Abstract:
The present invention provides a vacuum processing apparatus that includes gas supply means having a hard interlock of a pair of gas valves. 
     The present invention provides a vacuum processing apparatus including: a gas supply unit that supplies gas, for performing vacuum processing using normally closed type air-driven valves, to a processing chamber where the vacuum processing is performed, the gas supply unit having an interlock function in which, when a first valve of a pair of the air-driven valves is opened, a second valve of the pair is closed, the gas supply unit including an air circuit that controls air for driving the air-driven valves, the air circuit being configured using an electromagnetic valve having a solenoid coil corresponding to each of the pair of the air-driven valves.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a vacuum processing apparatus that performs processing such as etching, chemical vapor deposition (hereinafter called CVD), ashing, and surface modification for a processed object with the use of process gas. 
       BACKGROUND ART 
       [0002]    For use in fabricating semiconductor devices or electric elements such as liquid crystals or solar cells, a fabrication apparatus, which performs processing for a processed material, such as a wafer, with the use of high-purity gas of various properties called process gas, is now an indispensable, important industrial machine. The control of these process gases is implemented by opening or closing the valves, which are provided in the downstream side of a mass flow controller via a flow amount controller such as the mass flow controller and are called stop valves or gas valves, according to the step information on the processing recipe. 
         [0003]    In the actual processing, the process gas, introduced into the processing chamber or the reaction reactor (chamber), is changed to plasma or is reacted at a high temperature for performing processing such as etching, CVD, ashing, surface modification, or diffusion on a processed material. Because process gas flows into the stop valves and the gas valves, which configure the gas supply system, at a speed of several-cubic cm/minute to several linters/minute and because the valves are opened and closed according to the complex recipe step configuration, durability, reliability, and cleanliness for reducing the adherence of foreign matters onto a processed object are required. 
         [0004]    A valve has a cylinder that applies an air pressure of about 0.3 MPa to 0.65 MPa to operate and open the valve. Usually, a normally closed type valve, which is closed when the air supply is stopped to reduce the air pressure in the cylinder, is used. A valve is closed by the pressing force of a spring. A diaphragm or a bellows is used on the contact gas part as a moving part to prevent a leakage of process gas into the external environment. A normally closed type valve, which is closed to stop the gas supply when the electric conduction of the apparatus is turned off for safety, is used in a gas supply system in many cases. 
         [0005]    An electromagnetic valve (solenoid valve) is used to supply an air signal for causing these valves to open. The air signal is generated according to the on/off state of the electric signal. On the other hand, there are several types of process gas to be controlled: flammable gas, oxidation gas, poisonous gas, and corrosive gas. For safe use, mixture, and reaction of these gases, various interlock functions are provided on the apparatus to ensure safe processing and working. 
         [0006]    As an example in which the interlock function is provided in a circuit that controls the air pressure for controlling valve opening/closing, there is means disclosed in Patent Literature 1. 
       CITATION LIST 
     Patent Literature 
       [0007]    Patent Literature 1: JP-A-H05-007763 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0008]    Normally, an interlock for preventing a malfunction requires a dual mechanism of the hardware as the foolproof function. In the valve open/close operation for these process gases, the open/close operations among different valves are controlled, using an electric relay circuit according to the pressure signal and the pre-examined circuit, to create a method for preventing an abnormal reaction, gas leakage, and gas source contamination (mixture with other gases). 
         [0009]    Of course, the control for avoiding a mistakenly or intentionally entered dangerous operation is built in the apparatus-controlling software based on the interlock concept. However, in many cases, a software interlock is insufficient as the foolproof function. Therefore, in addition to an electric interlock, another different mechanism is required. One of the methods is to stop the supply of gas immediately when an abnormality is generated or when an abnormal operation is specified. 
         [0010]    When a gas leakage sensor, provided indoors, detects a gas, the supply to the above-described electromagnetic valve is electrically disconnected to prevent all air signals from being generated and thereby to close the valves of the process gas. At the same time, the function to disconnect the supply of air to the electromagnetic valve, which works as energy, is provided in order to eliminate valve-opening energy itself from within the pipe. This double mechanism can doubly stop the supply of process gas electrically and mechanically. 
         [0011]    Not only an all-stop interlock upon detection of a gas leakage as described above but also an interlock for use while actual process gas is used is necessary. Usually, when the vacuum gauge detects a pressure lower than a predetermined pressure (for example, 500 Pa) on the side of the processing chamber or the reaction reactor (chamber) in the downstream side of the gas flow, an apparatus is configured so that no problem is generated even if a mixture of flammable gas and oxidation gas flows and a rapid reaction occurs. 
         [0012]    For this apparatus, this vacuum gauge signal is used as an electric interlock for the flammable gas valve open state and the oxidation gas valve open state. In addition, in an apparatus in which corrosive gas is used (for example, etching apparatus), the last-stage valve is provided near the processing chamber or the reaction reactor (chamber) to minimize the number of process gas pipes exposed to the air during maintenance and to reduce the generation of foreign matters such as rust. 
         [0013]    In addition to the above-described signal that the valve won&#39;t be opened (unable to let gas flow) only when it is in the vacuum state, it is necessary to allow the exit valve of flammable gas and oxidation gas to be opened only when this last-stage valve is open. Otherwise, high supply-pressure gas flows to low-pressure gas via the pipe with the result that a high-pressure mixture of flammable gas and oxidation gas is produced, resulting in a very dangerous state. 
         [0014]    For use when a mass flow controller or these gas valves are replaced at a maintenance time, an N2 purge line from the low-reactivity nitrogen gas source is provided in the upstream side of the mass flow controller in order to fill the pipe with safe gas for removing poisonous or corrosive gas. Usually, a check valve is provided to prevent process gas from being flown backward into the N2 purge line pipe, and the N2 purge pressure is set higher than the process gas pressure to prevent a backward flow. 
         [0015]    Not only that, an interlock is necessary to prevent the valve, which supplies this purge N2 gas, and the supply source valve of the process gas from being opened at the same time. Usually, a high-reliability valve is used that minimizes the probability with which these two valves fail at the same time. Therefore, in addition to an electric interlock that opens the valve only in the vacuum state, an interlock that prevents these two valves from being opened at the same time must be provided separately as the foolproof function. 
         [0016]    In addition, in the gas supply system, some apparatuses have a normal gas line, through which the gas flows via the last-stage valve so that the gas contacts a processed object in the processing chamber or the reaction reactor (chamber) for processing it, and a line which is provided to dispose of the gas into the downstream side for exhausting it. In this case, the gas pipe is connected before and after the compression-type turbo molecular pump and, for example, when the valve in the last-stage and the valve of the pipe for gas disposal are opened at the same time, the compressed gas in the downstream of the turbo molecular pump flows backward from the last-stage valve to the processing chamber or the reaction reactor (chamber) via the gas pipe. Although there is no safety problem in some cases, the contaminated atmosphere or components or foreign matters in the downstream are supplied to the processing chamber or the reaction reactor (chamber) with the result that the processing cannot be performed. 
         [0017]    In view of the above problems, the present invention provides a vacuum processing apparatus that has gas supply means having a hard interlock for a pair of gas valves. 
       Solution to Problem 
       [0018]    The present invention provides a vacuum processing apparatus including: a gas supply unit that supplies gas, for performing vacuum processing using normally closed type air-driven valves, to a processing chamber where the vacuum processing is performed, the gas supply unit having an interlock function in which, when a first valve of a pair of the air-driven valves is opened, a second valve of the pair is closed, the gas supply unit including an air circuit that controls air for driving the air-driven valves, the air circuit being configured using an electromagnetic valve having a solenoid coil corresponding to each of the pair of the air-driven valves. 
         [0019]    In addition, the present invention provides a vacuum processing apparatus including: a gas supply unit that supplies gas, for performing vacuum processing using normally closed type air-driven valves, to a processing chamber where the vacuum processing is performed, the gas supply unit including an air circuit that controls air for driving the air-driven valves, the air circuit including a logic air circuit unit that configures a logic circuit OR or AND that establishes open/close conditions for the air-driven valves. 
       Advantageous Effects of Invention 
       [0020]    According to the present invention, a hard interlock for a pair of gas valves can be configured. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0021]      FIG. 1  is a schematic configuration diagram of a vacuum processing apparatus, which uses process gas, according to the present invention; 
           [0022]      FIG. 2  is a diagram showing the control system of air signals according to the present invention; 
           [0023]      FIG. 3  is a diagram showing the control system of air signals that configure a logic circuit; and 
           [0024]      FIG. 4  is a diagram showing the control system of air signals according to the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0025]    Respective embodiments of the present invention are described below with reference to  FIG. 1  to  FIG. 4 . 
         [0026]    A vacuum processing apparatus, which uses process gas, according to the present invention is described.  FIG. 1  is a schematic configuration diagram of the vacuum processing apparatus, which uses process gas, according to the present invention. The range surrounded by AA indicates a gas supply system (mass flow controller unit: hereinafter called an MFC). Process gases, a pressure detection unit, and a gas regulator for adjusting the supply pressure, not shown in the figure, may also be configured inside the range. The range surrounded by BB indicates a gas exhaust system the downstream of which includes a dry pump, an exhaust gas processing apparatus (not shown), and the like. 
         [0027]    A processed object such as a wafer (not shown) is mounted inside a processing chamber  1 . A main valve  2  is provided to protect the exhaust system from exposure to oxygen and moisture in the atmosphere when the processing chamber  1  is exposed to the atmosphere at a maintenance time. A pressure adjustment valve  3  is provided to give a desired pressure to the processing chamber  1  by changing its internal conductance. A turbo molecular pump  4  is arranged for compressing the process gas, supplied to the processing chamber  1 , at a high-pressure rate for exhausting it. In the downstream of the turbo molecular pump  4 , an angle valve  5  is used for maintaining the turbo molecular pump  4  in the vacuum state when the exhaust system is stopped. 
         [0028]    A pressure gauge  6  is a pressure gauge for the processing chamber, and a pressure gauge  7  is a pressure gauge for an exhaust line. The process gas in the gas supply system AA has its flow amount controlled by its respective MFC during usage and is mixed in a manifold  8  of the process gas. In one case, this mixed gas is sent via a gas supply pipe  9  and is introduced into the processing chamber  1  via a last-stage valve V 0 . In another case, this mixed gas is sent via a gas exhaust pipe  10  of the exhaust system and is disposed of to the exhaust system BB via a disposable gas valve V 00 . 
         [0029]    A valve V 1  is a valve at the exit (downstream) of the MFC for flammable gas, and a valve V 2  is a valve at the exit (downstream) of the MFC for oxidation gas. A valve V 11  is a valve for the process gas supply (upstream) of flammable gas, and a valve V 21  is a valve for the process gas supply (upstream) of oxidation gas. In the upstream of the MFCs, an N2-purge valve V 12  for supplying purge N2 for flammable gas and an N2-purge valve V 22  for supplying purge N2 for oxidation gas, as well as V 11  and V 12  that are the process gas supply (upstream) valves, are connected with pipes. 
         [0030]    As a combination of process gas valves that cannot be opened at the same time in this vacuum processing apparatus, first, there is a combination of the last-stage valve V 0  and the disposable gas valve V 00 . If these two valves are opened at the same time, the higher-pressure gas in the downstream of the angle valve  5  (compressed by the turbo molecular pump  4 ) flows backward into the processing chamber  1 . Next, there are a combination of the valve V 11 , which is the process gas supply (upstream) valve of flammable gas, and the N2-purge valve V 12  and a combination of the valve V 21 , which is the process gas supply (upstream) valve of oxidation gas, and the N2-purge valve V 22 . 
         [0031]    In addition, to prevent the gas from becoming turbid as it flows into the downstream side, it is required that the valve V 11  and the valve V 21 , which are the process gas supply (upstream) valves, not be opened unless one of the last-stage valve V 0  and the disposable gas valve V 00  is opened. 
         [0032]      FIG. 2  is a diagram showing the control system of air signals in the vacuum processing apparatus shown in  FIG. 1 . To an air supply line  15 , pressurized air is supplied from the air source. An air exhaust line  16  is a line via which the air, remaining in the cylinder after the valve being driven, is exhausted. Solenoid coil excitation elements S 0 -S 22  are solenoid coil excitation elements each of which generates air for driving the respective process gas valve open. 
         [0033]    In the system control system, each solenoid coil (denoted by the same number) is excited according to a respective gas valve open command and pressure is applied by the air signal (air supply) to open the valve. When the solenoid coil is not excited, air is not supplied to three-position spring return center exhaust type five-port electromagnetic valves  21 ,  24 , and  25  and air is removed from them via the air exhaust line  16 . 
         [0034]    Two-position spring return type electromagnetic valves  22  and  23  generate air for driving the valve V 1  out, which is a flammable gas MFC exit (downstream) valve, and the valve V 2 , which is a oxidation gas MFC exit (downstream) valve, according to an open command that excites solenoid coil excitation elements S 1  and S 2 . A pilot valve P 1 , which is a pilot valve for forming an air signal, forms a pilot air signal line  17 . Pilot valves P 2  to P 5 , which are driven by the pilot air signal line  17 , are pilot valves. 
         [0035]    Because the solenoid coil excitation elements S 0  and S 00  are arranged at both ends of the three-position spring return center exhaust type five-port electromagnetic valves  21 , the air signal is generated always on the excited side to prevent both the last-stage valve V 0  and the disposable gas valve V 00  from being opened at the same time. Similarly, the three-position spring return center exhaust type five-port electromagnetic valves  24  prevents both the valve V 11  and the N2-purge valve V 12  from being opened at the same time, and the three-position spring return center exhaust type five-port electromagnetic valves  25  prevents both the valve V 21  and the N2-purge valve V 22  from being opened at the same time. 
         [0036]    In  FIG. 2 , when the solenoid coil excitation element S 00  is excited, the disposable gas valve V 00  is opened and, at the same time, the pilot air signal line  17  is formed through the pilot valve P 1  that is a pilot valve for forming an air signal. Therefore, the pilot valves P 2  to P 5  are driven to allow the air to pass through the pilot valves. If the solenoid coil excitation elements S 1 , S 2 , S 11 , and S 21  are excited at this time, the corresponding valves, V 1 , V 2 , V 11 , and V 21 , are opened. Next, when the solenoid coil excitation element S 00  is turned off, the disposable gas valve V 00  is closed and the air in the pilot air signal line  17  is removed Therefore, even if the solenoid coil excitation elements S 1 , S 2 , S 11 , and S 21  are excited and the air is supplied, the air is blocked by the pilot valves P 2  to P 5  and the valves V 1 , V 2 , V 11 , and V 21  are closed. 
         [0037]    In addition, when the solenoid coil excitation element S 0  is excited, the last-stage valve V 0  is opened. At the same time, the pilot valve P 1 , which is a pilot valve for forming the air signal, is driven to generate the air signal in the pilot air signal line  17 , and the pilot valves P 2  to P 5  are driven to allow the air to pass through the pilot valves. Because the behavior of the valves when the solenoid coil excitation element S 0  is turned off is the same as the behavior of the valves when the solenoid coil excitation element S 00  is turned off the description is omitted. As described above, the air circuit is formed in which the valves V 1 , V 2 , V 11  and V 21  can be opened only when one of the last-stage valve V 0  and the disposable gas valve V 00  is opened. 
         [0038]    For the N2-purge valves V 12  and V 22  that are nitrogen purge lines, the N2 purge must be performed at a replacement or maintenance time of the apparatuses, such as the valves and mass flow controllers, in the gas supply system AA. Therefore, because those valves must be opened even when neither the last-stage valve V 0  nor the disposable gas valve V 00  is opened to allow the N2 purge to be performed, the N2-purge valves V 12  and V 22  are able to be opened directly, not via the pilot valves with the use of the pilot air signal line  17 , while solenoid coil excitation elements S 12  and S 22  are ON. 
         [0039]    The object of the present invention is achieved by an interlock, in which the valves must not be opened at the same time, and an interlock, in which valves cannot be opened unless one of the other valves is opened, that can be formed by this air circuit as described above. 
         [0040]    Although an example of control using an OR logic circuit, which requires that one of the valves be open, is shown in this embodiment, an air circuit composed of an AND logic circuit is, of course, formed in a configuration in which a plurality of valves is arranged in series in the downstream side. 
         [0041]    For example, the valve D shown in  FIG. 3A  is a valve that must not be opened unless all valves, the valve A, the valve B, and the valve C, arranged in series in the downstream side are in the open state. That is, the interlock function of an AND logic circuit can be implemented by the air circuit in  FIG. 3A  that shows an example of single-valve driving control. In addition,  FIG. 3B  shows an example of dual-valve driving control that indicates the case of valves in which both the valve D and the valve E must not be opened unless all of the valve A, the valve B, and the valve C described above are opened. The means shown in  FIG. 3B , which forms the control pilot signal (air pressure), has a merit in that the total number of pilot valves and the control elements can be reduced. In this way, the air circuit may be formed using an AND logic circuit. 
         [0042]    Another embodiment is described with reference to  FIG. 4 . The configuration differs from the configuration in  FIG. 2  in that the air pressure of the pilot air signal line  17  is used directly as the driving air for opening the valves V 1  and V 2 . If the solenoid coil excitation element S 1  and the solenoid  82  are turned on when the air pressure is supplied to the pilot air signal line  17 , that is, when one of the last-stage valve V 0  and the disposable gas valve V 00  is opened, each of the valves V 1  and v 2  can be opened. In addition, the configuration shown in  FIG. 4  has a merit that the three-position spring return center exhaust type five-port electromagnetic valves  21 ,  24 , and  25  can be well arranged in space in the manifold type. 
         [0043]    The present invention, with the configuration described above, can achieve the following effects. 
         [0044]    First, for a pair of valves both of which cannot be opened at the same time, the supply of air to the pair of valves, which cannot be opened at the same time, is assigned to the excitation of the left and right solenoids of the same electromagnetic valve in order to physically prevent the pair of valves from being opened at the same time. 
         [0045]    In the present invention, for a valve that can be opened only when a valve in the downstream side is opened, air is supplied via the pilot valve that uses the air signal itself which opens the valve in the downstream side, as the pilot signal; therefore, when the valve in the downstream side is closed first, the supply valve in the upstream side is also closed automatically and, thus, a continued mixture of process gases in the pipe can be prevented. 
         [0046]    In addition, the present invention may implement a dual interlock by applying these mechanical interlocks and a relay circuit which won&#39;t be activated electrically unless it is in vacuum to solenoid excitation. In addition, the present invention allows a software interlock to be combined with those hardware interlocks. 
         [0047]    As described above, the present invention can provide a dual interlock, formed by an electric interlock and a mechanical air-signal interlock, thus providing the foolproof function. This ensures the reliability and safety of the vacuum processing apparatus. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           1  processing chamber 
           2  main valve 
           3  pressure adjustment valve 
           4  turbo molecular pump 
           5  angle valve 
           6  pressure gauge 
           7  pressure gauge 
           8  manifold 
           9  gas supply pipe 
           10  gas exhaust pipe 
         V 0  last-stage valve 
         V 00  disposable gas valve 
         V 1 , V 2 , V 11 , V 21  valve 
         V 12 , V 22  N2-purge valve 
           15  air supply line 
           16  air exhaust line 
           17  pilot air signal line 
           21 ,  24 ,  25  three-position spring return center exhaust type five-port electromagnetic valve 
           22 ,  23  two-position spring return type electromagnetic valve 
         S 0 , S 00 , S 1 , S 2 , S 11 , S 12 , S 21 , S 22  solenoid coil excitation element 
         P 1 , P 2 , P 3 , P 45 , P 5  pilot valve