JP2001267097A - Plasma processing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a gas leakage to a work domain at the time of a breakage in a microwave guide window and a breakage of an equipment resulting from the gas leakage, and to safely stop the equipment operation. SOLUTION: A reserve vacuum tank 3 is arranged just in front of a plasma generation tank 2 in a microwave transmission line 12. The plasma generation tank 2 is vacuum-sealed by the microwave guide window 1, and the reserve vacuum tank 3 is vacuum-sealed by the microwave guide window 1 and a reserve vacuum window 6. A pressure gauge 8 which detects a pressure change in the reserve vacuum tank 3 is equipped. When a rapid pressure change in the reserve vacuum tank 3 is detected with the pressure gauge 8, it is judged that the microwave guide window 1 is damaged, and a control system 13 generates a stop signal. The stop signal is added to a gas supply equipment 7 and a microwave power supply 10, and the equipment is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus using microwave plasma, and more particularly to an apparatus for eliminating gas leakage when a microwave introduction window is broken.

[0002]

2. Description of the Related Art There is known an ECR type plasma CVD apparatus utilizing an electron cyclotron resonance phenomenon (ECR) which is an interaction between an electromagnetic wave in a microwave region and a magnetic field. As shown in FIG. 3, a conventional ECR-type plasma CVD apparatus introduces a microwave from a microwave power supply 10 into a plasma generation tank 2 through a microwave transmission line 12 and a microwave introduction window 1 to form an air core. A structure is employed in which ECR is generated between the magnetic field and a magnetic field generated by a coil (not shown) to generate plasma. The gas supplied from the gas supply facility 7 to the plasma generation tank 2 is turned into plasma and supplied to the processing tank 4, where it is subjected to plasma processing by acting on a substrate (not shown) and exhausted to the apparatus exhaust system 5.

As shown in a detailed view of FIG. 4 in which a circle drawn by a dotted line is enlarged, a plasma generation tank 2 is connected to a terminal of a microwave transmission line 12 through which microwaves are transmitted. The microwave introduction window 1 is provided between the microwave transmission path 12 and the plasma generation tank 2 to partition the microwave transmission path 12 and the plasma generation tank 2 by vacuum sealing the plasma generation tank 2. Reference numeral 14 denotes an O-ring for sealing. From the gas inlet 15 provided in the plasma generation tank 2,
A reactive gas is introduced into the reactor, and plasma is generated in the plasma generation tank 2 by microwaves introduced from the microwave transmission path 12 through the microwave introduction window 1 to activate the reactive gas. The plasma gas formed in the plasma generation tank 2 is sent from the plasma outlet 16 to the processing tank 4.

[0004]

However, the above-mentioned prior art has the following problems. The microwave introduction window 1 is subjected to chemical and thermal stresses such as erosion by reactive plasma and heating by microwave and plasma. For this reason, the microwave introduction window 1 often breaks during continuous use. In such a case, in the conventional device configuration, the reactive gas may flow backward through the microwave transmission line 12 and leak to the work area. Further, the apparatus itself may be damaged due to corrosion or the like by the leaked gas.

[0005] As mentioned above, erosion and heat are the main causes of window breakage. The microwave introduction window directly exposed to the plasma needs to be resistant to both, but at present, there is no material compatible with both. If alumina or the like that is resistant to erosion is selected, the material is damaged mainly by thermal stress. Conversely, if quartz that is resistant to heat is selected, it will be damaged mainly due to erosion. Whichever you choose, the risk of breakage cannot be avoided. For this reason, it is required that even if the micro introduction window is damaged, gas leakage does not occur.

SUMMARY OF THE INVENTION An object of the present invention is to provide a plasma processing apparatus which solves the above-mentioned problems of the prior art and eliminates gas leakage to a work area and breakage of the apparatus when a microwave introduction window is damaged. is there. Another object of the present invention is to provide a plasma processing apparatus having a protection mechanism and capable of safely stopping the apparatus.

[0007]

According to the present invention, there is provided a plasma generating chamber for converting a gas supplied into a plasma state into a plasma state by using a microwave, and a plasma generating chamber provided to vacuum seal the plasma generating chamber. A microwave transmission window for transmitting microwaves, and a microwave transmission line for transmitting the microwave and introducing microwaves from the microwave introduction window into the plasma generation chamber; and the microwave introduction window and the microwave transmission line. And a pressure detecting means for detecting a pressure change in the closed space.

[0008] It is preferable that the closed space is vacuum-sealed with the plasma generation chamber by the microwave introduction window, and the space between the closed space and the microwave transmission path is vacuum-sealed by a preliminary vacuum window. .

The closed space provided between the plasma generation chamber and the microwave transmission path is preferably evacuated for reasons of reducing the microwave transmission loss and for detecting a pressure change due to gas inflow from the plasma generation chamber. Further, for the former reason, the material of the preliminary vacuum window is preferably quartz having a small transmission loss.

[0010] It is assumed that the microwave introduction window is damaged by chemical or thermal stress such as erosion by reactive plasma or heating by microwave or plasma. Then, gas flows into the adjacent closed space from the plasma generation chamber, but stops here. At this time, rapid pressure fluctuation occurs in the closed space. This pressure fluctuation is immediately detected by the pressure detecting means provided in the closed space. Therefore, the inflow of gas can be automatically stopped using this detection signal. In this way, even if the microwave introduction window is damaged, it is possible to effectively prevent the reactive gas from flowing backward through the microwave transmission line and leaking into the work area, or to damage the apparatus itself due to corrosion or the like accompanying the gas leakage. Can be prevented.

In the above invention, when a sudden pressure change in the closed space is detected by the pressure detecting means, it is determined that the microwave introduction window is damaged, and a device stop signal is output from the pressure detecting means. Preferably, the device is stopped by a signal. As a result, if the microwave introduction window is broken, the device stops, and the reliability of the device is further improved.

[0012]

Embodiments of the present invention will be described below. FIG. 1 is an overall view of the plasma processing apparatus, and FIG. 2 is an enlarged view of a part circled by a dotted line in FIG.

As shown in FIG. 1, this apparatus comprises a plasma supply system 21, a pressure gauge 8 as pressure detecting means, a processing tank 4, a microwave transmission line 12, a power supply system 22, a gas supply system 23, a gas exhaust system 24, and a control system 13.

The plasma supply system 21 includes a plasma generation tank 2 for generating plasma, and a preliminary vacuum tank 3 provided adjacent to the plasma generation tank 2 and functioning as a buffer tank when the microwave introduction window 1 is damaged. This preliminary vacuum tank 3 forms a closed space. A microwave introduction window 1 is provided between the plasma generation tank 2 and the preliminary vacuum tank 3, and the plasma generation tank 2 is vacuum-sealed by the microwave introduction window 1. The microwave introduction window 1 is made of, for example, alumina, quartz, or the like. The preliminary vacuum chamber 3 is connected to a microwave transmission line 12 described later. A preliminary vacuum window 6 is provided between the preliminary vacuum chamber 3 and the microwave transmission path 12, and the preliminary vacuum chamber 3 is vacuum-sealed with the preliminary vacuum window 6. The preliminary vacuum window 6 is made of, for example, quartz.

The pressure gauge 8 is provided in the preliminary vacuum tank 3 and detects the pressure in the preliminary vacuum tank 3.

The processing tank 4 has an introduction passage 17 for introducing a plasma gas, and a plasma-converted gas in a shower shape.
It comprises a shower head 18 to be supplied into the inside, a substrate mounting table 19 for mounting a substrate to be processed (not shown), and an exhaust path 20. The substrate mounting table 19 is provided with a heating mechanism or a cooling mechanism, or a mechanism for applying a bias voltage such as direct current or high frequency, depending on the purpose of use.

The microwave transmission line 12 is composed of a waveguide that propagates microwaves. The power supply system 22 includes the microwave power supply 10, the microwave power supply 10 and the microwave transmission line 1.
2 and a matching circuit 11 for matching with 2.
The microwave taken out of the microwave power supply 10 and matched by the matching circuit 11 is introduced into the plasma generation tank 2 through the preliminary vacuum window 6, the preliminary vacuum tank 3, and the microwave introduction window 1. .

The gas supply system 23 includes a gas supply facility 7 and a gas introduction path 3 leading from the gas supply facility 7 to the plasma generation tank 2.
1 to supply the reactive gas from the gas supply facility 7 into the plasma generation tank 2 via the gas introduction path 31.

The gas exhaust system 24 is connected to the processing tank 4 and communicates with the apparatus exhaust system 5, and the preliminary exhaust path 32 is connected to the preliminary vacuum tank 3 and joins the exhaust path 20.
And a vacuum pump, such as a turbo molecular pump 9, provided in the middle of the preliminary exhaust passage 32, for exhausting the atmosphere in the processing tank 4 and forcing the atmosphere in the preliminary vacuum tank 3 to the apparatus exhaust system 5. It is designed to be extracted.

The control system 13 stops the gas supply equipment 7 and the microwave power supply 10 in accordance with the signal detected by the pressure gauge 8 to stop the supply of gas and microwave.

As shown in FIG. 2, the plasma generation tank 2
It is connected in series to the terminal of the microwave transmission line 12 via the preliminary vacuum chamber 3. The microwave introduction window 1 is provided between the preliminary vacuum tank 3 and the plasma generation tank 2, and the preliminary vacuum window 6 is provided between the microwave transmission line 12 and the preliminary vacuum tank 3. The left and right entrances of the auxiliary vacuum chamber 3 are vacuum-sealed by the microwave introduction window 1 using the O-ring 14 and the auxiliary vacuum window 6.

In the above-described configuration, the reactive gas supplied from the gas supply equipment 7 passes through the microwave transmission path 12 from the microwave power supply 10 to generate plasma from the preliminary vacuum tank 3 through the microwave introduction window 1. The plasma is generated in the plasma generation tank 2 by the microwave introduced into the tank 2. After being turned into plasma, it is introduced into the processing tank 4,
After performing a predetermined process, the gas is exhausted from the device exhaust system 5. The preliminary vacuum chamber 3 is evacuated by a turbo-molecular pump 9, and the pressure is monitored by a pressure gauge 8.

If the microwave introduction window 1 is broken during operation of the apparatus, a rapid pressure fluctuation occurs in the preliminary vacuum chamber 3. The pressure fluctuation is detected by the pressure gauge 8. When the pressure gauge 8 detects a pressure fluctuation, the control system 13 sends a stop signal to the gas supply equipment 7 to immediately stop the gas supply. Also, a stop signal is sent to the microwave power source 10 to immediately perform a safe stop process such as a microwave stop. At this time, the reactive gas leaked from the broken microwave introduction window 1 into the preliminary vacuum chamber 3 is exhausted from the preliminary vacuum chamber 3 to the exhaust system 24 by the turbo molecular pump 9 and the device exhaust system 5.

In the present embodiment, the provision of the auxiliary vacuum tank 3 between the plasma generation tank 2 (microwave introduction window 1) and the microwave transmission line 12 enables detection of breakage of the microwave introduction window 1 and Leakage of reactive gas at the time of breakage can be effectively prevented. In this case, it is possible to detect a break in the microwave introduction window 1 by detecting a change in pressure in the preliminary vacuum chamber 3 and perform a safe stop operation.

Further, if the inside of the preliminary vacuum chamber 3 is evacuated by the vacuum pump, even if the microwave introduction window 1 is damaged and the reactive gas flows into the preliminary vacuum chamber 3, the reactive gas is removed. Since the gas can be effectively evacuated from the preliminary vacuum chamber 3 to the exhaust system 24, the reactive gas is less likely to leak into the work area, and damage to the apparatus itself due to corrosion caused by the gas leak is reduced.

In this embodiment, the auxiliary vacuum chamber 3 is provided outside the microwave transmission path 12 so as to relay the microwave transmission path 12 and the plasma generation tank 2. A preliminary vacuum window 6 is provided between the pre-vacuum chamber 3 and the microwave transmission path 12 to provide a vacuum seal between the pre-vacuum tank 3 and the microwave transmission path 12. Plasma generation tank 2 and microwave transmission line 12
When the preliminary vacuum window 6 and the preliminary vacuum chamber 3 are interposed between the plasma generation tank 2 and the auxiliary vacuum window 6, the plasma generation efficiency in the plasma generation tank 2 may be slightly reduced. However, by selecting a window material with a small microwave transmission loss, such as quartz, for the auxiliary vacuum window 6, it is possible to minimize the decrease in plasma generation efficiency, and there is no practical problem.

The microwave introduction window 1 is required to be resistant to both erosion and heat, so that the risk of window breakage cannot be avoided. Requires only heat resistance, so by using quartz with low coefficient of thermal expansion and low dielectric loss,
The frequency of breakage can be reduced to a level that can hardly occur. Also, even if the preliminary vacuum window 6 is damaged, the leakage of the reactive gas does not occur unless the microwave introduction window 1 is simultaneously damaged.

In the above-described embodiment, the breakage of the microwave introduction window 1 is detected by detecting the pressure of the preliminary vacuum chamber 3. However, the gas flow rate of the preliminary vacuum chamber 3 is detected by detecting the gas flow rate of the preliminary vacuum chamber 3. It is also possible to detect the breakage of the microwave introduction window 1 and perform a safe stop operation. For this purpose, a flow sensor is provided in the preliminary vacuum chamber 3 in place of the pressure gauge, and the detected value of the gas flow rate flowing through the preliminary vacuum chamber 3 detected by the flow sensor is added to the control system 13. When the value exceeds the set flow rate, a stop signal is generated, and the stop signal is applied to the gas supply equipment 7 and the microwave power supply 10 to stop the gas supply and the microwave supply.

In the above embodiment, the preliminary vacuum tank 3
Is provided outside the microwave transmission line 12 so as to relay the microwave transmission line 12 and the plasma generation tank 2, but may be provided inside the microwave transmission line 12.

[0030]

According to the present invention, since a closed space serving as a buffer tank is provided between the plasma generation chamber and the microwave transmission line, the reactive gas leaks into the work area when the microwave introduction window is damaged. In addition, it is possible to effectively prevent damage to the device itself due to leaked gas.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a plasma processing apparatus according to an embodiment.

FIG. 2 is an enlarged view of a portion surrounded by a dotted line in FIG.

FIG. 3 is an overall configuration diagram of a conventional plasma processing apparatus.

FIG. 4 is an enlarged view of a main part of a conventional plasma processing apparatus.

[Explanation of symbols]

 2 Plasma generation tank (plasma generation chamber) 3 Preliminary vacuum chamber (closed space) 6 Preliminary vacuum window 8 Pressure gauge (pressure detecting means) 12 Microwave transmission line

Claims (2)

[Claims] A plasma generation chamber for converting a gas supplied into the plasma generation state into a plasma state by a microwave; a microwave introduction window provided to seal the plasma generation chamber in a vacuum and introducing a microwave into the plasma generation chamber. A microwave transmission path for transmitting the microwave and introducing microwaves from the microwave introduction window into the plasma generation chamber; and a closed space provided between the microwave introduction window and the microwave transmission path. A plasma processing apparatus comprising: a pressure detecting unit configured to detect a pressure change in the closed space. 2. The plasma processing apparatus according to claim 1, wherein when the pressure detecting means detects a rapid pressure change in the closed space, it is determined that the microwave introduction window is damaged and the apparatus is stopped. apparatus.