JPH10294306A - Plasma etching apparatus, plasma etching method, and plasma cleaning method for plasma etching apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the generation of reaction products attached to a ground electrode of a microwave etching apparatus for etching a semiconductor element substrate or the like, to lengthen a cleaning process cycle, and to increase the operation rate and the yield of the apparatus. Improve. SOLUTION: A magnetic field generating coil is housed inside an earth electrode arranged around a sample stage on which a workpiece is placed, and a ring-shaped magnetic field is formed around the earth electrode by excitation to generate a magnetic field and microwave. A configuration in which ions and electrons of the reaction product generated by the above are prevented from entering the surface of the ground electrode, and a configuration in which the temperature of the ground electrode is cooled to a low temperature to suppress the generation of a reaction product in the vicinity of the ground electrode. Alternatively, there is a configuration in which a portion other than the ground electrode is heated to suppress generation of a reaction product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma etching apparatus for generating a plasma by microwave discharge and etching a semiconductor element substrate or the like.

[0002]

2. Description of the Related Art As an example of a conventional plasma etching apparatus for generating a plasma discharge by a microwave discharge to perform an etching process on a semiconductor element substrate, see Japanese Patent Application Laid-Open No. 2-1.
There is one shown in FIG. 9 shown in Japanese Patent No. 42126. In the figure, 1 is a container having an opening at the top, 2 is a vacuum dome formed in a dome shape with an insulating member such as quartz which forms a processing space in the upper portion of the container 1, and 3 is formed at a lower portion of the vacuum dome 2. Processing space 4 surrounds the vacuum dome 2,
It is a waveguide arranged at the upper part of the container 1, and is formed by a body 4a and a connecting portion 4b. Reference numeral 5 denotes a microwave generating means constituted by a magnetron for generating a microwave, 6 denotes a solenoid coil disposed on the outer periphery of the waveguide 4 and applies a magnetic field to the processing space, and 7 denotes a decompression exhaust means for exhausting the processing space to a reduced pressure state. The container is connected to the container by an exhaust pipe 7a, and a pressure control valve is provided in the middle. Reference numeral 8 denotes a processing gas supply means for introducing a processing gas, one end is connected to a container, and the other end is connected to a processing gas container 8a in which the processing gas is sealed. 10 is a container 1
The sample stage 11 is arranged at the center of the opening 1a of the sample, 11 is a ring-shaped first ground electrode arranged between the inside of the container opening 1a and the sample stage 10, and 12 is the sample stage 10 and the first A ring-shaped second ground electrode arranged to be vertically movable between the ground electrode 11 and the second ground electrode 12 is formed of a dielectric containing no sample component. Reference numeral 13 denotes a high-frequency bias voltage power supply that applies a high-frequency bias voltage to the sample table 10.

In the configuration shown in FIG. 9, the processing space 3 is reduced to a predetermined pressure by operating the vacuum evacuation device, and a predetermined processing gas is introduced from the processing gas supply means 8 into the processing space 3 by adjusting the introduction amount. You. The processing space 3 is adjusted to a predetermined processing pressure by a pressure adjusting valve provided in the evacuation device 7.
An object to be processed is placed on the sample table 10 in the processing space 3 by a transport unit (not shown). Thereafter, the second earth electrode 12 is placed below the first earth electrode 11, and microwaves are transmitted by the microwave generating means 5, and the microwaves propagate through the waveguide 4 to cause the vacuum dome 2 to move. Through the upper wall and absorbed by the processing space 3 in the vacuum dome 2,
A high-frequency bias voltage is applied to the sample stage 10 by a high-frequency bias voltage power supply 13, thereby generating a high-frequency electric field including microwaves in the processing space 3, and a solenoid coil disposed on the outer periphery of the waveguide 4. 6 is excited, the processing gas in the processing space 3 is turned into plasma by the synergistic action of a high-frequency electric field including a microwave and a magnetic field, and the processing surface of the processing object 14 on the sample stage 10 is subjected to a predetermined etching process by the plasma. Is made. When the processing is completed, the microwave generating means 5, the high frequency bias voltage power supply 1
3. The operation of the solenoid 6 is stopped, the introduction of the processing gas into the processing space 3 is stopped, and the workpiece is carried out of the processing space 3 to the outside.

[0004] In the above-described processing of the workpiece, reaction products adhere to and accumulate on the inner wall around the processing space 3 and the surface of the sample table 10 as the processing proceeds. The reaction products generated by the etching adhere to the inner surface of the vacuum dome and other components of the device, causing the etching characteristics to change.In addition, the adhered reaction products peel off and become foreign substances, which is a factor that lowers the product yield. Therefore, cleaning is regularly performed.

In FIG. 9 of the related art, plasma is generated by microwave discharge, and the first
The second ground electrode 12 made of a material having a component different from that of the sample between the ground electrode 11 and the sample table is raised to serve as a ground electrode, and the sample table 10 and the second ground electrode 12
During this time, a high frequency bias voltage is applied, and a microwave and a magnetic field are applied to perform a cleaning process. According to this method, sputterability of ions in plasma is more effective for cleaning, and deterioration of the first ground electrode can be suppressed. Also, as a cleaning method,
For example, as shown in JP-A-2-83925, plasma cleaning in which a microwave output or a magnetic field is changed is also performed.

[0006]

As a material of the earth electrode of the plasma etching apparatus, an aluminum alloy is generally used. In the plasma etching, a halogen-based reaction gas is used. Then, the halogen-based gas and aluminum react with each other to deteriorate the grounding parts, and the reaction products are generated. Therefore, in addition to the physical sputtering of ions generated during the etching, the etching of the chemical reaction also contributes to the deterioration of the ground component.
As described above, the reaction product containing the constituent material of the device component is generated other than the reaction product containing the material of the workpiece to be etched (Si-based if the target is Si-based), and the vacuum dome 2
And adhere to the inner wall of the container 1. The deposited reaction products, when deposited to some extent, mainly cause separation due to thermal stress and cause the generation of foreign matter in the apparatus, and it has been necessary to frequently open the apparatus to the atmosphere and perform cleaning in the apparatus.

[0007] On the other hand, conventionally, the cleaning of the reaction product containing the material to be etched is performed to extend the period of the periodic cleaning. However, the cleaning of the reaction product containing aluminum is sufficiently performed. However, the periodic cleaning cycle had to be shortened. In particular, when using a fluorine-based etching gas,
Aluminum remained as AlF and was difficult to remove. Further, even with the provision of the second earth electrode, the deterioration of the first electrode during etching could not be suppressed, and the reaction products containing Al generated at that time could not be efficiently removed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In a plasma etching apparatus, a reaction product including an emission from a component material of the apparatus is reduced to reduce foreign substances in the apparatus. It is an object of the present invention to provide a plasma etching apparatus in which the efficiency of the apparatus is reduced and the product yield is improved.

[0009]

According to a first aspect of the present invention, there is provided a plasma etching apparatus having a sample table on which a workpiece is mounted, an opening above which the sample table is stored, and a lower part of the processing space. A container to be formed, a vacuum dome that forms and seals a processing space above the sample stage, a waveguide that surrounds the periphery of the vacuum dome, a microwave generation unit that is disposed above the waveguide,
A high frequency bias voltage is applied to a solenoid coil that applies a magnetic field to the processing space, an annular earth electrode placed between the inner periphery of the opening above the container, and the sample stage, and a workpiece placed on the upper surface of the sample stage. A high-frequency bias voltage power supply, a vacuum evacuation means for evacuating the processing space to a reduced pressure state, and a processing gas supply means for supplying a processing gas to the processing space, and apply a magnetic field and a microwave to the processing gas introduced into the reduced pressure processing space. A plasma etching apparatus for applying a plasma to a workpiece to etch the workpiece, wherein a magnetic field generating coil housed in a ground electrode is electrically insulated from the ground electrode.

According to a second aspect of the present invention, there is provided a plasma etching apparatus in which a magnetic field generating coil disposed inside a ground electrode according to the first aspect of the present invention can be cooled by sealing a refrigerant.

According to a third aspect of the present invention, in the plasma etching apparatus according to the first or second aspect, the magnetic field generating coil disposed in the ground electrode corresponds to a current value of a solenoid coil disposed on the outer periphery. Then, the magnetic field is adjusted so as to be connected to an individual power supply so that the magnetic field can be adjusted.

According to a fourth aspect of the present invention, there is provided a plasma etching method, wherein the temperature region of the ground electrode when the plasma etching is performed by the plasma etching apparatus according to the third aspect is defined by an etching gas and a component material of the ground electrode. The upper limit is the temperature at which the saturated vapor pressure of the product compound produced by the reaction and the pressure of the processing gas during the plasma etching process are equal to, and the vapor pressure of the etching gas and the processing gas during the plasma etching process The plasma etching process is performed with the temperature at which the pressure becomes the same as the lower limit.

In a plasma etching apparatus according to a fifth aspect of the present invention, a sample stage on which a workpiece is placed and a lower portion of a processing space are formed, a container in which the sample stage is accommodated above, and a process above the sample stage. A vacuum dome that forms and seals a space, a waveguide that surrounds the vacuum dome, means for generating microwaves placed above the waveguide, a magnetic field that is placed around the waveguide, and A ring-shaped earth electrode in which a magnetic field generating coil, which is disposed between the inner periphery of the opening above the container and the sample table and is electrically insulated and housed therein, is disposed; A high-frequency bias voltage power supply for applying a high-frequency bias voltage to the workpiece mounted on the upper surface; a decompression exhaust unit for evacuating the processing space to a reduced pressure state; and a processing gas supply unit for supplying a processing gas to the processing space. In the processing space A plasma etching apparatus for applying a magnetic field and a microwave to an input processing gas to convert the processing gas into plasma, and to etch an object to be processed, the processing space heating means for heating a processing space on a waveguide inner surface above a vacuum dome, and a container. And a container heating means for heating the container disposed around the container.

According to a sixth aspect of the present invention, there is provided a plasma etching method for performing a plasma etching process while heating a portion other than a ground electrode and a sample stage using the plasma etching apparatus according to the fifth aspect.

According to a seventh aspect of the present invention, there is provided a plasma cleaning method for a plasma etching apparatus according to any one of the first to sixth aspects, wherein after the plasma cleaning apparatus has been used to some extent, the magnetic field generating coil disposed inside the ground electrode is energized. Then, the ground electrode is heated, and a plasma is generated by applying a magnetic field and a microwave to the processing space in the same manner as in the plasma etching process to generate plasma.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 shows Embodiment 1 of the present invention. It is a block diagram of the plasma etching apparatus using a microwave. In the figure, 2 is a vacuum dome, 3 is a processing space, 4 is a waveguide, and 5 is a microwave generating means, which is the same as the conventional configuration of FIG. Reference numeral 21 denotes a container having an opening 1a above to form the processing space 3, 26 denotes a solenoid coil for applying a magnetic field to the processing space 3, 30 denotes a sample table on which a workpiece is placed,
Reference numeral 22 denotes a ring-shaped earth electrode disposed between the inner periphery above the container and the sample table 34, and its cross section is shown in FIG. 2
Reference numeral 3 denotes a magnetic field generating coil housed in the ground electrode 22 while being electrically insulated. Reference numeral 24 denotes an excitation power supply for exciting the magnetic field generating coil 23. Reference numeral 32 denotes a high-frequency bias voltage power supply for applying a high-frequency bias voltage between the ground electrode 22 and the sample table 30. Reference numeral 27 denotes a decompression exhaust unit for depressurizing the processing space 3 and is connected to the container 21 by an exhaust pipe 27a. Have been. Reference numeral 28 denotes a processing gas supply means for supplying a combination and flow rate of various processing gases required for the processing space 3 while controlling the flow rate with a valve and an adjustment valve.
8a. 34 is a workpiece. The ground electrode 22 is formed in a hollow ring shape from an aluminum-based alloy, and the hollow portion accommodates a magnetic field generating coil 23 which is electrically insulated.

In the plasma etching processing in this apparatus, the processing space 3 is depressurized by the decompression and exhaust means 27, the workpiece 34 is placed on the sample table 30, and an appropriate processing is performed according to the type of the workpiece 34. The gas is supplied to the processing space 3 by adjusting the combination flow rate of the kinds by the processing gas supply means 28,
Control pressure. The pressure in the processing space 3 varies depending on the type of the workpiece 34, but is adjusted to 1 to 200 mTorr.
Subsequently, the solenoid coils 26a and 26b are excited by a direct current to apply a magnetic field to the processing space. Solenoid coil 2
The excitation currents of the upper and lower coils 26a and 26b are, for example, 15 to 25 in order to give a magnetic field suitable for the type and shape of the workpiece 34.
A, the lower part is adjusted to be 5 to 15A. Further, the magnetic field generating coil 23 in the earth electrode 22 is excited by the DC excitation power supply 24, and the magnetic field distribution in the processing space 3 is formed to an appropriate distribution.

When the pressure and magnetic field of the processing gas in the processing space 3 are stabilized, a microwave is supplied from the microwave generation means 5 to the processing space 3 and a high frequency bias voltage is applied to the sample stage 30.
And the ground electrode 22 to apply a plasma etching process to the workpiece 34. When the plasma etching process is completed, the high-frequency bias voltage power supply 32, the microwave generation means 5, the excitation of the solenoid coils 26a and 26b, the excitation of the magnetic field generation coil in the ground electrode 22 are stopped, and the supply of the processing gas is also stopped. The inside of the processing space 3 is evacuated, and the workpiece is taken out by the transfer means.

During the plasma etching, the processing gas is ionized, and the generated ions and electrons make a so-called Larmor motion with respect to the magnetic field lines to reach the workpiece, and the workpiece is etched. You. The ionized ions and electrons of the processing gas around the earth electrode 22 during the etching are changed in the trajectory incident on the earth electrode 22 by the magnetic field formed by the magnetic field generating coil, and are hardly incident on the earth electrode. , Earth electrode 22
The number of ions and electrons incident on the ground electrode 22 is reduced, and the generation of spatter from the ground electrode 22 is suppressed. Also, the ground electrode 22
The decrease in the number of electrons incident on the ground electrode reduces the sheath voltage around the ground electrode, which leads to suppression of spatter generation on the ground electrode material. The sheath voltage is generated because the amount of electrons incident on the ground electrode is larger than that of the ions. Since the electrons are more easily captured by the lines of magnetic force than the ions, a magnetic field is generated around the ground electrode 22. By the generation, the amount of electrons incident on the ground electrode 22 decreases, and the sheath voltage decreases. By generating the magnetic field around the ground electrode 22 in this manner, the amount of incident electrons is reduced, the consumption of the ground electrode 22 is suppressed, and the amount of foreign substances generated in the device can be reduced.

Embodiment 2 Embodiment 2 FIG. Is the first embodiment. The magnetic field generating coil of the earth electrode portion having the configuration shown in FIG. 1 can be cooled by a cooling medium. FIG.
2 shows a cross-sectional view of the ground electrode portion. In this case, the earth electrode 22 is formed in a ring shape with a hollow circular cross section from an aluminum alloy, a magnetic field generating coil 23 is disposed inside, and a cooling medium is sealed in the inner diameter portion of the earth electrode 22 for use. When the earth electrode 22 is cooled, the magnetic field generating coil 2
3 prevents the earth electrode 22 from being heated by the temperature rise due to the exciting current and the collision of ions from the plasma. As a result, the etching accompanying the chemical reaction on the surface of the ground electrode 22 is suppressed, and the consumption of the ground electrode is suppressed.

Embodiment 3 Embodiment 3 FIG. Is the first embodiment. Second embodiment. The excitation current of the magnetic field generating coil 23 is specified. FIG. 4 shows the solenoid coils 26a and 26a of the plasma etching apparatus of the present invention.
FIG. 6B is a diagram illustrating an arrangement relationship between the magnetic field generating coil and a magnetic field generating coil. The magnetic field formed by the current flowing through these coils is represented by the vector sum of the magnetic fields formed by the respective coils. The magnetic flux density B ₀ at the center of the magnetic field due to the current flowing through the coil is expressed by Equation 1. B ₀ = μ ₀ · NI / (2R) ··· (Equation 1) μ ₀ : magnetic permeability in vacuum R: radius of annular coil N: number of coil turns I : Coil current value FIG. 6 shows the dependence of the magnetic flux density of the annular current on the radius R at the inner periphery of the coil.

In FIG. 6, the upper solenoid coil 2
The height with respect to the point P near the magnetic field generating coil 23 of FIG. 6a is set such that the distance between the center of the coil section of the upper solenoid coil 26a and the point P is substantially the same as the coil radius, and the center of the coil section of the lower solenoid coil 26b. The distance between the magnetic field generating coil 23 and the point P near the magnetic field generating coil 23 is set to a position of 1/2 of the coil radius, the radius of the magnetic field generating coil 23 is set to 2/3 of the radius of the lower solenoid coil, The distance from the point P is 1 of the radius of the magnetic field generating coil 23.
Consider the magnetic field at point P at position / 5.

The ground electrode 22 of the ionized plasma
The distance between the point P near the ground electrode 22 which influences the entry of the magnetic field and the center of each of the upper solenoid coil 26a, the lower solenoid coil 26b, and the magnetic field generating coil 23 in the ground electrode is Lp ₁ , Lp ₂ , respectively. , Lp ₃ , the respective radii are R ₁ , R ₂ , R _3, and the DC current values applied to the upper solenoid coil 26a, the lower solenoid coil 26b, and the magnetic field generating coil 23 are I ₁ , I ₂ , I ₃ , the number of turns of each coil is N ₁ , N ₂ , N _3, and the magnetic flux densities generated at point P by the upper solenoid coil 26 a, the lower solenoid coil 26 _b , and the conducting wire are Bp ₁ , Bp ₂ , Bp _3. The magnetic flux densities at the coil center are represented by B ₀₁ , B ₀₂ , and B ₀₃ , respectively, by the following equations 2, 3,
Equation 4 is obtained. B ₀₁ = μ ₀ · N ₁ · I ₁ / (2R ₁ ) (Equation 2) B ₀₂ = μ ₀ · N ₂ · I ₂ / (2R ₂ ) (Equation 3) B ₀₃ = μ ₀ · N ₃ · I ₃ / (2R ₃ ) (Equation 4) From these, Equation 5 is obtained. . B ₀₁ / B ₀₂ = ((N ₁ · I ₁ ) / (N ₂ · I ₂ )) · (R ₂ / R ₁ ) (Equation 5) where I ₁ = α · I ₂ Considering that R ₁ = R ₂
Therefore, B ₀₁ / B ₀₂ becomes (Equation 6). B ₀₁ / B ₀₂ = α · N ₁ / N ₂ (Equation 6) Since Lp ₁ ≒ R ₁ , Bp ₁ ≒ B ₀₁ and Lp _Two
Because it is ≒ R _2/2 is as Bp ₂ ≒ B ₀₂ in the graph of FIG. (Equation 7) is obtained from the above. Bp ₁ / Bp ₂ = B ₀₁ / B ₀₂ = α · N ₁ / N ₂ (Equation 7) Here, at point P, Bp ₁ and Bp ₂ are substantially parallel.
To change the direction of ions and electrons at point P, Bp ₁ and B
Bp ₃ needs to be controlled for the sum of p ₂ . Considering the case where these are just equal, the result is as shown in (Equation 8). Bp ₃ = Bp ₁ + Bp ₂ = α · (N ₁ / N ₂ ) · Bp ₂ + Bp ₂ = ((α · N ₁ + N ₂ ) / N ₂ ) · Bp ₂ 8)

Next, Bp ₃ will be considered. Lp ₃ ≒ R
A _3/5, Equation 9 is obtained from the graph of FIG. Bp ₃ ≒ 2B ₀₃ = 2μ ₀ N ₃ I ₃ / (2R ₃ ) (Equation 9) Assuming Equation 9 as Condition 1, Condition 1 is as shown in the following Equation 11. 2 · μ ₀ · N ₃ · I ₃ / (2R ₃ ) = ((α · N ₁ + N ₂ ) / N ₂ ) · B ₀₂ = ((α · N ₁ + N ₂ ) / N ₂ ) ·) · ( μ ₀ · N ₂ · I ₂ / (2R ₂ )) ··· (Equation 10) I ₃ = ((α · N ₁ + N ₂ ) / (2 · N ₃ ) · (R ₃ / R ₂ ) · I ₂ also ... (equation _{11), R 3 ≒ 2R 2} /3 condition 1 because it is becomes formula _{12. I 3 = ((α} · N 1 + N 2) / (3 · N 3)) · I 2 · ...... becomes (equation 12). to control the I ₃ this value as a reference.

The ground component near trajectories of ions and electrons is bent by, and as a condition never diffuse magnetic field is disturbed at the center, the value obtained was I ₃ in equation 12 from 0.3 to 0.
As shown in FIG. 5, the direction of the magnetic field directed to the ground electrode 22 is directed downward by the magnetic field generating coil 23, so that the amount of ions and electrons reaching the surface of the ground electrode 22 can be reduced efficiently. .

Embodiment 4 Embodiment 4 FIG. Defines the temperature of each part during the plasma etching process.
FIG. 7 shows a saturated vapor pressure curve of a processing gas and a reaction product formed by reacting with the processing gas. Considering the aluminum alloy as the earth electrode material, the reaction product of the processing gas and aluminum is also shown. By setting the temperature of the earth electrode 22 so that the saturated vapor pressure of the reaction product of the processing gas and aluminum is lower than the pressure at the time of the plasma etching, etching involving a chemical reaction occurring on the surface of the earth electrode 22 is performed. The reaction can be suppressed. Further, the adhesion of the processing gas and the reaction product of the Si system to the surface of the ground electrode 22 hinders the etching itself. Therefore, it is necessary to set the temperature of the ground electrode 22 so that these saturated vapor pressures become higher than the pressure of the processing gas during the etching process. As a method, as shown in FIG. 3, a low-temperature refrigerant such as liquid nitrogen or liquid helium is sealed in the inside of the earth electrode 22, and the earth electrode 22 is grounded so as to be within the temperature limit area shown in FIG. By cooling the temperature of the electrode 22, consumption of the ground electrode 22 during the plasma etching process can be suppressed.

Embodiment 5 FIG. Embodiment 5 FIG. Cooling the ground electrode 22 makes it easier for reaction products to adhere to the surroundings, which causes peeling and foreign matter generation.
The configuration is such that the temperature of the parts other than the ground electrode is increased so that the reaction products are less likely to adhere to the sample table 30 and the workpiece 34. FIG. 1 shows a configuration of a plasma etching apparatus. In the figure, a vacuum dome 2, a processing space 3,
Waveguide 4, microwave generating means 5, container 21, ground electrode 22, magnetic field generating coil 23, magnetic field coil exciting power supply 2
4, upper solenoid coil 26a, lower solenoid coil 26b, sample stage 30, high frequency bias voltage power supply 32,
The workpiece 34 is the first embodiment. Is the same as Reference numeral 41 denotes an infrared heater for heating the vacuum dome 2 forming the processing space 3, and reference numeral 42 denotes a container heating heater for heating the container.

With this configuration, while the earth electrode 22 is cooled, the vacuum dome 2 forming the processing space 3 is heated by the infrared heater 41, the wall of the container 21 is heated by the container heating heater 42, Numeral 30 is heated by both the infrared heater and the container heater 42, and the temperature of parts other than the ground electrode 22 is set at 150 to 200 ° C., so that reaction products are prevented from adhering to the apparatus during the plasma etching process. Thus, the number of foreign substances in the apparatus can be reduced.

Embodiment 6 FIG. Embodiment 6 FIG. In some cases, when the apparatus is operated to a certain extent by plasma etching, the ground electrode may be cooled, the amount of reaction products attached increases, and the amount of foreign substances generated in the apparatus increases due to separation. For this reason, the etching process is stopped at an appropriate cycle, and the self-cleaning is performed. At this time, the cooling of the ground electrode 22 is stopped, and the magnetic field generating coil 2 is turned off.
The cleaning time can be reduced by applying a current to 3 to heat the ground electrode using the heat generated by the coil itself and performing a cleaning process. At this time, it is desirable to use ClF3 or NF3 having a high etching rate for the Si-based deposit as a cleaning gas. By providing such a cleaning step, the periodic maintenance cycle that is performed by opening to the atmosphere can be lengthened, and the operation rate of the apparatus can be improved. When the temperature of the earth electrode 22 does not rise only by the heat generated by the magnetic field generating coil 23, it is effective to incorporate a heater for the earth electrode 22.

To cool the ground electrode during etching, the etching gas is slightly applied to the ground electrode 22.
Attached to the surface. Therefore, before the air is released to the atmosphere, the cooling of the earth electrode 22 is stopped to release the heated and adsorbed etching gas to prevent the etching gas from spreading in the air. By heating the electrode 22 and removing moisture adhering in the air, the etching characteristics become fast and stable after opening to the air.

In the plasma etching apparatus, if the container is released without time after completion of the plasma etching, the processing gas may remain in the container, and it is assumed that the processing gas is released to the atmosphere. In addition, when the operation is started after the apparatus is stopped, adsorption of moisture or the like on the surface of the container, the sample stage, or the like is also predicted. For this reason, the plasma etching apparatus is provided with a step of heating the earth electrode to release the processing gas before opening to the atmosphere after the etching process. It is also important to start the processing operation after heating the dry operation.

[0032]

According to a first aspect of the present invention, there is provided a plasma etching apparatus, which is disposed in an outer peripheral portion of a reduced processing space between a solenoid coil and a sample stage in an outer peripheral portion and to which a high-frequency bias voltage is applied. A magnetic field generating coil is housed in the inside, and an annular magnetic field is generated around the ground electrode during the plasma etching process, thereby reducing the amount of electrons flowing into the ground electrode and suppressing the consumption of the ground electrode. Can be

In the plasma etching apparatus according to a second aspect of the present invention, since the magnetic field generating coil disposed inside the earth electrode of the first aspect is configured to be capable of cooling by enclosing a coolant, the surface of the earth electrode can be cooled. Etching accompanying a chemical reaction is suppressed, and consumption of the ground electrode is suppressed.

According to a third aspect of the present invention, in the plasma etching apparatus according to the first or second aspect, the magnetic field generating coil disposed in the earth electrode corresponds to a current value of a solenoid coil disposed on the outer periphery. Then, the magnetic field is adjustable so that it is connected to an individual power supply, and the magnetic field is adjustable.
The magnetic field around the ground electrode 22 can be arbitrarily adjusted according to the state of the apparatus so that the amount of ions and electrons reaching the electrode surface can be reduced.

According to a fourth aspect of the present invention, there is provided a plasma etching method according to the third aspect, wherein the etching gas reacts with the ground electrode component in the temperature region of the ground electrode when performing the plasma etching process. The upper limit is the temperature at which the saturated vapor pressure of the produced compound generated by the process and the pressure of the processing gas during the plasma etching process are equal, and the vapor pressure of the etching processing gas and the pressure of the processing gas during the plasma etching process are The plasma etching process is performed with the same temperature as the lower limit, and the consumption of the ground electrode is suppressed.

In the plasma etching apparatus according to the fifth aspect of the present invention, the processing space other than the ground electrode, the sample stage and the vessel wall are heated to perform the plasma etching processing. Is suppressed, and the number of foreign substances in the apparatus can be reduced.

In the plasma etching method according to claim 6 of the present invention, plasma etching is performed while heating portions other than the ground electrode and the sample stage using the plasma etching apparatus according to claim 5. Adhesion of reaction products to the apparatus during the plasma etching process is suppressed, the number of foreign substances in the apparatus can be reduced, the cycle for cleaning the adhered substances can be lengthened, and the operation rate of the apparatus can be increased.

According to a seventh aspect of the present invention, there is provided a plasma cleaning method for a plasma etching apparatus according to any one of the first to sixth aspects, wherein after a certain degree of use, the magnetic field generating coil disposed inside the ground electrode is energized. Heating the earth electrode and applying a magnetic field and a microwave to the processing space in the same manner as in the plasma etching process to perform idle operation. Since plasma cleaning is performed, residual gas after processing is removed, processing gas is prevented from being released to the atmosphere, and cleaning is performed when processing is resumed, such as a ground electrode, sample stage, etc. Peripheral moisture and adsorbed gas are removed, making it possible to lengthen the periodic cleaning cycle It can improve the operation rate of the apparatus.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a plasma etching apparatus according to the present invention.

FIG. 2 is a partial cross-sectional view of a ground electrode portion of FIG.

FIG. 3 is a cross-sectional view in a case where a cooling medium of an earth electrode portion is sealed.

FIG. 4 is an explanatory diagram of a magnetic field distribution in a processing space of the plasma etching apparatus of the present invention.

FIG. 5 is a partial cross-sectional view illustrating a magnetic field near a ground electrode.

FIG. 6 is a characteristic diagram showing a relationship between a radial position of a solenoid coil and a magnetic flux distribution.

FIG. 7 is a vapor pressure-temperature characteristic diagram of a reaction product serving as a basis for determining a cooling temperature of an earth electrode.

FIG. 8 is a configuration diagram when a portion other than the ground electrode of the plasma etching apparatus according to the present invention is heated.

FIG. 9 is a cross-sectional view illustrating a configuration of a conventional plasma etching apparatus.

[Explanation of symbols]

2 vacuum dome, 3 processing space, 4 waveguide, 5 microwave generating means, 21 container, 22 ground electrode, 23
Magnetic field generating coil, 24 DC power supply, 25 cooling medium,
26 solenoid coil, 27 decompression exhaust means, 28
Processing gas supply means, 30 sample stage, 32 high frequency bias voltage power supply, 34 workpiece, 41 infrared heater, 4
2 Container heating heater.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tamio Matsumura 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation

Claims (7)

[Claims] 1. A sample table on which a workpiece is placed, a container having an opening above the sample table and forming a lower part of a processing space, and a processing space formed above the sample table. A vacuum dome for sealing the processing space, a waveguide surrounding the vacuum dome, microwave generating means disposed above the waveguide, and a magnetic field disposed around the waveguide to apply a magnetic field to the processing space A solenoid coil, an annular ground electrode disposed between the inner periphery of the opening above the container and the sample stage, and a high frequency bias voltage for applying a high frequency bias voltage to a workpiece mounted on the upper surface of the sample stage A power supply, a vacuum evacuation unit for evacuating the processing space to a reduced pressure state, a processing gas supply unit for supplying a processing gas to the processing space, and applying a magnetic field and a microwave to the processing gas introduced into the decompressed processing space to generate a plasma. And processed What is claimed is: 1. A plasma etching apparatus for performing an etching process on an object, wherein a magnetic field generating coil housed in a manner electrically insulated from the earth electrode is disposed inside the earth electrode. 2. The plasma etching apparatus according to claim 1, wherein the earth electrode is configured so that a coolant for cooling a magnetic field generating coil disposed therein can be filled therein. 3. A magnetic field generating coil disposed in an earth electrode is configured so that a magnetic field is adjustable and connected to an individual power supply in accordance with a current value of a solenoid coil disposed on an outer periphery. 3. The plasma etching apparatus according to claim 1, wherein: 4. The plasma etching apparatus according to claim 3, wherein the temperature region of the ground electrode when performing the plasma etching process is a saturated vapor of a compound produced by the reaction between the etching process gas and the component material of the ground electrode. Pressure and
Performing the plasma etching process with the upper limit being the temperature at which the processing gas pressure during the plasma etching process is the same and the lower limit being the temperature at which the vapor pressure of the etching processing gas and the processing gas pressure during the plasma etching process are the same. A plasma etching method characterized by the above-mentioned. 5. A sample table on which a workpiece is placed, a lower part of the processing space is formed, a container for accommodating the sample table above, a processing space above the sample table, and the processing space is sealed. Vacuum dome to be stopped, waveguide surrounding the vacuum dome, microwave generating means arranged above the waveguide, solenoid coil arranged around the waveguide and applying a magnetic field to the processing space, container An annular earth electrode in which a magnetic field generating coil, which is arranged between the inner periphery of the upper opening and the sample stage and is electrically insulated and housed inside, is placed on the upper surface of the sample stage. A high-frequency bias voltage power supply for applying a high-frequency bias voltage to the workpiece, reduced-pressure exhaust means for exhausting the processing space to a reduced pressure state, and processing gas supply means for supplying a processing gas to the processing space. Magnetizing the introduced process gas A plasma etching apparatus for generating plasma by applying a field and a microwave to etch a workpiece, wherein the processing space heating means heats the processing space and the vacuum dome on the inner surface of the waveguide above the vacuum dome, and A plasma etching apparatus comprising a container heating means disposed around the container to heat the container. 6. A plasma etching method using the plasma etching apparatus according to claim 5, wherein plasma etching is performed while heating portions other than the ground electrode and the sample stage. 7. The plasma etching apparatus according to claim 1, wherein after being used to some extent, a magnetic field generating coil disposed inside the ground electrode is energized to heat the ground electrode, and the plasma etching apparatus is used in the same manner as in the plasma etching process. A plasma cleaning method for a plasma etching apparatus, wherein self-cleaning is performed by generating a plasma by applying a magnetic field and a microwave to a processing space.