JP2006018767A - Vacuum pressure control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum pressure control system capable of early detecting abnormalities of the system such as abnormalities of a vacuum pressure sensor, leaks from a reactor, and clogging of pipes. <P>SOLUTION: When the degree of opening of a valve 16 opening/closing in proportion to vacuum, which is acquired through a potentiometer 18 reaches a preliminarily fixed set value X1 (S22:Yes), the occurrence of an abnormality of system, like an abnormality of the vacuum pressure sensor, a leakage from the reactor, or clogging of pipes is determined to perform abnormality processing (S25) when a vacuum pressure of a reaction chamber 10 acquired through pressure sensors 14 and 15 is higher than a preliminarily fixed set value X2 (S24:NO). Set values X1 and X2 are obtained in advance by experiments or the like so that abnormalities of the system such as abnormalities of the vacuum pressure sensor, leaks from the reactor, and clogging of pipes can be properly detected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vacuum pressure control system used in a semiconductor manufacturing apparatus. More specifically, the present invention relates to a vacuum pressure control system that can detect various abnormalities in the system.

  2. Description of the Related Art Conventionally, for example, in a CVD apparatus of a semiconductor manufacturing apparatus, a material gas composed of elements constituting a thin film material is supplied onto a wafer while keeping a reaction chamber in a reduced pressure state, that is, in a vacuum state. For example, in the CVD apparatus shown in FIG. 14, a material gas is supplied from the inlet 11 of the reaction chamber 10 to the wafer in the reaction chamber 10 that is a vacuum vessel, and the vacuum pump 13 is supplied from the outlet 12 of the reaction chamber 10. By evacuating, the inside of the reaction chamber 10 is kept in a vacuum state.

  At this time, it is necessary to keep the vacuum pressure in the reaction chamber 10 constant, but the constant value varies depending on various conditions and covers a wide range from atmospheric pressure or low vacuum close to atmospheric pressure to high vacuum. Therefore, it is necessary to maintain the vacuum pressure accurately and uniformly over a wide range from a low vacuum close to atmospheric pressure to a high vacuum. In order to further improve the quality of the thin film formed on the wafer in the reaction chamber 10, the vacuum pressure in the reaction chamber 10 is set to atmospheric pressure or atmospheric pressure from the viewpoint of preventing particles from rolling up in the reaction chamber 10. In the process of evacuation to reach the target vacuum pressure value from a low vacuum close to 2, it is also necessary to slowly carry out the progress process in which gas is discharged from the reaction chamber 10.

  As a vacuum pressure control system for satisfying such a need, for example, there is one disclosed in Japanese Patent Laid-Open No. 2000-163137. In this system, by operating the opening of the vacuum proportional on-off valve, the vacuum pressure in the vacuum vessel is changed from the inside of the vacuum vessel by changing the target vacuum pressure change rate given from the outside or set in advance in the controller. Slowly progress the process of exhausting gas to prevent particles from rolling up in the vacuum container, and freely control the rate of change in vacuum pressure in the vacuum container when exhausting gas from inside the vacuum container Be able to.

  More specifically, the vacuum pressure value changed at the target vacuum pressure change rate acquired with respect to the vacuum pressure in the reaction chamber measured by the vacuum pressure sensor is sequentially generated as an internal command, and is sequentially generated. By using the internal command as a target value for feedback control and sequentially changing the target value for feedback control, the feedback control is executed as follow-up control. Thereby, in this vacuum pressure control system, the vacuum pressure in the reaction chamber can be uniformly changed with the target vacuum pressure change rate.

JP 2000-163137 A (3rd to 4th pages, FIG. 1)

  However, in the above conventional vacuum pressure control system, for example, abnormalities such as “abnormality of vacuum pressure sensor”, “leak in reaction chamber”, “clogged piping” are detected by an operator, etc. Is implemented. That is, there is a problem that the system itself cannot detect an abnormality.

  Therefore, the present invention has been made to solve the above-described problems, and a vacuum pressure control system capable of early detection of abnormalities in a system such as a vacuum pressure sensor abnormality, a reactor leak, a piping clogging, etc. It is an issue to provide.

  The vacuum pressure control system according to the present invention, which has been made to solve the above problems, is on a pipe connecting a vacuum vessel and a vacuum pump, and changes the vacuum pressure in the vacuum vessel by changing the opening degree. In a vacuum pressure control system comprising a vacuum proportional on-off valve, a vacuum pressure sensor for measuring a vacuum pressure in the vacuum vessel, and a controller for controlling an opening degree of the vacuum proportional on-off valve based on an output of the vacuum pressure sensor The controller stores in advance the relationship between the output of the vacuum pressure sensor and the opening of the vacuum proportional on / off valve when the system operates normally, and the vacuum proportional on / off based on the output of the vacuum pressure sensor During valve opening control, the relationship between the actual output of the vacuum pressure sensor and the actual opening of the vacuum proportional on-off valve and the stored true It is characterized in that to detect the abnormality of the system by comparing the relationship between the opening degree of the output of the pressure sensor the vacuum proportional opening and closing valve.

  In this vacuum pressure control system, the controller measures the vacuum pressure in the vacuum vessel, and the opening of the vacuum proportional on-off valve is controlled based on the output of the vacuum pressure sensor to lower the pressure in the vacuum vessel. (See FIG. 5). Here, when the system is normal, the output of the vacuum pressure sensor and the opening of the vacuum proportional on-off valve always have a certain relationship. Therefore, in this vacuum pressure control system, the relationship between the output of the vacuum pressure sensor and the opening of the vacuum proportional on-off valve in such a normal state is stored in the controller.

  In the vacuum pressure control system, if an abnormality such as "abnormality of vacuum pressure sensor", "leakage of vacuum vessel", or "clogging of piping" occurs, the output of the above vacuum pressure sensor and the vacuum proportional open / close A certain relationship with the opening of the valve is broken. That is, the relationship between the actual output of the vacuum pressure sensor and the actual opening of the vacuum proportional on-off valve does not match the relationship stored in the controller. Therefore, when controlling the opening of the vacuum proportional on-off valve based on the output of the vacuum pressure sensor, the relationship between the actual output of the vacuum pressure sensor and the actual opening of the vacuum proportional on-off valve is stored in the controller. By comparing the relationship between the output of the vacuum pressure sensor and the opening degree of the vacuum proportional on-off valve, it is possible to detect the above-mentioned system abnormality at an early stage.

  Another embodiment of the vacuum pressure control system according to the present invention for solving the above-described problems is provided on a pipe connecting the vacuum vessel and the vacuum pump, and by changing the opening degree, A vacuum proportional on-off valve that changes the vacuum pressure of the vacuum vessel, a vacuum pressure sensor that measures the vacuum pressure in the vacuum vessel, and a controller that controls the opening of the vacuum proportional on-off valve based on the output of the vacuum pressure sensor. In the vacuum pressure control system, the controller controls the opening of the vacuum proportional on / off valve based on an output of the vacuum pressure sensor, and opens the predetermined opening of the vacuum proportional on / off valve. If the output of the vacuum pressure sensor is larger than a predetermined value when the degree is reached, it is determined that an abnormality has occurred in the system. A.

  Even in this vacuum pressure control system, the controller measures the vacuum pressure in the vacuum vessel, and the opening of the vacuum proportional on-off valve is controlled based on the output of the vacuum pressure sensor to reduce the pressure in the vacuum vessel. (See FIG. 5). Here, when the system is normal, the output of the vacuum pressure sensor and the opening of the vacuum proportional on-off valve always have a certain relationship. For this reason, the output of the vacuum pressure sensor when the opening degree of the vacuum proportional on-off valve reaches a predetermined opening degree set in advance can be predicted.

  And since the pressure in the vacuum vessel is lowered, when the opening of the vacuum proportional on-off valve reaches a predetermined opening that is set in advance, the output of the vacuum pressure sensor is larger than a predetermined value that is set in advance It is considered that an abnormality has occurred in the system. Thus, in this vacuum pressure control system, when the opening degree of the vacuum proportional on-off valve is controlled based on the output of the vacuum pressure sensor, the opening degree of the vacuum proportional on-off valve reaches a predetermined opening degree set in advance. In addition, when the output of the vacuum pressure sensor is greater than a predetermined value set in advance, it is determined that an abnormality has occurred in the system. Thereby, the abnormality of a system can be detected at an early stage.

  Here, the predetermined opening degree of the vacuum proportional on-off valve and the predetermined opening degree of the vacuum pressure sensor that are set to detect the abnormality of the system may be obtained by experiments or the like that are most suitable for the abnormality to be detected. . Therefore, the predetermined combination of the predetermined opening degree of the vacuum proportional on-off valve and the predetermined opening degree of the vacuum pressure sensor may be one set or a plurality of sets.

In the vacuum pressure control system according to the present invention, the controller may use an operation voltage input to the vacuum proportional on-off valve instead of the opening of the vacuum proportional on-off valve in order to detect an abnormality of the system. it can.
Alternatively, in the vacuum pressure control system according to the present invention, the controller uses the operation air pressure supplied to the vacuum proportional on-off valve instead of the opening of the vacuum proportional on-off valve in order to detect an abnormality in the system. You can also

  By doing in this way, even if a system is constructed with a valve that does not include a mechanism (for example, a potentiometer) for detecting the opening degree of the vacuum proportional on-off valve, it is possible to detect an abnormality in the system at an early stage.

  In the vacuum pressure control system according to the present invention, it is desirable that when the controller detects a system abnormality or determines that an abnormality has occurred in the system, the controller notifies the fact.

  This is because the operator can know the abnormality of the system at an early stage and can quickly take countermeasures thereafter. Note that “notification” includes everything for hearing, for vision, and the like. Notification by a single means (for example, only a warning sound) or notification by a composite means (for example, a warning sound and a warning display) ).

  In the vacuum pressure control system according to the present invention, when the controller detects an abnormality in the system or determines that an abnormality has occurred in the system, the controller operates the vacuum proportional on-off valve in a safe direction of the system. It is desirable to make it.

  Here, since the safety direction of the system differs depending on the configuration of each system, “to close the valve”, “open the valve” One of “maintain” is applicable. That is, in this vacuum pressure control system, the operation of the vacuum proportional on-off valve is controlled by the controller so as to enhance the safety of each system in the event of an abnormality. For this reason, since it is possible to automatically deal with an abnormality, the safety of the system can be further enhanced.

  According to the vacuum pressure control system of the present invention, abnormalities in the system such as abnormality of the vacuum pressure sensor, leakage of the reactor, clogging of piping, etc. can be detected at an early stage by the above-described means.

  Hereinafter, a most preferred embodiment in which the vacuum pressure control system of the present invention is embodied will be described in detail based on the drawings. Therefore, FIG. 1 shows a block diagram of the vacuum pressure control system according to the present embodiment with respect to FIG. 14 shown in the column of the prior art. The vacuum pressure control system according to the present embodiment includes a controller 20, an air pressure control unit 30, a vacuum proportional on-off valve 16 that is an operation unit 40, and vacuum pressure sensors 14 and 15 that are detection units 60.

  The controller 20 includes an interface circuit 21, a vacuum pressure control circuit 22, and a sequence control circuit 23. The interface circuit 21 sends a signal by a field input through a button on the front panel of the controller 20 and a signal by a remote input through a connector on the back panel of the controller 20 to the vacuum pressure control circuit 22 or the sequence control circuit 23. It converts to a suitable signal. Further, as will be described later, the controller 20 stores a fixed relationship between the output of the vacuum pressure sensor at normal times and the opening of the vacuum proportional on-off valve. A system abnormality is detected (determined) by comparing the output and the relationship between the actual opening of the vacuum proportional on-off valve.

  The vacuum pressure control circuit 22 is a circuit that performs feedback control with respect to the vacuum pressure in the reaction chamber 10 of FIG. 14 by PID control. The sequence control circuit 23 is predetermined for the drive coil SV1 of the first electromagnetic valve 34 and the drive coil SV2 of the second electromagnetic valve 35 in the pneumatic control unit 30 according to the operation mode given from the interface circuit 21. It is a circuit that operates.

  The pneumatic control unit 30 includes a position control circuit 31, a pulse drive circuit 32, a time opening / closing operation valve 33, a first electromagnetic valve 34, and a second electromagnetic valve 35. The position control circuit 31 compares the valve opening command value given from the vacuum pressure control circuit 22 with the measured valve opening value given via the amplifier 19 from the potentiometer 18 provided in the vacuum proportional on-off valve 16. Thus, the position of the vacuum proportional on-off valve 16 is controlled. The pulse drive circuit 32 transmits a pulse signal to the time opening / closing operation valve 33 based on a control signal from the position control circuit 31.

  The time opening / closing operation valve 33 incorporates an air supply side proportional valve and an exhaust side proportional valve (not shown), and the air supply side proportional valve and the exhaust side proportional valve are set in response to a pulse signal from the pulse drive circuit 32. A time opening / closing operation for adjusting the air pressure in the pneumatic cylinder 41 (see FIGS. 2 and 3 to be described later) of the vacuum proportional on / off valve 16 via the second solenoid valve 35 and the first solenoid valve 34. It is.

  The vacuum proportional on-off valve 16 serving as the operation unit 40 changes the conductance of the exhaust system from the reaction chamber 10 to the vacuum pump 13 in FIG. 2 and 3 show a cross section of the vacuum proportional on-off valve 16. As shown in the figure, a piston rod 43 is provided at the center thereof. The piston 44 is fixed to the piston rod 43 in the pneumatic cylinder 41 that is the upper part of the vacuum proportional on-off valve 16, and the poppet valve body is located in the bellows-type poppet valve 42 that is the lower part of the vacuum proportional on-off valve 16. 45 is fixed. Therefore, the poppet valve body 45 can be moved by the pneumatic cylinder 41.

  In this vacuum proportional on-off valve 16, when compressed air is not supplied into the pneumatic cylinder 41 via the supply port 18A and the inside of the pneumatic cylinder 41 communicates with the exhaust line via the exhaust port 18B, Since the downward urging force of the return spring 46 acts on the piston 44, the poppet valve body 45 is in close contact with the valve seat 47 and the vacuum proportional on-off valve 16 is shut off as shown in FIG.

  On the other hand, when compressed air is supplied into the pneumatic cylinder 41 via the air supply port 18A, the downward biasing force by the return spring 46 in the pneumatic cylinder 41 and the upward pressure by the compressed air in the pneumatic cylinder 41 Simultaneously act on the piston 44, and as shown in FIG. 3, the poppet valve body 45 is separated from the valve seat 47 and the vacuum proportional on-off valve 16 is opened according to the balance.

  Therefore, the distance at which the poppet valve body 45 is separated from the valve seat 47 can be operated by supplying compressed air to the pneumatic cylinder 41 and exhausting it as the lift amount of the valve. The distance at which the poppet valve body 45 is separated from the valve seat 47 is measured by the potentiometer 18 through the slide lever 48 connected to the piston 44 as the lift amount of the valve. It corresponds to the opening degree of.

  The vacuum pressure sensors 14 and 15 serving as detection units are capacitance manometers that measure the vacuum pressure in the reaction chamber 10 of FIG. Here, two capacitance manometers are used properly according to the range of the vacuum pressure to be measured.

  In the vacuum pressure control system according to the present embodiment having such a configuration, when the forced close mode (CLOSE) is selected as the operation mode by the controller 20, the sequence control circuit 23 includes the first electromagnetic valve 34 and the second electromagnetic valve 34. The electromagnetic valve 35 is operated as shown in FIG. Thereby, compressed air is not supplied into the pneumatic cylinder 41, and the pneumatic cylinder 41 communicates with the exhaust line, so that the air pressure in the pneumatic cylinder 41 becomes atmospheric pressure, and the vacuum proportional on-off valve 16 is shut off. .

  If the controller 20 selects the vacuum pressure control mode (PRESS) as the operation mode, the sequence control circuit 23 operates the first electromagnetic valve 34 to connect the time opening / closing operation valve 33 and the pneumatic cylinder 41. Let Thereby, the air pressure in the pneumatic cylinder 41 of the vacuum proportional on-off valve 16 is adjusted, and the lift amount of the valve can be operated by the pneumatic cylinder 41.

  At this time, the vacuum pressure control circuit 22 starts feedback control with the target vacuum pressure value designated by the field input or remote input as the target value. That is, in FIG. 14, the vacuum pressure value in the reaction chamber 10 is measured by the vacuum pressure sensors 14 and 15, and the lift of the vacuum proportional on-off valve 16 is lifted according to the difference (control deviation) between the value and the target vacuum pressure value. The vacuum pressure in the reaction chamber 10 is kept constant at the target vacuum pressure value by manipulating the amount and changing the conductance of the exhaust system.

  Further, in the vacuum pressure control circuit 22, when the control deviation of the feedback control is large, the operation amount of the feedback control is maximized, so that the speed of the feedback control is sufficiently ensured. On the other hand, when the control deviation of the feedback control is small, the time shifts to the time constant adjusted in advance, so that the vacuum pressure in the reaction chamber 10 can be maintained in a stable state.

  Specifically, as shown in the block diagram of FIG. 4, the value obtained by adjusting the vacuum pressure value in the reaction chamber 10 measured by the vacuum pressure sensors 14 and 15 by the proportional differentiation circuits 105 and 106 is input on site or remotely. After being compared with the target vacuum pressure value instructed in (1), it is inputted to the proportional differential integration circuits 102 and 103. Thereafter, the integration circuits 104 connected in series output a voltage in the range of 0 to 5 V in order to output to the position control circuit 31. The time constant of the integration circuit 104 is determined by the integration time adjustment circuit 101.

  When the measured values of the vacuum pressure sensors 14 and 15 are away from the target vacuum pressure value, the internal arithmetic circuit operates so that the integration time of the integration circuit is minimized. As a result, the integrating circuit 104 functions as an amplifier circuit having an almost infinite gain.

That is,
(Measurement value of vacuum pressure sensors 14 and 15)> (Target vacuum pressure value)
In this case, 5V, which is the maximum value of the integration circuit 104, is output to the position control circuit 31. As a result, the vacuum proportional on-off valve 16 operates in a direction to open rapidly. on the other hand,
(Measurement value of vacuum pressure sensors 14 and 15) <(Target vacuum pressure value)
In this case, 0 V, which is the minimum value of the integration circuit 104, is output to the position control circuit 31. As a result, the vacuum proportional on-off valve 16 operates in a direction to close rapidly.

  By these operations, the valve opening degree of the vacuum proportional on-off valve 16 can be reached in the shortest time to the vicinity of the position for obtaining the target vacuum pressure value. After that, the integration time adjusting circuit 101 that has determined that the position has reached the position for achieving the target vacuum pressure value keeps the vacuum pressure at that position in a stable state. Performs an operation that shifts to a constant step by step.

  Furthermore, in the vacuum pressure control system according to the present embodiment, when the controller 20 selects the vacuum pressure change rate control mode (SVAC) as the operation mode, the vacuum pressure in the reaction chamber 10 reaches the target vacuum pressure. In addition, it is possible to control the rate of change of the vacuum pressure in the reaction chamber 10.

  As described above, in the vacuum pressure change speed control mode (SVAC), the feedback control is performed to change the conductance (valve opening degree) of the vacuum proportional on-off valve 16 as shown in FIG. The pressure in the reaction chamber 10 is reduced at a rate of Therefore, in the vacuum pressure control system, when an abnormality such as “abnormality of the vacuum pressure sensors 14 and 15”, “leak of the reaction chamber 10”, or “clogging of piping” occurs, the rate of change of the vacuum pressure At a certain point in the control mode (SVAC), the relationship between “the valve opening degree of the vacuum proportional on-off valve 16” and “the values of the vacuum pressure sensors 14 and 15” does not become as shown in FIG. By utilizing this phenomenon, the vacuum pressure control system according to the present embodiment detects the above-described abnormality.

  Therefore, the operation in the vacuum pressure control system according to the present embodiment will be described with reference to FIGS. FIG. 6 is a flowchart for the vacuum pressure change rate control mode (SVAC). FIG. 7 is a flowchart of the preparation time for the vacuum pressure change rate control mode (SVAC). FIG. 8 is a flowchart of the execution time of the vacuum pressure change rate control mode (SVAC). FIG. 9 is a diagram showing an example of a change in the pressure in the reaction chamber and a change in the valve opening degree of the vacuum proportional on-off valve 16 in the normal vacuum pressure change rate control mode (SVAC). Note that the vacuum pressure change speed control mode (SVAC) is shifted from the forced close mode (CLOSE).

  In the vacuum pressure change speed control mode (SVAC), as shown in FIG. 6, two subroutines, that is, a preparation time process and an execution time process are executed. When the vacuum pressure change rate control mode (SVAC) is selected by the controller 20, first, a preparation time process is executed.

  Then, first, the current vacuum pressure in the reaction chamber 10 is acquired through the vacuum pressure sensors 14 and 15 (S1). Here, since the current vacuum pressure in the reaction chamber 10 is the atmospheric pressure V0 (see FIG. 9), the atmospheric pressure V0 is acquired.

  Next, the valve opening degree of the vacuum proportional on-off valve 16 is acquired via the potentiometer 18 (S2). Then, it is determined whether or not the acquired valve opening has reached the set value X1 (S3). At this time, when the valve opening degree has reached the set value X1 (S3: YES), the current vacuum pressure in the reaction chamber 10 is acquired via the vacuum pressure sensors 14 and 15 (S4). Then, it is determined whether or not the acquired current vacuum pressure in the reaction chamber 10 is equal to or less than the set value X2 (S5). At this time, if the current vacuum pressure in the reaction chamber 10 is larger than the set value X2 (S5: NO), it is determined that an abnormality has occurred and the vacuum pressure change rate control mode (SVAC) is terminated. Then, an abnormal process is performed (S6).

  Here, the set value X1 is a threshold value for detecting (judging) a system abnormality. That is, the system abnormality detection process is performed when the valve opening degree of the vacuum proportional on-off valve 16 reaches the set value X1. The set value X2 is a threshold value for determining whether an abnormality has occurred in the system when the abnormality detection process is performed. That is, when the abnormality detection process is performed and the current vacuum pressure in the reaction chamber 10 is larger than the set value X2, it is determined that an abnormality has occurred in the system.

  On the other hand, when the valve opening has not reached the set value X1 (S3: NO), or when the current vacuum pressure in the reaction chamber 10 is not more than the set value X2 (S5: YES), the valve lift A quantity ramp-up process is performed (S7). Here, since the forced close mode (CLOSE) is entered, when the vacuum pressure change rate control mode (SVAC) is selected, the vacuum proportional on-off valve 16 is in a shut-off state. Therefore, as shown in FIG. 10, the bias control circuit 110 outputs a command voltage to the position control circuit 31 so that the lift amount of the vacuum proportional on-off valve 16 changes in a ramp function, and the position control circuit 31 A control signal is transmitted to the pulse drive circuit 32 (see FIG. 4). Here, as an example, the time t1 is 10 seconds, and the valve lift amount L1 is 0.1266 mm.

  Then, it is determined whether or not 10 seconds, which is time t1, has elapsed (S8). When it is determined that the time t1 of 10 seconds has elapsed (S8: YES), the process proceeds to S11. When it is determined that the time t1 of 10 seconds has not elapsed (S3: NO), the process proceeds to S9. The current vacuum pressure in the reaction chamber 10 is acquired via the vacuum pressure sensors 14 and 15. Thereafter, it is determined whether or not there is a slight pressure drop in the vacuum pressure in the reaction chamber 10 (S10). When it is determined that there is no slight pressure drop (S10: NO), the process returns to S2 and the above-described processing is repeated. Here, a slight pressure drop is a pressure drop of 266 Pa or more.

  On the other hand, when it is determined that there is a pressure drop of 266 Pa or more (S10: YES), the process proceeds to S11 in the same manner as when it is determined that the time t1 of 10 sec has elapsed (S3: YES). In S11, the target value of the feedback control for the vacuum pressure in the reaction chamber 10 is set to a value V1 (see FIG. 9) obtained by subtracting 266 Pa from the current vacuum pressure.

  Then, the valve opening degree of the vacuum proportional on-off valve 16 is acquired via the potentiometer 18 (S12). Then, it is determined whether or not the acquired valve opening has reached the set value X1 (S13). At this time, if the valve opening degree has reached the set value X1 (S13: YES), the current vacuum pressure in the reaction chamber 10 is acquired via the vacuum pressure sensors 14 and 15 (S14). Then, it is determined whether or not the acquired current vacuum pressure in the reaction chamber 10 is equal to or less than the set value X2 (S15). At this time, if the current vacuum pressure in the reaction chamber 10 is larger than the set value X2 (S15: NO), it is determined that an abnormality has occurred and the vacuum pressure change rate control mode (SVAC) is terminated. Then, an abnormal process is performed (S16).

  On the other hand, when the valve opening does not reach the set value X1 (S13: NO), or when the current vacuum pressure in the reaction chamber 10 is not more than the set value X2 (S15: YES), the reaction chamber 10 For the internal vacuum pressure, the feedback control with the target value V1 (see FIG. 9) obtained by subtracting 266 Pa from the current vacuum pressure is performed as a constant value control until a predetermined time (10 sec in this case) elapses (S17). ). If it is determined that 10 seconds have elapsed since the feedback control was started (S18: YES), the process proceeds to an execution time process.

  In the abnormal state processing in S6 and S16, it is notified that an abnormality has occurred in the system, and the vacuum proportional control valve 16 is operated in the safe direction. In this embodiment, the vacuum proportional control valve 16 is operated in the closing direction. However, depending on the system, the valve may be operated in the opening direction or the current valve opening may be maintained. This is because the safety direction differs depending on the system. Therefore, it is sufficient to set the valve operation suitable for each system in the abnormal process. In addition, “notification” includes everything for hearing, for vision, and the like. Notification by a single means (for example, only a warning sound) or notification by a composite means (for example, a warning sound and a warning display) ).

  In the execution time process, first, the valve opening degree of the vacuum proportional on-off valve 16 is acquired via the potentiometer 18 (S21). Then, it is determined whether or not the acquired valve opening has reached the set value X1 (S22). At this time, when the valve opening degree has reached the set value X1 (S22: YES), the current vacuum pressure in the reaction chamber 10 is acquired via the vacuum pressure sensors 14 and 15 (S23). Then, it is determined whether or not the acquired current vacuum pressure in the reaction chamber 10 is equal to or lower than the set value X2 (S24). At this time, if the current vacuum pressure in the reaction chamber 10 is larger than the set value X2 (S24: NO), it is determined that an abnormality has occurred and the vacuum pressure change rate control mode (SVAC) is terminated. Then, an abnormal process is performed (S25).

  On the other hand, when the valve opening does not reach the set value X1 (S32: NO), or when the current vacuum pressure in the reaction chamber 10 is equal to or less than the set value X2 (S24: YES), on-site input or A target vacuum pressure value designated by remote input is acquired (S26). Further, the current vacuum pressure in the reaction chamber 10 is acquired via the vacuum pressure sensors 14 and 15 (S27). Then, it is determined whether or not the current vacuum pressure in the reaction chamber 10 has reached the target vacuum pressure value (S28). If the current vacuum pressure in the reaction chamber 10 has not reached the target vacuum pressure value (S28: NO), the target vacuum pressure change rate instructed by on-site input or remote input is acquired (S29).

  Further, the current vacuum pressure value in the reaction chamber 10 is acquired via the vacuum pressure sensors 14 and 15 (S30). Then, the controller 20 generates a vacuum pressure value that is changed at the target vacuum pressure change rate acquired in S29 with respect to the current vacuum pressure value of the reaction chamber 10 acquired in S30 as an internal command. Then, the internal command is used as a target value for feedback control, and the target value for feedback control is changed (S31). Thereafter, feedback control is performed (S32).

  Specifically, as shown in the block diagram of FIG. 4, the target vacuum pressure value and the vacuum pressure change rate instructed by on-site input or remote input are in the range of 0 to 5 V in the interface circuit 21 (see FIG. 1). The voltage is output and input to the internal command generation circuit 111. The internal command generation circuit 111 subtracts a predetermined vacuum pressure value from the current vacuum pressure value in the reaction chamber 10 according to the magnitude of the vacuum pressure change rate, and outputs the value as a target value for feedback control.

  On the other hand, when the current vacuum pressure in the reaction chamber 10 has reached the target vacuum pressure value (S28: YES), the target vacuum pressure value acquired in S26 is set as the target value for feedback control. Thereafter, feedback control is performed (S32).

  The feedback control in S32 is continued unless the operation mode is changed from the vacuum pressure change speed control mode (SVAC).

  Here, a case where an abnormality is detected and an abnormality process is performed will be described with reference to specific examples shown in FIGS. FIG. 11 is a diagram illustrating a state where an abnormality has occurred in the vacuum pressure sensors 14 and 15. FIG. 12 is a diagram illustrating a state in which the reaction chamber 10 is leaking. FIG. 13 is a diagram illustrating a state where the piping is clogged.

  First, when an abnormality occurs in the vacuum pressure sensors 14 and 15 and the pressure in the reaction chamber 10 does not drop as shown in FIG. 11, the valve opening degree of the vacuum proportional on-off valve 16 is set to a set value at time t2. Reach X1. At this time, the vacuum pressure in the reaction chamber 10 is not lower than the set value X2.

  That is, when 10 seconds have not elapsed since the start of the vacuum pressure change rate control mode (SVAC) at time t2, it is determined that an abnormality has occurred in the system in the processes of S3 to S6 in FIG. Then, an abnormality process for closing the vacuum proportional on-off valve 16 is executed. On the other hand, if the time t2 has passed 10 seconds since the start of the vacuum pressure change rate control mode (SVAC), it is determined that an abnormality has occurred in the system in the processes of S13 to S16 in FIG. Then, an abnormality process for closing the vacuum proportional on-off valve 16 is executed.

  Next, when a leak occurs in the reaction chamber 10 and the pressure does not decrease in the middle of the pressure drop in the reaction chamber 10 as shown in FIG. 12, the valve opening degree of the vacuum proportional on-off valve 16 at time t3. Reaches the set value X1. At this time, the vacuum pressure in the reaction chamber 10 is not lower than the set value X2.

  That is, if time t3 has not passed 10 seconds from the start of the pressure drop in the reaction chamber 10, it is determined that an abnormality has occurred in the system in the processes of S13 to S16 in FIG. Then, an abnormality process for closing the vacuum proportional on-off valve 16 is executed. On the other hand, when the time t3 has passed 10 seconds from the start of the pressure drop in the reaction chamber 10, it is determined that an abnormality has occurred in the system in the processing of S22 to S25 in FIG. Then, an abnormality process for closing the vacuum proportional on-off valve 16 is executed.

  Finally, when the piping is clogged and the pressure does not drop in the middle of the pressure drop in the reaction chamber 10 as shown in FIG. 12, the valve opening degree of the vacuum proportional on-off valve 16 reaches the set value X1 at time t4. To do. At this time, the vacuum pressure in the reaction chamber 10 is not lower than the set value X2.

  That is, when 10 seconds have not elapsed since the time t4 when the pressure drop in the reaction chamber 10 started, it is determined that an abnormality has occurred in the system in the processes of S13 to S16 in FIG. Then, an abnormality process for closing the vacuum proportional on-off valve 16 is executed. On the other hand, when 10 seconds have elapsed from the start of the pressure drop in the reaction chamber 10 at time t3, it is determined that an abnormality has occurred in the system in the processing of S22 to S25 in FIG. Then, an abnormality process for closing the vacuum proportional on-off valve 16 is executed.

  On the other hand, during normal operation, as shown in FIG. 9, the valve opening degree of the vacuum proportional on-off valve 16 reaches the set value X1 at time t, but the vacuum pressure in the reaction chamber 10 at that time is smaller than the set value X2. It is determined that no abnormality has occurred in the system.

  Thus, in the vacuum pressure control system according to the present embodiment, it is possible to quickly detect abnormalities in the system such as the vacuum pressure sensors 14 and 15, the leak in the reaction chamber 10, or the clogging of the piping. And when abnormality is detected, while notifying that, the vacuum proportional on-off valve 16 is closed. Therefore, a very safe vacuum pressure control system can be constructed.

  It should be noted that the set values X1 and X2 set for detecting each abnormality described above may be obtained in advance by experiments or the like so that each abnormality can be detected appropriately.

  Here, when using a valve that does not have a mechanism (potentiometer 18) for detecting the valve opening, such as the vacuum proportional on-off valve 16, instead of using the valve opening to detect a system abnormality. The operation voltage input to the valve or the operation air pressure supplied to the valve may be used. Thereby, even if a system is constructed with a valve that does not have a mechanism for detecting the opening degree of the valve, an abnormality of the system can be detected at an early stage.

  As described above, in the vacuum pressure control system according to the present embodiment as described in detail, when the controller 20 reaches the preset value X1 of the vacuum proportional on-off valve 16, the reaction chamber 10 When the vacuum pressure is larger than a preset set value X2, it is determined that an abnormality has occurred in the system. The set values X1 and X2 are obtained in advance by experiments or the like so that each abnormality can be detected appropriately. Therefore, according to the vacuum pressure control system according to the present embodiment, it is possible to quickly detect abnormalities in the system such as the vacuum pressure sensors 14 and 15, the leak in the reaction chamber 10, or the clogging of the pipes. And when abnormality is detected, while notifying that, the vacuum proportional on-off valve 16 is closed. Therefore, a very safe vacuum pressure control system can be constructed.

  It should be noted that the above-described embodiment is merely an example and does not limit the present invention in any way, and various improvements and modifications can be made without departing from the scope of the invention. For example, in the above-described embodiment, the case where the present invention is applied to the reaction chamber 10 of the CVD apparatus is illustrated, but the present invention can be applied to vacuum vessels of other semiconductor production lines. is there.

It is the block diagram which showed the outline of the vacuum pressure control system of embodiment. It is sectional drawing when it exists in the state which the vacuum proportional on-off valve interrupted | blocked. It is sectional drawing when a vacuum proportional on-off valve exists in the open state. It is the block diagram which showed the outline of the vacuum pressure control system of embodiment. In a vacuum pressure change speed control mode, it is a figure which shows a mode that the conductance (valve opening degree) of a vacuum proportional on-off valve is changed, and the pressure in a reaction chamber is reduced at the set constant speed. It is a flowchart which shows the processing content of the vacuum pressure change speed control mode. It is a flowchart which shows the content of the preparation time process of a vacuum pressure change speed control mode. It is a flowchart which shows the content of the execution time process of a vacuum pressure change speed control mode. It is a figure which shows an example of the pressure change of the reaction chamber in the vacuum pressure change speed control mode at the time of normal, and the change of the valve opening degree of a vacuum proportional on-off valve. It is the figure which showed the input signal in the lift amount ramp-up process of a valve. It is a figure which shows an example of the change of the pressure of a reaction chamber, and the change of the valve opening degree of a vacuum proportional on-off valve when abnormality is detected and the process at the time of abnormality is performed. It is a figure which shows an example of the change of the pressure of a reaction chamber, and the change of the valve opening degree of a vacuum proportional on-off valve when abnormality is detected and the process at the time of abnormality is performed. It is a figure which shows an example of the change of the pressure of a reaction chamber, and the change of the valve opening degree of a vacuum proportional on-off valve when abnormality is detected and the process at the time of abnormality is performed. It is the figure which showed the outline | summary of the CVD apparatus and its exhaust system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Reaction chamber 14 of CVD apparatus, 15 Vacuum pressure sensor 16 Vacuum proportional on-off valve 18 Potentiometer 20 Controller

Claims (6)

A vacuum proportional on-off valve that changes the vacuum pressure in the vacuum vessel by changing the opening degree on a pipe connecting the vacuum vessel and the vacuum pump, and a vacuum pressure sensor that measures the vacuum pressure in the vacuum vessel And a vacuum pressure control system having a controller for controlling the opening of the vacuum proportional on-off valve based on the output of the vacuum pressure sensor,
The controller is
The relationship between the output of the vacuum pressure sensor and the opening of the vacuum proportional on-off valve when the system operates normally is stored in advance,
The relationship between the actual output of the vacuum pressure sensor and the actual opening of the vacuum proportional on / off valve and the memory when performing the opening control of the vacuum proportional on / off valve based on the output of the vacuum pressure sensor An abnormality in the system is detected by comparing the relationship between the output of the vacuum pressure sensor and the opening of the vacuum proportional on-off valve. A vacuum proportional on-off valve that changes the vacuum pressure in the vacuum vessel by changing the opening degree on a pipe connecting the vacuum vessel and the vacuum pump, and a vacuum pressure sensor that measures the vacuum pressure in the vacuum vessel And a vacuum pressure control system having a controller for controlling the opening of the vacuum proportional on-off valve based on the output of the vacuum pressure sensor,
The controller, when performing the opening control of the vacuum proportional on-off valve based on the output of the vacuum pressure sensor, when the opening of the vacuum proportional on-off valve reaches a preset predetermined opening When the output of the vacuum pressure sensor is larger than a predetermined value set in advance, it is determined that an abnormality has occurred in the system. In the vacuum pressure control system according to claim 1 or 2,
The vacuum pressure control system, wherein the controller uses an operation voltage input to the vacuum proportional on-off valve in place of the opening of the vacuum proportional on-off valve in order to detect an abnormality of the system. In the vacuum pressure control system according to claim 1 or 2,
The controller uses an operation air pressure supplied to the vacuum proportional on-off valve in place of the opening of the vacuum proportional on-off valve in order to detect an abnormality of the system. The vacuum pressure control system according to any one of claims 1 to 4,
When the controller detects a system abnormality or determines that an abnormality has occurred in the system, the controller notifies the fact to that effect. The vacuum pressure control system according to any one of claims 1 to 5,
The vacuum pressure control system, wherein the controller detects a system abnormality or operates the vacuum proportional on-off valve in a safe direction of the system when it is determined that an abnormality has occurred in the system.

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