JP3729615B2 - Plasma processing apparatus and plasma processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and method for performing processing such as etching, ashing, or CVD on a semiconductor element substrate, a glass substrate for a liquid crystal display, etc. using plasma, and in particular, a plasma processing apparatus that generates plasma by introducing microwaves, and The present invention relates to a plasma processing method.
[0002]
[Prior art]
Plasma generated by applying energy to the reaction gas from the outside is widely used in manufacturing processes of LSI, LCD, and the like. In particular, the use of plasma has become an indispensable basic technology in dry etching processes.
[0003]
FIG. 4 is a schematic longitudinal sectional view showing a configuration of a conventional plasma processing apparatus proposed by the applicant of the present application. As shown in the figure, the plasma processing apparatus includes a reaction vessel 11 made of aluminum or stainless steel having a rectangular shell shape, a metal microwave introduction vessel 21 connected to the upper side of the reaction vessel 11, and the microwave introduction vessel. The waveguide 22 connected to the microwave introduction end 21 of the microwave, the microwave oscillator 23 connected to the microwave introduction side of the waveguide 22, and the microwave introduction container 21 are arranged to face each other with a gap. A dielectric line 24, a microwave introduction window 25, a counter electrode 13 having a circular opening disposed on the lower peripheral edge of the microwave introduction window 25, and a sample stage 15 disposed in the reaction vessel 11. Configured. The microwave introduction window 25 is arranged with its lower surface facing the reaction chamber 12 formed inside the reaction vessel 11, and seals the reaction chamber 12. The counter electrode 13 is electrically grounded.
[0004]
The sample stage 15 in the reaction chamber 12 is disposed at a position opposite to the microwave introduction window 25, and the sample S is placed on the sample stage. A high frequency power source 14 is connected to the sample stage 15. The reaction chamber 12 is formed with an inlet 16 for introducing gas and an exhaust port 17 connected to an exhaust device (not shown).
[0005]
In such a plasma apparatus, the dielectric line 24 is formed of a material having a small dielectric loss, for example, a fluororesin such as Teflon (registered trademark), and the microwave introduction window 25 has heat resistance and microwave transmission. For example, a dielectric material such as quartz glass or alumina (Al ₂ O ₃ ) is used. Further, the counter electrode 13 provided for stably generating a bias voltage on the surface of the sample S is anodized on a part of the surface of aluminum in order to prevent the generation of reactants during plasma generation. A so-called alumite treatment is performed, and at least a portion exposed to plasma in the reaction chamber 12 is covered with alumina (Al ₂ O ₃ ).
[0006]
[Problems to be solved by the invention]
When the sample S is subjected to plasma processing using the plasma processing apparatus configured as described above, the inside of the microwave introduction container 21 is heated. By setting the microwave introduction window 25 to a high temperature of about 200 ° C., the plasma processing is speeded up, and generation of particles due to deposition of the microwave introduction window 25 during etching is prevented. The microwave introduction window 25 is further heated by the introduction of the microwave into the microwave introduction container 21 during the plasma processing.
[0007]
Due to the heating of the microwave introduction window 25, the counter electrode 13 provided below the microwave introduction window 25 becomes a high temperature exceeding 200 ° C. during the plasma treatment. 5 is an enlarged view of the surface of the region A of the counter electrode 13 shown in FIG. 4, and FIG. 6 is an enlarged cross-sectional view of the region B shown in FIG. As described above, the counter electrode 13 covers a part of the surface of the base material (aluminum) 13a with the alumina coating 13b, and when the temperature is higher than 200 ° C., the expansion rate of the base material 13a and the alumina coating 13b is increased. Due to the difference, a crack 13c is generated on the surface of the alumina coating 13b. When the crack 13c is generated in the counter electrode 13, there is a problem that the reaction product adheres to the edge portion of the crack 13c and the exposed portion of the base material 13a due to the plasma and contaminates the sample S as particles.
[0008]
The present invention has been made in view of such circumstances, and provides a plasma processing apparatus and a plasma processing method for cooling a counter electrode by flowing a refrigerant through a hollow path of the counter electrode and preventing cracks generated on the surface of the counter electrode. The purpose is to provide.
[0009]
[Means for Solving the Problems]
The plasma processing apparatus according to the first invention comprises a reaction chamber counter electrode disposed opposite to the sample stage and the sample stage is provided, and a microwave introduction window that seals the reaction chamber at the opposite electrode side, A microwave introduction container connected to the reaction chamber via the microwave introduction window and having a dielectric line disposed therein, and the microwave propagates through the dielectric line to form a standing wave. Plasma that introduces an electric field generated inside the microwave introduction container into the reaction chamber through the microwave introduction window, generates plasma inside the reaction chamber, and performs plasma treatment on the sample on the sample stage in the processing apparatus, the counter electrode is made of aluminum which is formed an alumina film by anodic oxidation treatment a part of the surface, which have a hollow passage for allowing flowing a coolant therein, said Mai B wave introduction window is characterized in that through the formation site of the alumina coating are brought into contact with the counter electrode.
[0010]
In the first invention, while by Tsuryu coolant to flying in that provided on the counter electrode to effectively cool the counter electrode, the counter electrode made of aluminum, formed on a part of the surface by anodic oxidation treatment Cause the particles to be brought into contact with the microwave introduction window through the alumina (Al ₂ O ₃ ) coating, and the counter electrode is cooled to 200 ° C. or lower while suppressing the cooling of the microwave introduction window due to the flow of the refrigerant. Prevents the occurrence of cracks.
[0011]
The plasma processing apparatus according to a second aspect of the present invention is the plasma processing apparatus according to the first aspect, wherein the counter electrode has an opening for introducing a microwave into the reaction chamber at substantially the center, and the hollow path is at least around the opening. It is formed in the vicinity.
[0012]
In the second invention, the periphery of the opening of the counter electrode is mainly cooled. The portion of the counter electrode that is exposed to plasma is covered with a coating material, and cracks are likely to occur in the coating material when the temperature is higher than 200 ° C. The vicinity of the periphery of the opening, particularly the inner peripheral surface and the lower peripheral edge facing the reaction chamber, are portions exposed to strong plasma, and the occurrence of cracks can be prevented by cooling these portions.
[0013]
The plasma processing apparatus according to the third invention, you Keru refrigerant to the first or second invention, characterized in that a N ₂ gas.
[0015]
The plasma processing method according to the fourth invention comprises a reaction chamber counter electrode disposed opposite to the sample stage and the sample stage is provided, and a microwave introduction window that seals the reaction chamber at the opposite electrode side, A microwave introduction container connected to the reaction chamber via the microwave introduction window and having a dielectric line disposed therein, and the microwave propagates through the dielectric line to form a standing wave. Plasma that introduces an electric field generated inside the microwave introduction container into the reaction chamber through the microwave introduction window, generates plasma inside the reaction chamber, and performs plasma treatment on the sample on the sample stage in the processing method, the counter electrode is made of aluminum which is formed an alumina film by anodic oxidation treatment a part of the surface, has a hollow passage therein, the microwave introducing window, the Al Yes in contact with the counter electrode through the formation site of the Na coating, while flowing through the refrigerant routes in said, is characterized by allowed to generate a plasma by introducing the microwaves into the reaction chamber, also the fifth The plasma processing method according to the present invention is characterized in that N ₂ gas is used as a refrigerant to be passed through the hollow passage .
[0016]
The microwave introduction window needs to be maintained at a temperature higher than 200 ° C. in order to prevent deposition during plasma processing such as etching, and is heated before and after the introduction of the microwave. In the fourth aspect of the invention, at least during introduction of the microwave into the reaction chamber, only the counter electrode is maintained while allowing the coolant to flow through the hollow path and maintaining the high temperature of the microwave introduction window contacting through the alumina coating. To prevent the occurrence of cracks. Note that the coolant may be passed through the counter electrode before the introduction of the microwave, and generation of particles on the counter electrode can be prevented from the start of the plasma treatment.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
FIG. 1 is a schematic longitudinal sectional view showing a configuration of a plasma processing apparatus according to the present invention. As shown in the drawing, in the plasma processing apparatus of the present embodiment, a lid-shaped metal microwave introduction container 21 is connected to the upper side of an aluminum reaction container 11 having a rectangular parallelepiped shell shape. The microwave introduction container 21 connects a waveguide 22 for microwave introduction to one end side which is a microwave introduction side, and the other end side is closed. A microwave oscillator 23 is connected to the microwave introduction side of the waveguide 22.
[0018]
In the microwave introduction container 21, a plate-like dielectric line 24 is arranged in contact with the inside of the upper walls of the microwave introduction container 21 and the waveguide 22, and has a predetermined distance from the dielectric line 24. On the side, a plate-like microwave introduction window 25 is disposed so as to face each other. The reaction chamber 12 formed inside the reaction vessel 11 is sealed by the microwave introduction window 25. The microwave introduced from the waveguide 22 propagates in the dielectric line 24 in the length direction. The dielectric line 24 is formed of a fluororesin such as Teflon (registered trademark), and the microwave introduction window 25 is formed using a dielectric such as quartz glass or alumina (Al ₂ O ₃ ).
[0019]
A sample stage 15 is arranged at the bottom of the reaction chamber 12 so as to face the microwave introduction window 25, and a sample S such as a semiconductor substrate is placed on the sample stage 15 for plasma processing. ing. A supply port 16 for introducing reaction gas and an exhaust port 17 for evacuating the inside of the reaction chamber 12 are formed on the side wall of the reaction vessel 11. An exhaust device (not shown) is connected to the exhaust port 17.
[0020]
On the upper part of the reaction chamber 12, the counter electrode 3, which is a feature of the present invention, is provided in contact with the lower surface of the microwave introduction window 25. FIG. 2 is a plan view of the counter electrode of the present embodiment, and FIG. 3 is a sectional view taken along line III-III. As shown in the figure, the counter electrode 3 has a rectangular plate shape, and has a circular opening 3c substantially at the center. The counter electrode 3 is made of aluminum as the base material 3a, and the surface thereof is anodized, and an alumina coating 3b is formed on the inner peripheral surface of the opening 3c and the upper and lower surfaces near the opening 3c. Yes. In addition, since the outer peripheral part of the counter electrode 3 requires energization, the alumina film 3b is not formed.
[0021]
Inside the counter electrode 3, a cooling path 3s, which is a hollow path for allowing the refrigerant to flow therethrough, is formed. The cooling path 3s is formed in an annular shape around the opening 3c of the counter electrode 3, and both ends thereof are penetrated to one end face of the counter electrode 3 to be provided with a refrigerant supply port 3d and a refrigerant discharge port 3e, respectively. . A temperature measurement hole reaching the vicinity of the opening 3c is formed in the one end face of the counter electrode 3, and a thermocouple 4 is inserted. A tip portion which is a temperature measurement portion of the thermocouple 4 is disposed at a position 3 mm from the opening 3 c to the outer peripheral side, and measures the temperature near the opening 3 c of the counter electrode 3. The refrigerant is supplied from the refrigerant supply port 3d into the counter electrode 3 and flows through the cooling path 3s, and then is discharged from the refrigerant discharge port 3e.
[0022]
The counter electrode 3 in the present embodiment is a rectangular plate with outer dimensions of 483 mm × 440 mm × 10 mm, and the diameter of the opening 3c is 258 mm. The cooling path 3s is concentric with the opening 3c, has an outer diameter of 328 mm, an inner diameter of 278 mm, and a height of 4 mm, and is formed at the approximate center in the thickness direction of the counter electrode 3. The counter electrode 3 and the cooling path 3s to be formed are not limited to this dimension, and the shape of the opening 3c is not limited to a circle.
[0023]
When performing the etching process on the surface of the sample S using the plasma processing apparatus having the above-described configuration, the sample S is first loaded into the reaction chamber 12 and placed on the sample stage 15, and the reaction chamber 12 is set in a desired manner. Adjust to pressure. The microwave introduction window 25 is heated to about 200 ° C. N ₂ gas is supplied to the cooling path 3 s from the gas supply port of the counter electrode 3, and the temperature of the counter electrode 3 is measured by the thermocouple 4. After confirming that the temperature is a predetermined temperature, a reaction gas is introduced into the reaction chamber 12 from the supply port 16, and a microwave is oscillated from the microwave oscillator 23 and introduced into the dielectric line 24. The microwave propagates in the dielectric line 24 to form a standing wave, and forms an electric field below the dielectric line 24. The formed electric field passes through the microwave introduction window 25 and is introduced into the reaction chamber 12. At this time, due to the introduction of the microwave, the microwave introduction window 25 is further heated to exceed 200 ° C., but the counter electrode 3 is cooled by the flow of N ₂ and maintains a temperature of 200 ° C. or less. In the reaction chamber 12, plasma is generated by the introduced electric field, and the surface of the sample S is etched by this plasma.
[0024]
During such a plasma treatment, N ₂ gas was passed through the counter electrode 3 as a refrigerant, and the temperature measured by the thermocouple 4 was 200 ° C. or less. Thus, it was possible to cool only the counter electrode 3 to 200 ° C. or less even during the plasma processing without lowering the temperature of the microwave introduction window 25. Thereby, it was possible to prevent the surface of the counter electrode 3 from being cracked, and to suppress the generation of particles.
[0025]
In the above-described embodiment, the case where the sample S is etched by plasma has been described. However, the present invention is not limited to this and may be a case where ashing, CVD, or the like is performed.
[0026]
【The invention's effect】
As described above, in the present invention, since the hollow path for allowing the refrigerant to flow is formed inside the counter electrode, and the counter electrode is brought into contact with the microwave introduction window via the alumina coating , the refrigerant As a result of this, only the counter electrode can be cooled without cooling the microwave introduction window , which needs to be maintained at a high temperature for high-speed plasma treatment, and cracks generated on the surface of the counter electrode can be prevented to prevent particle generation. The present invention has excellent effects such as the suppression of occurrence.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view showing a configuration of a plasma processing apparatus according to the present invention.
FIG. 2 is a plan view of a counter electrode according to the present embodiment.
FIG. 3 is a cross-sectional view taken along line III-III in FIG.
FIG. 4 is a schematic longitudinal sectional view showing a configuration of a conventional plasma processing apparatus proposed by the applicant of the present application.
5 is an enlarged view of the surface of a counter electrode region A shown in FIG. 4;
6 is an enlarged cross-sectional view of a region B shown in FIG.
[Explanation of symbols]
3 Counter electrode 3a Base material 3b Alumina coating 3c Opening 3d Refrigerant supply port 3e Refrigerant discharge port 3s Cooling path 4 Thermocouple 12 Reaction chamber 15 Sample stage 22 Waveguide 23 Microwave oscillator 24 Dielectric line 25 Microwave introduction window

Claims (5)

A reaction chamber which oppositely disposed counter electrode to the sample stage and the sample stage is provided, and a microwave introduction window that seals the reaction chamber at the opposite electrode side, the reaction through the microwave introducing window And a microwave introducing container having a dielectric line disposed therein, and generated inside the microwave introducing container by a microwave propagating through the dielectric line to form a standing wave. In the plasma processing apparatus for introducing an electric field into the reaction chamber through the microwave introduction window, generating plasma in the reaction chamber, and performing plasma processing on the sample on the sample stage ,
The counter electrode is made of aluminum which is formed an alumina film by anodic oxidation treatment a part of the surface, which have a hollow passage for allowing flowing a coolant therein,
The plasma processing apparatus , wherein the microwave introduction window is in contact with the counter electrode through a portion where the alumina coating is formed .   2. The plasma processing apparatus according to claim 1, wherein the counter electrode has an opening for introducing a microwave into the reaction chamber at substantially the center, and the hollow path is formed at least near the periphery of the opening. The plasma processing apparatus according to claim 1 , wherein the refrigerant is N ₂ gas . A reaction chamber which oppositely disposed counter electrode to the sample stage and the sample stage is provided, and a microwave introduction window that seals the reaction chamber at the opposite electrode side, the reaction through the microwave introducing window And a microwave introducing container having a dielectric line disposed therein, and generated inside the microwave introducing container by a microwave propagating through the dielectric line to form a standing wave. In the plasma processing method of introducing an electric field into the reaction chamber through the microwave introduction window, generating plasma inside the reaction chamber, and performing plasma processing on the sample on the sample stage ,
The counter electrode is made of aluminum having an anodized alumina coating formed on a part of the surface thereof , and has a hollow path therein, and the microwave introduction window is a portion where the alumina coating is formed The plasma processing method is characterized in that the plasma is generated by introducing the microwave into the reaction chamber while allowing the refrigerant to flow through the hollow path, while contacting with the counter electrode through the channel. As a refrigerant flowing through the hollow path, N ₂ The plasma processing method according to claim 4, wherein a gas is used.

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