CN117627990B - Servo valve control system and control method thereof - Google Patents
Servo valve control system and control method thereof Download PDFInfo
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- CN117627990B CN117627990B CN202410102836.6A CN202410102836A CN117627990B CN 117627990 B CN117627990 B CN 117627990B CN 202410102836 A CN202410102836 A CN 202410102836A CN 117627990 B CN117627990 B CN 117627990B
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Abstract
The invention discloses a servo valve control system and a control method thereof, and relates to the technical field of semiconductors. The servo valve control system comprises a controller, a driver, a stepping motor, a coupler, a servo valve, an encoder and a bidirectional counter. The stepping motor is connected with the servo valve through a coupler, the driver, the stepping motor, the encoder, the bidirectional counter and the controller are sequentially connected end to end and form a control closed loop, and the driver is connected with the bidirectional counter. Compared with the prior art, the servo valve control system provided by the invention has the advantages that the bidirectional counter connected with the encoder and the driver and the deviation of the actual opening angle meeting the first relational expression are adopted, so that the adjustment precision of the servo valve can be effectively improved, the stability of the cavity air pressure is ensured, and the product quality is ensured.
Description
Technical Field
The invention relates to the technical field of semiconductors, in particular to a servo valve control system and a control method thereof.
Background
Currently, in semiconductor deposition equipment, a pressure control servo valve is a common component that is commonly used in downstream pressure control systems to maintain the chamber pressure within the process chamber at a set point. But the existing pressure control servo valve has lower adjustment precision and larger opening angle deviation, so that the air pressure of the cavity in the process cavity is not stable enough, and the product quality is directly influenced.
In view of the above, it is important to design a servo valve control system with high adjustment accuracy and a control method thereof, especially in semiconductor manufacturing.
Disclosure of Invention
The invention aims to provide a servo valve control system which can effectively improve the adjustment precision of a servo valve, ensure the stability of cavity air pressure and ensure the quality of products.
The invention further aims to provide a control method of the servo valve control system, which can effectively improve the adjustment precision of the servo valve, ensure the stability of the cavity air pressure and ensure the product quality.
The invention is realized by adopting the following technical scheme.
The servo valve control system comprises a controller, a driver, a stepping motor, a coupler, a servo valve, an encoder and a bidirectional counter, wherein the stepping motor is connected with the servo valve through the coupler, the stepping motor is used for adjusting the opening angle of the servo valve, and the servo valve is arranged at the exhaust port; the device comprises a driver, a stepping motor, an encoder, a bidirectional counter and a controller which are sequentially connected end to end and form a control closed loop, wherein the driver is connected with the bidirectional counter, the controller is used for calculating an opening angle error value according to a preset opening angle and an actual opening angle of a servo valve and sending a compensation speed calculated according to the opening angle error value to the driver, the driver is used for calculating a first pulse signal according to the compensation speed and simultaneously sending the first pulse signal to the stepping motor and the bidirectional counter, the stepping motor is used for driving the servo valve to rotate according to the first pulse signal, the encoder is used for converting the angular displacement of the stepping motor into a second pulse signal and sending the second pulse signal to the bidirectional counter, and the bidirectional counter is used for calculating the actual opening angle according to the first pulse signal and the second pulse signal; wherein the deviation of the actual opening angle satisfies a first relation:the method comprises the steps of carrying out a first treatment on the surface of the In the first relation, +_>Is the cavity air pressure of the process cavity, +.>For the servo valve to be subject to pressure deviations of the internal cavity pressure of the process chamber,/->For the conductance deviation of the servo valve, +.>For the opening angle of the servo valve>Deviation of the actual opening angle; opening angle +.>The second relation is satisfied: />The method comprises the steps of carrying out a first treatment on the surface of the In the second relation, +_>For the conductance of the servo valve->、/>C is a conductance parameter of a valve body in the servo valve which is dynamically determined through a Kalman filtering algorithm; cavity air pressure of process cavity>The third relation is satisfied: />The method comprises the steps of carrying out a first treatment on the surface of the In the third relation, +_>For the gas flow into the process chamber, +.>Is constant; deriving a fourth relationship from the first, second and third relationships:the method comprises the steps of carrying out a first treatment on the surface of the The driver comprises a conversion module and a driving module, the controller is connected with the stepping motor sequentially through the conversion module and the driving module, the conversion module is connected with the bidirectional counter, the conversion module is used for converting the compensation speed into a first pulse signal and simultaneously transmitting the first pulse signal to the driving module and the bidirectional counter, and the driving module is used for controlling according to the first pulse signalThe stepping motor rotates, wherein the first pulse signal comprises a first pulse number and a pulse direction, and the pulse direction is expressed as positive and negative of the first pulse number; the encoder comprises an encoding module, a counting module and a multiplying power calculating module, wherein the stepping motor is connected with the bidirectional counter through the encoding module, the counting module and the multiplying power calculating module in sequence, the encoding module is used for programming the angular displacement of the stepping motor to form a counting signal and sending the counting signal to the counting module, the counting module is used for converting the counting signal into a second pulse number and sending the second pulse number to the multiplying power calculating module, and the multiplying power calculating module is used for multiplying the second pulse number by a preset multiplying power and sending the obtained second pulse signal to the bidirectional counter; the up-down counter calculates the actual opening angle using the fifth relation: />The method comprises the steps of carrying out a first treatment on the surface of the In the fifth relation, +_>For the actual opening angle>Is a preset multiplying power->For the second pulse number, +.>For the first pulse number, +.>Sub-division resolution for the drive; the multiplying power calculating module calculates a preset multiplying power by using a sixth relation: />The method comprises the steps of carrying out a first treatment on the surface of the In the sixth relation, +_>Is a preset multiplying power, and is a multiplying power,for the line resolution of the encoder, +.>Is the subdivision resolution of the drive.
Optionally, the servo valve is subject to pressure deviations from the internal chamber pressure in the process chamberIn the range of 0.05% to 0.2%, the conductance deviation of the servo valve +.>In the range of 10 to 30, deviation of the actual opening angle +.>In the range of 0.002% to 0.02%.
Optionally, the subdivision resolution of the driverGreater than or equal to 12800 lines, line resolution of encoder +.>Less than or equal to 800 lines.
Optionally, the driver further includes an acceleration limiting module connected between the controller and the conversion module, the acceleration limiting module being configured to limit a maximum acceleration up to the compensation speed.
The control method of the servo valve control system is applied to the servo valve control system, and comprises the following steps: step one: calculating an opening angle error value by using a controller according to a preset opening angle and an actual opening angle of the servo valve, and calculating a compensation speed according to the opening angle error value, wherein the deviation of the actual opening angle meets a first relation:the method comprises the steps of carrying out a first treatment on the surface of the Step two: calculating a first pulse signal according to the compensation speed by using a driver; step three: the servo valve is driven to rotate by the stepping motor according to the first pulse signalThe method comprises the steps of carrying out a first treatment on the surface of the Step four: converting the angular displacement of the stepping motor into a second pulse signal by using an encoder; step five: and calculating an actual opening angle according to the first pulse signal and the second pulse signal by using a bidirectional counter.
The servo valve control system and the control method thereof provided by the invention have the following beneficial effects:
according to the servo valve control system provided by the invention, the stepping motor is connected with the servo valve through the coupler, the stepping motor is used for adjusting the opening angle of the servo valve, and the servo valve is used for being arranged at the exhaust port; the device comprises a driver, a stepping motor, an encoder, a bidirectional counter and a controller which are sequentially connected end to end and form a control closed loop, wherein the driver is connected with the bidirectional counter, the controller is used for calculating an opening angle error value according to a preset opening angle and an actual opening angle of a servo valve and sending a compensation speed calculated according to the opening angle error value to the driver, the driver is used for calculating a first pulse signal according to the compensation speed and simultaneously sending the first pulse signal to the stepping motor and the bidirectional counter, the stepping motor is used for driving the servo valve to rotate according to the first pulse signal, the encoder is used for converting the angular displacement of the stepping motor into a second pulse signal and sending the second pulse signal to the bidirectional counter, and the bidirectional counter is used for calculating the actual opening angle according to the first pulse signal and the second pulse signal; wherein the deviation of the actual opening angle satisfies a first relation:the method comprises the steps of carrying out a first treatment on the surface of the In the first relation, +_>For the servo valve to be subject to pressure deviations of the internal cavity pressure of the process chamber,/->For the conductance deviation of the servo valve, +.>Is the deviation of the actual opening angle. Compared with the prior art, the servo valve control system provided by the invention adopts the structure that the servo valve control system is simultaneously driven by an encoderThe bidirectional counter connected with the actuator and the deviation of the actual opening angle meeting the first relation can effectively improve the adjusting precision of the servo valve, ensure the stability of the air pressure of the cavity and ensure the quality of products.
The control method of the servo valve control system, which is provided by the invention, is applied to the servo valve control system, can effectively improve the adjustment precision of the servo valve, ensures the stability of the cavity air pressure and ensures the product quality.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a servo valve control system applied to a semiconductor deposition apparatus according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a servo valve control system according to an embodiment of the present invention;
FIG. 3 is a block diagram of a servo valve control system according to an embodiment of the present invention;
FIG. 4 is a graph showing the relationship between opening angle and conductance in a servo valve control system according to an embodiment of the present invention;
fig. 5 is a graph showing a relationship between an opening angle and a conductance deviation in a servo valve control system according to an embodiment of the present invention.
Icon: 10-a semiconductor deposition apparatus; 100-a servo valve control system; 110-a controller; 120-driver; a 121-conversion module; 122-a drive module; 123-an acceleration limiting module; 130-a stepper motor; 140-a coupling; 150-a servo valve; 160-an encoder; 161-an encoding module; 162-counting module; 163-multiplying factor calculation module; 170-a up-down counter; 200-process chamber; 300-flow control valve.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
In the description of the present invention, it should be noted that, directions or positional relationships indicated by terms such as "inner", "outer", "upper", "lower", "horizontal", etc., are directions or positional relationships based on those shown in the drawings, or those that are conventionally put in use of the inventive product, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or elements referred to must have a specific direction, be configured and operated in a specific direction, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used merely to distinguish between descriptions and should not be construed as indicating or implying relative importance.
In the description of the present invention, it should also be noted that, unless explicitly specified and limited otherwise, the terms "disposed," "connected," "mounted," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
Some embodiments of the present invention are described in detail below with reference to the accompanying drawings. Features of the embodiments described below may be combined with each other without conflict.
Referring to fig. 1-5 (the open arrows in fig. 1 and 2 indicate the flow direction of the process gas), a servo valve control system 100 is provided for adjusting the opening angle of a servo valve 150. It can effectively improve the regulation precision of servo valve 150, guarantees the stability of cavity atmospheric pressure, guarantees product quality.
It should be noted that the servo valve control system 100 is applied to the semiconductor deposition apparatus 10, and the semiconductor deposition apparatus 10 is provided with a process chamber 200, where the process chamber 200 is used for placing a semiconductor structure so as to deposit the semiconductor structure. Specifically, the process chamber 200 is relatively provided with an air inlet for inputting process gas into the process chamber 200 and an air outlet for exhausting process gas in the process chamber 200.
The servo valve control system 100 includes a controller 110, a driver 120, a stepper motor 130, a coupling 140, a servo valve 150, an encoder 160, and a up-down counter 170. The stepper motor 130 is connected to the servo valve 150 through a coupling 140, the stepper motor 130 is used to adjust the opening angle of the servo valve 150, and the servo valve 150 is used to be installed at the exhaust port. Specifically, the stepper motor 130 can drive the servo valve 150 to rotate through the coupling 140 during rotation (the rotation speed of the stepper motor 130 is proportional to the rotation speed of the servo valve 150) to adjust the opening angle of the servo valve 150 relative to the exhaust port, so that the servo valve 150 opens or closes the exhaust port, thereby adjusting the gas flow of the process gas exhausted from the process chamber 200. In this embodiment, a flow control valve 300 is installed in the gas inlet, the flow control valve 300 is used to control the gas flow of the process gas entering the process chamber 200, and the flow control valve 300 and the servo valve 150 cooperate to ensure the stability of the gas pressure in the process chamber 200.
It is noted that the driver 120, the stepper motor 130, the encoder 160, the up-down counter 170 and the controller 110 are connected end to end in sequence and form a control loop, and the driver 120 is connected to the up-down counter 170. In the control closed loop, the controller 110 is configured to calculate an opening angle error value according to a preset opening angle and an actual opening angle of the servo valve 150, and send a compensation speed calculated according to the opening angle error value to the driver 120; the driver 120 is used for calculating a first pulse signal according to the compensation speed and transmitting the first pulse signal to the stepper motor 130 and the up-down counter 170 at the same time; the stepper motor 130 is used for driving the servo valve 150 to rotate according to the first pulse signal; the encoder 160 is configured to convert the angular displacement of the stepper motor 130 into a second pulse signal, and send the second pulse signal to the up-down counter 170; the up-down counter 170 is used for calculating an actual opening angle according to the first pulse signal and the second pulse signal; the cycle is repeated in this way, and servo control of the stepping motor 130 is achieved, thereby achieving servo control of the servo valve 150. Specifically, since the actual opening angle is calculated by the first pulse signal sent by the driver 120 and the second pulse signal sent by the encoder 160, the calculation result of the actual opening angle is relatively accurate, so that the adjustment precision of the servo valve 150 can be effectively improved, the stability of the cavity air pressure is ensured, and the product quality is ensured.
In this embodiment, the deviation of the actual opening angle satisfies the first relation:. In the first relation, +_>For the chamber pressure of process chamber 200, +.>For the servo valve 150 to be subject to pressure deviations of the internal cavity pressure of the process chamber 200, +.>For the conductance deviation of the servo valve 150, +.>For the opening angle of the servo valve 150 +.>Is the deviation of the actual opening angle. The first relational expression characterizes that when the pressure deviation of the cavity air pressure is determined, the conductance deviation of the servo valve 150 and the deviation of the actual opening angle are inversely proportional, and the deviation of the actual opening angle is defined by the first relational expression, so that the adjustment accuracy of the servo valve 150 can be further improved, and the stability of the cavity air pressure can be improved.
Further, the servo valve is subject to pressure deviations from the internal chamber pressure of the process chamberIn the range of 0.05% to 0.2%, the conductance deviation of the servo valve +.>In the range of 10 to 30, deviation of the actual opening angle +.>In the range of 0.002% to 0.02%. In this embodiment, the servo valve 150 is subjected to the pressure deviation +.>=0.1% and the conductance deviation of the servo valve 150 +.>=20, the deviation of the actual opening angle +.>=0.005%, i.e. the quotient of the opening angle error value and the actual opening angle is equal to 0.005%, the accuracy of the adjustment of the servo valve 150 can be effectively improved by defining a smaller deviation of the actual opening angle. However, the present invention is not limited thereto, and in other embodiments, the deviation of the actual opening angle may be adjusted according to the pressure deviation of the chamber air pressure and the conductance deviation of the servo valve 150, and needs to be determined according to the actual situation.
It should be noted thatOpening angle of servo valve 150Satisfying the second relation, the chamber air pressure of the process chamber 200 +>The third relational expression is satisfied. Wherein the second relation is: />The method comprises the steps of carrying out a first treatment on the surface of the In the second relation, +_>For the opening angle of the servo valve 150 +.>For conductance of the servo valve 150 +.>、/>And c is the conductance parameter of the valve body in the servo valve 150 dynamically determined by a Kalman filter algorithm. The second relational expression characterizes that the conductance of the servo valve 150 varies with the variation of the opening angle of the servo valve 150, and the magnitude of the conductance of the servo valve 150 when the opening angle of the servo valve 150 is different can be calculated from the second relational expression.
The third relation is:the method comprises the steps of carrying out a first treatment on the surface of the In the third relation, +_>For the chamber pressure of process chamber 200, +.>For the gas flow into the process chamber 200, +.>Is constant. The third relationship characterizes the gas flow in the process chamber 200In certain cases, the chamber pressure of the process chamber 200 is inversely proportional to the conductance of the servo valve 150, and the chamber pressure of the process chamber 200 can be introduced into the second relationship by the third relationship to be related to the opening angle of the servo valve 150.
Further, a fourth relationship is derived from the first, second, and third relationships:. The fourth relational expression characterizes that the conductance deviation of the servo valve 150 varies with the variation of the opening angle of the servo valve 150, and the magnitude of the conductance deviation of the servo valve 150 when the opening angle of the servo valve 150 is different can be calculated from the fourth relational expression.
It should be noted that the second relation is obtained by a data fitting method, a least square method is used to fit a relation formula between the conductance and the opening angle of the servo valve 150, if the relation formula is confirmed to describe the correctness of the relation between the conductance and the opening angle, the relation formula is described as the second relation, and then the conductance parameter of the valve body in the servo valve 150 is dynamically determined by a Kalman filtering algorithm、/>C (the parameter difference and parameter drift of different valve bodies need to be considered).
Specifically, in the data fitting process, firstly, the cavity air pressure of the process cavity 200 under certain determined flow is measured under different opening angles, and a plurality of groups of corresponding opening angle data and cavity air pressure data are obtained; then, obtaining a plurality of groups of stream guidance data through third relation calculation; then assume that the relationship between the conductance and the opening angle is a relational formula (e.g., a second relational formula); then the corresponding opening angle data and the conductance data are brought into the relational formula, and the conductance parameters are calculated by adopting a least square method、/>C; and finally calculating a fitting error, and if the fitting error is small (tends to zero), considering that the fitting is successful, and indicating that the second relation is the correct relation.
The driver 120 includes a conversion module 121 and a driving module 122. The controller 110 is connected with the stepper motor 130 through the conversion module 121 and the driving module 122 in sequence, and the conversion module 121 is connected with the up-down counter 170. Specifically, the conversion module 121 is configured to convert the compensation speed into a first pulse signal, and send the first pulse signal to the driving module 122 and the up-down counter 170 at the same time; the driving module 122 is used for controlling the stepper motor 130 to rotate according to the first pulse signal; the up-down counter 170 is used to process the first pulse signal in order to calculate the actual opening angle later. The first pulse signal includes a first pulse number and a pulse direction, where the pulse direction is indicated as positive and negative of the first pulse number, that is, the first pulse signal can control not only a rotation angle of the stepper motor 130, but also a rotation direction of the stepper motor 130, the first pulse number with a positive number can control the stepper motor 130 to rotate along one direction, and the first pulse number with a negative number can control the stepper motor 130 to rotate along another direction.
It will be appreciated that the stepper motor 130 rotates one step when receiving a pulse, and the first pulse number is used to control the rotation step number of the stepper motor 130, thereby controlling the rotation angle of the stepper motor 130, and the pulse direction is used to control the rotation direction of the stepper motor 130 in the process that the driving module 122 controls the rotation of the stepper motor 130 according to the first pulse signal. In this embodiment, the first number of pulses with a positive number can control the stepper motor 130 to rotate in the clockwise direction by the number of steps corresponding to the first number of pulses, and the first number of pulses with a negative number can control the stepper motor 130 to rotate in the counterclockwise direction by the number of steps corresponding to the first number of pulses, so that bidirectional compensation of the stepper motor 130 can be achieved, and accuracy adjustment efficiency is improved.
Further, the driver 120 further includes an acceleration limiting module 123. The acceleration limiting module 123 is connected between the controller 110 and the conversion module 121, the compensation speed output by the controller 110 is first limited by the acceleration limiting module 123, and then the compensation speed is transmitted to the conversion module 121 after being processed by the acceleration limiting module 123, in this process, the acceleration limiting module 123 is used for limiting the maximum acceleration reaching the compensation speed, so as to prevent the situation that the stepping motor 130 is out of step due to overlarge acceleration (the situation that the stepping motor 130 receives a pulse and does not rotate due to a large load and the like may occur, and at this time, the actual rotation situation of the stepping motor 130 does not correspond to the situation that the pulse is received, namely out of step).
The encoder 160 includes an encoding module 161, a counting module 162, and a magnification calculation module 163. The stepper motor 130 is connected to the up-down counter 170 through the encoding module 161, the counting module 162 and the multiplying power calculating module 163 in sequence. Specifically, the encoding module 161 is configured to program the angular displacement of the stepper motor 130 to form a count signal, and send the count signal to the counting module 162; the counting module 162 is configured to convert the count signal into a second pulse number, and send the second pulse number to the multiplying factor calculating module 163; the multiplying factor calculating module 163 is configured to multiply the second pulse number by a preset multiplying factor, and send the obtained second pulse signal to the up-down counter 170; the up-down counter 170 is used for processing the second pulse signal and jointly calculating the actual opening angle in combination with the first pulse signal acquired before.
Notably, the up-down counter 170 calculates the actual opening angle using a fifth relation:the method comprises the steps of carrying out a first treatment on the surface of the In the fifth relation, +_>For the actual opening angle>Is a preset multiplying power->For the second pulse number, +.>For the first pulse number, +.>Which is the sub-division resolution of the driver 120. The fifth relation represents the relation between the actual opening angle and the first and second pulse numbers, and the magnitude of the actual opening angle when the first and second pulse numbers are at different values can be calculated through the fifth relation.
The magnification calculation module 163 calculates the preset magnification using the sixth relation:the method comprises the steps of carrying out a first treatment on the surface of the In the sixth relation, +_>Is a preset multiplying power->For the line resolution of the encoder 160, +.>Which is the sub-division resolution of the driver 120. The sixth relational expression characterizes a relation between the preset magnification and the line resolution of the encoder 160 and the subdivision resolution of the driver 120, and the magnitude of the preset magnification when the line resolution of the encoder 160 and the subdivision resolution of the driver 120 are at different values can be calculated by the sixth relational expression.
Further, let the subdivision resolution of the driver 120Greater than the linear resolution of encoder 160 +.>And->Is->The integer multiple of (2) is a preset multiplying power calculated by a sixth relation>Is an integer, at this time->In combination with the fifth relation +.>I.e. the actual opening angle, is determined jointly by the first number of pulses, the second number of pulses, the subdivision resolution of the driver 120 and the line resolution of the encoder 160.
Specifically, since the linear resolution of the encoder 160 is low and the sub-division resolution of the driver 120 is high, the opening angle calculated by the up-down counter 170 from the second pulse signal supplied from the encoder 160 is a coarse opening angle, the opening angle calculated by the up-down counter 170 from the first pulse signal supplied from the driver 120 is a fine opening angle, and the actual opening angle is equal to the coarse opening angle recorded and obtained by the encoder 160 plus the fine opening angle recorded and obtained by the driver 120. In other words, the linear resolution of the encoder 160 is low, i.e., the number of graduation lines passed by the encoder 160 per revolution is small, the angular difference between two adjacent graduation lines is large, and the encoder 160 is not readily accessible to a specific position between two adjacent graduation lines, and therefore, the encoder 160 records and derives a coarse opening angle that characterizes a substantial angle (e.g., an integer portion of the angle) of the actual opening angle. In contrast, the subdivision resolution of the driver 120 is high, i.e. the number of graduation lines passing by each revolution of the driver 120 is high, the angular difference between two adjacent graduation lines is small, and the rotational position of the driver 120 can be accurately acquired, so that the driver 120 records and derives a fine opening angle, which characterizes a fine angle (e.g. a fraction of the angle) of the actual opening angle.
It should be noted that in the prior art, only the encoder is used to perform servo control on the stepper motor, so that the servo valve is controlled, when the stepper motor accidentally loses synchronization, the encoder loses the specific rotation position of the current stepper motor, and then the encoder needs to return to zero again, and the encoder is restarted after finding the zero position, so that the working efficiency of the system is directly affected, and if the stepper motor frequently loses synchronization, the whole system cannot work normally. In the present invention, the encoder 160, the driver 120 and the up-down counter 170 are used to jointly perform servo control on the stepper motor 130, so that the servo valve 150 is controlled to perform servo control, when the stepper motor 130 is out of step accidentally, the fine opening angle recorded and obtained by the driver 120 is lost, but the coarse opening angle recorded and obtained by the encoder 160 is not lost, only the driver 120 is needed to make change and recount, the encoder 160 is not needed to make change, the instant recording and obtaining opening angle when the encoder 160 rotates to the next index line is absolutely accurate, and the driver 120 is controlled to make change and recount (because the preset multiplying power is an integer, the driver 120 is just located on the index line when the encoder 160 rotates to the next index line), so that the change of the driver 120 can be completed, convenience and rapidness are realized, time is saved, and the working efficiency of the system is ensured.
In this embodiment, the driver 120 is a high subdivision driver, and the subdivision resolution of the driver 120A line of 12800 or more; the encoder 160 is a low resolution encoder, the linear resolution of the encoder 160 is +.>Less than or equal to 800 lines; the reasonable resolution of the driver 120 and the encoder 160 can ensure the accuracy of the actual opening angle, thereby improving the adjustment accuracy of the servo valve 150 and ensuring the stability of the cavity air pressure.
The embodiment of the invention also provides a control method of the servo valve control system, which is used for controlling the servo valve control system 100, and the control method of the servo valve control system comprises the following steps:
step S110: the deviation of the actual opening angle is calculated by the controller 110 according to the preset opening angle and the actual opening angle of the servo valve 150, and according toThe deviation of the actual opening angle is calculated to obtain the compensation speed, wherein the deviation of the actual opening angle meets a first relation:。
in step S110, the deviation of the actual opening angle is defined by using the first relational expression, so as to improve the adjustment accuracy of the servo valve 150, ensure the stability of the cavity air pressure, and ensure the product quality.
Step S120: the first pulse signal is calculated from the compensation speed by the driver 120.
In step S120, the first pulse signal includes a first pulse number and a pulse direction, where the first pulse number is used to control the number of rotation steps of the stepper motor 130, thereby controlling the rotation angle of the stepper motor 130, and the pulse direction is used to control the rotation direction of the stepper motor 130.
Step S130: the servo valve 150 is driven to rotate by the stepping motor 130 according to the first pulse signal.
It should be noted that, in step S130, the stepper motor 130 receives a pulse and rotates by one step; the first pulse number with positive number can control the stepper motor 130 to rotate clockwise for the step number corresponding to the first pulse number, so as to drive the servo valve 150 to rotate clockwise for a corresponding angle; the first number of pulses, which is negative, can control the stepper motor 130 to rotate a number of steps corresponding to the first number of pulses in a counter-clockwise direction, thereby driving the servo valve 150 to rotate a corresponding angle in the counter-clockwise direction.
Step S140: the angular displacement of the stepper motor 130 is converted to a second pulse signal using the encoder 160.
It should be noted that, in step S140, the stepper motor 130 generates an angular displacement during rotation, and the encoder 160 can program and convert the angular displacement of the stepper motor 130 to obtain the second pulse signal.
Step S150: the actual opening angle is calculated from the first pulse signal and the second pulse signal using the up-down counter 170.
In step S150, the up-down counter 170 processes the first pulse signal obtained in step S120 and the second pulse signal obtained in step S140, and calculates an actual opening angle. In this way, the actual opening angle is calculated by the first pulse signal sent by the driver 120 and the second pulse signal sent by the encoder 160, so that the calculation result of the actual opening angle is accurate, the adjustment precision of the servo valve 150 can be effectively improved, the stability of the cavity air pressure is ensured, and the product quality is ensured.
It should be noted that, in the control method of the servo valve control system, the steps S110, S120, S130, S140 and S150 are repeated in a cyclic manner, so as to implement servo control of the stepper motor 130, thereby implementing servo control of the servo valve 150, improving the adjustment precision of the servo valve 150, and ensuring the stability of the cavity air pressure.
In the servo valve control system 100 provided by the embodiment of the invention, the stepping motor 130 is connected with the servo valve 150 through the coupling 140, the stepping motor 130 is used for adjusting the opening angle of the servo valve 150, and the servo valve 150 is used for being installed at an exhaust port; the driver 120, the step motor 130, the encoder 160, the up-down counter 170 and the controller 110 are sequentially connected end to end and form a control closed loop, the driver 120 is connected with the up-down counter 170, the controller 110 is used for calculating the deviation of the actual opening angle according to the preset opening angle and the actual opening angle of the servo valve 150 and sending the compensation speed calculated according to the deviation of the actual opening angle to the driver 120, the driver 120 is used for calculating a first pulse signal according to the compensation speed and sending the first pulse signal to the step motor 130 and the up-down counter 170 at the same time, the step motor 130 is used for driving the servo valve 150 to rotate according to the first pulse signal, the encoder 160 is used for converting the angular displacement of the step motor 130 into a second pulse signal and sending the second pulse signal to the up-down counter 170, and the up-down counter 170 is used for calculating the actual opening angle according to the first pulse signal and the second pulse signal; wherein the deviation of the actual opening angle satisfies a first relation:the method comprises the steps of carrying out a first treatment on the surface of the In the first relation, +_>For the servo valve 150 to be subject to pressure deviations of the internal cavity pressure of the process chamber 200, +.>For the conductance deviation of the servo valve 150, +.>Is the deviation of the actual opening angle. Compared with the prior art, the servo valve control system 100 provided by the invention adopts the up-down counter 170 connected with the encoder 160 and the driver 120 and the deviation of the actual opening angle meeting the first relation, so that the adjustment precision of the servo valve 150 can be effectively improved, the stability of the cavity air pressure is ensured, and the product quality is ensured. The control method of the servo valve control system is simple in steps and high in adjustment precision.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. A servo valve control system applied to a semiconductor deposition device (10), wherein the semiconductor deposition device (10) is provided with a process cavity (200) and an exhaust port communicated with the process cavity (200), and the servo valve control system is characterized by comprising a controller (110), a driver (120), a stepping motor (130), a coupler (140), a servo valve (150), an encoder (160) and a bi-directional counter (170), wherein the stepping motor (130) is connected with the servo valve (150) through the coupler (140), the stepping motor (130) is used for adjusting the opening angle of the servo valve (150), and the servo valve (150) is used for being installed at the exhaust port;
the driver (120), the stepper motor (130), the encoder (160), the up-down counter (170) and the controller (110) are sequentially connected end to end and form a control closed loop, the driver (120) is connected with the up-down counter (170), the controller (110) is used for calculating an opening angle error value according to a preset opening angle and an actual opening angle of the servo valve (150) and transmitting a compensation speed calculated according to the opening angle error value to the driver (120), the driver (120) is used for calculating a first pulse signal according to the compensation speed and simultaneously transmitting the first pulse signal to the stepper motor (130) and the up-down counter (170), the stepper motor (130) is used for driving the servo valve (150) to rotate according to the first pulse signal, the encoder (160) is used for converting the angular displacement of the stepper motor (130) into a second pulse signal and transmitting the second pulse signal to the driver (120), and the up-down counter (170) is used for calculating the first pulse signal according to the opening angle;
wherein the deviation of the actual opening angle satisfies a first relation:
；
in the first relational expression,for the chamber air pressure of the process chamber (200)>For the servo valve (150) to be subjected to a pressure deviation of the internal cavity pressure of the process cavity (200), ->For the conductance deviation of the servo valve (150,/-)>For the opening angle of the servo valve (150,>deviation of the actual opening angle;
opening angle of the servo valve (150)The second relation is satisfied:
；
in the second relational expression, the first relational expression,for the conductance of the servo valve (150)>、/>C is a conductance parameter of a valve body in the servo valve (150) dynamically determined by a Kalman filtering algorithm;
cavity air pressure of the process cavity (200)The third relation is satisfied:
；
in the third relational expression,for the gas flow into the process chamber (200), a +_>Is normalAn amount of;
deriving a fourth relationship from the first, second and third relationships:
；
the driver (120) comprises a conversion module (121) and a driving module (122), the controller (110) is connected with the stepping motor (130) sequentially through the conversion module (121) and the driving module (122), the conversion module (121) is connected with the up-down counter (170), the conversion module (121) is used for converting the compensation speed into a first pulse signal and simultaneously transmitting the first pulse signal to the driving module (122) and the up-down counter (170), and the driving module (122) is used for controlling the stepping motor (130) to rotate according to the first pulse signal, wherein the first pulse signal comprises a first pulse number and a pulse direction, and the pulse direction is expressed as positive and negative of the first pulse number;
the encoder (160) comprises an encoding module (161), a counting module (162) and a multiplying power calculating module (163), the stepping motor (130) is connected with the bi-directional counter (170) sequentially through the encoding module (161), the counting module (162) and the multiplying power calculating module (163), the encoding module (161) is used for programming the angular displacement of the stepping motor (130) to form a counting signal and sending the counting signal to the counting module (162), the counting module (162) is used for converting the counting signal into a second pulse number and sending the second pulse number to the multiplying power calculating module (163), and the multiplying power calculating module (163) is used for multiplying the second pulse number by a preset multiplying power and sending the obtained second pulse signal to the bi-directional counter (170);
the up-down counter (170) calculates the actual opening angle using a fifth relation:
；
in the fifth relational expression, in the case of the fifth relational expression,for said actual opening angle +.>For the preset multiplying power, < > and->For the second pulse number, +.>For the first pulse number, +.>-a sub-division resolution for the driver (120);
the multiplying power calculation module (163) calculates the preset multiplying power using a sixth relational expression:
；
in the sixth relation of the present invention,for the preset multiplying power, < > and->For the line resolution of the encoder (160)>Is a sub-division resolution of the driver (120).
2. The servo valve control system of claim 1 whereinIn that the servo valve (150) is subject to pressure deviations from the internal chamber pressure of the process chamber (200)In the range of 0.05% to 0.2%, the conductance deviation of the servo valve (150)>In the range of 10 to 30, the deviation of the actual opening angle>In the range of 0.002% to 0.02%.
3. The servo valve control system of claim 1 wherein the actuator (120) has a sub-division resolutionGreater than or equal to 12800 lines, the line resolution of the encoder (160)>Less than or equal to 800 lines.
4. The servo valve control system of claim 1, wherein the actuator (120) further comprises an acceleration limiting module (123), the acceleration limiting module (123) being connected between the controller (110) and the conversion module (121), the acceleration limiting module (123) being configured to limit a maximum acceleration up to the compensation speed.
5. A control method of a servo valve control system according to any one of claims 1 to 4, characterized by being applied to the servo valve control system, comprising:
step one: calculating, by means of the controller (110), a preset opening angle and an actual opening angle of the servo valve (150)Obtaining an opening angle error value, and calculating a compensation speed according to the opening angle error value, wherein the deviation of the actual opening angle meets a first relation:；
step two: calculating a first pulse signal from the compensation speed using the driver (120);
step three: driving the servo valve (150) to rotate according to the first pulse signal by using the stepping motor (130);
step four: converting the angular displacement of the stepper motor (130) to a second pulse signal using the encoder (160);
step five: the actual opening angle is calculated from the first pulse signal and the second pulse signal using the up-down counter (170).
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