JP5382566B2 - Impedance matching device - Google Patents

Description

  The present invention relates to an impedance matching apparatus used for matching impedance between a high frequency power source and a load in a plasma processing apparatus or the like used in a semiconductor manufacturing apparatus.

  When power is supplied from a high-frequency power source to a load such as a plasma generator provided in the process chamber, for example, as disclosed in Patent Document 1, the reflection of power from the load is eliminated and the load is efficiently processed. In order to supply electric power, an impedance matching device is provided between the high-frequency power source and the load to match the output impedance of the power source and the impedance of the load.

  The impedance matching device is provided between the power source and the load and is operated when matching the impedance between the power source and the load, and the operation shaft of the variable impedance element is operated using the motor as a drive source. An operation mechanism that performs operation, a target position setting unit that sets a target position of the operation axis necessary for impedance matching, an operation axis position detection unit that detects a current position of the operation axis, and an operation axis of the variable impedance element A motor control unit that controls the motor so that the position matches the target position set by the target position setting unit, and operates the variable impedance element to achieve impedance matching between the high-frequency power source and the load. Control the axis. A variable capacitor or a variable inductance is used as the variable impedance element.

  For example, the impedance matching device disclosed in Patent Document 1 includes an input detection unit that detects an input voltage and an input current that are input from a high-frequency power source to a load, and a phase difference between the input voltage and the input current; A first variable capacitor connected in parallel to the output terminals of the high frequency power supply, a second variable capacitor connected between one output terminal of the high frequency power supply and one end of the load, and a first variable An operation for operating the operating shafts of the first variable capacitor and the second variable capacitor with the first and second motors provided for the capacitor and the second variable capacitor, respectively. Based on the mechanism and the value of the output impedance of the power source obtained from the input voltage and input current detected by the input detector, the position of the operating axis of the first variable capacitor is set as the target position. A motor control unit that controls the motor, and a motor control that controls the motor so that the position of the operation axis of the second variable capacitor is a target position based on the phase difference between the input voltage and the input current detected by the input detection unit Department. As the first variable capacitor and the second variable capacitor, in many cases, as shown in Patent Document 2 and Patent Document 3, a vacuum variable capacitor in which a fixed electrode and a movable electrode are sealed in a vacuum vessel is used. It is used.

  In a variable impedance element such as a vacuum variable capacitor used in an impedance matching device, a lubricant (such as grease) on an operation shaft is solidified with use, and a load torque applied to the motor from the operation shaft increases. Also, a displacement transmission mechanism that transmits mechanical wear of the contact part between the operating shaft and its bearing part and rotational displacement of the operating shaft to the movable part of the variable impedance element (movable electrode in the case of a variable capacitor) is configured. The load torque applied to the motor from the operation shaft also increases due to mechanical wear of the parts to be performed. In particular, in the case of a vacuum variable capacitor configured to convert the rotational displacement of the operation shaft into a linear displacement by a screw mechanism and transmit the linear displacement to a movable electrode disposed in the vacuum chamber, the screw of the screw constituting the screw mechanism Among them, one of the screws connected to the movable electrode arranged in the vacuum chamber is always subjected to a suction force from the vacuum chamber side, and a biased force is applied to the contact portions of the screws constituting the screw mechanism. The wear of the thread progresses in a relatively short period of time, and the torque necessary for operating the operating shaft increases. In the present specification, as described above, the lubricant of the operation shaft of the variable impedance element is solidified, or the components of the displacement transmission mechanism that transmits the rotational displacement of the operation shaft to the movable portion of the variable impedance element are worn out. Thus, the state in which the torque required to operate the variable impedance element increases is called deterioration of the mechanism portion of the variable impedance element.

  As described above, the load torque applied to the motor becomes excessive due to the deterioration of the mechanism portion of the variable impedance element, and the operating shaft cannot be rotated when the limit of the driving capability of the motor is exceeded. I can't do that. For example, a pulse motor or a stepping motor is often used as a motor for operating a variable impedance element. When these motors are used, a drive pulse eventually increases as the load torque applied to the motor increases. And the motor rotation cannot be synchronized, and the motor cannot be rotated. Conventionally, the output torque of the motor has been set to a sufficiently large value (a constant value) so that it can be operated even when the deterioration of the mechanism of the variable impedance element has advanced to near the end of its life. .

If the mechanism of the variable impedance element has deteriorated and the motor cannot operate the variable impedance element, maintenance such as exchanging the variable impedance element or parts of the mechanism There is a need to do. Further, it is necessary to readjust the impedance matching device during maintenance. When the variable impedance element can no longer be operated, the entire impedance matching device may be replaced. In this case as well, the impedance matching device needs to be readjusted, and this operation takes a long time.
JP 2001-16779 A JP 11-97293 A JP-A-10-106888

  As described above, when the load torque applied to the motor increases due to the deterioration of the mechanism portion of the variable impedance element, and the variable impedance element cannot be normally operated, impedance matching between the power source and the load cannot be performed. Therefore, it is necessary to perform maintenance work such as repair and replacement of the alignment device, which takes a long time.

  If the alignment operation, which is the original role of the alignment apparatus, does not function, the semiconductor manufacturing process will be interrupted, but such a situation requires efforts as much as possible. Therefore, in the past, it was recommended to take measures such as shortening the maintenance cycle of the variable impedance element by predicting the deterioration time or replacing the matching device early, but depending on the usage conditions, excessive maintenance may be required. There is room for further improvement.

  In order to economically maintain the performance of the impedance matching device, it is preferable that maintenance work of the impedance matching device can be performed on a preset maintenance day. For that purpose, it is necessary to be able to predict when maintenance is necessary.

  Normally, the determination of the life of a device having a mechanical movable part or the determination that maintenance is necessary is performed based on the operation time of the device, but in the case of an impedance matching device, the operation axis of the variable impedance element is Since the operation time and number of times vary greatly depending on the load state and cannot be predicted, it is difficult to accurately determine the life and maintenance time from the operation time of the impedance matching device.

  An object of the present invention is to provide an impedance matching device capable of predicting that the lifetime of a variable impedance element is near and performing maintenance accurately.

  The present invention provides a variable impedance element provided between a power source and a load and operated when matching impedance between the power source and the load, and operation of the variable impedance element using a motor as a drive source. An operation mechanism for operating an axis, a target position setting unit for setting a target position of an operation axis necessary for impedance matching, an operation axis position detection unit for detecting the current position of the operation axis, and a variable impedance element A motor control unit that controls the motor so that the position of the operation axis matches the target position set by the target position setting unit, and the target position and current position of the operation axis are monitored and the target position and current position remain. An impedance matching apparatus including an abnormality determination unit that performs abnormality determination when a deviation exceeds an allowable value is an object.

  In the present invention, focusing on the fact that the variable impedance element can be operated with a small torque in a state where the deterioration of the mechanism portion of the variable impedance element has not progressed, the output torque of the motor is initially set to a relatively small “initial torque”. The first abnormality determination is performed when the deterioration of the mechanism section of the variable impedance element progresses to the extent that it is necessary to perform maintenance of the variable impedance element after the set fixed period has elapsed. When the abnormality determination is made, the motor output torque is changed to “torque after abnormality detection” larger than the initial torque.

  Therefore, in the present invention, after the abnormality determination unit makes the first abnormality determination, the motor output torque is set to the initial torque until the abnormality determination unit performs the first abnormality determination. Is an output torque setting unit that sets the output torque of the motor to a torque after abnormality detection greater than the initial torque, and a motor drive unit that drives the motor so that the output torque of the motor is set to the torque set by the output torque setting unit And provided.

In the present invention, a maintenance necessity determination unit is provided that determines that maintenance of the variable impedance element is necessary when abnormality determination is performed in a state where the output torque of the motor is set to the torque after abnormality detection. .

  The post-abnormality detection torque is basically set to a magnitude equivalent to the motor output torque set in the conventional impedance matching device. The magnitude of the initial torque is smaller than the torque after the abnormality is detected, and the target position of the operating axis of the variable impedance element and the current position until the mechanical part of the variable impedance element is deteriorated to the extent that maintenance is required in the near future. The size is set so that the residual deviation from the position can be maintained within an allowable range. That is, when the mechanism of the variable impedance element has deteriorated to a level that requires maintenance after a certain period of time, the residual deviation between the target position of the operating axis of the variable impedance element and the current position exceeds the allowable value. The magnitude of the initial torque is set so that the abnormality determination unit performs abnormality determination.

  With the above configuration, for example, the first abnormality determination is performed, or the output torque of the motor is switched from the initial torque to the torque after abnormality detection. It is possible to know that the deterioration has occurred to such an extent that maintenance is necessary (to the extent that maintenance can be said to be near). Accordingly, it is possible to prevent a situation in which the operation is continued and the production line needs to be stopped suddenly from being overlooked that maintenance is necessary.

Also, with the above configuration, it is time to perform maintenance on the variable impedance element before the impedance matching device cannot perform impedance matching due to deterioration of the mechanism of the variable impedance element. Therefore, it is possible not only to prevent interruption of the semiconductor manufacturing process but also to prevent excessive maintenance.

  In a preferred aspect of the present invention, when the abnormality determination unit makes the first abnormality determination, or when the output torque of the motor is switched from the initial torque to the torque after abnormality detection, the maintenance time of the variable impedance element is approaching. Alarm generating means for generating an alarm signal is further provided.

  As described above, an alarm indicating that the maintenance time of the variable impedance element is approaching when the abnormality determination unit makes the first abnormality determination or when the motor output torque is switched from the initial torque to the torque after abnormality detection By providing an alarm generating means for generating a signal, information indicating that the maintenance time is near can be reliably given to the manager of the apparatus, so that it is possible to accurately maintain the performance of the impedance matching apparatus.

  Even when it is determined that maintenance is required by the maintenance necessity determination unit, impedance matching can be performed within an allowable error range at least until the processing of the product being processed in the production line is completed. It is preferable to set the torque after abnormality detection to be slightly smaller than the upper limit value of the output torque so that it can be performed. In other words, if the output torque setting unit makes an abnormality determination while the output torque of the motor is set to the torque after abnormality detection, the motor can be driven again if the output torque can be slightly increased. Increases nature. By doing so, the possibility of completing the processing of the product being processed is increased.

  In a preferred aspect of the present invention, after the abnormality determination unit makes the initial abnormality determination, the motor output torque is set to the initial torque until the abnormality determination unit makes the first abnormality determination. The output torque setting unit for setting the output torque of the motor to the post-abnormality detection torque that is larger than the initial torque and increases every time abnormality determination is performed, and the output torque setting unit of the motor And a motor drive unit for driving the motor so as to obtain the torque set by.

  With the above configuration, detailed information on the approaching maintenance period can be obtained, making it easier to plan maintenance and performing maintenance at the optimum timing in relation to the product manufacturing plan. be able to.

  When configured as described above, it indicates that the time for maintenance of the variable impedance element is approaching when the number of times that the abnormality determination unit has performed the abnormality determination reaches a preset first set value. An alarm generating means for generating an alarm signal can be provided.

  In the case of the configuration described above, the number of times that the abnormality determination is performed increases as the deterioration of the mechanism unit of the variable impedance element progresses. When the first set value set as the value is reached, it can be determined that the time for maintenance of the variable impedance element is approaching.

  Further, when configured as described above, an alarm signal is generated indicating that the time for maintenance of the variable impedance element is approaching when the torque after abnormality detection reaches the first determination value set in advance. Alarm generation means can also be provided. The first determination value is set equal to the magnitude of the torque after abnormality detection that is set when the number of abnormality determinations reaches the first set value.

  Further, when configured as described above, maintenance of the variable impedance element is performed when the number of times that the abnormality determination unit performs abnormality determination reaches a second set value set to a value larger than the first set value. It is possible to provide a maintenance necessity determination unit that determines that the above is necessary.

  As described above, after the abnormality determination unit makes the first abnormality determination, the motor output torque is set to a torque after abnormality detection that is larger than the initial torque and increases every time abnormality determination is performed. In the case of being configured to do so, as the deterioration of the mechanism portion of the variable impedance element progresses, the number of times that the abnormality determination unit performs abnormality determination increases, so the number of times that the abnormality determination unit performs abnormality determination Since the second set value set to a value larger than the first set value has been reached, it can be determined that maintenance of the variable impedance element is necessary.

  When configured as described above, the degree of deterioration of the mechanism portion of the variable impedance element is also reflected in the magnitude of the torque after abnormality detection. It can also be configured to determine that the maintenance of the variable impedance element is necessary when the second determination value set to a value larger than the determination value is reached.

  The output torque setting unit previously determines an increment of the torque after abnormality detection when the value of the torque after abnormality detection is increased every time the abnormality determination is performed after the abnormality determination unit performs the first abnormality determination. It is preferable to be configured to be a value (for example, a predetermined constant value).

  The output torque setting unit calculates the increment when the value of the torque after abnormality detection is increased every time the abnormality determination is performed after the abnormality determination unit performs the first abnormality determination as the number of times the abnormality determination is performed. It is preferable that the determination is made based on a predetermined relationship with the torque to be set. For example, the output torque setting unit can be configured to increase the increase in the value of the torque after abnormality detection as the abnormality determination is performed and the number of times increases.

  In a preferred aspect of the present invention, a signal output terminal is provided for outputting a signal indicating the determination result of the abnormality determination unit and a signal indicating the magnitude of the torque set by the output torque setting unit to the outside.

  As described above, if a signal output terminal for outputting a signal indicating the determination result of the abnormality determination unit and a signal indicating the magnitude of the torque set by the output torque setting unit to the outside is provided, these signals are provided. The information obtained by the above can be given to an external computer to be used for control and management of the production line, or the monitor information of the impedance matching device can be given to the monitoring device installed outside.

According to the first to sixth aspects of the present invention, it is possible to know from the magnitude of the output torque of the motor that the deterioration of the mechanism portion of the variable impedance element has progressed to some extent and that the maintenance time is approaching. Therefore, it is possible to prevent a situation in which it is necessary to stop the production line due to the deterioration of the mechanism portion of the variable impedance element due to the deterioration of the mechanism portion of the variable impedance element by overlooking that the time for maintenance has come.

According to the invention described in claims 2 to 6 , an alarm signal indicating that the maintenance time of the variable impedance element is approaching is generated, and the maintenance time of the variable impedance element is close to the administrator of the apparatus. Since information can be given reliably, the performance of the impedance matching device can be accurately maintained.

According to the first to sixth aspects of the present invention, since the maintenance necessity determination unit for determining that the maintenance of the variable impedance element is necessary when a predetermined condition is satisfied, the variable impedance element is provided. It can be known that the maintenance of the variable impedance element is necessary before the impedance matching device becomes unable to match the impedance due to the deterioration of the mechanism portion. Therefore, it is possible not only to prevent interruption of the semiconductor manufacturing process, but also to prevent excessive maintenance.

According to the sixth aspect of the present invention, the signal output terminal for outputting the signal indicating the determination result of the abnormality determination unit and the signal indicating the magnitude of the torque set by the output torque setting unit to the outside is provided. Therefore, the information obtained from the signal indicating the determination result of the abnormality determination unit and the signal indicating the magnitude of the set motor torque is given to an external computer for use in the control and management of the production line, The monitoring information of the impedance matching device can be given to the monitoring device installed in.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows the configuration of an impedance matching apparatus according to an embodiment of the present invention. In FIG. A load of the high frequency power source 1 such as a plasma generator is accommodated in the process chamber 2. Reference numerals 3 and 4 denote first and second variable impedance elements provided between the high frequency power source 1 and the process chamber (load) 2, and the first variable impedance element 3 is parallel to the high frequency power source 1 and the load. The second variable impedance element 4 is connected in series with the high frequency power source 1 and the process chamber 2 (load). In the present embodiment, the first variable impedance element 3 is composed of a first variable capacitor VC1, and the second variable impedance element 4 is composed of a second variable capacitor VC2. A vacuum variable capacitor is used as the first variable capacitor VC1 and the second variable capacitor VC2.

  In the illustrated example, an inductance 5 is inserted between the second variable capacitor VC2 and the load. An input detection unit 6 that detects the voltage Vin input to the load, the current Iin, and the phase difference θin between the voltage Vin and the current Iin is provided between the high-frequency power source 1 and the second variable capacitor VC2. Is provided. Since the detection method of the voltage Vin, the current Iin, and the phase difference θin by the input detector 6 is well known, the description thereof is omitted.

  For the first variable capacitor VC1, there is provided a first operating mechanism for operating the operating shaft of the first variable capacitor VC1 using the first motor 7a as a drive source, and for the second variable capacitor VC2. Thus, a second operating mechanism is provided for operating the operating shaft of the second variable capacitor VC2 using the second motor 7b as a drive source. In the present embodiment, step motors are used as the motors 7a and 7b. Each operation mechanism can be configured by a mechanism that transmits the rotation of each motor to the operation shaft of each variable capacitor. For example, it can be configured by a mechanism using a coupling that connects the rotation shaft of each motor and the operation shaft of each variable capacitor. In some cases, the motor can be configured by a mechanism that decelerates the rotation of each motor and transmits it to the operation shaft of each variable capacitor.

  Further, an operation provided with a first position detector 8a for detecting the position of the operating axis of the first variable capacitor VC1 and a second position detector 8b for detecting the position of the operating axis of the second variable capacitor VC2. The shaft position detector 8 is provided, and the output signals Spa and Spb of the first and second position detectors 8a and 8b are obtained from the input voltage detection signal Sv, the input current detection signal Si and the phase difference obtained from the input detector 6, respectively. It is input to the target position setting unit 9 together with the detection signal Sθ.

  The target position setting unit 9 uses the input voltage Vin and the input current Iin detected by the input detection unit 6 to calculate the impedance viewed from the input side of the impedance matching device (input end of the input detection unit 6). Thus, the target positions of the operation axes of the variable capacitors VC1 and VC2 necessary for impedance matching between the high-frequency power source 1 and the process chamber (load) 2 are calculated. That is, the impedance on the power supply side (usually 50Ω) viewed from the input end of the impedance matching device via the transmission line and the load side viewed from the input end of the impedance matching device to the process chamber (load) 2 side. The target positions of the operation axes of the variable capacitors VC1 and VC2 necessary for matching the impedance are calculated. The deviation between the calculated target position of the operating axis of the first variable capacitor VC1 and the current position of the operating axis of the variable capacitor VC1 detected by the first position detector 8a is required to be zero. The drive amount of the step motor 7a (number of pulses given to the step motor 7a) is calculated, and a target position setting signal Sda indicating the calculated drive amount is supplied to the first motor drive unit 10a.

  The calculation of the target position of each operation axis of the variable capacitors VC1 and VC2 is performed by means for calculating the reactance value of the variable capacitors VC1 and VC2 necessary for impedance matching as the target reactance value, and for each variable capacitor. Using the relationship between the rotation angle position of the operation shaft determined in advance and the capacitance of each variable capacitor, the rotation angle position (target position) of the operation shaft of each variable capacitor corresponding to each calculated target reactance value And a means for calculating. The first and second position detectors 8a and 8b can be configured using, for example, an encoder that generates a position detection pulse each time the operation axes of the variable capacitors VC1 and VC2 rotate by a minute angle.

  The target position setting unit 9 also calculates the target position calculated for the operation axis of the second variable capacitor VC2 and the current position of the operation axis of the second variable capacitor VC2 detected by the second position detector 8b. The drive amount (number of pulses applied to the step motor) necessary for making the deviation zero is calculated, and a target position setting signal Sdb indicating the calculated drive amount is supplied to the second motor drive unit 10b. In the present embodiment, the motor driving unit 10 is configured by the first motor driving unit 10a and the second motor driving unit 10b.

  Reference numeral 11 denotes an abnormality determination unit that monitors the target position and current position of the operation axis of the first variable capacitor VC1 and the target position and current position of the operation axis of the second variable capacitor VC2. When the residual deviation between the target position of the operation axis of the first variable capacitor VC1 and the current position exceeds the allowable value, an abnormality determination is made that the mechanism portion of the first variable capacitor VC1 is abnormal, and the first When the residual deviation between the target position of the operation axis of the second variable capacitor VC2 and the current position exceeds an allowable value, it is determined that the mechanism of the second variable capacitor VC2 is abnormal.

  The “residual deviation” between the target position and the current position of the variable capacitor operation axis is determined when the motor drive unit 10 drives the motor by the drive amount calculated by the target position setting unit 9. This is a deviation existing between the target position and the current position. Here, “the time when the motor driving unit 10 drives the motor by the driving amount calculated by the target position setting unit 9” is usually considered that the motor is actually driven in consideration of a detection delay. Indicates the time. In other words, it is inevitable that the detection of the current position of the operation axis of the variable capacitor is accompanied by a delay, and the data of the target position of the operation axis of the variable capacitor and the detection data of the current position corresponding to the target position are generated simultaneously. Therefore, some device is required to accurately detect the deviation existing between the target position of the operating axis of the variable capacitor and the current position when the motor is out of step. For example, when the target position data is output from the target position setting unit 9 to the abnormality determination unit 11, the process of delaying the timing of outputting the current position detection data in consideration of the detection delay is performed, so that the motor is removed. The deviation existing between the target position of the operation axis of the variable capacitor and the current position can be accurately detected when the adjustment state is reached. In addition, the abnormality determination unit 11 is provided with a memory that temporarily stores target position data and current position detection data, and the above deviation can be accurately detected by performing processing such as reading from the memory in consideration of the delay. be able to.

  The abnormality determination unit 11 generates a first abnormality determination signal Saa when performing an abnormality determination that the mechanism unit of the first variable capacitor VC1 is abnormal, and the movable part of the second variable capacitor VC2 is abnormal. When the abnormality determination is made, the second abnormality determination signal Sab is generated. The first abnormality determination signal Saa and the second abnormality determination signal Sab output from the abnormality determination unit 11 are provided to the first output torque setting unit 12a and the second output torque setting unit 12b, respectively.

  The first output torque setting unit 12a and the second output torque setting unit 12b are parts for setting the output torque of the first motor 7a and the second motor 7b according to the determination result by the abnormality determination unit 11. The output torque setting unit 12a sets the output torque of the motor 7a to the initial torque until the abnormality determination unit 11 performs the first abnormality determination on the first motor 7a. After the abnormality determination is made, the output torque of the motor is set to a torque after abnormality detection larger than the initial torque.

  The second output torque setting unit 12b sets the output torque of the motor 7b to the initial torque until the abnormality determination unit 11 performs the first abnormality determination, and the abnormality determination unit 11 performs the first abnormality determination. Thereafter, the output torque of the motor 7b is set to a torque after abnormality detection that is larger than the initial torque.

  The first motor driving unit 10a applies driving pulses to the first motor 7a by the number of pulses set by the target position setting unit 9, and outputs the output torque of the first motor 7a to the first output torque setting unit 12a. The drive current passed through the first motor is adjusted so as to be equal to the torque set by.

  The second motor drive unit 10b gives drive pulses to the second motor 7b by the number of pulses set by the target position setting unit 9, and outputs the output torque of the second motor 7b to the second output torque setting unit. The drive current passed through the second motor is adjusted so as to be equal to the torque set by 12b.

  The first motor 7a and the second motor 7b are set so that the output torques of the first motor 7a and the second motor 7b are equal to the torques set by the first output torque setting unit 12a and the second output torque setting unit 12b, respectively. The method of adjusting the drive current flowing through the second motor 7b is performed by changing the resistance value, for example. Further, as a means for changing the resistance value, for example, a variable resistance may be used, or an IC capable of changing the resistance value may be used. When a signal is output from the output torque setting unit 12 to the motor drive unit 10 so as to change the output torque, the resistance value is changed in accordance with the signal to adjust the drive current flowing to each motor. Good.

  In the present embodiment, the output torque setting unit 12 is configured by the first output torque setting unit 12a and the second output torque setting unit 12b, and the motor drive unit 10 and the output torque setting unit 12 include a variable capacitor (variable impedance). A motor control unit 13 is configured to control the motors 7a and 7b so that the position of the operation axis of the element) matches the target position set by the target position setting unit 9.

  When the movable portion of the first variable capacitor VC1 deteriorates due to solidification of grease or wear of the mechanical sliding portion, the load torque applied to the first motor 7a from the operation shaft of the first variable capacitor increases. . When the load torque applied to the first motor 7a increases and exceeds a certain limit, the rotation of the motor is not synchronized with the drive pulse (step-out state), and the motor cannot be rotated. When such a state occurs, the operating shaft of the first variable capacitor 7a cannot be rotated to the target position, and impedance matching between the high-frequency power source 1 and the load 2 cannot be achieved. The residual deviation between the current position of the operating shaft of the variable capacitor VC1 and the target position at the time when the drive unit 10a completes driving of the motor 7a becomes large.

  Similarly, when the movable part of the second variable capacitor VC2 deteriorates, the rotation of the motor 7b is not synchronized with the drive pulse (step-out state), and the motor cannot be normally rotated. When such a state occurs, the operating shaft of the second variable capacitor 7b cannot be rotated to the target position, and impedance matching between the high-frequency power source 1 and the load cannot be achieved. The residual deviation between the current position of the operating axis of the variable capacitor VC2 and the target position at the time when the unit 10b completes driving of the motor 7b increases.

  Accordingly, the abnormality determination unit 11 monitors the current position and the target position of the operation axis of each variable capacitor, and determines whether or not the residual deviation between both positions exceeds the allowable value, thereby determining each variable capacitor. It can be determined whether or not the movable part is abnormal.

  The torque after abnormality detection is as large as the motor output torque set in the conventional impedance matching device, that is, even when the mechanism portion of the variable impedance element has deteriorated to the extent that maintenance is required. The size is set so that the operating axis of the impedance element can be rotated to the target position.

  In the above embodiment, the magnitude of the initial torque is smaller than the torque after abnormality detection and while the mechanism portion of the variable capacitor is in a state before being deteriorated to such an extent that maintenance is required after a certain period of time, The operation axis of the variable capacitor can be operated. However, when the mechanism of the variable capacitor has deteriorated to a level that requires maintenance after a certain period of time, the operation axis of the variable impedance element cannot be operated. Set to size. That is, when the mechanism of the variable capacitor has deteriorated to the extent that it can be said that maintenance is required after a certain period of time, the residual deviation between the target position of the operation axis of the variable capacitor and the current position exceeds the allowable value and the abnormality determination unit The magnitude of the initial torque is set so as to perform abnormality determination.

  As described above, when the abnormality determination unit 11 performs the first abnormality determination, if the motor output torque is reset to a torque after abnormality detection larger than the initial torque, the first abnormality determination is performed. Or the output torque of the motor has been switched from the initial torque to the torque after abnormality detection, so that the mechanism of the variable impedance element needs to be maintained after a certain time (to the extent that the maintenance time is close) ) You can know that it has deteriorated. Accordingly, it is possible to prevent a situation in which the operation is continued and the production line needs to be stopped suddenly from being overlooked that maintenance is necessary. Further, by resetting the output torque of the motor to the torque after abnormality detection that is larger than the initial torque, it is possible to drive the motor again so that the residual deviation falls within the allowable value.

  In the illustrated example, the output of the abnormality determination unit 11 and the output of the output torque setting unit 12 are given to the maintenance necessity determination unit 14. The maintenance necessity determination unit 14 is the first when the abnormality determination unit 11 performs abnormality determination in a state where the first output torque setting unit 12a sets the output torque of the motor 7a to the torque after abnormality detection. It is determined that maintenance of the variable capacitor VC1 is necessary.

  The maintenance necessity determination unit 14 also performs the second operation when the abnormality determination unit 11 performs abnormality determination while the second output torque setting unit 12b sets the output torque of the motor 7b to the torque after abnormality detection. It is determined that maintenance of the variable capacitor VC2 is necessary.

  In the present embodiment, the output of the abnormality determination unit 11 is given to the alarm generation means 15. The alarm generation means 15 generates an alarm signal indicating that the maintenance time of the variable capacitor VC1 is approaching when the abnormality determination unit 11 makes the first abnormality determination for the variable capacitor VC1, and the abnormality determination unit 11 is variable. When the first abnormality determination is made for the capacitor VC2, an alarm signal indicating that the maintenance time of the variable capacitor VC2 is approaching is generated.

  In the present embodiment, signals Sta and Stb indicating the magnitude of the torque set by the output torque setting unit 12 and signals Saa and Sab indicating the determination results of the abnormality determination unit 11 are output to the outside. Terminals t1 to t4 are provided.

  If a signal output terminal for outputting a signal indicating the determination result of the abnormality determination unit and a signal indicating the magnitude of the torque set by the output torque setting unit to the outside as in the present embodiment is provided, A signal indicating the determination result of the determination unit and information indicating the degree of deterioration of the movable portion of the variable capacitor obtained from the signal indicating the magnitude of the set motor torque are given to an external computer, and It can be used for control and management, or monitor information of an impedance matching device can be given to a monitoring device installed outside.

  As in the above embodiment, until the abnormality determination unit 11 performs the first abnormality determination, the output torque of the motors 7a and 7b is set to the initial torque, and the abnormality determination unit 11 performs the first abnormality determination. After that, if the output torque of the motors 7a and 7b is set to a torque after abnormality detection that is larger than the initial torque, the first abnormality determination is made. It is possible to know that the deterioration has occurred to such an extent that maintenance is necessary (to the extent that maintenance can be said to be near). Accordingly, it is possible to prevent a situation in which the operation is continued and the production line needs to be stopped suddenly from being overlooked that maintenance is necessary.

  Further, as in the above-described embodiment, when the alarm generation unit 15 that generates an alarm signal indicating that the maintenance time of the variable capacitor is approaching when the abnormality determination unit performs the first abnormality determination, the variable generation unit 15 is variable. Since it is possible to obtain information that the maintenance time of the capacitor is close, it is possible to easily plan maintenance of the impedance matching device. Therefore, it is possible to accurately maintain the performance of the impedance matching device, and prevent the impedance matching device from suddenly performing a normal matching operation and preventing an inconvenient state in which the production line stops. it can.

  Further, as in the above-described embodiment, when the abnormality determination is performed in a state where the output torque setting unit 12 sets the motor output torque to the torque after abnormality detection, it is determined that maintenance of the variable capacitor is necessary. If a maintenance necessity determination unit is provided, the variable impedance element needs to be maintained before the impedance matching device cannot perform impedance matching due to deterioration of the variable capacitor mechanism. be able to. Therefore, it is possible to prevent a situation in which a line must be stopped during the processing of a product in a production line in which an impedance matching device is used.

  In the above description, when the mechanism of the variable capacitor has deteriorated to the extent that maintenance can be said to be necessary after a certain period of time, the residual deviation between the target position of the variable capacitor operating shaft and the current position exceeds the allowable value and is abnormal. The magnitude of the initial torque of the motor is set so that the determination unit makes the first abnormality determination, and when the abnormality determination unit makes the first abnormality determination, an alarm signal indicating that the maintenance time is near is generated However, the initial torque of the motor is set to a small value so that the abnormality determination is performed a plurality of times before the mechanism of the variable capacitor deteriorates to the extent that it can be said that maintenance is required after a certain period of time. Also good.

  That is, the motor control unit 13 sets the output torque of the motor to the initial torque until the abnormality determination unit 11 performs the first abnormality determination, and after the abnormality determination unit performs the first abnormality determination, The output torque is set by the output torque setting unit, and the output torque setting unit sets the output torque of the motor, which is larger than the initial torque and increases after detection of abnormality, and the output torque of the motor. And a motor drive unit that drives the motor so as to obtain a sufficient torque.

  In this case, the alarm generating means 15 is approaching the time when maintenance of the variable capacitor is approached when the number of times that the abnormality determination unit 11 has performed the abnormality determination reaches the first set value ns1 set to a value of 1 or more. It is configured to generate an alarm signal indicating that

  In addition, when generating an alarm signal indicating that the time for maintenance is approaching, based on the set output torque of the motor, the torque after abnormality detection is preset to a value larger than the initial torque. The alarm generation means is configured to generate an alarm signal indicating that the time for maintenance of the variable impedance element is approaching when the first determination value is reached.

  As described above, in the case of adopting a configuration in which the value of the torque after abnormality detection is increased every time abnormality determination is performed, the maintenance necessity determination unit 14 determines that the number of times the abnormality determination unit performs abnormality determination is the first. It is configured to determine that maintenance of the variable impedance element is necessary when the second set value set to a value larger than the set value is reached, or the torque after abnormality detection is greater than the first determination value. When the second determination value set to a larger value is reached, it is determined that maintenance of the variable impedance element is necessary.

  When increasing the magnitude of torque after abnormality detection every time abnormality determination is performed as described above, the output torque setting unit 12 performs abnormality determination after the abnormality determination unit 11 performs the first abnormality determination. The increment of the torque after abnormality detection when increasing the value of the torque after abnormality detection every time can be configured to be a predetermined value (for example, a predetermined constant value).

  Further, when the magnitude of the torque after abnormality detection is increased every time abnormality determination is performed as described above, the output torque setting unit 12 performs the abnormality determination after the abnormality determination unit performs the first abnormality determination. The increment when increasing the value of the torque after abnormality detection every time can also be determined based on a predetermined relationship between the number of times the abnormality determination has been performed and the torque to be set. . For example, the output torque setting unit can be configured to increase the increase in the value of the torque after abnormality detection as the abnormality determination is performed and the number of times increases.

  In the embodiment shown in FIG. 1, the abnormality determination unit 11, the first output torque setting unit 12 a and the second output torque setting unit 12 b, the maintenance necessity determination unit 14, and the alarm generation unit 15 are connected to a computer. FIG. 2 is a flowchart showing an example of a task algorithm executed by a computer when configured by using it.

  The task shown in FIG. 2 is executed for each of the first variable capacitor VC1 and the second variable capacitor VC2 at each control loop timing for controlling the driving of the motors 7a and 7b by the motor driving unit 10. In the task shown in FIG. 2, n is the number of times the abnormality determination unit 11 performs abnormality determination (abnormality determination number), and its initial value is zero. ns1 to ns3 are first to third set values set for the abnormality determination number n, respectively, and have a relationship of ns1 <ns2 <ns3. The value of ns1 is set to 1 or more, and the value of ns2 is set to 2 or more. Also, τ is the output torque of the motor, τ1 is the initial torque, and Δτ is the increment of the output torque. ΔP is a residual deviation between the target position of the operation axis of the variable capacitor and the current position, and ΔPa is an allowable value of the residual deviation.

  In a state where the abnormality detection unit 11 has not made any abnormality determination, the output torque of the motor is set to an initial value when performing various initial settings. When the driving of the motors 7a and 7b by the motor driving units 10a and 10b is completed, the task of FIG. 2 is executed for the first variable capacitor and the second variable capacitor. When the task shown in FIG. 2 is started for the first variable capacitor VC1, first, the target position of the operating axis of the first variable capacitor VC1 and the first position detector 8a are detected in step S101. A residual deviation ΔP from the current position of the operation axis is calculated. Next, in step S102, it is determined whether or not the residual deviation ΔP is less than or equal to the allowable value ΔP1, and if it is determined that the deviation ΔP is less than or equal to the allowable value ΔP1, do nothing thereafter (without changing the motor output torque). To finish this task.

  When it is determined in step S102 that the deviation ΔP is not less than or equal to the allowable value ΔP1 (exceeds the allowable value ΔP), the process proceeds to step S103 to generate an abnormal signal, and in step S104, the abnormality determination number n is incremented by 1. . Next, in step S105, it is determined whether or not the abnormality determination number n is equal to or less than a third set value (allowable limit value) ns3. As a result, when it is determined that the abnormality determination number n is equal to or smaller than the third set value, the output torque τ of the motor is increased by a predetermined increment Δτ in step S106. Next, in step S107, it is determined whether or not the abnormality determination number n is equal to or greater than the first set value ns1, and if the abnormality determination number n is not equal to or greater than the first set value ns1, the task is terminated without doing anything thereafter. To do. If the abnormality determination number n is greater than or equal to the first set value ns1 in step S107, it is then determined in step S108 whether or not the abnormality determination number n is greater than or equal to the second set value ns2. As a result, when it is determined that the abnormality determination count n is not equal to or greater than the second set value ns2, the process proceeds to step S109, where an alarm signal indicating that the maintenance time is near is generated and this task is terminated.

  When it is determined in step S108 that the abnormality determination count n is equal to or greater than the second set value ns2, the process proceeds to step S110, where a maintenance command indicating that the maintenance time has come is generated and this task is terminated.

  If it is determined in step S105 that the abnormality determination count n exceeds the third set value, a stop command is issued to stop the motor drive in step S111, and this task ends. At this time, an alarm signal may be generated.

  In the case of the above algorithm, when it is not determined that the variable capacitor is abnormal, the output torque of the motor is set to the initial torque. Once the abnormality determination is performed, the value of n is set to 1 in step S104 of the task in FIG. 2, and the output torque of the motor is set to a torque after abnormality detection that is larger than the initial torque by a certain increment Δτ in step S106.

  Each time the abnormality determination is repeated, the value of n increases, and the output torque of the motor is increased in step S106. When n ≧ ns1, an alarm signal is generated indicating that it is almost time for maintenance in step S109. This alarm signal continues to be generated while the value of n is smaller than the second set value. When the value of n becomes equal to or greater than the second set value ns2, a maintenance command indicating that the maintenance time has come is generated in step S110. Even after the value of n exceeds the second set value ns2, the output torque of the motor is increased while the value of n is less than the third set value ns3, but the value of n is the third set value. After reaching ns3 or more, the drive of the motor is prohibited in step S111 in order to prevent the motor from being damaged. The value of ns3 (the upper limit value of the number of times the motor output torque is increased) is set to an appropriate value in consideration of the limit value of the drive current that can be passed through the motor.

  In the case of the above algorithm, the abnormality determination unit 11 is configured by steps S101, S102, and S103 in FIG. Further, the output torque setting unit 12 is configured by steps S104 and S106, and the maintenance necessity determination unit 14 is configured by steps S108 and S110. Furthermore, the alarm generation means 15 is comprised by step S107, S108, and S109. Note that step S108 belongs to both the maintenance necessity determination unit 14 and the alarm generation means 15.

It is the blocks which showed the structure of one Embodiment of the impedance matching apparatus concerning this invention. It is the flowchart which showed an example of the algorithm of the task which a computer performs in order to comprise the torque abnormality detection part of the embodiment of FIG. 1, an output torque setting part, an alarm generation means, and a maintenance necessity determination part.

DESCRIPTION OF SYMBOLS 1 High frequency power supply 2 Process chamber 3 1st variable capacitor 4 2nd variable capacitor 5 Inductance 6 Input detection part 7a 1st motor 7b 2nd motor 8 Position detection part 8a 1st position detector 8b 2nd position Detector 9 Target position setting unit 10 Motor drive unit 11 Abnormality determination unit 12 Output torque setting unit 13 Motor control unit

Claims (6)

A variable impedance element provided between a power source and a load and operated when matching impedance between the power source and the load, and the operation axis of the variable impedance element using a motor as a drive source An operation mechanism for operating the operation axis, a target position setting unit for setting a target position of the operation axis necessary for matching the impedance, an operation axis position detection unit for detecting the current position of the operation axis, and the variable A motor control unit for controlling the motor so as to match the position of the operation axis of the impedance element with the target position set by the target position setting unit; and the target position and the current position of the operation axis are monitored and the target An impedance matching device including an abnormality determination unit that performs abnormality determination when a residual deviation between a position and a current position exceeds an allowable value,
The motor control unit sets the output torque of the motor to an initial torque until the abnormality determination unit performs the first abnormality determination, and after the abnormality determination unit performs the first abnormality determination, the motor output An output torque setting unit for setting the torque to a torque after abnormality detection greater than the initial torque, and a motor driving unit for driving the motor so that the output torque of the motor is set to the torque set by the output torque setting unit ; With
A maintenance necessity determining unit is provided that determines that the maintenance of the variable impedance element is necessary when the abnormality determination is performed in a state where the output torque of the motor is set to the torque after the abnormality detection. about,
An impedance matching device characterized by the above.   An alarm signal indicating that the maintenance time of the variable impedance element is approaching when the abnormality determination unit makes a first abnormality determination or when the output torque of the motor is switched from the initial torque to the torque after abnormality detection. The impedance matching apparatus according to claim 1, further comprising an alarm generation unit that generates the alarm. A variable impedance element provided between a power source and a load and operated when matching impedance between the power source and the load, and the operation axis of the variable impedance element using a motor as a drive source An operation mechanism for operating the operation axis, a target position setting unit for setting a target position of the operation axis necessary for matching the impedance, an operation axis position detection unit for detecting the current position of the operation axis, and the variable A motor control unit for controlling the motor so as to match the position of the operation axis of the impedance element with the target position set by the target position setting unit; and the target position and the current position of the operation axis are monitored and the target An impedance matching device including an abnormality determination unit that performs abnormality determination when a residual deviation between a position and a current position exceeds an allowable value,
The motor control unit sets the output torque of the motor to an initial torque until the abnormality determination unit performs the first abnormality determination, and after the abnormality determination unit performs the first abnormality determination, An output torque setting unit that sets an output torque that is larger than the initial torque and increases after each abnormality determination, and that increases in value every time the abnormality determination is performed; and an output torque setting unit that sets the output torque of the motor A motor drive unit that drives the motor to have a torque set by
The variable impedance when the number of times that the abnormality determination unit performs abnormality determination reaches a preset first set value, or when the post-abnormality detection torque reaches a preset first determination value. An alarm generating means for generating an alarm signal indicating that the time for performing maintenance of the element is approaching, and a number of times that the abnormality determination unit performs abnormality determination is set to a value larger than the first set value. Maintenance of the variable impedance element is necessary when the set value of 2 is reached or when the post-abnormality detection torque reaches a second determination value set to a value larger than the first determination value. A maintenance necessity determination unit for determining that
An impedance matching device characterized by the above. The output torque setting unit calculates an increment of the torque after abnormality detection when increasing the value of the torque after abnormality detection every time the abnormality determination is performed after the abnormality determination unit performs the first abnormality determination. Configured to have a predetermined value;
  The impedance matching device according to claim 3. The output torque setting unit performs an abnormality determination on an increment when the value of the torque after abnormality detection is increased every time the abnormality determination is performed after the abnormality determination unit performs the first abnormality determination. Configured to be determined based on a predetermined relationship between the number of times and the torque to be set,
  The impedance matching device according to claim 3. 6. A signal output terminal for outputting a signal indicating the determination result of the abnormality determination unit and a signal indicating the magnitude of torque set by the output torque setting unit to the outside. The impedance matching device according to claim 1.

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