Radio-frequency power source, and stacked control loop of radio-frequency power source

Abstract

A radio-frequency power source, and a stacked control loop of a radio-frequency power source, which belong to the technical field of radio-frequency power source control, and solve the problem of the delay of power control over an existing radio-frequency plasma power source system being relatively long. In the radio-frequency power source, a power output end of the radio-frequency power source is connected to a power input end of a matcher; the output power of the radio-frequency power source is adjusted on the basis of a first electrical signal from the power output end of the radio-frequency power source, a second electrical signal from a power output end of the matcher, and an electrical signal reference value of a cavity load; and the adjusted output power of the radio-frequency power source is sent to the power input end of the matcher.

Description

Radio frequency power supply and stacked control loop of radio frequency power supply Technical Field

[0001] The present invention relates to the technical field of radio frequency power supply control, and in particular to a radio frequency power supply and a stacked control loop of the radio frequency power supply. Background Art

[0002] RF plasma power systems are widely used in PECVD chemical vapor deposition, reactive ion etching and other fields. The overall architecture of the RF plasma power system includes an RF power supply, a matcher and a chamber load. The RF power supply outputs the power signal to the matcher, which performs impedance matching and then transfers the power signal to the chamber load. Among them, the output end of the RF power supply performs V / I measurement and feeds back to the internal motherboard to adjust the output power (such as adjusting the power to infinitely approach the recommended reference value P through PID calculation). SET ), the matcher also calculates the input impedance (the combined impedance of the matcher and the chamber load) and performs impedance matching (matcher self-modulation) based on the input / output power signal, so that the power signal can be input to the chamber load with higher efficiency.

[0003] Although the RF power introduced by the chamber load depends on the power output control of the RF power supply, the RF power supply only regulates its own power output. There is no direct control relationship between the two. Instead, the system host computer or external detection instruments obtain various detection data from these three devices, and the RF power supply signal reference value is set through manual control. In this way, the power control of the entire system has a long delay.

[0004] Summary of the Invention

[0005] In view of the above analysis, embodiments of the present invention aim to provide a radio frequency power supply and a stacked control loop of the radio frequency power supply to solve the problem of long hysteresis in power control of existing radio frequency plasma power supply systems.

[0006] In one aspect, the present invention discloses a radio frequency power supply, wherein a power output end of the radio frequency power supply is connected to a power input end of a matching device;

[0007] The RF power supply adjusts the output power of the RF power supply based on the first electrical signal at the power output end of the RF power supply, the second electrical signal at the power output end of the matcher, and the electrical signal reference value of the chamber load; and sends the adjusted output power of the RF power supply to the power input end of the matcher.

[0008] On the basis of the above solution, the present invention also makes the following improvements:

[0009] Furthermore, the radio frequency power supply has a built-in first sensor, a power reference value operator, a PID operator and a power controller; wherein,

[0010] The first sensor is provided at the power output end of the radio frequency power supply and is used to transmit back the first electrical signal of the power output end of the radio frequency power supply in real time;

[0011] The power reference value operator is configured to obtain a power reference value based on the second electrical signal at the power output end of the matcher and the electrical signal reference value of the chamber load requirement;

[0012] The PID operator is configured to perform a PID operation based on the first electrical signal at the power output end of the RF power supply and the power reference value to obtain an output power control parameter of the RF power supply;

[0013] The power controller is used to adjust the output power of the radio frequency power supply based on the output power control parameter of the radio frequency power supply.

[0014] Furthermore, the power reference value operator is a PID operation controller having at least one of a bias voltage control function and a bias current control function.

[0015] Furthermore, the PID operator converts the first electrical signal at the power output end of the RF power supply into an actual power value of the RF power supply, performs PID operation on the actual power value and the power reference value, and obtains an output power control parameter of the RF power supply.

[0016] Furthermore, the first electrical signal at the power output end of the RF power supply includes at least one of a voltage signal and a current signal.

[0017] On the other hand, the present invention also discloses a stacked control loop of a radio frequency power supply, the control loop comprising: the radio frequency power supply, a matcher, and a chamber load; the power output end of the matcher is connected to the power input end of the chamber load; wherein,

[0018] The matcher performs impedance matching based on the adjusted output power of the radio frequency power supply, adjusts the output power of the matcher, and sends the adjusted output power of the matcher to the power input end of the chamber load.

[0019] On the basis of the above solution, the present invention also makes the following improvements:

[0020] Furthermore, a second sensor is provided at the power output end of the matcher for collecting a second electrical signal from the power output end of the matcher in real time, and feeding the second electrical signal collected by the second sensor in real time to the RF power supply.

[0021] Furthermore, the second electrical signal at the power output end of the matcher is a normal cycle signal or a pulse cycle signal.

[0022] Furthermore, when the second electrical signal at the power output end of the matching device is a pulse cycle signal, the stack control loop is further externally connected to a pulse tester;

[0023] The pulse tester is used to feed back the oscillation duration of the pulse cycle signal to the power reference value operator; the power reference value operator also delays the acquisition of the second electrical signal at the power output end of the matcher according to the oscillation duration.

[0024] Furthermore, the second electrical signal at the power output end of the matcher and the electrical signal reference value of the chamber load are of the same signal type.

[0025] Furthermore, the signal type is any one of a power signal, a voltage signal, a current signal, or a combination of a voltage signal and a current signal.

[0026] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0027] The RF power supply provided by the present invention can realize real-time adjustment of the output power of the RF power supply based on the first electrical signal of the power output end of the RF power supply, the second electrical signal of the power output end of the matcher, and the electrical signal reference value of the chamber load, and the adjustment method is simple and effective. In the specific implementation process, the power reference value operator obtains a reference adjustable power reference value based on the second electrical signal of the power output end of the matcher and the electrical signal reference value of the chamber load requirement. Since the power reference value is automatically adjusted according to the demand, it effectively reduces human interference and increases the accuracy, flexibility and real-time performance of the output power adjustment of the RF power supply. At the same time, the PID operator performs PID operation based on the first electrical signal of the power output end of the RF power supply and the power reference value to obtain the output power control parameter of the RF power supply. Finally, the power controller adjusts the output power of the RF power supply based on the output power control parameter of the RF power supply, thereby effectively improving the control efficiency and control effect of the output power of the RF power supply.

[0028] The stacked control loop of the RF power supply provided by the present invention, the RF power supply's output feedback, power PID calculation, and power output control, form an internal closed-loop control for the RF power supply. Simultaneously, the RF power supply's internal closed-loop control, the matcher's output feedback, and the reference value calculation for the internal closed-loop control form an external closed-loop control for the RF power supply. The two loops are superimposed and combined, and coupled with the positive signal change relationship, the RF power supply's power output control directly affects the electrical signal control of the chamber load demand, reducing the hysteresis of the overall system's power control. Furthermore, because both the inner and outer loops are closed-loop controls, the control effect of the stacked control loop is relatively stable.

[0029] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are only used for the purpose of illustrating specific embodiments and are not to be considered as limiting the present invention. Throughout the drawings, the same reference symbols denote the same components.

[0031] FIG1 is a schematic diagram of the structure of a radio frequency power supply provided by an embodiment of the present invention;

[0032] FIG2 is a schematic structural diagram of a stacked control loop of a radio frequency power supply provided by an embodiment of the present invention.

[0033] FIG3 is a schematic structural diagram of another stacked control loop of a radio frequency power supply provided by an embodiment of the present invention;

[0034] FIG4 is a flow chart of a stack control method of a radio frequency power supply provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0036] A specific embodiment of the present invention discloses a radio frequency power supply, the structural diagram of which is shown in Figure 1. The power output terminal of the radio frequency power supply is connected to the power input terminal of a matching device. The radio frequency power supply adjusts the output power of the radio frequency power supply based on a first electrical signal at the power output terminal of the radio frequency power supply, a second electrical signal at the power output terminal of the matching device, and a reference value of the electrical signal of the chamber load. The adjusted output power of the radio frequency power supply is then transmitted to the power input terminal of the matching device.

[0037] Preferably, in this embodiment, the RF power supply has a built-in first sensor, a power reference value operator, a PID operator and a power controller; wherein,

[0038] The first sensor is provided at the power output end of the RF power supply and is used to transmit the first electrical signal of the power output end of the RF power supply in real time. Preferably, the first sensor includes at least one of a voltage sensor and a current sensor. Accordingly, the first electrical signal of the power output end of the RF power supply includes at least one of a voltage signal and a current signal. In a specific implementation process, when the first sensor is a voltage sensor, the first electrical signal of the power output end of the RF power supply transmitted back in real time only includes the voltage signal (V value); when the first sensor is a current sensor, the first electrical signal of the power output end of the RF power supply transmitted back in real time only includes the current signal (I value); and when the first sensor includes both a voltage sensor and a current sensor, the first electrical signal of the power output end of the RF power supply transmitted back in real time includes the voltage signal (V value) and the current signal. At this time, the voltage signal and the current signal of the power output end of the RF power supply can be obtained independently or simultaneously.

[0039] A power reference value operator is configured to obtain a power reference value based on a second electrical signal at the power output of the matching element and a reference electrical signal of a chamber load requirement. The reference electrical signal of the chamber load requirement can be specifically defined based on actual process requirements. The power conversion algorithm employed by the power reference value operator is not limited, as long as it can calculate a power reference value. Exemplarily, the power reference value operator is a PID controller having at least one of a bias voltage control (BVC) function and a bias current control (BCC) function.

[0040] PID operator, for determining the power output terminal of the radio frequency power supply based on the first electrical signal and the power reference value (P SET ) performs PID calculation to obtain the output power control parameters of the RF power supply. Specifically,

[0041] The PID operator converts the first electrical signal at the power output end of the RF power supply into the actual power value of the RF power supply, performs PID operation on the actual power value and the power reference value, and obtains the output power control parameter of the RF power supply. It should be noted that the methods of converting different first electrical signals into the actual power value of the RF power supply are different, as described below: (1) When the RF power supply is under constant current control, the first electrical signal at the power output end of the RF power supply is a voltage signal; in this case, the actual power value of the RF power supply is obtained by multiplying the voltage signal with the constant current under constant current control. (2) When the RF power supply is under constant voltage control, the first electrical signal at the power output end of the RF power supply is a current signal; in this case, the actual power value of the RF power supply is obtained by multiplying the current signal with the constant voltage under constant voltage control. (3) When the RF power supply is under conventional control (both voltage and current are variable), the first electrical signal at the power output end of the RF power supply includes a current signal and a voltage signal; in this case, the voltage signal and the current signal at the power output end of the RF power supply are multiplied to obtain the actual power value of the RF power supply. Exemplarily, the actual power value may also be converted by other operation modules and then provided to the PID operator to perform PID operation together with the power reference value.

[0042] The power controller is used to adjust the output power of the RF power supply based on the output power control parameter of the RF power supply.

[0043] In another specific embodiment of the present invention, a stacked control loop for an RF power supply is disclosed, with schematic structural diagrams shown in Figures 2 and 3. The control loop includes the RF power supply, a matching device, and a chamber load described in the aforementioned embodiments; the power output of the matching device is connected to the power input of the chamber load; the matching device adjusts the output power of the matching device by performing impedance matching based on the adjusted output power of the RF power supply; and transmits the adjusted output power of the matching device to the power input of the chamber load.

[0044] Preferably, the power output end of the matcher is provided with a second sensor for collecting the second electrical signal of the power output end of the matcher in real time, and feeding back the second electrical signal of the power output end of the matcher collected in real time by the second sensor to the radio frequency power supply. That is, a signal feedback connection is provided between the matcher and the radio frequency power supply, so that the second electrical signal of the power output end of the matcher collected in real time by the second sensor can be fed back to the radio frequency power supply. In the present embodiment, the second sensor can be any one of a power sensor, a voltage sensor, and a current sensor, or a combination of a voltage sensor and a current sensor. Accordingly, the signal type of the second electrical signal of the power output end of the matcher collected by the second sensor is any one of a power signal, a voltage signal, and a current signal, or a combination of a voltage signal and a current signal. In the present embodiment, the second electrical signal of the power output end of the matcher is the same as the signal type of the electrical signal reference value of the chamber load.

[0045] Preferably, the second electrical signal at the power output of the matching device is a regular cyclic signal or a pulse cyclic signal. When the second electrical signal at the power output of the matching device is a pulse cyclic signal, the stack control loop is further connected to an external pulse tester. In this case, the pulse tester is configured to feed back the oscillation duration of the pulse cyclic signal to the power reference value calculator. The power reference value calculator also delays acquisition of the second electrical signal at the power output of the matching device based on the oscillation duration to suppress oscillation in this section.

[0046] During specific implementations, to improve control accuracy, the PID operator or power controller will synchronously transmit the portion of the power control parameter that has the same properties as the second electrical signal returned by the matching device to the power reference value operator. The power reference value operator will then match the power control parameter with the digitized signal fed back by the matching device. Because the matching device's operations are set to high speed by default, the power signal / electrical signal is transmitted at the speed of light, and the signal delay is very small. Although the signal changes slightly, the phase / frequency remains almost unchanged. Therefore, the eligibility of the acquired electrical signal can be compared within the same timing period. Furthermore, the digitization process of the second electrical signal fed back by the matching device can be implemented in the power reference value operator of the RF power supply. That is, during specific implementations, the operation of digitizing the first electrical signal from the power output terminal of the RF power supply, which is fed back in real time by the first sensor, and the second electrical signal from the power output terminal of the matching device, which is collected in real time by the second sensor, can also be added. The PID operator can be used to digitize the first electrical signal from the power output terminal of the RF power supply, which is fed back in real time by the first sensor, and complete the subsequent PID processing process. The matching unit may also be provided with an electrical signal operator (in this case, the structure of the stacked control loop is shown in FIG3 ) to perform digital processing on the second electrical signal at the power output terminal of the matching unit, which is acquired in real time by the second sensor, and then feed the digitally processed second electrical signal back to the RF power supply. Alternatively, the matching unit may directly feed the second electrical signal at the power output terminal of the matching unit, which is acquired in real time by the second sensor, back to the RF power supply, and the power reference value operator may perform digital processing on the second electrical signal at the power output terminal of the matching unit, which is acquired in real time by the second sensor, and complete the process of generating the power reference value.

[0047] In summary, since the rise and fall of the RF power supply's output power forms a positive relationship with the rise and fall of the chamber load's electrical signal, the only difference is the rise and fall slopes of the two signals. Therefore, in the stacked control loop of the RF power supply provided in this embodiment, the RF power supply's output feedback, power PID calculation, and power output control form an internal closed-loop control of the RF power supply. At the same time, the RF power supply's internal closed-loop control, the matcher's output feedback, and the reference value calculation of the internal closed-loop control form an external closed-loop control of the RF power supply. The superposition of the two loops, combined with the positive signal change relationship, enables the RF power supply's power output to control the electrical signal control that directly affects the chamber load demand.

[0048] In addition, it should be noted that in this embodiment, through the existing safety mechanism of the inner loop, power can be shut down or operation intervention can be performed at the control critical point. Even if any detection device in the outer loop is incorrect, causing the electrical signal to be unable to be raised or lowered to the reference point, other equipment will not be damaged.

[0049] Another embodiment of the present invention further discloses a stacking control method for a radio frequency power supply, the flow chart of which is shown in FIG4 , and includes the following steps:

[0050] Step S1: The RF power supply adjusts the output power of the RF power supply according to the first electrical signal received from its own power output terminal in real time, the second electrical signal received from the power output terminal of the matcher, and the electrical signal reference value of the chamber load.

[0051] In step S1 , the RF power supply adjusts the output power of the RF power supply by performing the following operations.

[0052] Step S11: using a first sensor provided at the power output end of the RF power supply to transmit back a first electrical signal from the power output end of the RF power supply in real time, and using a second sensor provided at the power output end of the matcher to collect a second electrical signal from the power output end of the matcher in real time.

[0053] Step S12: obtaining a power reference value based on the second electrical signal at the power output end of the matcher and the electrical signal reference value of the chamber load requirement.

[0054] In a specific implementation process, the second electrical signal at the power output end of the matcher is a normal cycle signal or a pulse cycle signal.

[0055] When the second electrical signal at the power output end of the matcher is a pulse cycle signal, the second electrical signal at the power output end of the matcher is obtained in the following manner: obtaining the oscillation duration of the pulse cycle signal; and delaying the acquisition of the second electrical signal at the power output end of the matcher according to the oscillation duration.

[0056] Preferably, in this embodiment, the second electrical signal at the power output end of the matcher and the reference value of the electrical signal of the chamber load are of the same signal type. In a specific implementation, the signal type is any one of a power signal, a voltage signal, a current signal, or a combination of a voltage signal and a current signal.

[0057] Step S13: performing a PID operation based on the first electrical signal transmitted back in real time from the power output terminal of the RF power supply and the power reference value to obtain an output power control parameter of the RF power supply.

[0058] Specifically, the first electrical signal at the power output end of the RF power supply is converted into the actual power value of the RF power supply, and the actual power value and the power reference value are subjected to PID operation to obtain the output power control parameter of the RF power supply.

[0059] In this embodiment, the first electrical signal at the power output end of the RF power supply includes at least one of a voltage signal and a current signal.

[0060] When the RF power supply is under constant current control, the first electrical signal at the power output end of the RF power supply is a voltage signal. At this time, the first electrical signal at the power output end of the RF power supply is converted into the actual power value of the RF power supply by multiplying the voltage signal at the power output end of the RF power supply by the constant current under constant current control to obtain the actual power value of the RF power supply.

[0061] When the RF power supply is under constant voltage control, the first electrical signal at the power output end of the RF power supply is a current signal. At this time, the first electrical signal at the power output end of the RF power supply is converted into the actual power value of the RF power supply by multiplying the current signal at the power output end of the RF power supply by the constant voltage under constant voltage control to obtain the actual power value of the RF power supply.

[0062] When the RF power supply is under conventional control (both voltage and current are variable), the first electrical signal at the power output end of the RF power supply is a current signal and a current signal; at this time, the first electrical signal at the power output end of the RF power supply is converted into the actual power value of the RF power supply by multiplying the current signal at the power output end of the RF power supply and the current signal to obtain the actual power value of the RF power supply.

[0063] Step S14: adjusting the output power of the RF power supply based on the output power control parameter of the RF power supply.

[0064] Step S2: The RF power supply sends the adjusted output power of the RF power supply to the power input end of the matching device.

[0065] Step S3: After receiving the adjusted RF power supply, the matcher performs impedance matching based on the output power of the adjusted RF power supply to adjust the output power of the matcher; and sends the adjusted output power of the matcher to the power input end of the chamber load.

[0066] The stacked control method of the RF power supply provided by the present invention, the first electrical signal feedback, PID operation and power output control of the power output end of the RF power supply form an internal closed-loop control process of the RF power supply. At the same time, the internal closed-loop control of the RF power supply, the output feedback of the matcher and the reference value operation of the internal closed-loop control form the external closed-loop control of the RF power supply. The internal closed-loop control and the external closed-loop control of the RF power supply are superimposed and combined, and the positive change relationship of the signal is combined to make the power output control of the RF power supply directly affect the electrical signal control of the chamber load demand, thereby reducing the hysteresis of the power control in the system formed by the RF power supply, the matcher and the chamber load. At the same time, since both the inner loop and the outer loop are closed-loop controlled, the control effect of the stacked control method is relatively stable.

[0067] Those skilled in the art will appreciate that all or part of the processes of the above-described embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, such as a magnetic disk, an optical disk, a read-only memory, or a random access memory.

[0068] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A radio frequency power supply, characterized in that: The power output end of the radio frequency power supply is connected to the power input end of the matching device; The RF power supply adjusts the output power of the RF power supply based on a first electrical signal at the power output end of the RF power supply, a second electrical signal at the power output end of the matcher, and an electrical signal reference value of the chamber load; and sends the adjusted output power of the RF power supply to the power input end of the matcher.

2. The radio frequency power supply according to claim 1, characterized in that: The radio frequency power supply has a built-in first sensor, a power reference value operator, a PID operator and a power controller; wherein, The first sensor is arranged at the power output end of the radio frequency power supply and is used to transmit back the first electrical signal of the power output end of the radio frequency power supply in real time; The power reference value operator is used to obtain a power reference value based on the second electrical signal at the power output end of the matcher and the electrical signal reference value of the chamber load requirement; The PID operator is used to perform PID operation based on the first electrical signal at the power output end of the RF power supply and the power reference value to obtain the output power control parameter of the RF power supply; The power controller is used to adjust the output power of the radio frequency power supply based on the output power control parameter of the radio frequency power supply.

3. The radio frequency power supply according to claim 2, characterized in that: The power reference value operator is a PID operation controller having at least one of a bias voltage control function and a bias current control function.

4. The radio frequency power supply according to claim 2, characterized in that: The PID operator converts the first electrical signal at the power output end of the RF power supply into an actual power value of the RF power supply, performs PID operation on the actual power value and the power reference value, and obtains an output power control parameter of the RF power supply.

5. The radio frequency power supply according to any one of claims 1 to 4, characterized in that: The first electrical signal at the power output end of the RF power supply includes at least one of a voltage signal and a current signal.

6. A stacked control loop of a radio frequency power supply, characterized in that: The control loop comprises: a radio frequency power supply, a matcher and a chamber load according to any one of claims 1 to 5; the power output end of the matcher is connected to the power input end of the chamber load; wherein, The matcher performs impedance matching based on the adjusted output power of the RF power supply to adjust the output power of the matcher; and sends the adjusted output power of the matcher to the power input end of the chamber load.

7. The stacked control loop of the radio frequency power supply according to claim 6, characterized in that: The power output end of the matcher is provided with a second sensor for collecting a second electrical signal at the power output end of the matcher in real time, and feeding back the second electrical signal at the power output end of the matcher collected in real time by the second sensor to the RF power supply.

8. The stacked control loop of the radio frequency power supply according to claim 6, characterized in that: The second electrical signal at the power output end of the matcher is a normal cycle signal or a pulse cycle signal.

9. The stacked control loop of the radio frequency power supply according to claim 8, characterized in that: When the second electrical signal at the power output end of the matcher is a pulse cycle signal, the stack control loop is further externally connected to a pulse tester; The pulse tester is used to feed back the oscillation duration of the pulse cycle signal to the power reference value operator; the power reference value operator also delays the acquisition of the second electrical signal at the power output end of the matcher according to the oscillation duration.

10. The stacked control loop of the radio frequency power supply according to any one of claims 6 to 9, characterized in that: The second electrical signal at the power output end of the matcher is of the same signal type as the electrical signal reference value of the chamber load.

11. The stacked control loop of the radio frequency power supply according to claim 10, characterized in that: The signal type is any one of a power signal, a voltage signal, a current signal, or a combination of a voltage signal and a current signal.

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