JP4024389B2 - Plasma processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for performing processing such as etching or ashing on a semiconductor substrate or a glass substrate for a liquid crystal display by plasma generated using microwaves.
[0002]
[Prior art]
Plasma generated by applying energy to the reaction gas from the outside is widely used in manufacturing processes such as LSI or LCD. In particular, the use of plasma is an indispensable basic technology in the dry etching process. As the size of the substrate to be processed by the plasma increases, it is required to generate the plasma uniformly over a wider area. Also, in the dry etching technique or the embedding process technique in thin film formation, it is also required that the generation of plasma and the acceleration energy applied to ions in the plasma can be controlled separately. For this reason, the following plasma processing apparatus has been proposed.
[0003]
FIG. 8 is a side sectional view showing a conventional plasma processing apparatus, in which 1 is a reactor formed by molding aluminum or stainless steel into a rectangular box shape. A microwave inlet is provided in the upper part of the reactor 1, and the microwave inlet is sealed in an airtight state by a sealing plate 33. The sealing plate 33 is made of a dielectric material such as quartz glass or alumina, which has heat resistance and microwave transparency and has a low dielectric loss.
[0004]
Between the sealing plate 33 and the reactor 1, an annular electrode plate 5 having an outer diameter substantially the same as the outer diameter of the reactor 1 and an inner diameter smaller than the inner diameter of the reactor 1 is interposed. The annular electrode plate 5 and the reactor 1 are each electrically grounded.
[0005]
A rectangular lid-shaped cover member 8 that covers the upper portion of the reactor 1 is connected to the reactor 1. A dielectric line 9 is attached to the ceiling portion in the cover member 8, and an air gap 10 is formed between the dielectric line 9 and the sealing plate 33. The dielectric line 9 is made of a dielectric material such as Teflon (registered trademark) such as fluororesin, polyethylene resin, or polystyrene resin, which is formed into a substantially feather-plate shape in plan view, and its convex portion is connected to the peripheral surface of the cover member 8. The waveguide 21 is fitted inside. A microwave oscillator 20 is connected to the waveguide 21, and the microwave oscillated by the microwave oscillator 20 propagates from the convex portion of the dielectric line 9 to the entire dielectric line 9 through the waveguide 21.
[0006]
This microwave is reflected by the end face of the cover member 8 facing the waveguide 21, and the incident wave and the reflected wave are superimposed to form a standing wave in the dielectric line 9. Due to this standing wave, a leakage electric field is formed below the dielectric line 9, which is introduced into the reactor 1 through the air gap 10 and the sealing plate 33. The inside of the reactor 1 is a processing chamber 2, and a mounting table 11 on which the workpiece W is mounted is disposed at the center of the bottom of the processing chamber 2. A high frequency power supply 18 is connected to the mounting table 11, and a high frequency electric field is formed between the mounting table 11 and the annular electrode plate 5 by applying a voltage of a predetermined frequency from the high frequency power supply 18 to the mounting table 11. .
[0007]
In such a plasma processing apparatus, since microwaves are introduced into the processing chamber 2 from the dielectric line 9 provided on the cover member 8 that covers the reactor 1, the plasma processing apparatus is substantially uniformly distributed over a wide area in the processing chamber 2. Plasma can be generated. Further, by adjusting the high frequency applied to the mounting table 11, the energy of ions in the plasma generated in the processing chamber 2 can be controlled.
[0008]
[Problems to be solved by the invention]
By the way, when etching a silicon oxide film, a reactive gas using C ₄ F ₈ gas as a base gas may be used instead of a reactive gas using CHF ₃ gas as a base gas. This is because, when opening a hole in a silicon oxide film, the corner of the hole is suppressed from becoming tapered in the case of C ₄ F ₈ gas compared to CHF ₃ gas, and the dependency of the etching shape on the hole diameter is suppressed. This is because it can be suppressed.
[0009]
However, when the workpiece W on which the silicon oxide film is formed is etched using a reaction gas having a C ₄ F ₈ gas as a base gas with a conventional apparatus, the process proceeds from the center of the workpiece W toward the peripheral portion. The etching rate tends to decrease, and it is difficult to obtain processing conditions for uniformly etching the entire region of the workpiece W.
[0010]
The present invention has been made in view of such circumstances, and the object of the present invention is to form a ring-shaped or spiral groove in a sealing member that seals a part of the container. An object of the present invention is to provide a plasma processing apparatus capable of easily and uniformly processing the entire region of an object to be processed even when a reaction gas using C ₄ F ₈ gas as a base gas is used.
[0011]
[Means for Solving the Problems]
The plasma processing apparatus according to the present invention generates plasma by introducing a microwave through a sealing member that is partially sealed with a sealing member, and the generated plasma generates the plasma. an apparatus for processing an object to be processed which is disposed opposite to the sealing member, wherein the sealing member, Ri tear formed vortex winding grooves, the eddy-winding grooves is of the object to be processed in the sealing member wherein the formed tear Rukoto so as to include a portion which faces in the vicinity of the peripheral portion.
[0012]
In the plasma processing apparatus according to the present invention, a microwave is incident on a dielectric line provided to face a sealing member that seals a part of the container, and the sealing member enters the container from the dielectric line. the by transmitting to generate plasma by introducing microwaves, the apparatus for processing an object to be processed which is disposed opposite to the sealing member by the generated plasma, the sealing member, the eddy-winding grooves formed tear is, eddy-winding groove is characterized by the formation tare Rukoto so as to include a portion facing the peripheral portion near the object to be processed in the sealing member.
[0013]
The plasma processing apparatus according to the present invention generates plasma by introducing a microwave through a sealing member that is partially sealed with a sealing member, and the generated plasma generates the plasma. In the apparatus for processing an object to be processed disposed opposite to the sealing member, a microwave limiting plate having a hole having a predetermined diameter for limiting a region where the microwave is introduced into the container is formed on the surface of the sealing member. is arranged, discontinuous grooves in the the back surface opposite to the object to be processed in multiple circular of the sealing member corresponds to a region where the microwave restriction plate surrounds the thickness direction of the sealing member The plurality of annular discontinuous grooves are formed so as to include a portion facing the periphery of the object to be processed of the sealing member.
[0014]
In the plasma processing apparatus according to the present invention, a microwave is incident on a dielectric line provided to face a sealing member that seals a part of the container, and the sealing member enters the container from the dielectric line. In the apparatus for generating a plasma by introducing microwaves and processing an object to be processed disposed opposite to the sealing member by the generated plasma, a microwave is placed on the surface of the sealing member into a container. A microwave restricting plate having a hole with a predetermined diameter for restricting a region where the microwave is introduced is disposed on the back surface of the sealing member facing the object to be processed corresponding to the region surrounded by the microwave restricting plate. the discontinuous grooves of multiple annular Yes formed in the thickness direction of the sealing member, discontinuous grooves of said plurality of annular near the peripheral portion of the object to be processed in the sealing member It must be formed to include opposing parts And features.
[0015]
In the plasma processing apparatus according to the present invention, a groove is formed in the sealing member that seals a part of the container, thereby reducing the thickness of the other part of the sealing member. Since the energy intensity of the microwave introduced into the reactor is larger when the sealing member is thinner than when the sealing member is thicker, the plasma generated in the former case is more than the latter case. The density of is high. The groove is formed so as to correspond to a portion where the processing speed of the object to be processed is relatively slow, that is, to include a portion facing the periphery of the object to be processed of the sealing member or to include the portion.
[0016]
As a result, even when a reaction gas having a C ₄ F ₈ gas as a base gas is introduced into the reactor, a plasma having a substantially uniform density can be easily generated in the reactor. The surface of the substrate is processed substantially uniformly over its entire area.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below with reference to the drawings.
(Embodiment 1)
FIG. 1 is a side sectional view showing a plasma processing apparatus according to the present invention. In the figure, 1 is a reactor formed by forming aluminum or stainless steel into a rectangular box shape. A microwave inlet is opened in the upper center of the reactor 1, and the microwave inlet is sealed in an airtight state by a sealing plate 3. The sealing plate 3 is formed of a dielectric material such as quartz glass or alumina, which has heat resistance and microwave transparency and has a low dielectric loss.
[0018]
Between the sealing plate 3 and the reactor 1, an annular electrode plate 5 having an outer diameter substantially the same as the outer diameter of the reactor 1 and an inner diameter smaller than the inner diameter of the reactor 1 is interposed. . The annular electrode plate 5 and the reactor 1 are each electrically grounded.
[0019]
A rectangular lid-shaped cover member 8 that covers the upper portion of the reactor 1 is connected to the reactor 1. A dielectric line 9 is attached to the ceiling portion in the cover member 8, and an air gap 10 is formed between the dielectric line 9 and the sealing plate 3. The dielectric line 9 is made of a dielectric material such as Teflon (registered trademark) such as fluororesin, polyethylene resin, or polystyrene resin, which is formed into a substantially feather-plate shape in plan view, and its convex portion is connected to the peripheral surface of the cover member 8. The waveguide 21 is fitted inside. A microwave oscillator 20 is connected to the waveguide 21, and the microwave oscillated by the microwave oscillator 20 propagates from the convex portion of the dielectric line 9 to the entire dielectric line 9 through the waveguide 21.
[0020]
This microwave is reflected by the end face of the cover member 8 facing the waveguide 21, and the incident wave and the reflected wave are superimposed to form a standing wave in the dielectric line 9. Due to this standing wave, a leakage electric field is formed below the dielectric line 9, which passes through the air gap 10 and the sealing plate 3 and is introduced into the reactor 1. Further, on the sealing plate 3, there is a microwave limiting plate 7 in which a hole having an appropriate diameter is opened so as to face the above-described microwave inlet in order to limit the region where the microwave is introduced into the reactor 1. The microwave limiting plate 7 restricts the introduction of microwaves in the vicinity of the inner peripheral surface of the reactor 1.
[0021]
The inside of the reactor 1 is a processing chamber 2, and a required gas is introduced into the processing chamber 2 from a gas introduction pipe 15 fitted in a through hole penetrating the peripheral wall of the processing chamber 2. An exhaust port 16 is provided in the peripheral wall of the reactor 1, and the inside air of the processing chamber 2 is discharged from the exhaust port 16.
[0022]
In the center of the bottom of the processing chamber 2, a mounting table 11 on which the workpiece W is mounted is disposed, and the mounting table 11 is attached to the upper surface of the base 12. The base 12 is fixed to the reactor 1 via an insulating member 14, and the sides of the base 12 and the mounting base 11 are covered with a plasma shield member 13. A high frequency power source 18 is connected to the mounting table 11, and a high frequency electric field is applied between the mounting table 11 and the annular electrode plate 5 by applying a voltage of a predetermined frequency from the high frequency power source 18 to the mounting table 11. Form. The mounting table 11 is provided with a flow path (not shown) through which a heat medium flows so as to adjust the temperature of the mounting table 11.
[0023]
Using such a plasma processing apparatus, for example, in order to perform an etching process on the workpiece W on which a silicon oxide film is formed, a heating medium having an appropriate temperature is passed through the flow path of the mounting table 11, The mounting table 11 is adjusted to a required temperature and exhausted from the exhaust port 16 to depressurize the inside of the processing chamber 2 to a desired pressure, and then C ₄ F ₈ gas is introduced into the processing chamber 2 from the gas introduction pipe 15 as a base gas. The reaction gas was supplied.
[0024]
Next, a microwave is oscillated from the microwave oscillator 20 and introduced into the dielectric line 9 through the waveguide 21, and a standing wave is formed in the dielectric line 9. By this standing wave, a leakage electric field is formed below the dielectric line 9, which is introduced into the processing chamber 2 through the air gap 10, the opening of the microwave limiting plate 7 and the sealing plate 3. In this way, the microwave propagates into the processing chamber 2 and plasma is generated in the processing chamber 2. A high-frequency voltage is applied to the mounting table 11 from a high-frequency power source 18, and ions in the plasma are guided onto the workpiece W by a high-frequency electric field formed thereby, and the surface of the workpiece W is etched.
[0025]
FIG. 2 is a plan view of the sealing plate 3 shown in FIG. As shown in FIGS. 2 and 1, an annular groove 4 is provided concentrically with the central axis of the reactor 1 in a portion of the sealing plate 3 facing the opening of the annular electrode plate 5. The dimensions of the groove 4 are determined by the inner diameter of the annular electrode plate 5 and the thickness of the sealing plate 3 described above.
[0026]
By forming the groove 4 in the sealing plate 3 in this way, the thickness in the vicinity of the peripheral portion of the introduction port for introducing the microwave into the reactor 1 is made thinner than the thickness of the central portion of the introduction port. is there. The energy intensity of the microwave introduced into the reactor 1 is generated more in the former case than in the latter case because the thickness of the sealing plate 3 is smaller when the sealing plate 3 is thicker. The plasma density is high. Therefore, even when a reaction gas using C ₄ F ₈ gas as a base gas is introduced into the reactor 1, a plasma with a substantially uniform density is generated in a region facing the inlet in the reactor 1. can do. The ions in the plasma are guided to the surface of the workpiece W mounted on the mounting table 11 by the electric field formed between the mounting table 11 and the annular electrode plate 5, and the workpiece W is etched. Therefore, the surface of the workpiece W is processed substantially uniformly in the entire area.
[0027]
As described above, in the plasma processing apparatus according to the present invention, the microwave can be propagated substantially uniformly as a leakage electric field from the dielectric line 9 to the entire region of the sealing plate 3 opposed to the dielectric line 9 and sealed. By changing the width, depth, diameter, etc. of the groove 4 provided in the stop plate 3, the energy intensity of the microwave in the region facing the sealing plate 3 in the processing chamber 2 can be finely adjusted.
[0028]
(Embodiment 2)
FIG. 3 is a plan view showing another sealing plate according to the present invention. As shown in FIG. 3, a spiral groove 4 a is provided on the back surface of the substantially square sealing plate 3. As a result, plasma having a substantially uniform density is generated in a region facing the inlet in the reactor 1 as before, and the surface of the workpiece W (both see FIG. 1) is substantially uniform in the entire region. Is plasma treated. Further, the density of the plasma can be made more uniform by gradually reducing the width of the groove 4a from the outer peripheral side toward the inner peripheral side.
[0029]
In this embodiment, the number of turns of the spiral groove 4a is plural, but the present invention is not limited to this, and the spiral groove may be one. In this case, when the etching rate at a plurality of positions in the diameter direction of the workpiece is different from the etching rate at a plurality of positions in the direction orthogonal to the direction, by adjusting the direction in which the sealing plate is arranged The etching rate at a plurality of positions in both directions can be made uniform.
[0030]
In both of the above-described embodiments, the side surface of the groove is formed perpendicular to the bottom surface. However, the present invention is not limited to this, and the side surface of the groove may be tapered. In addition, although one annular groove or spiral groove is provided on the sealing plate, the present invention is not limited to this, and a plurality of annular grooves or spiral grooves may be provided on the sealing plate.
[0031]
Furthermore, although the groove | channel is provided continuously, it cannot be overemphasized that a discontinuous groove | channel may be provided in a sealing board not only this but this invention. In both the embodiments, the case where the present invention is applied to an apparatus in which microwaves are introduced into a reactor from a dielectric line opposed to each other on a sealing plate is shown, but the present invention is not limited thereto. Needless to say, the present invention can be applied to any plasma processing apparatus such as an electron cyclotron resonance plasma processing apparatus that introduces microwaves into a reactor through a sealing plate.
[0032]
【Example】
Next, the results of comparative tests will be described.
FIG. 4 is an explanatory view for explaining dimensions of main parts of the plasma processing apparatus according to the present invention, and FIG. 6 is an explanatory view for explaining dimensions of main parts of the plasma processing apparatus used in the comparative test. As shown in FIG. 4, in the plasma processing apparatus according to the present invention, the thickness TW1 of the central portion of the sealing plate is 30 mm, the thickness TW2 of the portion facing the annular electrode plate of the sealing plate is 20 mm, The inner diameter DA1 of the groove provided in the sealing plate is 200 mm, the outer diameter DA2 of the groove provided in the sealing plate is 280 mm, the depth HA1 of the groove provided in the sealing plate is 5 mm, and the inner diameter DA3 of the annular electrode plate is 298 mm. There is.
[0033]
On the other hand, as shown in FIG. 6, the plasma processing apparatus used in the comparative test is provided with a sealing plate having a cylindrical recess at the center of the back surface, and the thickness TW1 of the sealing plate is 30 mm, the thickness TW2 of the portion of the sealing plate facing the annular electrode plate is 20 mm, the diameter da1 of the recess is 280 mm, the depth ha1 of the recess is 10 mm, and the inner diameter DA3 of the annular electrode plate is 298 mm.
[0034]
A plasma is generated by introducing a reaction gas having C ₄ F ₈ gas as a base gas into both plasma processing apparatuses, and the object to be processed having a silicon oxide film formed on the surface is etched by the generated plasma. The etching rate was measured at appropriate intervals from the center of the processed product toward the peripheral edge.
[0035]
FIG. 7 is a graph showing the result of etching a workpiece on which a silicon oxide film is formed by the plasma processing apparatus used in the comparative test, where the vertical axis represents the relative etching rate and the horizontal axis represents the center of the workpiece. Indicates the position. In the figure, ◯ indicates the result of measurement at a plurality of positions in the diameter direction of the workpiece, and □ indicates the result of measurement at a plurality of positions in a direction orthogonal to the direction.
[0036]
As is clear from FIG. 7, in the plasma processing apparatus used for the comparative test, the etching rate decreases from the center of the object to be processed toward the peripheral part, and the entire area of the object to be processed is uniformly etched. I can't.
[0037]
FIG. 5 is a graph showing a result of etching a workpiece on which a silicon oxide film is formed by the plasma processing apparatus according to the present invention. Is shown. In the figure, ◯ indicates the result of measurement at a plurality of positions in the diameter direction of the workpiece, and □ indicates the result of measurement at a plurality of positions in a direction orthogonal to the direction.
[0038]
As apparent from FIG. 5, in the plasma processing apparatus according to the present invention, the etching rate at the center of the object to be processed and the etching rate at the periphery of the object to be processed are substantially the same, and the entire region of the object to be processed is Could be etched almost uniformly.
[0039]
【The invention's effect】
As described above in detail, in the plasma processing apparatus according to the present invention, even when a reaction gas containing C ₄ F ₈ gas as a base gas is introduced into the reactor, the reactor is substantially uniform in the reactor. The present invention has excellent effects, such as being able to generate plasma with a high density and being able to treat the surface of an object to be processed in a substantially uniform manner over the entire region.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing a plasma processing apparatus according to the present invention.
FIG. 2 is a plan view of the sealing plate shown in FIG.
FIG. 3 is a plan view showing another sealing plate according to the present invention.
FIG. 4 is an explanatory view illustrating dimensions of main parts of a plasma processing apparatus according to the present invention.
FIG. 5 is a graph showing a result of etching an object to be processed on which a silicon oxide film is formed by the plasma processing apparatus according to the present invention.
FIG. 6 is an explanatory diagram for explaining the main dimensions of a plasma processing apparatus used in a comparative test.
FIG. 7 is a graph showing a result of etching an object to be processed on which a silicon oxide film is formed by the plasma processing apparatus used in the comparative test.
FIG. 8 is a side sectional view showing a conventional plasma processing apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Reactor 2 Processing chamber 3 Sealing plate 4 Groove 5 Annular electrode plate 9 Dielectric line 11 Mounting base 18 High frequency power supply W Processed object

Claims (4)

A plasma is generated by introducing a microwave through a portion of the sealing member that is sealed with the sealing member, and the object to be processed is disposed opposite to the sealing member by the generated plasma. In an apparatus for processing things,
The sealing member is formed with a spiral groove,
2. The plasma processing apparatus according to claim 1, wherein the spiral groove is formed so as to include a portion facing the vicinity of the peripheral edge of the object to be processed of the sealing member. A microwave is incident on a dielectric line provided facing a sealing member that seals a part of the container, and the microwave is introduced from the dielectric line into the container through the sealing member. In the apparatus for generating the plasma by processing the object to be processed disposed facing the sealing member by the generated plasma,
The sealing member is formed with a spiral groove,
2. The plasma processing apparatus according to claim 1, wherein the spiral groove is formed so as to include a portion facing the vicinity of the peripheral edge of the object to be processed of the sealing member. A plasma is generated by introducing a microwave through a portion of the sealing member that is sealed with the sealing member, and the object to be processed is disposed opposite to the sealing member by the generated plasma. In an apparatus for processing things,
On the surface of the sealing member, a microwave restricting plate having a hole with a predetermined diameter for restricting a region where the microwave is introduced into the container is disposed, and the microwave restricting plate surrounds the region surrounding the microwave restricting plate. the back surface facing the object to be processed in the sealing member discontinuous grooves of multiple annular Yes formed in the thickness direction of the sealing member,
The plasma processing apparatus, wherein the plurality of annular discontinuous grooves are formed so as to include a portion facing a vicinity of a peripheral portion of the object to be processed of a sealing member. A microwave is incident on a dielectric line provided facing a sealing member that seals a part of the container, and the microwave is introduced from the dielectric line into the container through the sealing member. In the apparatus for generating the plasma by processing the object to be processed disposed facing the sealing member by the generated plasma,
On the surface of the sealing member, a microwave restricting plate having a hole with a predetermined diameter for restricting a region where the microwave is introduced into the container is disposed, and the microwave restricting plate surrounds the region surrounding the microwave restricting plate. the back surface facing the object to be processed in the sealing member discontinuous grooves of multiple annular Yes formed in the thickness direction of the sealing member,
The plasma processing apparatus, wherein the plurality of annular discontinuous grooves are formed so as to include a portion facing a vicinity of a peripheral portion of the object to be processed of a sealing member.

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