JP3595885B2 - Plasma processing method and plasma apparatus - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a plasma processing method for processing a sample such as a semiconductor element and an electronic material using plasma, and a plasma apparatus used for performing the method.
[0002]
[Prior art]
An ECR plasma apparatus that processes a sample using electron cyclotron resonance can generate plasma with a low gas pressure and a high degree of ionization. Therefore, the ion energy can be selected in a wide range, and it has advantages such as excellent ion directivity and uniformity. Therefore, it is indispensable for processes such as thin film formation and etching in the production of highly integrated semiconductor devices. The technology is not available, and its research and development are underway.
[0003]
FIG. 6 is a schematic sectional view showing a conventional ECR plasma device. In the figure, reference numeral 1 denotes a cylindrical plasma chamber, on the upper side of which a microwave introduction tube 6 is connected via a microwave introduction window 11. A reaction chamber 3 is provided below the plasma chamber 1 via a plasma extraction window 12. Further, an excitation coil 10 is arranged around the plasma chamber 1. The center of the bottom of the reaction chamber 3 protrudes in a trapezoidal shape, and the center forms a sample stage 5 for holding the sample S by electrostatic attraction.
[0004]
A gas pipe 7 for supplying a reaction gas is provided on an upper side wall of the reaction chamber 3, and an exhaust port 8 for exhausting gas is provided on a lower side wall of the reaction chamber 3. A loading / unloading port 9 for loading / unloading the sample S is opened in a lower side wall of the reaction chamber 3 facing the exhaust port 8. An inner bell jar 2, which is a transparent quartz glass container, is fitted to the inner wall of the plasma chamber 1 to protect the wall from plasma. The window frame of the plasma extraction window 12 is formed by a part of the inner bell jar 2. A portion of the inner wall of the reaction chamber 3 excluding the positions where the gas pipe 7, the exhaust port 8 and the loading / unloading port 9 are attached, the periphery of the sample S, and the side surface of the sample table 5 are frost-treated quartz deposition plates. 4 is covered.
[0005]
In the ECR plasma apparatus configured as described above, the inside of the plasma chamber 1 and the reaction chamber 3 is maintained at a required degree of vacuum by exhausting from the exhaust port 8 while supplying the reaction gas from the gas pipe 7. At the same time, a magnetic field is formed by the exciting coil 10 and microwaves are introduced from the microwave introducing tube 6 to apply a high-frequency electric field to generate plasma. The generated plasma is introduced from the plasma chamber 1 to the vicinity of the sample S in the reaction chamber 3 through the plasma extraction window 12 by the diverging magnetic field formed by the excitation coil 10, and ions in the plasma flow are generated on the surface of the sample S. A surface reaction is caused by the radical particles, and a process such as film formation and etching is performed on the surface of the sample S.
[0006]
[Problems to be solved by the invention]
However, in such a conventional plasma apparatus, a reaction product is generated when the sample S is subjected to the plasma processing, and adheres to the inner bell jar 2 of the plasma chamber 1 and the quartz deposition plate 4 of the reaction chamber 3. At the start and end of the plasma processing, the attached matter is separated by minute vibrations or impacts such as on / off of plasma generation or on / off of supply of a reaction gas, thereby forming particles. The particles fall on the sample S to cause processing defects of the sample S, and when the sample S is not mounted, the particles fall on the sample table 5 to contaminate the back surface of the sample S.
[0007]
The present invention has been made in view of such circumstances, and supplies an inert gas that does not affect the processing of a sample to a reaction chamber between processings, and / or turns on / off the reaction gas. A plasma processing method that can greatly reduce the number of particles adhering to a sample by covering the sample stage with a quartz glass plate when the plasma is turned off and when plasma irradiation is turned on and off, and a plasma apparatus used for performing the method. The purpose is to provide.
[0008]
[Means for Solving the Problems]
In the plasma processing method according to the present invention, a plasma is generated by introducing a reaction gas and a microwave, the plasma is introduced into a reaction chamber, a plurality of samples are sequentially placed on a sample table in the reaction chamber, and a sample is placed. In the plasma processing method, the sample stage is covered with a quartz glass plate before the plasma generation is stopped after one plasma processing is completed, the supply of the reaction gas is stopped, and the supply of the inert gas is started. The completed sample is removed from the reaction chamber, the next sample is loaded into the reaction chamber, placed on the sample table, the supply of inert gas is stopped, the supply of reaction gas is restarted, and plasma generation is restarted. and, moved, characterized in that to resume the processing of the samples the quartz glass plate from the sample stage toward the exhaust port provided in the reaction chamber.
Further, the plasma processing method according to the present invention is characterized in that the supplied inert gas is exhausted from the exhaust port.
[0009]
The plasma apparatus according to the present invention is a plasma apparatus that introduces a plasma generated by introduction of a reaction gas and a microwave into a reaction chamber, and sequentially mounts a plurality of samples on a sample table in the reaction chamber to perform plasma processing on the samples. And a gas pipe for supplying an inert gas to the reaction chamber, and a gas pipe which can be moved to a position covering the sample stage and a position on the side of an exhaust port provided in the reaction chamber. And a quartz glass at a position covering the sample stage until the plasma generation is resumed before stopping, and when the quartz glass plate is at a position covering the sample stage and the introduction of the reaction gas is stopped, the gas tube is A configuration in which the supply of the inert gas is started, and the supply of the inert gas is stopped and the supply of the reaction gas is restarted when the processed sample is unloaded and the next sample is placed on the sample table. West Characterized in that there.
The plasma apparatus according to the present invention is characterized in that the supplied inert gas is exhausted from the exhaust port.
[0010]
[Action]
In the present invention, the separation of the reaction product is promoted by supplying an inert gas that does not affect the processing of the sample to the reaction chamber between the processings. Further, the inert gas in which the reaction product floats is discharged outside the reaction chamber by exhaustion from an exhaust port provided conventionally. Thereby, particles in the reaction chamber can be removed.
When the reaction gas is turned on and off, and when plasma irradiation is turned on and off, the sample table is covered with a quartz glass plate, so particles that have separated from the side of the reaction chamber due to minute vibrations or shocks fall on the sample table. Can be prevented. Thereby, the number of particles adhering to the back surface of the sample is greatly reduced.
By using the supply of the inert gas and the use of the quartz glass plate in combination, the number of particles adhering to the front and back surfaces of the sample can be further reduced.
[0011]
【Example】
Hereinafter, the present invention will be specifically described with reference to the drawings showing the embodiments.
FIG. 1 is a schematic sectional view showing a plasma apparatus according to the present invention. In the figure, reference numeral 1 denotes a cylindrical plasma chamber made of stainless steel and having an inner diameter of 275 mm and a height of 200 mm, and a microwave introduction pipe 6 is connected to the upper side of the plasma chamber via a microwave introduction window 11. A cylindrical reaction chamber 3 made of stainless steel and having an inner diameter of 450 mm is continuously provided below the plasma chamber 1 through a plasma extraction window 12. Further, an excitation coil 10 is arranged around the plasma chamber 1. A central portion of the bottom of the reaction chamber 3 is formed in a trapezoidal shape, and a central portion thereof serves as a sample stage 5 for holding the sample S by electrostatic attraction. The distance from the lower end of the plasma chamber 1 to the sample S on the sample stage 5 is 270 mm.
[0012]
A gas pipe 7 for supplying a reaction gas is provided on an upper side wall of the reaction chamber 3, and an exhaust port 8 for exhausting gas is provided on a lower side wall of the reaction chamber 3. A loading / unloading port 9 for loading / unloading the sample S is opened in a lower side wall of the reaction chamber 3 facing the exhaust port 8. An inner bell jar 2, which is a transparent quartz glass container, is fitted to the inner wall of the plasma chamber 1 to protect the wall from plasma. The window frame of the plasma extraction window 12 is formed by a part of the inner bell jar 2. A portion of the inner wall of the reaction chamber 3 excluding the positions where the gas pipe 7, the exhaust port 8 and the loading / unloading port 9 are attached, the periphery of the sample S, and the side surface of the sample table 5 are frost-treated quartz deposition plates. 4 is covered.
[0013]
Further, a gas pipe 14 for introducing an inert gas is provided on the upper surface of the plasma chamber 1 outside the microwave introduction window 11. A disk 15 (diameter: 270 mm, thickness: 3 mm) made of quartz glass for covering the sample table 5 between treatments is made of aluminum so that the moving device 13 can move in the left-right direction in the figure. Supported by the tool 16.
[0014]
In the ECR plasma apparatus configured as described above, the inside of the plasma chamber 1 and the reaction chamber 3 is maintained at a required degree of vacuum by exhausting from the exhaust port 8 while supplying the reaction gas from the gas pipe 7. At the same time, a magnetic field is formed by the exciting coil 10 and microwaves are introduced from the microwave introducing tube 6 to apply a high-frequency electric field to generate plasma. The generated plasma is introduced from the plasma chamber 1 to the vicinity of the sample S in the reaction chamber 3 through the plasma extraction window 12 by the diverging magnetic field formed by the excitation coil 10, and ions in the plasma flow are generated on the surface of the sample S. A surface reaction is caused by the radical particles, and a process such as film formation and etching is performed on the surface of the sample S.
[0015]
Immediately before the plasma irradiation is turned off to carry out the processed sample S and carry in the next sample S, the moving device 13 is driven to move the disk 15 above the sample table 5 (shown by a solid line). After that, the supply of the reaction gas from the gas pipe 7 is turned off. When the supply of the reaction gas is turned off, introduction of the inert gas from the gas pipe 14 is started. Then, the processed sample S is carried in and taken out of the carry-out port 9, the next sample S is carried in, carried into the reaction chamber 3 through the carry-out port 9, and placed on the sample table 5. Thereafter, the introduction of the inert gas from the gas pipe 14 is stopped, the supply of the reaction gas from the gas pipe 7 is restarted, and the plasma irradiation is restarted. After the plasma is stabilized, the moving device 13 is driven to move the disk 15 from above the sample table 5 to a standby position (shown by a broken line), and processing of the sample S is restarted.
[0016]
FIG. 2 is a graph showing the number of particles of the sample S processed in the apparatus of the present invention having the above-described configuration in accordance with the number of processed samples. 3 shows the case where the inert gas is introduced but the disk 15 is not used, FIG. 4 shows the case where the disk 15 is used but the inert gas is not introduced, and FIG. It is a graph shown respectively. Even if the inert gas is introduced only as shown in FIG. 3, the number of particles is reduced as compared with the conventional case (FIG. 5), and if only the disk 15 is used as shown in FIG. 4, the inert gas shown in FIG. 3 is introduced. The number of particles is smaller than that of the case only, and the number of particles is particularly significantly reduced on the back surface. As shown in FIG. 2, when both the inert gas and the disk 15 are used, the number of particles is further reduced, and the tendency is particularly remarkable on the surface.
[0017]
In this embodiment, the case of the ECR plasma apparatus is described. However, the present invention can be applied to a plasma apparatus that does not use cyclotron resonance.
[0018]
【The invention's effect】
As described above, the plasma processing method according to the present invention and the plasma apparatus used for carrying out the method are characterized by supplying an inert gas that does not affect the processing of the sample to the reaction chamber between the processings. Promotes exfoliation of the product. Further, the inert gas in which the reaction product floats is discharged outside the reaction chamber by exhaustion from an exhaust port provided conventionally. Thereby, particles in the reaction chamber can be removed.
When the reaction gas is turned on and off, and when plasma irradiation is turned on and off, the sample table is covered with a quartz glass plate, so particles that have separated from the side of the reaction chamber due to minute vibrations or shocks fall on the sample table. Can be prevented. Thereby, the number of particles adhering to the back surface of the sample is greatly reduced. As described above, the present invention has excellent effects, for example, it is possible to improve the yield rate in plasma processing.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a plasma device according to the present invention.
FIG. 2 is a graph showing the number of particles of a sample processed in the apparatus according to the present invention in correspondence with the number of processed samples.
FIG. 3 is a graph showing the number of particles when an inert gas is introduced but a disk is not used.
FIG. 4 is a graph showing the number of particles when a disk is used but no inert gas is introduced.
FIG. 5 is a graph showing the number of particles when processed by a conventional apparatus.
FIG. 6 is a schematic sectional view showing a conventional plasma device.
[Explanation of symbols]
3 Reaction chamber 5 Sample table 7, 14 Gas pipe 8 Exhaust port 9 Carry in / out port 13 Moving device 15 Disk S Sample

Claims (4)

In a method of introducing plasma into a reaction chamber by introducing a reaction gas and a microwave, introducing the plasma into a reaction chamber, and sequentially mounting a plurality of samples on a sample table in the reaction chamber to perform plasma processing on the samples,
Before one plasma processing is completed and the plasma generation is stopped, the sample stage is covered with a quartz glass plate,
Stop supplying the reaction gas,
Start supplying inert gas,
Remove the processed sample from the reaction chamber,
The next sample is carried into the reaction chamber and placed on the sample table,
Stop supplying inert gas,
Restart the supply of reaction gas,
Restart plasma generation,
The plasma processing method characterized in that the quartz glass plate is moved from the sample stage toward the exhaust port provided in the reaction chamber to resume processing of the sample. The plasma processing method according to claim 1, wherein the supplied inert gas is exhausted from the exhaust port. In a plasma apparatus for introducing plasma generated by the introduction of a reaction gas and a microwave into a reaction chamber, and sequentially processing a plurality of samples on a sample table in the reaction chamber to perform plasma processing on the samples,
  A gas pipe for supplying an inert gas to the reaction chamber;
  It can be moved between a position covering the sample stage and a position on the side of the exhaust port provided in the reaction chamber, and a position covering the sample stage until the plasma generation is restarted after stopping the plasma generation at the end of one plasma process. Quartz glass
  With
  When the quartz glass plate is at a position covering the sample table and the introduction of the reaction gas is stopped, the supply of the inert gas from the gas pipe is started, and the processed sample is carried out and the next sample is loaded. A plasma apparatus characterized in that the supply of an inert gas is stopped and the supply of a reaction gas is restarted when the apparatus is placed on a table. The plasma device according to claim 3, wherein the supplied inert gas is exhausted from the exhaust port.

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