TW200531154A - Apparatus and method for preventing corrosion of a vacuum gauge - Google Patents

Abstract

A vacuum process apparatus for preventing corrosion of a vacuum gauge is disclosed. The apparatus includes a process chamber used to proceed a vacuum process reaction. A vacuum gauge is connected to the process chamber. A protective gas source without water vapor which supplies a protective gas without water vapor into the process chamber to break vacuum in the process chamber after the vacuum process reaction within the process chamber is over. An isolation device between the process chamber and the vacuum gauge is actuated to isolate the process chamber from the vacuum gauge in an atmospheric pressure state caused by the protective gas without water vapor to avoid a pressure differential between the process chamber and the vacuum gauge.

Description

200531154 ---- '__ V. Description of the invention (1) 1. [Technical field to which the invention belongs] The present invention is related to ~ methods for preventing corrosion of vacuum gauges, especially about a method which can be designed for different semiconductor process machines Methods to prevent corrosion of the vacuum gauge. 2. [Previous Technology] Many semiconductor processes need to be performed in a step-down or glow discharge environment. For example, low pressure chemical vapor deposition (LPCVD), plasma assisted chemical vapor deposition (pECVD), evaporation, epitaxy, ion implantation, sputtering deposition, Dry etching, etc. Many machines used in these processes therefore require the use of a vacuum system to achieve the required process conditions. A vacuum system typically used for thin film deposition, as shown in the first figure, mainly includes a process chamber 10, a loading chamber 12, a process gas 14, a heating base 16, a vacuum gauge 18, and a rough gauge. Pumping pump 20, a high vacuum pump 22, a throttle valve 24 and a valve 26, etc. The purpose of the load lock chamber 12 (load lock chamber) is to maintain a certain degree of vacuum in the process chamber 10 to Reduce pollution and shorten process cycles. The roughing pump 20 is mostly a mechanical pump. After the wafer 28 is placed in the loading chamber 12, the loading chamber 12 is depressurized from an atmospheric pressure. When the loading chamber 12 reaches a certain vacuum degree After that, the valve 2 6 (va 1 ve) between the loading chamber 12 and the process chamber 10 will be opened.

Page 5 200531154_ V. Description of the invention (2) On, the wafer 2 8 is transferred from the loading chamber 12 to the heating base 16 in the process chamber 10. Prior to this, the process chamber 10 was first pumped with another rough pump 20, with a gas ballast (not shown in the figure), to a certain vacuum. After the wafer 2 8 is transferred to the process chamber 10, the high vacuum pump 2 2 is used, such as a diffusion pump, a turbo mol ecu 1 ar pump, and a cryogenic pump. 〇pump) or Roots blower, etc., to increase the vacuum of the process chamber 10. The wafer 28 is then heated to the deposition or process temperature. The process gas 14 is passed through a mass flow controller (MFC) 34 into the process chamber 10. The degree of vacuum is measured with a vacuum gauge 18, such as a capacitance manometer, a thermocouple gauge, or an ionization gauge, for measuring and controlling the process. At the end of the process, all process gases 14 or by-products (by-products) are pumped away and filtered through an exhaust gas abatement equipment for process, such as a combustion chamber 3 0 (bur n box). The process gas 14 or the by-product impurity gas contains a flammable or toxic part of the gas. Finally, the process gas 14 or the by-product impurity gas that has been safely processed is exhausted through the exhaust system 32 to the vacuum system for film deposition. . In a vacuum system, in addition to the pump, important parts are a vacuum gauge, tubing, and valve. Which chooses the vacuum timing, must consider the ultimate vacuum degree. At vacuum technology t, the vacuum is divided into five regions according to the pressure: rough vacuum (rough

Page 6 200531154 V. Description of the invention (3) vacuum), medium vacuum, high vacuum, very high vacuum and ultra high vacuum. In different semiconductor processes, different vacuum requirements are required. For example, sputtering and dry etching are between rough and moderate vacuum, and ion implantation must be performed in a high vacuum environment. In the semiconductor process, a reactive process gas is often used to react with the wafer surface in the process chamber to form a thin film or produce an etching effect. Because the reaction products will not only be deposited on the wafer, they will also be attached to the metal walls of the process chamber. If these deposits are poorly attached, they will often fall off and become a source of particles (par r 1 e) in the process, resulting in products. The yield (yie 1 d) decreases. Therefore, in order to prevent excessive deposits from accumulating on the surface of the process room, the equipment engineer must regularly perform preventive maintenance (PM) on the machine. Although at the end of the semiconductor process, the process gas or by-product impurity gases will be pumped out of the process chamber via vacuum pumping, there will still be some remaining process gas adsorbed on the metal walls of the process chamber and pipelines. Among them, the vacuum gauge responsible for detecting the pressure in the process chamber and whether it reaches the pressure range required by the process will also have these residual process gas adsorption. When the equipment engineer performs preventive maintenance of the machine in the atmosphere, these residual process gases, because they contain fluorine or gas molecules, will encounter acidic money and corrosive substances after encountering water and gas in the atmosphere, and then rot the surname. The vacuum gauge causes problems such as shortening the service life of the vacuum gauge and deviation in accuracy when measuring the degree of vacuum.

Page 7 200531154 V. Description of the invention (4) To prevent the above problems, the current design of the machine is equipped with a pneumatic valve between the vacuum gauge and the communication pipeline of the process chamber. Before cleaning and maintenance of the process chamber The pneumatic valve will be activated in a vacuum state to close the communication pipeline between the vacuum gauge and the process chamber, and then the process chamber will be evacuated to isolate the atmospheric water from entering the vacuum gauge. At present, the isolation devices of machine protection vacuum gauges are pneumatic valves, which are controlled by signals detected by pressure sensors in the process chamber. When the pressure in the process chamber is greater than a set value, such as 10 Torr (t 〇rr), The pressure sensor will send a signal to the pneumatic valve for closing action. At this time, the pressure in the internal space of the vacuum gauge belongs to a vacuum environment of 10 torr. When the pressure in the process chamber reaches a large atmospheric pressure, that is 7 6 0 Torr, the pressure sensor will send a signal to the machine to show that the process chamber has reached an atmospheric pressure. At this time, the equipment engineer can open the valve of the process chamber to clean and maintain the machine. Since the pressure in the process chamber is at atmospheric pressure of 760 torr, and the pressure in the internal space of the vacuum gauge is under a vacuum condition of 10 torr, it is inevitable that some water vapor in the atmosphere will cause The pressure difference penetrates into the internal space of the vacuum gauge. What's more, if the pipeline of the pneumatic valve has the adsorption of reactive gas or its by-product impurities, and deposits are formed on the pipe wall, the pneumatic valve will be incomplete. The condition of the air makes the water vapor in the atmosphere directly enter the internal space of the vacuum gauge through the gap between the pneumatic valve and the valve seat, forming an acid substance to cause corruption of the vacuum gauge. At present, the manufacturers of general semiconductor machines have some machines that do not have an isolator at all.

Page 8 200531154 V. Description of the invention (5) The service life of the vacuum gauge often does not reach half the service life of the vacuum gauge with a designed isolation device. In addition, some machines are designed with pneumatic valves, but because Pneumatic valves are closed in a vacuum state, so the internal space of the vacuum gauge is controlled under vacuum conditions. It is easy to occur when the pneumatic valve is incompletely closed, causing leakage, which causes corrosion of the vacuum gauge. Therefore, the current design of the machine, whether or not an isolation device is installed, will infiltrate the water vapor of the atmosphere and react with the process gas or by-product impurity gas adsorbed on the vacuum gauge to form corrosive substances, causing the corrosion of the vacuum gauge. This makes the problems of reduced service life and inaccurate readings of the vacuum gauge. 3. Summary of the Invention In view of the above background of the invention, the traditional method of not using an isolation device or using a pneumatic isolation device today will cause the corrosion of the vacuum gauge. An object of the present invention is to provide a method for preventing corrosion of a vacuum gauge. It is characterized by keeping the vacuum gauge under a protective gas that is clean and free of water vapor. Since the protective gas does not contain water vapor, it does not react with the remaining process gas adsorbed on the vacuum gauge, thereby preventing the corrosion of the vacuum gauge. Another object of the present invention is to provide a device which can prevent the corrosion of the vacuum gauge by adding a manual valve. Because the manual valve is a simple, inexpensive, and easy-to-maintain isolating device, it can be directly installed in the communication line between the vacuum gauge and the process room.

Page 9 200531154_ V. Description of the invention (6) The machine of the dynamic isolation device must also have a good effect of preventing the corrosion of the vacuum gauge. Another object of the present invention is to provide a method for preventing corrosion of a vacuum gauge by using an isobaric principle. Its characteristic is to keep the gas pressure in the internal space of the vacuum gauge consistent with the atmospheric pressure outside the isolation device, so it is possible to avoid the situation where the airtightness of the isolation device is caused by the incomplete sealing or leakage of the isolation device. According to the above-mentioned purpose, a vacuum process equipment for preventing corrosion of a vacuum gauge is disclosed, which includes a process chamber for performing a vacuum process reaction, a vacuum gauge communicating with the process chamber, and a source of anhydrous protective gas during the process. After the reaction of the vacuum process in the chamber is completed, an anhydrous protective gas is passed into the process chamber to break the vacuum in the process chamber, and an isolation device is provided between the process chamber and the vacuum gauge. The isolation device is protected by the anhydrous protective gas. In a state of atmospheric pressure, start to isolate the communication between the process chamber and the vacuum gauge to avoid a pressure difference between the process chamber and the vacuum gauge. Fourth, [implementation method] Some embodiments of the present invention will be described in detail as follows. However, in addition to the detailed description, the present invention can be widely implemented in other embodiments. That is, the scope of the present invention is not limited by the proposed embodiments, but should be based on the scope of patent applications filed by the present invention. Moreover, in this specification, different parts of each element are not drawn according to size. Some scales have been exaggerated or simplified compared to other related scales to provide a clearer description

Page 10 200531154 V. Description of the invention (7) and understanding of the present invention. In this embodiment, a vacuum process equipment for preventing the vacuum gauge from remaining is disclosed. The vacuum process equipment includes a process chamber for performing a vacuum process reaction, a vacuum gauge communicating with the process chamber, and a source of anhydrous protective gas during the process. After the reaction of the vacuum process in the chamber is completed, an anhydrous protective gas is passed into the process chamber to break the vacuum in the process chamber, and an isolation device is provided between the process chamber and the vacuum gauge. The isolation device is protected by the anhydrous protective gas. In a state of atmospheric pressure, start to isolate the communication between the process chamber and the vacuum gauge to avoid a pressure difference between the process chamber and the vacuum gauge. Refer to the second figure Isolation device, such as machine, plasma etching, manual valve 60, etc. Valves (without valves (without gas in 50 as pressure, body gas 62 neutral gas, (BCla) 54, allergic gas First of all, there are reactions in the picture to extract the work in the picture body can be equal. Then, This is a preferred embodiment of the present invention, which uses a valve such as a manual valve to isolate the vacuum gauge from the process chamber, which includes a process chamber 50, a capacitive vacuum gauge 5 2, a radio frequency generator 5 6, and a vacuum. Pump 5 8. Throttle body source 6 2. A mass flow controller 64 and an anhydrous protective gas. A substrate, such as wafer 66, is displayed on the electrode base by a process chamber 50 (shown in the form). Block 6 8 on the 'style display after)' off. Then, the process chamber 70 is evacuated with vacuum pump 5 8 until the working pressure under the plasma etching process conditions is about 0 to 10 Torr (t 〇 r r). The reactive gas is sent into the process chamber 50. The commonly used reactive gas (C10, hydrogen bromide (HBr), boron trichloride) starts a radio frequency generator 5 6 and uses the radio frequency field to reverse the reaction.

Page 11 200531154_ V. Description of the invention (8) Plasma is generated by the release of the reactive gas (not shown in the figure), and the wafer 6 6 is anisotropically etched. Reactive gas flow is continuously supplied and pumped continuously with vacuum pump 5 8 because some reactive gases and their by-products are toxic. After the plasma etching process is completed, the gas supply must be stopped and the RF generator turned off 5 6 The reactive gas and its by-products are drawn out of the process chamber 50 through a vacuum pump 58, and then a clean, protective gas, such as nitrogen (N0), is filled with an anhydrous protective gas source 72, so as to break the vacuum. The valve (not shown in the figure) of the process chamber 50 can be opened, and the wafer 6 6 can be taken out. When the process chamber 50 is filled with clean and anhydrous nitrogen, the internal space of the vacuum gauge 5 2 and the process chamber 5 0 is connected by a communication tube, so at this time the internal space of the vacuum gauge 52 is also filled with isostatic nitrogen. When the nitrogen pressure in the process chamber 50 is equal to the atmospheric pressure, the pressure sensor in the process chamber 50 ( (Not shown in the diagram) will send a signal to the machine controller (not shown in the diagram), and a display (not shown in the diagram) will be used to show that the pressure in the process chamber 50 is equal to the atmospheric pressure, and then ,this A main feature of the invention is that the manual valve 54 between the vacuum gauge 52 and the process chamber 50 is closed at this time to isolate the communication between the vacuum gauge 52 and the process chamber 50, and then the valve of the process chamber 50 is opened to perform the process chamber. Cleaning and maintenance of 50. Since the air pressure in the internal space of the vacuum gauge 50 is the same as that of the process chamber 50, the water vapor in the atmosphere in the process chamber 50 cannot easily enter the internal space of the vacuum gauge 5 2 due to the pressure difference. The purpose of preventing corrosion of the vacuum gauge is achieved. On the other hand, another main feature of the present invention is the use of a manual valve 54, the detailed structure of which is shown in the third figure, including a rotary button 80, a live

Page 12 200531154 V. Description of the invention (9) Moving rod 8 2, a valve cap 8 4, a valve body 8 6, a bellows 8 8, a disc 9 0, a washer 92, a gasket 94 , A combined seat 96, a process chamber interface 98 and a vacuum gauge interface 100. The sealing washer 92 can be made of an elastomer washer, such as a 0-ring washer. Because 0-ring washer of different materials has different anti-corrosion effects on different process gases, it can be targeted at the machine. The process gas used is fitted with a 0-ring washer of suitable material to achieve cost savings. In addition, if automatic control is to be considered, the manual valve 54 mentioned above may also be a pneumatic valve. As shown in the fourth figure, it includes a movable rod 110, a washer 112, a bonnet 114, a disc body 116, A process chamber interface 1 1 8 and a vacuum gauge interface 1 2 0. Among them, the movable rod 1 1 0 uses a 0-ring washer double seal or a bellows seal. In addition to pneumatic operation, it can also be designed in the form of a solenoid valve. Then, referring to the fifth figure, another preferred embodiment of the present invention is a step-down chemical vapor deposition furnace that uses a manual valve to isolate the vacuum gauge from the process chamber, which includes a process chamber 1 3 0, a capacitive vacuum gauge 1 3 2, a manual valve 1 3 4, a heater 1 3 6, a reactive gas 1 3 8, a vacuum pump 1 4 0, this machine is commonly used to deposit polycrystalline silicon, two Silicon oxide and silicon nitride. First, the wafer 1 2 4 enters the processing chamber 1 3 0 through the loading and unloading door 1 4 4 and is pumped out of the processing chamber 1 30 by a vacuum pump 140, such as a Roots blower, until the pressure is about 0. · 25 ~ 2 Torr, at this time the heater 1 3 6 heats the wafer 1 4 2 to a temperature of about 3 0 ~ 9 0 0 ° C, and

Page 13 200531154_ V. Description of the invention (ίο) Reactive gas 1 3 8 is introduced, and the gas flow rate is about 100 to 100 cubic meters per minute (seem). After the reaction of the deposition process is completed, the reaction will be The gas 138 and its by-products are pumped out, and then filled with clean anhydrous nitrogen (not shown in the diagram) to break the vacuum until the measured value of the pressure sensor (not shown in the diagram) in the process chamber 130 reaches one atmosphere. At this time, the manual valve 1 3 4 can be closed, the loading and unloading door 1 4 4 can be opened, and the wafer 1 4 2 can be taken out. After that, the equipment engineer can clean and maintain the process room 1 3 0. Since the air pressure in the internal space of the vacuum gauge 1 3 2 is the same as that of the process chamber 130, the water vapor in the atmosphere in the process chamber 130 cannot easily enter the internal space of the vacuum gauge 1 32 due to the pressure difference. To prevent the effect of vacuum gauge corrosion. Finally, referring to the sixth figure, another preferred embodiment of the present invention is a flow chart of preventive maintenance operations for preventing corrosion of the vacuum gauge. The steps include: first, providing a wafer on the pedestal of the process chamber. The vacuum chamber is used to pump out the gas in the process chamber to the working pressure 2 1 0 under the process conditions, and the reactive gas is sent into the process chamber to perform the process reaction 2 2 0. After the process reaction is completed, the gas supply is stopped 2 3 0. The gas and its by-products are pumped out of the process chamber 2 40 through a vacuum pump, and the process chamber is backfilled with clean, protective water to break the vacuum 2 50. The manual valve between the vacuum gauge and the process chamber is closed 2 6 0 and the process is opened The valve of the chamber is used to take out the wafer 270, and the preventive maintenance of the process chamber is performed 280. When a clean and water-free protective gas is injected into the process chamber, because the internal space of the vacuum gauge is connected to the process chamber by a connecting pipe, the internal space of the vacuum gauge is also filled with protective gas of equal pressure at the same time. When the protective gas pressure in the process chamber is equal to the atmospheric pressure,

Page 14 200531154_ V. Description of the invention (11) The manual valve between the process chamber and the process chamber is closed to isolate the connection between the vacuum gauge and the process chamber, and then the process chamber valve can be opened to clean and maintain the process chamber. Since the air pressure in the internal space of the vacuum gauge is the same as that of the process chamber, the water vapor in the atmosphere in the process chamber cannot easily enter the internal space of the vacuum gauge due to the pressure difference, so as to prevent the corrosion of the vacuum gauge. The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of patent application of the present invention. Any other equivalent changes or modifications made without departing from the spirit disclosed by the present invention shall be included in the following Within the scope of patent application.

Page 15 200531154 Brief description of the drawings 5. [Simplified description of the drawings] The first figure shows a schematic diagram of a vacuum system for thin film deposition. The second figure is a schematic diagram of a preferred embodiment of the present invention. The third figure is a schematic diagram of a manual valve structure of the present invention. The fourth figure is a schematic diagram of a pneumatic valve structure according to the present invention. The fifth diagram is a schematic diagram of another preferred embodiment of the present invention. Fig. 6 is a flowchart of another preferred embodiment of the present invention.

Representative symbols of the main parts: 10 Process chamber 12 Loading chamber 1 4 Process gas 1 6 Heating base 1 8 Vacuum gauge 2 0 Rough pump 2 2 High vacuum pump 2 4 Throttle valve 2 6 Valve 2 8 Wafer

3 0 Combustion chamber 3 2 Exhaust 3 4 Mass flow controller 5 0 Process chamber 5 2 Capacitive vacuum gauge

Page 16 200531154 Brief description of drawings 5 4 Manual valve 5 6 Radio frequency generator 5 8 Vacuum pump 6 0 Throttle valve 6 2 Reactive gas source 6 4 Mass flow controller 6 6 Wafer 6 8 Electrode base 7 0 Gas extraction 7 2 Anhydrous protective gas source 8 0 Turn knob 8 2 Movable rod 8 4 Bonnet 8 6 Valve body 8 8 Bellows 90 disc 9 2 Sealing washer 9 4 Gasket 9 6 Sealing seat 9 8 Process chamber interface 1 0 0 Vacuum gauge interface I 1 0 Moving rod II 2 Washer 1 1 4 Bonnet

Page 17 200531154_ Simple illustration 1 1 6 plate 1 1 8 process chamber interface 1 2 0 vacuum gauge interface 1 3 0 process chamber 1 3 2 capacitance vacuum gauge 1 3 4 manual valve 1 3 6 heater 1 3 8 reaction Gas 1 14 0 Vacuum pump 14 2 Wafer 1 4 4 Loading and unloading door 2 0 0 First supply the wafer on the base of the process chamber 2 1 0 Use the vacuum pump to extract the gas from the process chamber to the process conditions. Working pressure 2 2 0 Send reactive gas into process chamber for process reaction 2 3 0 Stop gas supply after process reaction is completed 2 4 0 Pull reactive gas and its by-products out of process chamber through vacuum pump 2 5 0 Protective gas backfill process chamber to break vacuum 2 6 0 Close manual valve between vacuum gauge and process chamber 2 7 0 Open process chamber valve to remove wafer 2 8 0 Preventive maintenance of process chamber

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Claims (1)

200531154 6. Scope of patent application 1. A vacuum process equipment for preventing corrosion of a vacuum gauge, comprising: a process chamber for performing a vacuum process reaction; a vacuum gauge in communication with the process chamber; an anhydrous protective gas source in After the vacuum process reaction in the process chamber is completed, an anhydrous protective gas is passed into the process chamber to break the vacuum degree in the process chamber; and an isolation device is provided between the process chamber and the vacuum gauge. The isolation device is activated to isolate the communication between the process chamber and the vacuum gauge when the anhydrous protective gas reaches a pressure of one atmosphere, so as to avoid a pressure difference between the process chamber and the vacuum gauge. 2. The vacuum process equipment for preventing corrosion of the vacuum gauge according to item 1 of the scope of patent application, wherein the vacuum gauge includes a capacitance vacuum gauge. 3. The vacuum process equipment for preventing corrosion of the vacuum gauge according to item 1 of the scope of the patent application, wherein the source of anhydrous protective gas includes a nitrogen gas (N 2). 4. The vacuum process equipment for preventing corrosion of the vacuum gauge according to item 1 of the scope of the patent application, wherein the vacuum process reaction includes a plasma etching reaction. 5. The vacuum process equipment for preventing corrosion of the vacuum gauge according to item 1 of the scope of the patent application, wherein the vacuum process reaction includes a chemical vapor deposition reaction. 6. Vacuum system to prevent corrosion of vacuum gauge as described in item 1 of the scope of patent application Page 19 200531154_ VI. Scope of Patent Application Process, where the isolation device includes a valve. 7. The vacuum process equipment for preventing corrosion of a vacuum gauge as described in claim 6 of the scope of patent application, wherein the valve includes an elastomer washer. 8. The vacuum process equipment for preventing corrosion of the vacuum gauge as described in claim 7 of the scope of the patent application, wherein the elastomer washer comprises a 0-ring washer. 9. The vacuum processing equipment for preventing the corrosion of the vacuum gauge as described in item 6 of the patent application scope, wherein the valve comprises a bellows. 10. The vacuum process equipment for preventing corrosion of the vacuum gauge according to item 6 of the scope of the patent application, wherein the valve includes a manual valve. 1 1 The vacuum process equipment for preventing corrosion of the vacuum gauge according to item 6 of the patent application scope, wherein the valve comprises a gas valve. 12. The vacuum process equipment for preventing corrosion of a vacuum gauge according to item 6 of the scope of patent application, wherein the valve includes a solenoid valve. 1 3. A method for preventing corrosion of a vacuum gauge, comprising: providing a process chamber, the process chamber being in communication with a vacuum gauge; and after a vacuum process reaction in the process chamber is completed, passing through an anhydrous Page 20 200531154_ VI. The protection gas in the patent application scope enters the process chamber to break the vacuum in the process chamber; and isolates the process chamber from the vacuum gauge when the anhydrous protective gas reaches a pressure of one atmosphere. To avoid a pressure difference between the process chamber and the vacuum gauge. 14. The method for preventing corrosion of a vacuum gauge as described in item 13 of the scope of patent application, further comprising: opening a valve of the process chamber to be in contact with an atmosphere. 15. The method for preventing corrosion of a vacuum gauge according to item 13 of the scope of patent application, wherein the vacuum gauge comprises a capacitance vacuum gauge. 16. The method for preventing corrosion of a vacuum gauge as described in item 13 of the scope of patent application, wherein the anhydrous protective gas contains a nitrogen gas (N0. 1) 7. The vacuum gauge as described in item 13 of the scope of patent application A method for etching, wherein the vacuum process reaction includes a plasma etching reaction. 18. The method for preventing corrosion of a vacuum gauge as described in item 13 of the patent application scope, wherein the vacuum process reaction includes a chemical vapor deposition reaction. Page 21