JP2011117054A - Alumina member for plasma treatment device and method for producing alumina member for plasma treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alumina member for a plasma treatment device worked in such a manner that the surface is not ground even if being exposed to plasma. <P>SOLUTION: The microwave plasma treatment device includes: a treatment vessel 10 in which plasma is excited at the inside; a microwave source feeding electromagnetic waves required for exciting the plasma into the treatment vessel; and an alumina member 30 provided in the treatment vessel, and the surface at least exposed to the plasma in the alumina member is coated with a film of aluminum nitride. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an alumina member for a plasma processing apparatus, a plasma processing apparatus provided with the alumina member, and a method for manufacturing an alumina member for a plasma processing apparatus.

  In a plasma processing apparatus, many dielectrics are used in a portion exposed to plasma in a processing chamber, such as an electrode portion, a mounting table, and a gas showerhead. For example, in a RLSA (Radial Line Slot Antenna) plasma processing apparatus and a microwave plasma processing apparatus, a dielectric window is provided on the ceiling surface of the processing chamber to maintain airtightness in the processing chamber and to transmit electromagnetic waves through the dielectric window. Then, plasma is generated by the electric field energy of electromagnetic waves (see, for example, Patent Documents 1 and 2).

Alumina (Al ₂ O ₃ ) is often used as the dielectric material used in the plasma processing apparatus. This is because alumina has many advantages such as being relatively easy to manufacture even in a large area, stable performance, high mechanical strength, and low cost.

JP 2008-13816 A JP 2008-91571 A

  However, during plasma treatment, the portion of the alumina exposed to the plasma is damaged by the plasma and scraped off, and the peeled material may enter the film and deteriorate the process performance. For example, in hydrogen plasma treatment, an alumina surface is sputtered by hydrogen plasma and an oxidation-reduction reaction occurs. When such physical impact and chemical reaction occur on the alumina surface, the surface of the alumina member is damaged and aluminum and oxygen are ejected from the alumina to become a contamination source, which are mixed into the film and deteriorate the film quality.

  On the other hand, it is conceivable to use a material that is not damaged even if exposed to plasma instead of alumina. However, because of the advantages of alumina described above, an alumina member is currently used as a dielectric for a plasma processing apparatus. Is one of the most suitable materials.

  In view of the above problems, the present invention provides an alumina member for a plasma processing apparatus processed so that the surface is not scraped even when exposed to plasma, a plasma processing apparatus in which the alumina member is disposed, and a method for manufacturing the alumina member. The purpose is to provide.

  In order to solve the above-described problems, according to an aspect of the present invention, a plasma treatment comprising: a treatment vessel in which plasma is excited; and an electromagnetic wave source that supplies an electromagnetic wave for plasma excitation in the treatment vessel. An alumina member for use in an apparatus, which is an alumina member for a plasma processing apparatus in which an alumina substrate is coated with an aluminum nitride film is provided.

  According to this, it is an alumina member used for a plasma processing apparatus, and the alumina member is configured by coating an alumina base material with an aluminum nitride film. As a result, even when the alumina member is exposed to plasma, the aluminum nitride coating does not cause a redox reaction on the surface of the alumina member, and also prevents damage due to ion attack on the surface of the alumina member. As a result, even if the alumina member is exposed to plasma during the plasma treatment, the alumina member is not damaged and scraped, and the problem of metal contamination and contamination in the processing chamber due to scraping of the alumina member can be solved.

The alumina base material is coated with the aluminum nitride film by thermal CVD treatment of a mixed gas containing trimethylaluminum (Trimethylaluminium, chemical formula Al (CH ₃ ) ₃ , hereinafter referred to as TMA) and ammonia (NH ₃ ). May be.

  The flow rate of ammonia gas with respect to the flow rate of TMA gas in the mixed gas used for the thermal CVD process may be 10 times or more. In addition, the flow volume in this specification means the flow volume normalized by the volume in 0 degreeC and 1 atmosphere.

  You may adjust the temperature of the inside of the thermal CVD processing apparatus which performs the said thermal CVD process to 400 degreeC or more.

By the thermal CVD treatment of a mixed gas containing allene N-methylpyrrolidine (Alane-N-methylpyrrolidine, chemical formula AlH ₃ : N (CH ₃ ) (CH ₂ ) ₄ , hereinafter referred to as MPA) and ammonia, the alumina group The material may be coated with the aluminum nitride film.

  The aluminum nitride coating film may be 1 μm or less.

  The alumina member for the plasma processing apparatus may be provided in the processing container, and an aluminum nitride film may be coated on at least a surface of an alumina base that is exposed to plasma during the plasma processing.

  The alumina member for the plasma processing apparatus may be a dielectric window that is provided facing the inside of the processing container and transmits electromagnetic waves supplied from the electromagnetic wave source toward the processing container.

  The alumina member for the plasma processing apparatus may be removed from the plasma processing apparatus, recoated with the aluminum nitride film by the thermal CVD process, and then attached to the plasma processing apparatus again for reuse.

  In order to solve the above-described problems, according to another aspect of the present invention, a processing container in which plasma is excited inside, and an electromagnetic wave source that supplies electromagnetic waves necessary for exciting the plasma in the processing container; There is provided a plasma processing apparatus comprising: an alumina member provided in the processing container; and at least a surface of an alumina base material exposed to plasma of the alumina member is coated with an aluminum nitride film. .

  In order to solve the above problems, according to another aspect of the present invention, a step of adjusting the temperature of the inside of a thermal CVD processing apparatus to 400 ° C. or higher, and a mixed gas containing TMA and ammonia in the thermal CVD processing apparatus An alumina member for a plasma processing apparatus, comprising: a step of supplying an alumina base material with an aluminum nitride film inside the thermal CVD processing apparatus by a thermal CVD process using the mixed gas; A manufacturing method is provided.

  As described above, according to the present invention, by using an alumina member for a plasma processing apparatus in which an alumina base material is coated with an aluminum nitride film, the surface of the alumina member is damaged and scraped by the action of plasma. And contamination by aluminum and oxygen in the alumina member can be prevented.

It is the figure which showed typically the thermal CVD processing apparatus for manufacturing the alumina member which concerns on one Embodiment of this invention. It is the graph which showed the relationship between the pressure and the film thickness in the thermal CVD processing apparatus which concerns on the same embodiment. It is the graph which showed the relationship between the pressure in the thermal CVD processing apparatus which concerns on the same embodiment, and the composition ratio in a film | membrane. It is the graph which showed the relationship in the thermal CVD processing apparatus which concerns on the same embodiment, and the carbon ratio in a film | membrane. It is the graph which showed the thermal decomposition characteristic of TMA. It is the graph which showed the relationship between the ammonia gas concentration supplied to the thermal CVD processing apparatus which concerns on the same embodiment, and the carbon ratio in a film | membrane. It is the graph which showed the thermal decomposition characteristic of ammonia. It is the graph which showed the relationship between the processing time and the film thickness in the thermal CVD processing apparatus which concerns on the same embodiment. It is a longitudinal cross-sectional view of the microwave plasma processing apparatus provided with the alumina member which concerns on the same embodiment. It is the figure which showed the ceiling surface of the microwave plasma processing apparatus which concerns on the same embodiment. It is a partially expanded view of the alumina member installed in the microwave plasma processing apparatus according to the embodiment. 12A and 12B are diagrams showing the composition ratio of the alumina surface layer before and after plasma irradiation of the alumina member (TMA coat). FIGS. 13A and 13B are diagrams showing the composition ratio of the alumina surface layer before and after plasma irradiation of the alumina member (MPA coat). FIGS. 14A and 14B are diagrams showing the composition ratio of the alumina surface layer before and after plasma irradiation of the alumina base material (without coating).

Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol. In the following description, the gas flow rate will be described using the unit of SCCM or SLM. SCCM and SLM represent flow rates normalized at a temperature of 0 ° C. and a pressure of 1 atm, that is, 101325 Pa. For example, xSLM means a flow rate at which a mass equal to a gas whose volume is xL (L is liter) at a temperature of 0 ° C. and 1 atm, that is, 101325 Pa, flows per minute. Similarly, ySCCM means a flow rate at which a mass equal to a gas whose volume is ycc (cc is cm ³ ) at a temperature of 0 ° C. and 1 atm, that is, 10125 Pa, flows per minute. As can be seen from the above, SCCM and SLM have a relationship in which, for example, 1 SLM has a flow rate equal to 1000 SCCM.

The description will be made in the following order.
[1. Manufacturing method of alumina member]
(Configuration of thermal CVD processing equipment)
(Alumina member manufacturing method)
(Process conditions)
[2. Plasma processing apparatus with alumina member]
(Configuration of microwave plasma processing equipment)
[3. Evaluation of plasma resistance of alumina members]
(Plasma resistance evaluation TMA coating)
(Plasma resistance evaluation MPA coat)
(Plasma resistance evaluation without coat)

[1. Manufacturing method of alumina member]
First, the manufacturing method of the alumina member which concerns on one Embodiment of this invention is demonstrated. This alumina member is for a plasma processing apparatus, and the following processing is applied to a plate-like alumina base material in order to enhance plasma resistance.

(Configuration of thermal CVD processing equipment)
The alumina member according to the present embodiment is subjected to thermal CVD (Chemical Vapor Deposition) processing in the thermal CVD processing apparatus 100 shown in FIG. In the thermal CVD process, a gas is chemically reacted with thermal energy to form a thin film.

  The thermal CVD processing apparatus 100 includes a tube-shaped reactor 105, and performs thermal CVD processing on the plate-like alumina substrate 30a inside the reactor 105. An infrared lamp 110 is mounted outside the reactor 105. Nichrome wires 115 are disposed in the vicinity of the infrared lamp 110, and each nichrome wire 115 is connected to the temperature controller 120. The reactor 105 is made of alumina and stainless steel (SUS), but quartz or the like may be used. Further, instead of the infrared lamp 110, another lamp heater can be used. Further, instead of the nichrome wire 115, another heater can be used.

The gas system will be described. The gas system mainly has a gas line L1, a gas line L2, and a gas line L3. From the gas line L1, nitrogen gas (N ₂ ) is supplied to the reactor 105 as a purge gas. The gas used for the purge gas is not limited to nitrogen gas as long as it is an inert gas. From the gas line L2, ammonia (NH ₃ ) gas and argon (Ar) gas are supplied to the reactor 105. From the gas line L 3, trimethylaluminum (chemical formula Al (CH ₃ ) ₃ , hereinafter referred to as TMA) is supplied to the reactor 105 using argon gas as a carrier gas. TMA is an aluminum liquid metal material and is housed in a raw material container 135 so that the gasified TMA gas is carriered with argon gas. The gas used for the carrier gas is not limited to argon gas as long as it is an inert gas.

(Alumina member manufacturing method: coating)
Next, the manufacturing method of an alumina member is demonstrated in order of a pre-process and this process. First, in the pre-process for coating the alumina substrate 30a, the infrared lamp 110 is heated by piping from the nichrome wire 115 by adjusting the temperature of the temperature controller 120, and the temperature inside the reactor 105 is adjusted to 400 ° C. or higher. The valve V1 is opened, the other valves are closed, and the purge gas nitrogen gas is supplied into the reactor 105 from the gas line L1. The inside of the reactor 105 is exhausted to a predetermined degree of vacuum by an exhaust device (not shown). In the previous step, pre-baking is performed for 30 minutes while adjusting the flow rate of nitrogen gas to 1 SLM.

After the pre-baking, the thermal CVD process which is this process is started. In this step, the purge gas is switched to the actual gas. That is, the supply of nitrogen gas is stopped by closing the valve V1, the valve groups (V2 to V9) of the gas lines L2 and L3 are appropriately opened, and TMA gas, ammonia gas, and argon gas are supplied to the reactor 105. Specifically, the gas flow is adjusted by the mass flow controller 125 while the valve V2 is opened, and a mixed gas of ammonia gas and argon gas is supplied from the gas line L2 to the reactor 105, and the valves V3 to V6 are opened and the mass flow controller 130 is opened. The mixed gas of TMA gas and argon gas is supplied to the reactor 105 from the gas line L3 while adjusting the gas flow rate.
At that time, the ratio of the ammonia gas flow rate to the total gas flow rate of the mixed gas, that is, the sum of the total gas flow rates supplied to the reactor 105 is 1000 ppm (0.1%). A mixed gas of ammonia gas of 1 SCCM and argon gas of 499 SCCM is supplied from the gas line L2 to the reactor 105 so that the ratio of the TMA gas flow rate becomes 100 ppm (0.01%), and 0.1 SCCM of the gas line L3 is supplied. A mixed gas of TMA gas and 499.9 SCCM argon gas is supplied to the reactor 105.

  When infrared rays are irradiated from the infrared lamp 110 into the reactor 105 by heating the pipe of the infrared lamp 110, TMA and ammonia gas are thermally decomposed by the energy of the infrared rays to cause a chemical reaction. As a result, the entire alumina base material 30a is caused. A thin film of aluminum nitride (AlN) is deposited. After a predetermined time, this process is terminated, and the valves V2 to V9 and the like are exhausted while being appropriately opened and closed.

Note that an aluminum nitride coating film is formed using Allen-N-methylpyrrolidine (Alane-N-methylpyrrolidine, chemical formula AlH ₃ : N (CH ₃ ) (CH ₂ ) ₄ , hereinafter referred to as MPA) instead of TMA. May be. In that case, MPA is stored in the raw material container 135, and a gas mixture of MPA gas and argon gas gasified from the gas line L3 is supplied. At that time, the ratio of the flow rate of the MPA gas becomes 100 ppm (0.01%) with respect to the total gas flow rate (that is, the sum of the flow rates of the mixed gas from the gas line L2 and the mixed gas from the gas line L3). As described above, a mixed gas of 0.1 SCCM MPA gas and 499.9 SCCM argon gas is supplied to the reactor 105 from the gas line L3, and a mixed gas of 1 SCCM ammonia gas and 499 SCCM argon gas is supplied to the reactor from the gas line L2. It supplies to 105.

(Process conditions)
In the thermal CVD process described above, a coating film having high plasma resistance can be formed by optimizing process conditions. In other words, unless the process conditions are optimized, carbon (C) remains in the aluminum nitride film or oxygen is mixed, resulting in poor plasma resistance. Therefore, the inventors conducted experiments for optimizing the pressure and temperature in the reactor 105, the processing time of thermal CVD, and the like.

(Pressure condition)
First, thermal CVD treatment was performed while changing the pressure, and the film quality of the produced aluminum nitride film was examined. The process conditions during the thermal CVD process are as follows.

Process conditions / gas type, flow rate 500 SCCM of 2000 ppm NH 3 / Ar mixed gas and 500 SCCM of 200 ppm TMA / Ar mixed gas are supplied. That is, the condition regarding the gas during the experiment is that the sum of the ammonia gas flow rate, the TMA gas flow rate, and the argon gas flow rate is 1 SLM, and the ammonia gas flow rate is 1000 ppm with respect to the sum of the flow rates. The TMA gas flow rate is 100 ppm. That is, the ammonia gas flow rate is 1 SCCM, the TMA gas flow rate is 0.1 SCCM, and the argon gas in the mixed gas of ammonia gas and argon gas and the argon gas in the mixed gas of TMA gas and argon gas are added. The flow rate (that is, the total flow rate of argon gas) is 998.9 SCCM.
・ Temperature 600 ℃
・ Processing time 30 minutes ・ Pressure XTorr (variable)

  As a result of the experiment, the change in the aluminum nitride film thickness accompanying the change in pressure is shown in FIG. 2, and the change in the composition ratio of nitrogen N and oxygen O in the aluminum nitride film accompanying the change in pressure is shown in FIG. According to the experimental results of FIG. 2, it can be seen that the lower the pressure, the thicker the aluminum nitride film. Further, according to the experimental results of FIG. 3, it can be seen that the lower the pressure, the lower the oxygen content of the aluminum nitride film and the higher the nitrogen content. Since the plasma resistance improves as the oxygen content in the aluminum nitride film decreases, it is better to reduce the oxygen content by lowering the pressure.

(Aluminum nitride film thickness)
However, the aluminum nitride film for coating the alumina base material 30a needs to be 1 μm or less. This is because if the thickness of the aluminum nitride film exceeds 1 μm, there is a high possibility that the aluminum nitride film will crack due to thermal expansion during plasma processing. The coated alumina member is installed in a plasma processing apparatus as will be described later, exposed to a high temperature during the plasma processing, and cooled when the substrate is carried out. The thermal expansion coefficient of the alumina base material is 8.0 × 10 ⁻⁶ K ⁻¹ , and the thermal expansion coefficient of aluminum nitride coating the alumina base material is 4.9 × 10 ⁻⁶ K ⁻¹ . Due to this difference in thermal expansion, in an aluminum nitride film having a thickness of more than 1 μm, the aluminum nitride film is broken by repeated heating and cooling of the alumina member during plasma processing. Therefore, in this embodiment, the coating film of aluminum nitride is controlled to 1 μm or less.

(Temperature conditions)
Next, thermal CVD treatment was performed while changing the temperature, and the film quality of the produced aluminum nitride film was examined. The process conditions during the thermal CVD process are as follows.

As for the process condition gas type and flow rate, a mixed gas of 200 ppm NH ₃ / Ar of 500 SCCM and a mixed gas of 200 ppm TMA / Ar of 500 SCCM are supplied to the reactor 105. Thereby, the ammonia gas flow rate becomes 100 ppm and the TMA gas flow rate becomes 100 ppm with respect to the sum of the total gas flow rates supplied to the reactor 105. That is, the conditions relating to the flow rate of each gas during the experiment are the sum of the ammonia gas flow rate, the TMA gas flow rate, and the argon gas flow rate is 1 SLM, the ammonia gas flow rate is 0.1 SCCM, the TMA gas flow rate is 0.1 SCCM, and the argon gas flow rate is 999.8 SCCM.
The temperature is variable at X ° C. and the processing time is 30 minutes.

As a result of the experiment, the carbon content in the aluminum nitride film accompanying the change in temperature is shown in FIG. According to the experimental results of FIG. 4, it can be seen that the higher the temperature, the higher the carbon content in the aluminum nitride film. It is better that carbon does not enter the aluminum nitride film as much as possible. This is because carbon has a property of reacting with oxygen (O) or hydrogen (H) to be methylated (CH ₃ ) and volatilized. When such a chemical reaction occurs in the aluminum nitride film, the surface layer of the aluminum nitride film cannot be flattened, unevenness is generated on the surface of the aluminum nitride film, and electric field energy concentrates on the convex part of the surface of the aluminum nitride film. This is because peeling occurs and causes contamination. Therefore, the temperature in the reactor 105 is desirably 700 ° C. or lower at which the carbon content in the aluminum nitride film is 40% or lower.

FIG. 5 shows the thermal decomposition characteristics of TMA on the surface of the alumina passivation film (Al ₂ O ₃ —SUS). The condition at this time is
-Gas type, flow rate 5 SCCM of 100 ppm TMA / Ar mixed gas, that is, 0.0005 SCCM of TMA gas and 49995 SCCM of argon gas are supplied.
Pre-bake Heat at 500 ° C. for 1 hour while flowing 500 SCCM of argon gas.
In other words, this thermal decomposition characteristic experiment was performed by heating at 500 ° C. for 1 hour while flowing 500 SCCM of argon gas per minute as a pre-bake, and then waiting for the temperature to stabilize at room temperature while flowing argon gas. After holding for a while, the temperature is increased at a rate of 2 ° C./min while flowing a mixed gas of 0.0005 SCCM TMA gas and 49995 SCCM argon gas, and the temperature and the discharge are increased while the temperature is being increased. This was done by measuring the components of the gas to be produced.

As a result, it is understood that thermal decomposition of TMA starts at a temperature of 350 ° C. or higher, and methane (CH ₄ ) is generated along with the decomposition. When the temperature is 400 ° C. or higher, TMA is stably thermally decomposed. From the results of FIGS. 4 and 5, the lower limit of the temperature of the thermal CVD process needs to be 400 ° C. or higher at which TMA is stably thermally decomposed. In addition, the upper limit of the temperature of the thermal CVD process is preferably 700 ° C. or less in consideration of the ratio of carbon contained in the aluminum nitride film.

(Ammonia concentration condition)
Next, an aluminum nitride film formed when the thermal CVD treatment was performed while changing the ammonia concentration was examined. The process conditions during the thermal CVD process are as follows.

Process conditions The conditions regarding the gas at the time of the experiment are as follows. The sum of the ammonia gas flow rate, the TMA gas flow rate, and the argon gas flow rate supplied into the reactor 105 is fixed to 1 SLM (= 1000 SCCM). The ammonia gas flow rate is set to X × 10 ⁻⁶ SLM (= X × 10 ⁻³ SCCM) and the TMA gas flow rate is set to 0.1 SCCM (that is, with respect to the sum of the flow rates) so that the ammonia gas concentration becomes X (variable) ppm. The TMA gas concentration is 100 ppm), and the argon gas flow rate is 1000- (X × 10 ⁻³ )-(0.1) SCCM so that the total flow rate becomes 1 SLM as the ammonia gas flow rate is varied. . The temperature is 600 ° C. and the treatment time is 30 minutes.

As a result of the experiment, the carbon content in the aluminum nitride film accompanying the change in the ammonia gas concentration is shown in FIG. According to the experimental results of FIG. 6, the carbon content is around 38% when the ammonia gas concentration is 10 ppm and 100 ppm, and becomes zero when the concentration is 1000 ppm. That is, it can be seen that there is a point where the carbon content starts to decrease when the ammonia gas concentration is between 100 ppm and 1000 ppm. As described above, carbon (C) reacts with oxygen (O) and hydrogen (H) and has the property of being methylated (CH ₃ ) and volatilizing, so that carbon does not enter the aluminum nitride film as much as possible. Better. Therefore, the ammonia gas concentration is preferably 1000 ppm or more where the carbon content in the aluminum nitride film is low, and the lower limit can be said to be between 100 ppm and 1000 ppm at which the carbon content starts to decrease.
When the ammonia gas concentration is 100 ppm, the ammonia gas flow rate is 1 times the TMA gas flow rate, and when the ammonia gas concentration is 1000 ppm, the ammonia gas flow rate is 10 times the TMA gas flow rate.

FIG. 7 shows the thermal decomposition characteristics of ammonia (NH ₃ ) on the surface of the alumina passivation film (Al ₂ O ₃ —SUS). The condition at this time is
Gas species and flow rate A mixed gas of 100 ppm NH ₃ / Ar is flowed through 5 SCCM, that is, 0.0005 SCCM ammonia gas and 49995 SCCM argon gas.
Pre-bake Heat at 500 ° C. for 1 hour while flowing argon gas of 500 SCCM per minute.
In other words, this thermal decomposition characteristic experiment was performed by heating at 500 ° C. for 1 hour while flowing 500 SCCM of argon gas per minute as a pre-bake, and then waiting for the temperature to stabilize at room temperature while flowing argon gas. After holding for a while, the temperature is increased at a rate of 2 ° C./min while flowing a mixed gas of 0.0005 SCCM ammonia gas and 49995 SCCM argon gas, and the temperature and the temperature are discharged while the temperature is being increased. This was done by measuring the gas components.

  As a result, it can be seen that thermal decomposition of ammonia starts at a temperature of 370 ° C. or higher, and is almost completely decomposed at 600 ° C. Therefore, if the temperature condition at the time of forming the aluminum nitride film is set to 400 ° C. or higher where TMA is stably thermally decomposed, ammonia is also sufficiently thermally decomposed, and a chemical reaction for forming the aluminum nitride film is performed. It turns out that it is promoted.

(processing time)
Finally, the thickness of the aluminum nitride film when the thermal CVD processing time was changed was examined. The process conditions at that time are as follows.

Process Conditions The conditions regarding the gas at the time of the experiment are that the sum of the ammonia gas flow rate, the TMA gas flow rate, and the argon gas flow rate is 1 SLM, and the ammonia gas flow rate is 1000 ppm and the TMA gas flow rate is 100 ppm. That is, ammonia gas is 1 SCCM, TMA gas is 0.1 SCCM, and argon gas is 998.9 SCCM. The temperature is 600 ° C., and the processing time is variable for X hours.

  As a result of the experiment, the relationship between the processing time and the aluminum nitride film thickness is shown in FIG. According to the experimental results of FIG. 8, the film thickness is about 135 nm in 30 minutes. As described above, cracks do not occur if the film thickness is 1 μm or less. Therefore, the treatment time may be any of 30 minutes to 2 hours, and even if the treatment time is 30 minutes, it is preferable because it has plasma resistance as described later and the throughput is improved.

From the above results, the optimized process conditions in the thermal CVD processing apparatus (FIG. 1) are as follows.
Process conditions, gas types and flow rates Gas line L2 2000 ppm NH ₃ / Ar mixed gas 500 SCCM (ammonia gas 1 SCCM, argon gas 499 SCCM) gas line L3 200 ppm TMA / Ar mixed gas 500 SCCM (TMA gas 0.1 SCCM, argon Gas 499.9 SCCM) Supply / temperature 400 ° C. or higher (preferably 500 ° C. to 700 ° C.)
・ Treatment time 30 minutes ・ Pressure No limitation (however, lower to lower the oxygen content)

  The flow rate of ammonia gas is preferably at least 1 time, preferably 10 times or more the flow rate of TMA gas. This makes it possible to form an aluminum nitride film that hardly contains carbon groups. On the other hand, for example, when the flow rate of ammonia gas is set to be less than 1 times the flow rate of TMA gas, carbon groups enter the aluminum nitride film, and a coating film having necessary plasma resistance cannot be obtained. When the flow rate of ammonia gas is at least 10 times the flow rate of TMA gas, the number of carbon groups entering the aluminum nitride film can be greatly reduced, and a coating film having good plasma resistance can be obtained.

  As described above, the step of adjusting the temperature inside the thermal CVD processing apparatus to 400 ° C. or more, the step of supplying a mixed gas containing TMA and ammonia to the thermal CVD processing apparatus in a predetermined ratio, and the thermal CVD using the mixed gas A method of manufacturing an alumina member for a plasma processing apparatus including a step of coating an alumina substrate with an aluminum nitride film by processing and optimization of process conditions during thermal CVD processing have been described. Next, a plasma processing apparatus according to this embodiment in which the alumina member manufactured in this manner is arranged will be described with reference to FIGS. In the present embodiment, a case where the alumina member 30 is used for a dielectric window of a microwave plasma processing apparatus will be described as an example.

[2. Plasma processing apparatus with alumina member]
(Configuration of microwave plasma processing equipment)
FIG. 9 is a view schematically showing a longitudinal sectional view of the microwave plasma processing apparatus 200 according to the present embodiment. FIG. 10 shows the ceiling surface of the apparatus. In the following description, a plasma CVD process is performed on the substrate G using the microwave plasma processing apparatus according to the present embodiment.

  The microwave plasma processing apparatus 200 includes a processing container 10 and a lid 20. The processing container 10 has a bottomed cubic shape whose upper part is opened. The processing container 10 and the lid 20 are hermetically sealed by an O-ring 32 disposed on the contact surface between the lid 20 (lid body 21) and the processing container 10, whereby the processing chamber U in which plasma processing is performed. Is formed. The processing container 10 and the lid 20 are made of a metal such as aluminum, for example, and are electrically grounded.

  The processing container 10 is provided with a susceptor 11 (mounting table) for mounting a glass substrate (hereinafter referred to as “substrate”) G therein. The susceptor 11 is made of, for example, aluminum nitride, and a power feeding unit 11a and a heater 11b are provided therein.

  A high frequency power source 12b is connected to the power supply unit 11a via a matching unit 12a (for example, a capacitor). In addition, a high-voltage DC power supply 13b is connected to the power supply unit 11a via a coil 13a. The matching unit 12a, the high-frequency power source 12b, the coil 13a, and the high-voltage DC power source 13b are provided outside the processing container 10. The high frequency power supply 12b and the high voltage DC power supply 13b are grounded.

  The power feeding unit 11a applies a predetermined bias voltage to the inside of the processing container 10 by the high frequency power output from the high frequency power source 12b. The power feeding unit 11a is configured to electrostatically attract the substrate G with a DC voltage output from the high-voltage DC power supply 13b.

  An AC power supply 14 provided outside the processing container 10 is connected to the heater 11b, and the substrate G is held at a predetermined temperature by an AC voltage output from the AC power supply 14.

  The bottom surface of the processing container 10 is opened in a cylindrical shape, and one end of a bellows 15 is attached to the periphery of the bottom surface. The other end of the bellows 15 is fixed to the elevating plate 16. In this way, the opening at the bottom of the processing container 10 is sealed by the bellows 15 and the lifting plate 16.

  The susceptor 11 is supported by a cylindrical body 17 disposed on the lifting plate 16 and moves up and down integrally with the lifting plate 16 and the cylindrical body 17. Thereby, the susceptor 11 is adjusted to a height corresponding to the processing process. A baffle plate 18 for controlling the gas flow in the processing chamber U to a preferable state is provided around the susceptor 11.

  A vacuum pump (not shown) provided outside the processing container 10 is provided at the bottom of the processing container 10. The vacuum pump is configured to depressurize the processing chamber U to a desired degree of vacuum by discharging gas from the processing container 10 through the gas discharge pipe 19.

The lid 20 is provided with a lid main body 21, six waveguides 33, a slot antenna 31, and a plurality of alumina members 30. The six waveguides 33 have a rectangular cross-sectional shape and are provided in parallel inside the lid body 21. The inside is filled with a dielectric member 34 such as fluororesin (for example, Teflon (registered trademark)), alumina (Al ₂ O ₃ ), quartz or the like, and λg ₁ = λc / (ε ₁ ) by the dielectric member 34. ^The guide wavelength λg ₁ of each waveguide 33 is controlled according to the expression of ^1/2 . Here, λc is the wavelength of free space, and ε ₁ is the dielectric constant of the dielectric member 34.

The slot antenna 31 is formed integrally with the lid body 21 below the lid body 21. The slot antenna 31 is made of a metal that is a nonmagnetic material such as aluminum. In the slot antenna 31, 13 slots 37 (openings) shown in FIG. 10 are arranged in series on the lower surface of each waveguide 33. Each slot 37 is filled with a dielectric member 38 such as fluororesin, alumina (Al ₂ O ₃ ), or quartz, and the dielectric member 38 allows λg ₂ = λc / (ε ₂ ) ^1/2 . The guide wavelength λg ₂ of each slot 37 is controlled according to the equation. Here, λc is the wavelength of free space, and ε ₂ is the dielectric constant of the dielectric member 38 inside the slot 37.

  An alumina member 30 is used for the dielectric window. As shown in a partially enlarged view in FIG. 11, the alumina member 30 is a member obtained by coating an alumina base 30a with an aluminum nitride film 30b. As shown in FIG. 10, the alumina members 30 are formed in a tile shape, and 39 sheets are evenly installed facing the inside of the processing container 10. Thirteen members 30 are provided in three rows at the same pitch so as to straddle the two waveguides 33. The six waveguides 33 are connected to the three microwave sources 40 through the Y branch tube 41 in pairs. Each alumina member 30 is adjacent to two slots 37. As a result, a microwave transmission path composed of the six waveguides 33, the plurality of slots 37, and the plurality of alumina members 30 is constructed.

  Thus, the alumina member 30 according to the present embodiment is provided facing the inside of the processing container 10 and functions as a dielectric window that transmits the microwave supplied from the microwave source 40 toward the processing container. . It should be noted that the alumina member 30 is provided in the processing vessel 10, and at least the surface exposed to the plasma during the plasma processing may be coated with an aluminum nitride film, and does not necessarily coat all of the alumina base material. It does not have to be.

  On the lower surface of the slot antenna 31, as shown in FIGS. 9 to 11, beams 26 formed in a lattice shape are provided to support 39 alumina members 30. The beam 26 is formed of a nonmagnetic material such as aluminum.

  Returning to FIG. 9 again, the description will be continued. The gas supply source 43 supplies a gas having a desired concentration into the processing container 10 by controlling the opening / closing of a plurality of valves (not shown) and the openings of a plurality of mass flow controllers (not shown), respectively. To do. When the plasma resistance is evaluated, hydrogen gas and argon gas are supplied. The desired gas output from the gas supply source 43 is passed through the gas introduction pipe 29 through the beam 26 via the gas line 42, and is introduced into the processing chamber from the tip opening A of the gas introduction pipe 29.

  A cooling water supply source 45 is connected to the cooling water pipe 44, and the cooling water supplied from the cooling water supply source 45 circulates in the cooling water pipe 44 and returns to the cooling water supply source 45. The main body 21 is maintained at a desired temperature.

  With the configuration described above, a desired gas output from the gas supply source 43 is excited by, for example, 2.45 GHz × 3 microwaves output from the three microwave sources 40 shown in FIG. Is generated, and the substrate G is subjected to etching and film formation by the action of plasma.

[3. Evaluation of plasma resistance of alumina members]
Next, the plasma resistance of the alumina member 30 was evaluated using the alumina member 30 mounted on a parallel plate type plasma processing apparatus having an upper electrode and a lower electrode.

(Plasma resistance evaluation TMA coating)
First, an alumina member 30 coated with TMA (coating with an aluminum nitride film using TMA as a raw material) was placed on a parallel plate type plasma processing apparatus and subjected to hydrogen plasma processing. The process conditions are as follows.

Process conditions / High frequency power 13.56MHz
・ Bias voltage 50V
・ Gas type and flow rate Hydrogen (H ₂ ) gas 5 sccm, Argon gas 45 sccm
・ Pressure 20mTorr
・ Processing time: 1 hour

  FIG. 12 shows the result of analyzing the alumina member 30 before and after the hydrogen plasma treatment in this case by X-ray photoelectron spectroscopy. 12A shows the composition ratio of the surface layer portion of the alumina member 30 before the hydrogen plasma irradiation, and FIG. 12B shows the composition ratio of the surface layer portion of the alumina member 30 after the hydrogen plasma irradiation.

  The outermost layer 0 nm to 10 nm of the alumina member 30 in the graph is contaminated and cannot be used for consideration. This is because after the hydrogen plasma treatment, the alumina member 30 is once released into the atmosphere and then analyzed by X-ray photoelectron spectroscopy. Accordingly, when the surface layer of the alumina member 30 in FIGS. 12 (a) and 12 (b) is viewed in the vicinity of 10 nm to 100 nm, oxygen (O) indicates an alumina base material (a base portion of the alumina member). Aluminum (Al) and nitrogen (N) indicate a coating film of aluminum nitride. According to this, the composition ratio of aluminum and nitrogen in the vicinity of 10 nm to 100 nm of the surface layer of the alumina member 30 is not changed.

  Thereby, it can be seen that the oxidation-reduction reaction does not occur even by the hydrogen plasma irradiation, and the aluminum nitride film of the alumina member 30 is not shaved. This proved that the TMA-coated alumina member 30 has plasma resistance. Carbon does not exist at a depth of 10 nm or more of the surface layer of the aluminum nitride film formed by TMA coating. Therefore, the formed aluminum nitride film by the TMA coating does not cause gasification by carbon and is a high quality film.

(Plasma resistance evaluation MPA coat)
Next, the alumina member 30 coated with MPA coating (coating with an aluminum nitride film using MPA as a raw material) was placed on a parallel plate type plasma processing apparatus and subjected to hydrogen plasma processing. The process conditions are the same as in the above TMA coating.

  FIG. 13 shows the result of analyzing the alumina member 30 before and after the hydrogen plasma treatment in this case by X-ray photoelectron spectroscopy. FIG. 13A shows the composition ratio of the surface layer portion of the alumina member 30 before the hydrogen plasma irradiation, and FIG. 13B shows the composition ratio of the surface layer portion of the alumina member 30 after the hydrogen plasma irradiation.

  Also in this case, when the surface layer of the uncontaminated aluminum nitride film is observed in the vicinity of 10 nm to 100 nm, there is no significant change in the composition ratio of aluminum (Al) and nitrogen (N). As a result, it can be seen that, even in the case of MPA coating, no oxidation-reduction reaction occurs due to the hydrogen plasma irradiation, and the aluminum nitride film is not scraped. This proved that the MPA-coated alumina member 30 has plasma resistance. Carbon (C) does not exist at a depth of 10 nm or more of the surface layer of the aluminum nitride film formed by MPA coating. Therefore, the formed aluminum nitride film by the MPA coat does not cause gasification by carbon and is a high quality film.

(Plasma resistance evaluation without coat)
Finally, hydrogen plasma treatment was performed using a parallel plate plasma treatment apparatus on which only an alumina base material not coated with an aluminum nitride film (no coating) was placed. The process conditions are the same as in the above TMA coating.

  FIG. 14 shows the result of analyzing only the alumina base material (without coating) before and after the hydrogen plasma treatment in this case by X-ray photoelectron spectroscopy. FIG. 14A shows the composition ratio of the surface layer portion of the alumina base material before the hydrogen plasma irradiation, and FIG. 14B shows the composition ratio of the surface layer portion of the alumina base material after the hydrogen plasma irradiation.

  Also in this case, when the surface layer of the alumina base material that is not contaminated is considered to be near 10 nm to 100 nm, aluminum is reduced. According to this, it is thought that aluminum protruded from the alumina base material. In this case, it is considered that the aluminum that has come out is contaminated with metal in the processing chamber and aluminum is mixed in the film. Thereby, it was proved that the alumina member 30 to which the TMA coat or the MPA coat is applied has plasma resistance, compared to the case where the uncoated alumina base material has no plasma resistance.

(Other materials, other coating films)
In the above description, the plasma resistance is improved by coating an alumina base material with an aluminum nitride film to produce an alumina member.

On the other hand, it is also conceivable to use an alumina member coated with an aluminum oxide (AlO) film instead of the alumina member coated with an aluminum nitride film. However, the Al—N bond strength of aluminum nitride is greater than the Al—O bond strength of aluminum oxide. Looking at the stretching vibration of the bond by the IR spectrum, the Al-N (wurtzite), since whereas about 691cm ^-1, the Al-O, is about 465cm ^-1, the Al-N Has a higher frequency than Al-O. That is, Al—N has a higher bond strength than Al—O. For this reason, coating the alumina base material with an aluminum nitride film enhances the plasma resistance compared to coating the alumina base material with an aluminum oxide film, and the mixing of aluminum and oxygen into the film formation is further reduced. Therefore, it is not a good idea to manufacture an alumina member by coating an alumina base material with an aluminum oxide film instead of coating the alumina base material with an aluminum nitride film.

Further, instead of coating an alumina base material with an aluminum nitride film to produce an alumina member, it is also conceivable that the alumina member is composed only of aluminum nitride. However, the dielectric loss tangent tan δ of aluminum nitride is 3.5 × 10 ^−3, which is an order of magnitude larger than 1 × 10 ⁻⁴ which is the dielectric loss tangent tan δ of alumina. Therefore, with aluminum nitride alone, the loss during microwave transmission becomes larger than when the alumina base material is coated with aluminum nitride. Furthermore, with aluminum nitride alone, even if process conditions are changed and optimized, carbon remains in the film or oxygen is mixed, making it difficult to produce a large-area aluminum nitride alone plate. This has been confirmed by experiments. On the other hand, the alumina base material is relatively easy to manufacture even in a large area, and the cost is low. Therefore, when the aluminum base material is coated with aluminum nitride, it is easy to manufacture even in a large area and the cost is low. There are advantages. Therefore, instead of coating the alumina base material with an aluminum nitride film to produce an alumina member, it is not a good idea to form the alumina member with only aluminum nitride.

  Therefore, it is a good idea to manufacture an alumina member by coating an alumina base material with an aluminum nitride film. However, as described above, carbon remains in the aluminum nitride film or oxygen is mixed in as well. In order to prevent this, it is very important to form an aluminum nitride film based on the optimized process conditions. That is, by forming an aluminum nitride film on an alumina substrate based on the above process conditions, it is possible to manufacture an alumina member 30 for a plasma processing apparatus with high plasma resistance.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, the alumina member for a plasma processing apparatus according to the present invention is exposed to plasma, not only a dielectric window of a microwave plasma processing apparatus, but also an electrode portion and mounting table of various plasma processing apparatuses, a gas showerhead, and the like. It can be used for the dielectric part.

  Further, for example, the thermal CVD processing apparatus according to the present invention can perform thermal CVD processing using another heater or heating method instead of the nichrome wire and the infrared lamp.

  In addition, the alumina member for a plasma processing apparatus according to the present invention can be removed from the plasma processing apparatus, recoated with the aluminum nitride film by thermal CVD, and then attached to the plasma processing apparatus again for reuse. is there. As a result, it becomes possible to reuse the member, to reduce the cost, and to manufacture and distribute one part of the environment-friendly plasma processing apparatus.

  The plasma processing apparatus in which the alumina member according to the present invention is used is an ICP (Inductively Coupled Plasma) plasma processing apparatus, an RLSA (Radial Line Slot Antenna) plasma processing apparatus, an MSEP (Metal Surface-Wave Excitation Plasma processing apparatus, parallel plasma processing apparatus). Any plasma processing apparatus may be used as long as the plasma processing apparatus performs plasma processing on an object to be processed such as a substrate or a wafer.

  Examples of the plasma processing performed by the plasma processing apparatus according to the present invention include CVD, etching processing, and ashing processing.

  The electromagnetic wave source according to the present invention is not limited to a microwave source, and may be a power source that supplies an electromagnetic wave necessary for exciting plasma in a processing vessel of a plasma processing apparatus using an alumina member such as a high frequency power source. That's fine.

The size of the substrate G (glass substrate) is, for example, 400 mm × 500 mm (G3 substrate size: dimensions in the processing chamber: 720 mm × 720 mm), G4.5 substrate size is 730 mm × 920 mm (dimensions in the processing chamber: 1000 mm × 1190 mm), The G5 substrate size is 1100 mm × 1300 mm (dimensions in the processing chamber: 1470 mm × 1590 mm). A microwave having a power of 1 to 8 W / cm ² is supplied into the processing chamber having the above size.

DESCRIPTION OF SYMBOLS 10 Processing container 20 Lid 26 Beam 33 Waveguide 30 Alumina member 30a Alumina base material 31 Slot antenna 37 Slot 40 Microwave source 100 Thermal CVD processing apparatus 105 Reactor 110 Infrared lamp 115 Nichrome wire 120 Temperature controller 135 Raw material container 200 Microwave Plasma processing equipment

Claims (11)

An alumina member used in a plasma processing apparatus comprising: a processing vessel in which plasma is excited inside; and an electromagnetic wave source that supplies an electromagnetic wave for plasma excitation into the processing vessel,
The alumina member is an alumina member for a plasma processing apparatus in which an alumina base material is coated with an aluminum nitride film.   The alumina member for a plasma processing apparatus according to claim 1, wherein the alumina base material is coated with the aluminum nitride film by a thermal CVD process of a mixed gas containing trimethylaluminum and ammonia.   The alumina member for a plasma processing apparatus according to claim 2, wherein a flow rate of the ammonia gas is 10 times or more with respect to a flow rate of the trimethylaluminum gas in the mixed gas used for the thermal CVD process.   The alumina member for a plasma processing apparatus according to any one of claims 2 and 3, wherein the temperature of the inside of the thermal CVD processing apparatus that performs the thermal CVD process is adjusted to 400 ° C or higher.   The alumina member for a plasma processing apparatus according to claim 1, wherein the alumina base material is coated with the aluminum nitride film by a thermal CVD process of a mixed gas containing allene, n, methylpyrrolidine and ammonia.   The alumina member for a plasma processing apparatus according to claim 1, wherein the aluminum nitride coating film has a thickness of 1 μm or less.   The alumina member for the plasma processing apparatus is provided in the processing container, and an aluminum nitride film is coated on at least a surface of an alumina base that is exposed to plasma during the plasma processing. The alumina member for a plasma processing apparatus according to one item.   The alumina member for the plasma processing apparatus is a dielectric window that is provided facing the inside of the processing container and transmits the electromagnetic wave supplied from the electromagnetic wave source toward the processing container. The alumina member for plasma processing apparatuses as described in any one of these.   The alumina member for the plasma processing apparatus is removed from the plasma processing apparatus, recoated with the aluminum nitride film by the thermal CVD process, and then attached to the plasma processing apparatus again and reused. An alumina member for a plasma processing apparatus according to any one of the above. A processing vessel in which plasma is excited;
An electromagnetic wave source for supplying an electromagnetic wave necessary for exciting plasma in the processing container;
An alumina member provided in the processing container,
A plasma processing apparatus, wherein an aluminum nitride film is coated on at least a surface of an alumina base material exposed to plasma of the alumina member. Adjusting the temperature inside the thermal CVD processing apparatus to 400 ° C. or higher;
Supplying a mixed gas containing trimethylaluminum and ammonia to the thermal CVD processing apparatus;
A method of manufacturing an alumina member for a plasma processing apparatus, comprising: coating an alumina substrate with an aluminum nitride film inside the thermal CVD processing apparatus by a thermal CVD process using the mixed gas.

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