TWI728602B - System for preventing corrosion of etching gas supply pipeline and operation method of plasma reactor - Google Patents

Abstract

The present invention discloses a system for preventing corrosion of an etching gas supply pipeline and an operation method of a plasma reactor. The operation method includes the following steps: when the top cover of the etching reaction chamber is opened, a controllable valve is opened to connect to the etching reaction chamber. Inert gas is introduced into the gas supply device connected to the body to prevent water vapor in the air from entering the etching gas supply pipeline; when the top cover of the etching reaction chamber is closed for plasma etching, the controllable valve is closed to allow the etching gas to flow Into the gas supply device. The invention can effectively prevent water vapor in the air from entering the etching gas supply pipeline, thereby fundamentally avoiding the problem of water vapor corroding the etching gas supply pipeline after encountering corrosive gas, thereby ensuring that the wafer will not be corroded by the supply pipeline The resulting metal pollution.

Description

System for preventing corrosion of etching gas supply pipeline and operation method of plasma reactor

The invention relates to the field of semiconductor manufacturing, in particular to a system for preventing corrosion of an etching gas supply pipeline and a plasma reactor operation method.

In the existing plasma etching technology, the inductively coupled plasma (ICP, Inductive Coupled Plasma) etching machine often introduces corrosive gases such as _{Cl 2} , COS, HBr, SiCl _{4 to etch silicon.}

These corrosive gases need to enter the reaction chamber through a gas line (gas line) metal pipe. At present, most gas supply pipelines are made of stainless steel pipes such as SST316L. When the reaction chamber is opened, water vapor in the atmosphere will enter the exposed SST316L pipeline. Studies have shown that when the water vapor concentration exceeds 0.5 PPM, the pipeline will be corroded; when the water vapor concentration is greater than 100 PPM, the corrosion points are visible to the naked eye.

Therefore, after each cavity is opened, the water vapor will stay in the gas supply pipeline and is difficult to volatilize. Water vapor will corrode the weld when it encounters corrosive gases. The corrosion of the pipeline will bring out the heavy metals such as Cr and Mn in the stainless steel and deposit them on the wafer, causing metal contamination to the wafer.

The current common practice is to replace the gas supply pipeline every time the cavity is opened, which is costly and time-consuming for maintenance. Or, replace SST316L stainless steel with Hurst alloy stainless steel, but Hurst alloy stainless steel is expensive and the cost increases; in addition, Hurst alloy is a Ni-based alloy, which is not suitable for etching gases such as CO. Therefore, there is currently no method that can effectively avoid corrosion of the gas supply pipeline by water vapor.

The purpose of the present invention is to provide a system for preventing corrosion of the etching gas supply pipeline and a plasma reactor operation method, so as to solve the problem that the corrosion of the etching gas supply pipeline by water vapor cannot be effectively avoided in the prior art.

To achieve the above objective, the present invention provides a plasma reactor operating method, wherein the plasma reactor includes: An etching reaction chamber, the etching reaction chamber includes a susceptor for supporting the wafer to be processed, the top of the etching reaction chamber includes a top cover, and an air inlet device is provided on the top cover; The gas supply device is used for supplying reaction gas to the air inlet device, and the gas supply device includes: an etching gas supply pipe for connecting to an etching gas source and an inert gas supply pipe for connecting to an inert gas source and an inert gas supply pipe The road also includes a controllable valve, and both the etching gas supply pipeline and the inert gas supply pipeline are connected to the air inlet device; The operation method includes the following steps: when the top cover of the etching reaction chamber is opened, the controllable valve is opened, and inert gas is introduced into the gas supply device connected with the etching reaction chamber to prevent water vapor in the air from entering the etching gas supply Pipeline; when the top cover of the etching reaction chamber is closed for plasma etching, the controllable valve is closed so that the etching gas is passed into the gas supply device.

In the above-mentioned plasma reactor operation method, the inert gas is preheated before being introduced, and/or the etching gas supply line is heated while the inert gas is introduced, so as to be adsorbed in the etching gas supply line The water vapor in the wall is desorbed.

In the above-mentioned plasma reactor operation method, the inert gas is nitrogen.

The present invention also provides a system for preventing corrosion of an etching gas supply pipeline realized by the above method, which includes an inert gas source and an inert gas supply pipeline connected with the inert gas source; the inert gas supply pipeline is in communication with the etching gas supply pipeline, Used to pass inert gas.

In the above system for preventing corrosion of the etching gas supply pipeline, the inert gas supply pipeline has a restrictor valve for restricting the flow of the inert gas.

The above-mentioned system for preventing corrosion of the etching gas supply pipeline, wherein the system further includes a first heating device for heating the etching gas supply pipeline, and/or is arranged on the inert gas supply pipeline, and is used for performing heat on the inert gas The second heating device for heating.

In the above system for preventing corrosion of the etching gas supply pipeline, the first heating device is a heating belt.

In the above system for preventing corrosion of the etching gas supply pipeline, the heating belt is wrapped with an insulating layer.

In the above system for preventing corrosion of the etching gas supply pipeline, the second heating device is a heater.

In the above system for preventing corrosion of the etching gas supply pipeline, the heater is an electric heater or a heat exchanger.

Compared with the prior art, the present invention has the following beneficial effects:

In the existing plasma etching technology, the system for preventing the corrosion of the etching gas supply pipeline and the operation method of the plasma reactor provided by the present invention can effectively prevent water vapor in the air from entering the etching gas supply pipeline, and thus fundamentally It avoids the problem of water vapor corroding the etching gas supply pipeline after encountering corrosive gas, so as to ensure that the wafer will not have metal contamination caused by the corrosion of the supply pipeline. The method and system are simple and easy to implement. There is no need to replace the etching gas supply pipeline, nor does it need to replace the more expensive Hester alloy stainless steel. It is suitable for various etching gases, greatly prolongs the service cycle of the etching gas supply pipeline, and is convenient Technical transformation and construction.

The present invention will be further described below with specific embodiments in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention.

As shown in FIG. 1, it is a schematic structural diagram of an existing embodiment of the etching reaction chamber 6 and its gas supply device. The first gas supply pipeline 1 for conveying etching gas is divided by the flow divider 4 to obtain a second gas supply pipeline 2 and a third gas supply pipeline 3, and finally communicate with the inside of the etching reaction chamber 6. The first gas supply pipe 1, the second gas supply pipe 2 and the third gas supply pipe 3 together constitute the etching gas supply pipe of the present embodiment. The tuning gas supply pipeline 5 for delivering tuning gas is simultaneously connected to the second gas supply pipeline 2 and the third gas supply pipeline 3 to mix the tuning gas into the etching gas and then deliver it to the etching reaction chamber 6 . At present, most of the etching gas supply pipelines are made of easily-obtained and inexpensive SST316L stainless steel and other easily corroded pipes. However, this design also brings the following problems: When the etching reaction chamber 6 is opened every time After the top cover, the etching gas supply pipeline directly connected to the etching reaction chamber 6 will be directly exposed to the air. The water vapor in the air will stay in the first gas supply pipe 1, the second gas supply pipe 2 and the third gas supply pipe 3 shown in Figure 1 and is difficult to volatilize. The water vapor encounters the etching gas in the The corrosive gas will corrode the etching gas supply pipeline. The existing solution is to replace the first gas supply line 1, the second gas supply line 2 and the third gas supply line 3 in time, or change the material of the etching gas supply line to more corrosion-resistant Herst Alloy stainless steel to extend the service life of the supply pipeline. However, the current practice has the problem of greatly increasing the cost, and the Hester alloy stainless steel cannot be applied to the situation where there is CO and other gases in the etching gas.

In view of the problems of the foregoing existing embodiments, the present invention provides a plasma reactor operating method, wherein the plasma reactor includes: An etching reaction chamber 6, the etching reaction chamber 6 includes a susceptor for supporting the wafer 9 to be processed, the top of the etching reaction chamber 6 includes a top cover, and an air inlet device is provided on the top cover; The gas supply device is used for supplying reaction gas to the air inlet device, and the gas supply device includes: an etching gas supply line for connecting to an etching gas source, an inert gas supply line for connecting to an inert gas source, and an inert gas supply The pipeline also includes a controllable valve 14, and the etching gas supply pipeline and the inert gas supply pipeline are both connected to the air inlet device; The operation method includes the following steps: when the top cover of the etching reaction chamber 6 is opened, the controllable valve 14 is opened, and an inert gas is introduced into the gas supply device connected with the etching reaction chamber 6, so that the inert gas is filled with the first A gas supply pipeline 1, a second gas supply pipeline 2 and a third gas supply pipeline 3 prevent water vapor in the air from entering the etching gas supply pipeline, thereby fundamentally preventing water vapor from corroding and etching after encountering corrosive gases The problem of the gas supply pipeline, so as to ensure that the wafer 9 does not have metal contamination caused by the corrosion of the supply pipeline; when the top cover of the etching reaction chamber 6 is closed for plasma etching, the controllable valve 14 is closed to make the etching The gas is passed into the gas supply device. The inert gas can be low-priced and common nitrogen, which can be led out from the existing nitrogen pipe network at the production site without causing additional cost burden. The method is simple and easy to implement, neither the etching gas supply pipeline needs to be replaced, nor the more expensive Heschst alloy stainless steel material, which greatly prolongs the service period of the etching gas supply pipeline to facilitate the technical transformation and construction.

In the above-mentioned embodiments of the invention, a very small amount of water vapor may still be adsorbed on the inner wall of the etching gas supply pipeline. In order to completely eradicate this problem, further improvements can be made on the basis of the above methods. For example, the inert gas is preheated before being introduced, that is, the inert gas is preheated to a certain temperature and then introduced into the etching gas supply pipeline, or the etching gas is supplied while the inert gas is introduced into the etching gas supply pipeline The pipeline is heated, or the inert gas and the etching gas supply pipeline are heated at the same time, so as to desorb the water vapor adsorbed on the inner wall of the etching gas supply pipeline. The most suitable solution among the above methods can be selected to achieve the best anti-corrosion effect according to the specific site conditions and implementation results.

In a specific embodiment, the SST316L etching gas supply line, which is exposed to the atmosphere when the etching reaction chamber 6 is opened, is heated, and heated nitrogen gas is passed into the etching gas supply line for purging. When the etching reaction chamber 6 is opened, the heated etching gas supply pipeline and the heated nitrogen gas are easier to desorb the water vapor from the inner wall of the etching gas supply pipeline when purging. When the etching reaction chamber 6 is evacuated to 100 mtorr, the pressure in the etching gas supply pipeline is about 10 torr. At this time, the temperature corresponding to the vapor pressure of water is 12°C. The heated etching gas supply pipeline and the heated Nitrogen can more easily take the water vapor away from the etching gas supply line into the etching reaction chamber 6, and finally be pumped away. In this embodiment, the selection of the heating temperature of the nitrogen and etching gas supply lines is not particularly limited, and the appropriate heating temperature can be determined on the basis of the effect and cost.

In order to put the above method into practical industrial application, the present invention also provides a system for preventing corrosion of the etching gas supply pipeline by adopting the above method. The system includes an inert gas source and an inert gas supply pipeline connected with the inert gas supply pipeline; The path is communicated with the etching gas supply pipe for introducing inert gas so as to fill the etching gas supply pipe with the inert gas, which can effectively avoid the problem of water vapor entering the etching gas supply pipe due to the opening of the etching reaction chamber 6. In this embodiment, the inert gas source can be a nitrogen storage tank, or a nearby nitrogen pipe network at the production site can be used. For example, it is only necessary to draw out the nitrogen supply pipeline from the existing nitrogen pipe network and connect it with the etching gas supply pipeline by welding. The structure of the system is extremely simple, requiring only SST316L stainless steel pipes as the inert gas supply pipeline, which is convenient and easy to implement, has low cost of transformation, and is beneficial to large-scale popularization and application.

As shown in Figure 2, it is a schematic view of the improved structure of the existing etching reaction chamber 6 and its gas supply device shown in Figure 1 to solve the problem of corrosion of the etching gas supply pipeline after water vapor encounters corrosive gas. problem. Connect the high-purity nitrogen supply pipe 12 in the nitrogen pipe network to the first gas supply pipe 1 by welding to pass the high-purity nitrogen into the first gas supply pipe 1 and then through the second gas supply pipe 2 And the third gas supply pipeline 3 enters the etching reaction chamber 6. The etching reaction chamber 6 is composed of an insulating window 7, a side wall of the cavity, a bottom wall of the cavity, etc., and an electrostatic chuck 8 is arranged inside, and a wafer 9 can be placed on the electrostatic chuck 8. The exhaust port (not shown in the figure) is connected to a vacuum device to make the etching reaction chamber 6 into a vacuum environment. The coil 10 above the insulating window 7 is supplied with radio frequency energy, and the insulating window 7 is coupled to react in the etching reaction. Plasma is formed in the cavity 6 to etch the wafer 9 on the electrostatic chuck 8. The side wall of the etching reaction chamber 6 is provided with a side wall lining 11, so that the side wall of the chamber no longer directly contacts the plasma, avoids the bombardment of the plasma, and facilitates cleaning and replacement. In this embodiment, when the etching reaction chamber 6 is opened, the nitrogen supply pipe is used to purge the inside of the etching reaction chamber 6 with nitrogen, which effectively prevents the wafer 9 from being corroded by the etching gas supply pipe. Metal pollution improves the quality of the product.

Wherein the inert gas supply pipeline 12, in addition to being connected to the upstream of the splitter 4 as shown in Figure 2, can also be connected to the two downstream supply pipelines of the splitter 4, but two inert gas supply pipelines need to be set to connect separately To the second and third gas supply pipelines, or directly connected to the air inlet device, such as the gas nozzle 13 in the center of the insulating window 7 in Figure 2.

In the above embodiment, in order to effectively control the inert gas introduction, a controllable valve 14 may be provided on the inert gas supply pipeline for adjusting the inert gas flow rate. Furthermore, the controllable valve 14 can be incorporated into the existing DCS control system to achieve more convenient operation and monitoring. In order to control the flow of inert gas, it is also possible to modify the body of the inert gas supply pipeline. For example, a restrictor valve 15 is provided on the inert gas supply pipeline to limit the flow of inert gas. The restrictor valve 15 can also be replaced with a reducer. The reducer can be a concentric or eccentric orifice, which can be obtained by stamping to achieve a fixed flow restriction.

In order to more effectively desorb the water vapor adsorbed on the inner wall of the etching gas supply pipeline, the above-mentioned system for preventing corrosion of the etching gas supply pipeline may further include a first heating for heating the etching gas supply pipeline The device, or a second heating device for heating the inert gas, is installed on the inert gas supply pipeline, or the first heating device and the second heating device are installed at the same time.

By heating the etching gas supply pipeline and the inert gas by the first heating device and the second heating device, the etching gas supply pipeline can be effectively adsorbed on the inner wall of the etching gas supply pipeline while preventing water vapor from entering the etching gas supply pipeline When the etching gas reaction chamber 6 is evacuated, the water vapor is evacuated by the air extraction device to prevent the water vapor adsorbed on the inner wall of the etching gas supply pipeline from corroding the etching gas supply pipeline, thereby preventing the corrosion of the etching gas supply pipeline. Circle 9 causes metal pollution, and the system can be compatible with various etching gases, including CO gas which is not compatible with Hester alloy stainless steel.

In some specific embodiments, the above-mentioned first heating device can select a cheap heating belt, and only need to coat the heating belt on the outer wall of the etching gas supply pipeline, and technical transformation can be realized without hot work. . Furthermore, the outer side of the heating belt can be wrapped with an insulating layer to achieve better heating effect. The thermal insulation layer can be selected from polyurethane thermal insulation layer, thermal insulation cotton or polylactic acid foam material. In addition, the second heating device can be selected as an electric heater, and the electric heater can be selected from various electric heaters on the market that can heat the inert gas according to the gas medium. The gas heater can also be realized by selecting a heat exchanger, and at the same time, the existing waste heat in the production site can be further recycled, saving energy and realizing heating of inert gas.

In addition to being applied to inductively coupled plasma processors (ICP), the present invention can also be applied to capacitively coupled plasma processors (CCP). In the capacitive coupling type plasma processor, the top cover is replaced from an insulating window 7 with an upper electrode, and the air inlet device is also replaced from a gas nozzle 13 in the center with a disc-shaped gas shower head. As long as there is a maintenance process for opening the cavity, the capacitive coupling plasma processor will also have the risk of water vapor entering the gas pipeline. Therefore, it is also necessary to add the unique inert gas supply pipeline of the present invention to the etching gas supply pipeline to supply it when the cavity is opened. The inert gas enters the air inlet device so that the air pressure at the outlet of the air inlet device is greater than the atmospheric pressure, preventing the air with water vapor from flowing backwards such as the gas supply pipeline.

In summary, in the existing plasma etching technology, the system for preventing the corrosion of the etching gas supply pipeline and the operation method of the plasma reactor provided by the present invention can effectively prevent water vapor in the air from entering the etching gas supply pipeline. Therefore, the problem of water vapor corroding the etching gas supply pipeline after encountering corrosive gas is fundamentally avoided, thereby ensuring that the wafer does not appear to be metal contamination caused by corrosion of the supply pipeline. The method and system are simple and easy to implement. There is no need to replace the etching gas supply pipeline or the more expensive Heschst alloy stainless steel. It is suitable for various etching gases and greatly prolongs the service cycle of the etching gas supply pipeline. Facilitate technical transformation and construction.

Although the content of the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be regarded as limiting the present invention. Various modifications and alternatives to the present invention will be obvious after reading the above content by those with ordinary knowledge in the field. Therefore, the scope of protection of the present invention should be limited by the scope of the attached patent application.

1: The first gas supply line 2: The second gas supply line 3: The third gas supply line 4: shunt 5: Tuning the gas supply line 6: Etching the reaction chamber 7: Insulation window 8: Electrostatic chuck 9: Wafer 10: Coil 11: Side wall lining 12: Inert gas supply pipeline 13: Gas nozzle 14: Controllable valve 15: restrictor valve

Figure 1 is a schematic view of the structure of a conventional etching reaction chamber and its gas supply device.

Fig. 2 is a schematic structural view of an etching reaction chamber and its gas supply device including the system for preventing corrosion of an etching gas supply pipeline according to the present invention.

1: The first gas supply line

2: The second gas supply line

3: The third gas supply line

4: shunt

5: Tuning the gas supply line

6: Etching the reaction chamber

7: Insulation window

8: Electrostatic chuck

9: Wafer

10: Coil

11: Side wall lining

12: Inert gas supply pipeline

13: Gas nozzle

14: Control valve

15: restrictor valve

Claims (10)

A method for operating a plasma reactor, wherein the plasma reactor includes: An etching reaction chamber, the etching reaction chamber includes a susceptor for supporting the wafer to be processed, the top of the etching reaction chamber includes a top cover, and an air inlet device is provided on the top cover; and A gas supply device for supplying a reaction gas to the air inlet device, the gas supply device comprising: an etching gas supply pipe for communicating with an etching gas source, and an inert gas supply pipe for communicating with An inert gas source, the inert gas supply pipeline further includes a controllable valve, the etching gas supply pipeline and the inert gas supply pipeline are both connected to the air inlet device; and The operating method includes the following steps: when the top cover of the etching reaction chamber is opened, the controllable valve is opened, and an inert gas is introduced into the gas supply device connected with the etching reaction chamber to prevent air The water vapor in the etching reaction chamber enters the etching gas supply pipeline; when the top cover of the etching reaction chamber is closed for plasma etching, the controllable valve is closed so that an etching gas is passed into the gas supply device. The plasma reactor operation method according to claim 1, wherein the inert gas is preheated before being introduced, and/or the etching gas supply line is heated while the inert gas is input, so as to absorb The water vapor in the inner wall of the etching gas supply pipeline is desorbed. The method for operating a plasma reactor according to claim 1, wherein the inert gas is nitrogen. A system for preventing corrosion of an etching gas supply pipeline realized by the method of claim 1, which includes the inert gas source and the inert gas supply pipeline communicating with the inert gas source; the inert gas supply pipeline and the etching gas supply The pipeline is connected to pass in the inert gas. The system for preventing corrosion of an etching gas supply pipeline according to claim 4, wherein the inert gas supply pipeline has a restrictor valve for restricting the flow of the inert gas. The system for preventing corrosion of an etching gas supply pipe according to claim 4, wherein the system further comprises a first heating device for heating the etching gas supply pipe, and/or is arranged on the inert gas supply pipe On the road, a second heating device for heating the inert gas. The system for preventing corrosion of the etching gas supply pipeline according to claim 6, wherein the first heating device is a heating belt. The system for preventing the corrosion of the etching gas supply pipeline according to claim 7, wherein the outside of the heating belt is wrapped with an insulating layer. The system for preventing corrosion of the etching gas supply pipeline according to claim 6, wherein the second heating device is a heater. The system for preventing corrosion of an etching gas supply line according to claim 9, wherein the heater is an electric heater or a heat exchanger.

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