 3 are aligned by etching. Then, the process proceeds to step S16.

  Step S16 is a cutting process by dicing. The manufacturing method of the inkjet head 10 of the present embodiment uses wafer-like substrates (glass substrate 1, silicon substrate 2, nozzle plate 3), and one unit of electrostatic actuator 20 corresponding to the plurality of nozzles 12 is used. As shown, a plurality of formation regions in which a plurality of inkjet heads 10 are formed are partitioned in the wafer. Therefore, as shown in FIG. 5.3 (p), the ink jet head 10 is taken out by cutting along the dicing line 33 (see FIG. 3). The manufacturing process of the inkjet head 10 is completed through the above steps. Needless to say, there is a mounting process for connecting the oscillation circuit 22 (see FIG. 2) and an assembling process for incorporation into a recording apparatus such as a printer.

  Next, an alignment mark forming method will be described in detail with reference to FIG. 6A to 6G are schematic views illustrating a method for forming alignment marks.

  FIG. 6A is a schematic plan view in which alignment marks are arranged on a wafer-like substrate. The glass substrate 1 and the silicon substrate 2 are in the form of a wafer and are partitioned to form a plurality of electrode portions 8 and a plurality of diaphragm portions 4 each having a plurality of electrostatic actuators 20 corresponding to the plurality of nozzles 12 as a unit. A plurality of formation regions 61 are provided in each wafer-like substrate (wafer 60), and a set of alignment marks 62 is formed in a wafer region (outside the formation regions) other than the plurality of formation regions 61. Further, the alignment mark 62 is formed at a substantially point-symmetrical position with respect to the center of the wafer 60.

  The alignment mark 62 is a generic term for the concave portion 15 as the first alignment mark and the concave portion 16 (or the concave portion 17) as the second alignment mark. Further, at least one set of alignment marks 62 may be formed for each formation region 61. According to this, the alignment mark 62 will exist for every completed inkjet head 10, and the joining state of the glass substrate 1 and the silicon substrate 2 can be confirmed for every inkjet head 10. FIG.

  6B to 6D are schematic plan views showing the shape of alignment marks formed on the silicon substrate. The silicon substrate 2 as the second substrate which is a single crystal silicon substrate has recesses 16 and 17 as second alignment marks having a parallelogram or trapezoidal plane shape on the plane orientation (110) plane. It is formed by etching. For example, in the case of a parallelogram having a predetermined angle as shown in FIG. 6B, the etching proceeds along the (111) plane, stops at a depth at which the edge indicated by the imaginary line appears, and proceeds further. Absent. Therefore, the recesses 16 and 17 as the second alignment mark are parallelograms having a stable shape. The same applies to the parallelogram in FIG. 3C and the trapezoid in FIG.

  FIG. 6E is a schematic plan view showing the relative positional relationship of the alignment marks when the glass substrate and the silicon substrate are aligned. A recess 15 as the first alignment mark formed on the bonding surface of the glass substrate 1 as the first substrate and a recess 16 as the second alignment mark formed in the silicon substrate 2 as the second substrate (or When the recesses 17) are correctly aligned, they are positioned at a predetermined interval in plan view. For example, as shown in FIG. 6 (e), if the recesses 15 and 16 are overlapped as a parallelogram, the predetermined interval is 8 μm, and alignment on the micron order is possible.

  FIG. 6F is a schematic cross-sectional view showing the alignment mark cut along the line AA in FIG. When the concave portion 15 formed on the glass substrate 1 shown in FIG. 6E and the concave portion 16 formed on the silicon substrate 2 face each other at the bonding surface, the state shown in FIG. A ridge 16a appears at an angle of 30 degrees in the depth direction and the anisotropic etching is stopped.

  FIG. 6G is a schematic plan view showing the arrangement of other alignment marks. For example, as shown in FIG. 6 (g), four concave portions 15 are arranged on the bonding surface of the glass substrate 1, and the silicon substrate 2 is positioned at a predetermined interval in the central portion where the concave portions 15 are arranged in plan view. You may form the recessed part 16 in this. Such an alignment mark arrangement method may be appropriately arranged in consideration of the wide field of view of the optical system used in the alignment step, the size of the alignment mark that is easily visible, and the like.

  Next, an alignment process for performing alignment using the above alignment marks will be described with reference to FIG. In the method for manufacturing the inkjet head 10 of the present embodiment, the bonding step of anodic bonding the glass substrate 1 as the first substrate and the silicon substrate 2 as the second substrate before the vibration plate portion 4 is formed is as follows. An alignment step of adjusting the position of the glass substrate 1 and the silicon substrate 2 using the first alignment mark formed on the glass substrate 1 and the second alignment mark formed on the silicon substrate 2 is provided. 7A to 7E are schematic cross-sectional views showing an alignment method between a glass substrate and a silicon substrate. This alignment method is a method of observing and recognizing an alignment mark with an optical system having a visible light camera 50.

  One of them is that, as shown in FIG. 7A, first, the visible light camera 50 is positioned above the bonding surface of the glass substrate 1, and the recess 15 as the first alignment mark formed on the glass substrate 1. Is captured and stored as an image. Next, as shown in FIG. 7B, the silicon substrate 2 is disposed on the bonding surface of the glass substrate 1 in a state where the bonding surface is opposed to the glass substrate 1 at a predetermined interval. The concave portion 17 as the second alignment mark formed on the surface opposite to the joint surface is imaged and stored as an image every time. The glass substrate 1 and the silicon substrate 2 are moved relative to each other in the plane direction so that the previously stored image of the recess 15 and the image of the recess 17 are superimposed. Then, as shown in FIG. 7C, the aligned glass substrate 1 and silicon substrate 2 are anodically bonded. Thereafter, if the diaphragm portion 4 is etched and formed on the silicon substrate 2 with the concave portion 17 as a reference, the diaphragm portion 4 and the electrode portion 8 can be disposed to face each other at a predetermined position. In this case, the concave portion 16 of the silicon substrate 2 formed on the bonding surface side with the glass substrate 1 may be eliminated.

  Another one is a recess 15 as a first alignment mark and a recess 16 as a second alignment mark facing each other at the bonding surface between the glass substrate 1 and the silicon substrate 2 as shown in FIG. Is recognized and imaged by an optical system having a visible light camera 50 from the opposite surface side to the bonding surface of the glass substrate 1 to perform alignment. In this case, with the glass substrate 1 and the silicon substrate 2 facing each other at a predetermined interval, the glass substrate 1 is seen from the transparent glass substrate 1 side, and the concave portions 15 and the concave portions 16 located on the bonding surface are formed. Positioning can be performed while taking images and storing them as images. Then, as shown in FIG. 7E, the aligned glass substrate 1 and silicon substrate 2 are anodically bonded. Thereafter, if the diaphragm portion 4 is etched and formed on the silicon substrate 2 with the concave portion 16 as a reference, the diaphragm portion 4 and the electrode portion 8 can be disposed to face each other at a predetermined position. In this case, the concave portion 17 of the silicon substrate 2 may be eliminated.

  8A to 8C are schematic cross-sectional views showing an alignment method using infrared light. In addition to the above-described method using visible light, it is a method using infrared light. Since the silicon substrate 2 is an opaque substrate, it has an IR (infrared) camera 51 for recognizing the recess 16 as the second alignment mark formed on the bonding surface of the silicon substrate 2 with the glass substrate 1. An optical system is used. As shown in FIG. 8A, first, the glass substrate 1 and the silicon substrate 2 are arranged to face each other, and the concave portion 15 as the first alignment mark formed on the glass substrate 1 is imaged through the silicon substrate 2. It is memorized as an image. Subsequently, as shown in FIG. 8B, the concave portion 16 as the second alignment mark formed on the bonding surface of the silicon substrate 2 is imaged and stored as an image every time. Then, alignment is performed by relatively moving the glass substrate 1 and the silicon substrate 2 in the plane direction so that the image of the recess 16 stored later is superimposed on the image of the recess 15 stored previously. According to this, it is possible to align the glass substrate 1 and the silicon substrate 2 while observing the concave portion 15 and the concave portion 16 in a state where the glass substrate 1 and the silicon substrate 2 are opposed to each other. Then, as shown in FIG. 8C, the aligned glass substrate 1 and silicon substrate 2 are anodically bonded. Thereafter, if the diaphragm portion 4 is etched and formed on the silicon substrate 2 with the concave portion 16 as a reference, the diaphragm portion 4 and the electrode portion 8 can be disposed to face each other at a predetermined position. In this case, the concave portion 17 of the silicon substrate 2 can be eliminated.

  The alignment step is a method in which an operator observes the monitor. However, the first substrate and the second substrate are recognized by recognizing that two alignment marks are coincident or in a predetermined relative position by image processing. May be aligned.

  Further, the method for forming the alignment mark and the method for bonding the silicon substrate made of single crystal silicon having the alignment mark formed by this method can be applied as a MEMS (Micro Electro Mechanical Systems) technique.

  Next, an ink jet printer according to an embodiment of the present invention will be described with reference to FIG. An ink jet printer 400 as a droplet discharge device of the present embodiment is equipped with an ink jet head 10 as a droplet discharge head.

  FIG. 9 is a schematic view showing the structure of an inkjet printer. Specifically, it is a schematic view seen from the scanning direction of the carriage 406 on which the inkjet head 10 is mounted.

  As shown in FIG. 9, the inkjet printer 400 includes feed rollers 402 and 405 for transporting the recording paper 401, press rollers 403 and 404 for pressing the recording paper 401 disposed to face the feed rollers 402 and 405, and an inkjet head. 10, an ink supply pipe 41, and an ink tank member 409.

  The inkjet head 10 is fixed to the carriage 406 via the base member 43 so that the nozzle surface 44 is parallel to the printing surface of the recording paper 401 at a predetermined interval. An ink supply pipe 41 connected to the ink tank member 409 is joined to the glass surface 45.

  A carriage 406 that moves the inkjet head 10 is supported by a carriage shaft 408 and includes a belt 407 that moves the carriage 406 in connection with a driving mechanism (not shown).

  The ink jet printer 400 includes a face ink jet type ink jet head 10, and ink is supplied from an ink tank member 409 through an ink supply pipe 41 joined to a glass surface 45 of the ink jet head 10. That is, the ink supply direction K and the ink discharge direction L are configured to be the same direction. Therefore, when the inkjet head 10 is driven, the ink droplets 42 are ejected onto the recording paper 401 positioned in parallel with the nozzle surface 44, and printing is performed by scanning the carriage 406 and feeding the recording paper 401.

The effect of this embodiment is as follows.
(1) The manufacturing method of the inkjet head 10 is formed on the silicon substrate 2 before the concave portion 15 as the first alignment mark formed on the glass substrate 1 having the electrode portion 8 and the vibration plate portion 4 are formed. The glass substrate 1 and the silicon substrate 2 are positioned using the concave portion 16 (or the concave portion 17) as the second alignment mark, and the glass substrate 1 and the silicon substrate 2 are anodically bonded. Thereafter, in order to form the vibration plate portion 4 on the silicon substrate 2 with the concave portion 16 (or the concave portion 17) as a reference, the ink jet head 10 in which the vibration plate portion 4 and the electrode portion 8 are arranged to face each other at a predetermined position with high accuracy. Can be manufactured.
(2) Since the diaphragm portion 4 and the electrode portion 8 are positioned so as to face each other at a predetermined position with high accuracy, the glass substrate 1 is bonded to the glass substrate 1 when the glass substrate 1 and the silicon substrate 2 are anodic bonded. The formed equipotential point 25 is surely in contact with the boron doped layer 4a of the silicon substrate 2 and is anodically bonded without causing a discharge between the vibration plate portion 4 and the electrode portion 8, so that the electrode portion 8 is damaged. Defects can be prevented.
(3) Since the vibration plate portion 4 and the electrode portion 8 can be positioned so as to face each other at a predetermined position with high accuracy on the order of microns, and the glass substrate 1 and the silicon substrate 2 are anodically bonded, vibration The electrostatic actuator 20 having the electromechanical conversion element 19 composed of the plate portion 4 and the electrode portion 8 disposed to face the plate portion 4 operates normally with high bonding reliability even when formed at a high density. Can do. Therefore, it is possible to provide the inkjet head 10 having the electrostatic actuator 20 formed with high density and having high reliability.
(4) The concave portion 16 or the concave portion 17 as the second alignment mark is formed by anisotropic etching so as to be a parallelogram or trapezoid in a plane shape on the plane orientation (110) plane of the silicon substrate 2. Therefore, the etching proceeds along the plane orientation (111), stops at a depth having an angle of 30 degrees, and does not proceed further. Therefore, the concave portion 16 or the concave portion 17 having a stable shape with little dimensional variation can be formed. Therefore, the accuracy of alignment using the recess 16 or the recess 17 can be improved.
(5) The concave portion 15 as the first alignment mark and the concave portion 16 as the second alignment mark have a predetermined interval (8 μm) in plan view when the glass substrate 1 and the silicon substrate 2 are properly bonded. Since the glass substrate 1 and the silicon substrate 2 are positioned relative to each other so as to be positioned, if this distance is confirmed, it can be easily determined whether or not the alignment is correctly performed.
(6) The inkjet head 10 is manufactured by anodically bonding the glass substrate 1 on which the electrode portion 8 is formed and the silicon substrate 2 (thickness of 525 μm) before the diaphragm portion 4 is formed, and then bonding the silicon substrate 2 Since the vibration plate portion 4 is formed by anisotropic etching after grinding to a thickness of 140 μm, the silicon substrate 2 is damaged due to the handling compared to the case where the thin silicon substrate 2 having a thickness of 140 μm is processed from the beginning. Can be reduced. Therefore, the inkjet head 10 can be manufactured with a high yield.
(7) Since at least one set of the alignment marks 62 is formed in the wafer 60 region other than the plurality of formation regions 61 at positions substantially symmetrical with respect to the center of the wafer 60, the alignment mark 62 has good visibility. In addition, it is easy to determine the correction direction and the correction amount even if the position is shifted in the rotation direction. Further, as compared with the case where the alignment mark 62 is arranged in the formation region 61, it is not necessary to secure the arrangement space of the alignment mark 62, and the formation region 61 can be arranged in the wafer 60 efficiently. Therefore, it is possible to prevent the number of ink jet heads 10 taken from the wafer 60 from decreasing.
(8) In the alignment step, the concave portion 15 as the first alignment mark formed on the glass substrate 1 is imaged using visible light and stored as an image. And the recessed part 17 as a 2nd alignment mark formed in the opposite surface with respect to the joint surface with the glass substrate 1 of the silicon substrate 2 is imaged, it memorize | stores it as an image every time, the image and recessed part of the recessed part 15 which were memorize | stored previously The first substrate and the second substrate are aligned by superimposing the 17 images. Therefore, the silicon substrate 2 is opaque but can be accurately aligned.
(9) In the alignment step, the glass substrate 1 is moved from the transparent glass substrate 1 side to the concave portion 15 and the concave portion 16 that are positioned opposite to each other on the bonding surface between the glass substrate 1 and the silicon substrate 2 using visible light. Since the image is picked up in a watermark and stored as an image every time, the concave portion 15 and the concave portion 16 can be aligned while being observed simultaneously.
(10) In the alignment step, IR (infrared light) is used to make the concave portion 15 and the concave portion 16 that are positioned opposite to each other at the bonding surface between the glass substrate 1 and the silicon substrate 2 from the opaque silicon substrate 2 side. Since the images are captured and stored as images, it is possible to align the concave portions 15 and 16 while simultaneously observing the concave portions 15 and 16 from the side opposite to the bonding surface of the silicon substrate 2 with the glass substrate 1.
(11) In the alignment step, the method of imaging each alignment mark (first alignment mark and second alignment mark) using IR (infrared light) is a rough surface of the surface on which each alignment mark is formed. In some cases, the captured image is unclear due to light scattering caused by light or attenuation of light in the thickness direction of the substrate. On the other hand, the method of capturing each alignment mark using visible light and recognizing or storing it as an image captures each alignment mark formed on each substrate (first substrate, second substrate) more clearly. can do. Therefore, the first substrate and the second substrate can be more accurately aligned.
(12) Since the inkjet printer 400 includes the inkjet head 10 including the electrostatic actuator 20 that operates reliably even when formed at a high density, the inkjet printer 400 having high quality characteristics can be provided. it can.

Modifications other than the present embodiment are as follows.
(Modification 1) The nozzle plate 3 is not limited to a wafer shape. For example, when a material other than silicon is used, the shape may be other than a wafer shape.
(Modification 2) The liquid that fills the inkjet head 10 as a droplet discharge head is not limited to ink. For example, if a dispersion solution in which fine particles of a metal material are dispersed in a liquid medium is used, this can be ejected as droplets onto a substrate (work) to form a wiring pattern made of the metal material.

The technical idea grasped from this embodiment and the modification is as follows.
(1) A first substrate having an electrode portion, a second substrate having a vibration plate portion, and a third substrate having a nozzle, and filled in a discharge chamber located facing the vibration plate portion. The liquid is pressurized by an electrostatic actuator having an electromechanical conversion element composed of the vibrating plate portion and the electrode portion arranged to face the vibrating plate portion at a predetermined interval, and the liquid is discharged as a droplet from the nozzle. In the method of manufacturing a droplet discharge head, the first mark forming step of forming a first alignment mark on the bonding surface of the first substrate to be bonded to the second substrate, and the first mark forming step. A second mark forming step of forming a second alignment mark on at least one surface of the second substrate at a position corresponding to the first alignment mark; and the first substrate and the second substrate. Said Method for manufacturing a droplet discharge head provided with a bonding step of bonding aligning and using one of the alignment mark and the second alignment mark.
(2) In (1), in the bonding step, the first substrate which is a glass substrate on which the electrode portion is formed and the second substrate which is a single crystal silicon substrate before the diaphragm portion is formed. Manufacturing method of a droplet discharge head.
(3) In (1) or (2), the second mark formation step includes a second alignment in which the planar shape is a parallelogram or trapezoid in the (110) plane of the second substrate which is a single crystal silicon substrate. A method of manufacturing a droplet discharge head, wherein at least one set of marks is formed by anisotropic etching.
(4) In any one of (1) to (3), the first mark formation step includes the first mark and the second substrate when the first substrate and the second substrate are correctly aligned. A droplet discharge head that forms at least one pair of the first alignment marks on the bonding surface of the first substrate so that the alignment marks and the second alignment marks are positioned at a predetermined interval in a plan view. Production method.
(5) In any one of (1) to (4), in the second mark formation step, the second alignment mark is placed on the first substrate before the diaphragm portion is formed on the second substrate. A method of manufacturing a droplet discharge head formed on a bonding surface with a substrate.
(6) In any one of (1) to (4), in the second mark formation step, the second alignment mark is moved to the first alignment mark before the diaphragm portion is formed on the second substrate. A method of manufacturing a droplet discharge head formed on a surface opposite to a bonding surface with a substrate.
(7) In any one of (1) to (4), in the second mark formation step, the second alignment mark is placed on the first substrate before the diaphragm portion is formed on the second substrate. A manufacturing method of a droplet discharge head formed on a bonding surface and an opposite surface to a substrate.
(8) In any one of (1) to (7), the first substrate and the second substrate are in a wafer shape, and a plurality of the electrostatic actuators corresponding to the plurality of nozzles are provided as one. A plurality of partitioned formation regions for forming a plurality of electrode portions and a plurality of diaphragm portions as a unit are formed in each wafer-like substrate, and the first alignment mark and the second alignment mark A method for manufacturing a droplet discharge head formed in a wafer region other than the plurality of formation regions.
(9) In any one of (1) to (7), the first substrate and the second substrate are in a wafer shape, and the plurality of electrostatic actuators corresponding to the plurality of nozzles are set to one. The first mark forming step and the second mark forming step have a plurality of partitioned forming regions for forming the plurality of electrode portions and the plurality of diaphragm portions as a unit in each wafer-like substrate. A method for manufacturing a droplet discharge head, wherein at least one set of the first alignment mark and the second alignment mark is formed for each of the formation regions.
(10) In (8) or (9), in the first mark forming step, at least one set of the first alignment marks is formed at a position substantially point-symmetric with respect to the center of the wafer-like first substrate. In the second mark forming step, at least the second alignment mark is placed on the second substrate so as to have the same coordinates relative to the first alignment mark formed on the first substrate. A manufacturing method of a droplet discharge head for forming one set.
(11) In any one of (1) to (5) and (7) to (10), the joining step includes the first substrate and the diaphragm that are glass substrates on which the electrode portions are formed. An alignment step of aligning the second substrate, which is a single crystal silicon substrate before the portion is formed, at a predetermined bonding position, and the alignment step includes the first substrate and the second substrate. The first alignment mark and the second alignment mark that are opposed to each other on the bonding surface with respect to the first substrate are imaged with visible light from the opposite surface side to the bonding surface of the first substrate and stored as an image every time. A method of manufacturing a droplet discharge head for alignment.
(12) In any one of (1) to (5) and (7) to (10), the bonding step includes the first substrate and the diaphragm that are glass substrates on which the electrode portions are formed. An alignment step of aligning the second substrate, which is a single crystal silicon substrate before the portion is formed, with a predetermined bonding position, and the alignment step is performed by first forming the first substrate on the first substrate. The first alignment mark is imaged with infrared light and stored as an image, and then formed on a surface opposite to the bonding surface of the second substrate disposed above the bonding surface of the first substrate. The second alignment mark is imaged with the infrared light and stored as an image every time, and the previously stored image of the first alignment mark and the image of the second alignment mark are stored. The first substrate and Method for manufacturing a droplet discharge head to align by relatively moving the serial second substrate in a planar direction.
(13) In any one of (1) to (4) and (6) to (10), the joining step includes the first substrate and the diaphragm that are glass substrates on which the electrode portions are formed. An alignment step of aligning the second substrate, which is a single crystal silicon substrate before the portion is formed, with a predetermined bonding position, and the alignment step is performed by first forming the first substrate on the first substrate. The first alignment mark was imaged with visible light and stored as an image, and then formed on the surface opposite to the bonding surface of the second substrate disposed above the bonding surface of the first substrate. The second alignment mark is imaged with the visible light and stored as an image, and the image of the first alignment mark and the image of the second alignment mark stored in advance are overlapped with each other. A first substrate and the first substrate Method for manufacturing a droplet discharge head for aligning by moving of the substrate in the planar direction relative.
(14) A droplet discharge head manufactured using the method for manufacturing a droplet discharge head according to any one of (1) to (13).

FIG. 2 is a schematic exploded perspective view showing a structure of a droplet discharge head according to the present embodiment. FIG. 2 is a schematic cross-sectional view of a droplet discharge head in which the substrates of FIG. 1 are stacked. FIG. 2 is a schematic plan view of the first substrate of FIG. 1. The flowchart which shows the manufacturing process of an inkjet head. (A)-(f) is a schematic sectional drawing which shows the processing state of each board | substrate corresponding to the flowchart of FIG. (G)-(k) is a schematic sectional drawing which shows the processing state of each board | substrate corresponding to the flowchart of FIG. (L)-(p) is a schematic sectional drawing which shows the processing state of each board | substrate corresponding to the flowchart of FIG. (A)-(g) is schematic which shows the formation method of an alignment mark. (A)-(c) is a schematic sectional drawing which shows an example of the alignment method of a glass substrate and a silicon substrate, (d), (e) is a schematic sectional drawing which shows another example of the alignment method. (A)-(c) is a schematic sectional drawing which shows the alignment method using infrared light. Schematic which shows the structure of an inkjet printer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Glass substrate as 1st substrate, 2 ... Silicon substrate as 2nd substrate, 3 ... Nozzle substrate as 3rd substrate, 4 ... Vibration plate part, 5 ... Discharge chamber, 8 ... Electrode part, 10 DESCRIPTION OF SYMBOLS ... Inkjet head as droplet discharge head, 12 ... Nozzle, 15 ... Recessed portion as first alignment mark, 16, 17 ... Recessed portion as second alignment mark, 19 ... Electromechanical transducer, 20 ... Electrostatic actuator , 50 ... Visible light camera, 51 ... IR (infrared) camera, 60 ... Wafer, 61 ... Formation region, 62 ... Alignment mark formed at substantially point-symmetrical position on wafer-like substrate, 400 ... Droplet ejection device As an inkjet printer.

Claims (17)

A method for bonding substrates,
A first mark forming step of forming a first alignment mark on at least one surface of the first substrate;
A second mark forming step of forming a second alignment mark on at least one surface of a second substrate which is a silicon substrate;
An alignment step of aligning the first alignment mark and the second alignment mark to adjust the position of the first substrate and the second substrate;
A method for bonding substrates, comprising: a bonding step of bonding the first substrate and the second substrate whose positions are adjusted.   The method for bonding substrates according to claim 1, wherein the first substrate is a glass substrate, and the first substrate and the second substrate are anodically bonded.   3. The substrate according to claim 1, wherein in the second mark forming step, the second alignment mark having a parallelogram shape or a trapezoid shape is formed on the second substrate by anisotropic etching. 4. Joining method.   The said 1st mark formation process WHEREIN: The said 1st alignment mark is formed in the substantially point-symmetrical position with respect to the center of the said 1st board | substrate. Substrate bonding method.   In the alignment step, each of the first alignment mark and the second alignment mark is imaged and one alignment mark is stored as an image, and the stored image of the first alignment mark and the second alignment mark are stored. 5. The substrate according to claim 1, wherein alignment is performed by relatively moving the first substrate and the second substrate so as to overlap an image of an alignment mark. 6. Joining method.   The alignment step includes aligning the first alignment mark and the second alignment mark while observing the first alignment mark and the second alignment mark from the opposite side to the bonding surface of the first substrate. 5. The method for bonding substrates according to any one of items 4 to 4. At least a first substrate constituting an actuator, a second substrate having a flow path serving as a discharge chamber filled with liquid on at least one surface, and a third substrate having a nozzle communicating with the discharge chamber A method of manufacturing a droplet discharge head configured to pressurize the liquid filled in the discharge chamber by the actuator and discharge the liquid as droplets from the nozzle;
A method for manufacturing a droplet discharge head, comprising: bonding the first substrate and the second substrate using the substrate bonding method according to claim 1. The diaphragm unit includes a first substrate having an electrode part, a second substrate having a diaphragm part constituting one surface of the discharge chamber, and a third substrate having a nozzle communicating with the discharge chamber. And the displacement of the diaphragm portion by an actuator having an electromechanical conversion element composed of the electrode portion disposed opposite to the diaphragm portion at a predetermined interval, so that the volume of the discharge chamber containing the liquid is increased. A method of manufacturing a droplet discharge head that discharges the liquid as droplets from the nozzle by changing,
A method for manufacturing a droplet discharge head, comprising: bonding the first substrate and the second substrate using the substrate bonding method according to claim 1. The diaphragm unit includes a first substrate having an electrode part, a second substrate having a diaphragm part constituting one surface of the discharge chamber, and a third substrate having a nozzle communicating with the discharge chamber. And the volume of the discharge chamber containing the liquid is changed by displacing the diaphragm part by an actuator having an electromechanical conversion element composed of the electrode part disposed opposite to the diaphragm part at a predetermined interval. A liquid droplet discharge head for discharging the liquid from the nozzle,
A first alignment mark is formed on at least one surface of the first substrate, and a second alignment mark is formed on at least one surface of the second substrate which is a silicon substrate. A droplet discharge head.   The droplet discharge head according to claim 9, wherein the first alignment mark is formed on a bonding surface of the first substrate that is bonded to the second substrate.   The said 1st alignment mark is formed in the joint surface with a said 2nd board | substrate in the substantially point-symmetrical position with respect to the center of the said 1st board | substrate. Droplet discharge head.   The liquid droplet ejection head according to claim 9, wherein the second alignment mark is formed on a bonding surface of the second substrate that is bonded to the first substrate.   10. The droplet discharge head according to claim 9, wherein the second alignment mark is formed on a surface opposite to a bonding surface of the second substrate bonded to the first substrate.   10. The droplet discharge head according to claim 9, wherein the second alignment mark is formed on a bonding surface and an opposite surface of the second substrate to be bonded to the first substrate.   The said 2nd alignment mark is formed in the said 2nd board | substrate by anisotropic etching so that it may become a parallelogram or trapezoid shape, It is any one of Claim 9 thru | or 14 characterized by the above-mentioned. Droplet discharge head. The first alignment mark is formed outside the formation region of the electrode part,
The liquid droplet ejection head according to claim 9, wherein the second alignment mark is formed outside a region where the vibration plate portion is formed. A droplet discharge apparatus comprising the droplet discharge head according to any one of claims 9 to 16.

Images