阅读说明：本技术 等离子体功率输送系统的周期间控制系统及其操作方法 (Intercycle control system for plasma power delivery system and method of operating the same ) 是由 G·J·J·范齐尔 于 2018-07-05 设计创作，主要内容包括：一种发生器产生输出,例如输送的功率、电压、电流、正向功率等,其遵循预定的输出对时间的规定模式,其中,通过基于在过去的一个或多个重复周期中进行的测量来控制模式的各部分而以重复周期重复该模式。可变阻抗匹配网络可以控制呈现给射频发生器的阻抗,同时发生器产生的输出遵循规定输出对时间变化的模式,其中,通过基于在过去的一个或多个重复周期取得的测量结果控制所述模式的部分期间的匹配中可变阻抗元件,所述模式以重复周期重复。(A generator generates an output, such as delivered power, voltage, current, forward power, etc., that follows a predetermined prescribed pattern of output versus time, wherein the pattern is repeated in a repeating cycle by controlling portions of the pattern based on measurements taken in the past repeating cycle or cycles. The variable impedance matching network may control the impedance presented to the radio frequency generator while the generator produces an output that follows a pattern that specifies the output as a function of time, wherein the pattern repeats at a repeating cycle by controlling the variable impedance elements in matching during portions of the pattern based on measurements taken at one or more repeating cycles in the past.)

1. A power delivery system, comprising:

a generator that generates a repetitive output pattern; and

a control element that controls the repetitive pattern based on a measurement of a value of the repetitive pattern taken at a period prior to a current period.

2. The power delivery system of claim 1, wherein: the control element also controls the repeated output pattern based on a combination of measurements of the repeated pattern taken at a period prior to the current period and measurements of values of the repeated pattern during the current period.

3. The power delivery system of claim 1, wherein the repeated output pattern follows a prescribed pattern of output versus time, wherein the prescribed pattern repeats at a repeating cycle, and wherein the measurements of the values of the repeated pattern taken over a cycle prior to the current cycle occur over one or more repeating cycles in the past.

4. The power delivery system of claim 3, further comprising: a device that receives a multi-dimensional input and produces a multi-dimensional output, wherein a correlation between an element of a control input to the device within a particular time period in the pattern and an element of an output from the device within the same particular time period is determined and used by the control element.

5. The power delivery system of claim 4, wherein the correlation between elements of the control input and elements of the output is determined by perturbing the control input and observing a response to the perturbation.

6. A power delivery system according to claim 4, wherein the control input to the device and the output from the device are multidimensional, and wherein the correlation between elements of the control input and elements of the output from the device within a particular time period in a periodic pattern and within time periods adjacent to the particular time period is determined and used by the control unit.

7. The power delivery system of claim 6, wherein the correlation between elements of the control input and elements of the output is determined by perturbing the control input and observing the response to the perturbation.

8. The power delivery system of claim 1, wherein the generator is one of a single radio frequency generator or a direct current generator, and the output is at least one of a voltage, a current, and a power.

9. A power delivery system according to claim 1, wherein the generator comprises a plurality of radio frequency generators, or a plurality of direct current generators, or a combination of radio frequency generators and direct current generators, and the output is at least one of voltage, current and power delivered to the plasma system.

10. A power delivery system according to claim 4, wherein one element of the output is one or a combination of voltage, current and power and another element of the output is one of an impedance presented to the generator and a source impedance of the generator.

11. A power delivery system according to claim 6, wherein one element of the output is one or a combination of voltage, current and power and another element of the output is one of an impedance presented to the generator and a source impedance of the generator.

12. A power delivery system, comprising:

a control system in communication with the memory for generating an output following a prescribed pattern of output versus time, wherein the prescribed pattern is repeated at a repetition period by controlling repetition of the prescribed pattern based on measurements of the output stored in the memory, the output stored in the memory being taken from one or more previous repetitions of the prescribed pattern of output versus time.

13. A power delivery system according to claim 12, wherein the control system combines measurements taken from one or more previous repetitions with measurements taken from a current repetition.

14. The power delivery system of claim 12, wherein a control input to a device of the plasma power delivery system and an output of the plasma power delivery system are multi-dimensional, wherein correlations between a plurality of control input elements of the control input at one time relative to a start of the repetition of the prescribed pattern and a plurality of output elements of the output at a same time relative to the start of the repetition period are determined and used by the control system.

15. The power delivery system of claim 14, wherein the correlation between the control input element of the control input and the output element of the output is determined by perturbing the control input and measuring a response to the perturbation.

16. A power delivery system according to claim 13, wherein the control input and the output to the device are multidimensional, wherein the correlation between a plurality of control input elements of the control input at one time relative to the start of the repeating cycle and a time adjacent to the one time and a plurality of output elements of the output at the one time relative to the start of the repeating cycle is determined and used by the control system.

17. The power delivery system of claim 16, wherein the correlation between the control input element of the control input and the output element of the output is determined by perturbing the control input and measuring a response to the perturbation.

18. A power delivery system in accordance with claim 12, wherein the power delivery system comprises a single Radio Frequency (RF) generator or a Direct Current (DC) generator, and the element of the output comprises at least one of a voltage, a current, and a power level delivered to a plasma system.

19. The power delivery system of claim 18, further comprising a plurality of generators, the plurality of generators comprising an RF generator, a DC generator, or a combination of an RF generator and a DC generator, and the elements of each of the outputs of the generators comprising at least one of a voltage, a current, and a power level.

20. A power delivery system according to claim 14, wherein one of the output elements of the output comprises at least one of a voltage, a current and a power, wherein another output element of the output comprises at least one of a load impedance presented to a generator and a source impedance of the generator.

21. A power delivery system according to claim 16, wherein one output element of the output comprises at least one of a voltage, a current, and a power level, wherein another output element of the output comprises at least one of a load impedance presented to a generator and a source impedance of the generator.

22. A power delivery system, comprising:

a controller for generating an output, the controller being subject to a periodic disturbance, wherein the periodic disturbance is caused to repeat with a repetition period by controlling the output based on measurements of values of the output taken over one or more repetition periods in the past.

23. The power delivery system of claim 22, wherein the plasma power delivery system receives a signal synchronized with the periodic disturbance.

24. A plasma power delivery system, comprising:

an impedance matching network that matches a load impedance to a desired impedance, wherein the load impedance is subject to a periodic modulation pattern that repeats with a repeating cycle; and

a control element operatively associated with the impedance matching network, the control element controlling a variable impedance element in the impedance matching network based on measurements of the value of the load impedance taken over one or more past repeating cycles.

25. The plasma power delivery system of claim 25, wherein the control unit controls a variable impedance element in the impedance matching network based on a combination of measurements of the value of the load impedance taken over one or more past repeating cycles and measurements of the value of the load impedance taken over less than past repeating cycles.

Technical Field

Aspects of the present disclosure relate to improved methods and systems for controlling power delivery systems, and in particular for controlling plasma power delivery systems.

Background

Plasma processing systems are used to deposit thin films on substrates by processes such as Chemical Vapor Deposition (CVD) and Physical Vapor Deposition (PVD), and to remove thin films from substrates using etching processes. The plasma is typically created by coupling a Radio Frequency (RF) or Direct Current (DC) generator to a plasma chamber filled with a gas that is injected into the plasma chamber at a low pressure. Typically, the generator delivers RF power to an antenna in the plasma chamber, and the power delivered at the antenna ignites and sustains the plasma. In some cases, the RF generator is coupled to an impedance matching network that can match the plasma impedance to a desired impedance, typically 50 Ω, at the generator output. Direct current power is typically coupled to the chamber via one or more electrodes. A single generator or a combination of generators and other pieces of equipment (e.g., impedance matching network), other generators coupled to the same plasma, cable, etc., make up the plasma power delivery system.

It is often necessary to modulate the power delivered to the plasma system. Most modulation schemes are repetitive, i.e., the same modulation waveform is repeated at a waveform repetition rate. The associated waveform repetition period is equal to one divided by the waveform repetition rate. The ability to follow a prescribed modulation waveform using conventional control schemes requires a high bandwidth from the controller and ultimately from the measurement system. Many plasma systems apply power to the plasma at different frequencies. The non-linear nature of the plasma load creates modulation artifacts that can interfere with the measurement system of the generator. Therefore, it is sometimes advantageous to use a narrow band measurement system to limit such interference. In many applications, the power delivered to the plasma load is not the only parameter that is controlled. For example, in an RF power delivery system, the impedance provided to the generator by the plasma load may be controlled by controlling the frequency of the generator output or by controlling a variable impedance matching network between the generator and the plasma load. In some cases, the generator source impedance may also be controlled. Tracking and controlling power in accordance with these various issues presents an increasing control challenge.

With these observations in mind, and others, aspects of the present disclosure are contemplated.

Disclosure of Invention

According to one embodiment, a generator generates an output, such as delivered power, voltage, current, forward power, etc., that follows a predetermined prescribed pattern of output versus time, wherein the pattern is repeated at a repetition period by controlling portions of the pattern based on measurements taken during one or more repetition periods in the past. In one example, the power delivery system comprises a generator that generates a repetitive output pattern, and the control element controls the repetitive pattern based on a measurement of a value of the repetitive pattern made a time period prior to a current time period. The control element may further control the repetitive output pattern based on a combination of measurements of the repetitive pattern made at a period prior to the current period and measurements of values of the repetitive pattern during the current period. The repeating output pattern may follow a prescribed pattern of outputs versus time, wherein the prescribed pattern repeats with a repeating cycle, wherein measurements of the repeating pattern values made in a cycle prior to the current cycle occur in the past one or more repeating cycles.

According to yet another embodiment, the variable impedance matching network controls the impedance presented to the RF generator while the generator produces an output, e.g., delivered power, voltage, current, forward power, etc., that follows a prescribed pattern of outputs versus time, wherein the pattern is repeated at a repeating period by controlling the variable impedance elements in the matching terms in various portions of the pattern based on measurements taken over the past one or more repeating periods. In various possible embodiments, the generator may provide delivered power, voltage, current, forward power, etc. to the plasma system to ignite and sustain the plasma.

According to yet another embodiment, the generator generates an output that follows a predetermined output versus time pattern, wherein the pattern repeats at a repeating cycle by controlling portions of the pattern based on measurements taken over one or more repeating cycles. The controller is combined with an intra-cycle controller that calculates a control output based on measurements taken over less than a repeating cycle.

According to yet another embodiment, the variable impedance matching network controls the impedance presented to the RF generator while the generator produces an output, e.g., delivered power, voltage, current, forward power, etc., that follows a prescribed pattern of outputs versus time, wherein the pattern is repeated at a repeating period by controlling the variable impedance elements in the matching terms in various portions of the pattern based on measurements taken over the past one or more repeating periods. And combining the controller with an intra-cycle controller that calculates control of the variable impedance element in the match based on measurements taken over less than a repeating cycle.

According to another embodiment, the generator generates an output that follows a predetermined output versus time pattern, wherein the pattern is repeated with a repetition period by controlling portions of the pattern based on measurements made over the past repetition period or periods, while adjusting another parameter (e.g., a generator output frequency or a variable impedance element included in the generator or a variable impedance matching network coupled between the generator and the plasma) that is based on measurements taken over the past repetition period or periods, wherein a correlation between a control input (e.g., power control and frequency of the generator) and a control output (e.g., output power and impedance provided to the generator) is determined and used by the control system.

According to yet another embodiment, the generator generates an output that follows a predetermined output versus time pattern, wherein the pattern is repeated with a repetition period by: controlling the same portion of the pattern based on measurements made over the past one or more repetition periods for the portion of the pattern; and by perturbing such measurements for other parts of the pattern on the control input, determining a response to the perturbation and using the response to the perturbation to compensate for coupling between adjacent or closely located time periods in the waveform.

Drawings

As shown in the drawings, various features and advantages of the techniques of this disclosure will become apparent from the following description of specific embodiments of those techniques. It should be noted that the drawings are not necessarily to scale; instead, emphasis is placed upon illustrating the principles of the technical concepts. Also, in the drawings, like reference numerals may refer to like parts throughout the different views. The drawings depict only typical embodiments of the disclosure and are not therefore to be considered to be limiting of its scope.

Fig. 1A shows a simple analog in-cycle control system that can be used to control the plasma power delivery system, and fig. 1B shows a simple digital in-cycle control system that can be used to control the plasma power delivery system.

FIG. 2A shows the response of the control system to a periodic input during a relatively slow period, and FIG. 2B shows the response of the control system to a periodic input during a relatively fast period.

Fig. 3A and 3B illustrate block diagrams of an example inter-cycle controller that can be implemented in a plasma power delivery system, according to an embodiment of the present disclosure.

4A-4D illustrate the response of an exemplary periodic controller to a periodic input.

Fig. 5 illustrates a block diagram of an exemplary cycle duration and in cycle combination controller, which may be implemented in a plasma power delivery system, according to one embodiment of the present disclosure.

Fig. 6A shows the loop gain as a function of frequency for an example pure inter-cycle controller.

Fig. 6B shows a nyquist plot of the loop gain of the inter-period controller used to generate the loop gain of fig. 6A.

Fig. 6C shows the closed loop response as a function of frequency for the period controller to produce the loop gain of fig. 6A.

FIG. 6D shows the closed loop response as a function of frequency at or near harmonics of the input waveform for a pure inter-cycle controller.

Fig. 7A shows an exemplary combined cycle and cycle controller loop gain as a function of frequency, with a weighting of 0.1 for the part of the cycle and 0.9 for the part of the cycle.

Fig. 7B shows a nyquist plot of the loop gain associated with fig. 7A.

FIG. 7C illustrates a closed loop response of the example combination controller associated with FIG. 7A as a function of frequency.

FIG. 7D illustrates the closed loop response as a function of frequency at or near harmonics of the input waveform for the combined cycle duration and cycle duration controller associated with FIG. 7A.

Fig. 8A shows the loop gain of an exemplary combined periodic and intra-periodic controller as a function of frequency, with a weighting of 0.01 for the periodic portion and 0.99 for the intra-periodic portion.

Fig. 8B shows a nyquist plot of the loop gain of the combined controller associated with fig. 8A.

FIG. 8C illustrates the closed loop response of the combination controller associated with FIG. 8A as a function of frequency.

FIG. 8D shows the closed loop response as a function of frequency at or near harmonics of the input waveform for the same combined cycle-duration and cycle-duration controller as related to FIG. 8A.

FIG. 9 illustrates a block diagram of a combined cycle-in-cycle and cycle-out multiple-input multiple-output version of a controller according to one embodiment of the present disclosure.

Detailed Description

Embodiments of the present disclosure provide a plasma power delivery system that produces outputs, such as delivered power, voltage, current and forward power, that follow a pattern that specifies output versus time, where the pattern repeats at a repeating cycle by controlling portions of the pattern based on measurements taken over the past repeating cycle or cycles (rather than the present cycle). Such an inter-cycle controller can reproduce the output more accurately with a lower bandwidth measurement and control system than conventional controllers. The benefits provided by the inter-period controller may be advantageous in various situations, including in the presence of plasma-generated mixing and intermodulation products. In further embodiments, the inter-cycle controller may be combined with a conventional intra-cycle controller. In further embodiments, a parameter such as generator output frequency may be adjusted along with the primary output based on measurements taken over one or more past repeating cycles, where the correlation between the control input (e.g., power control and generator frequency) and the control output (e.g., output power and impedance provided to the generator) is determined and used by the control system. In a further embodiment, the generator generates an output that follows a predetermined output versus time pattern, wherein the pattern repeats at a repetition period by: controlling the same portion of the pattern based on measurements taken for the portion of the pattern over one or more past repetition periods; and by perturbing such measurements for other parts of the pattern on the control input, determining a response to the perturbation and using the response to the perturbation to compensate for coupling between adjacent or closely located time periods in the waveform.

Although described primarily with reference to a controller for a generator, aspects of the present disclosure are applicable to a switched mode power supply and controller therefor, which may be used in eV source applications, such as providing a bias voltage to a substrate as part of an overall power delivery system, and other substrate biasing schemes. The controller and control schemes discussed herein may also be used to control variable impedance elements (e.g., vacuum variable capacitors or switched variable reactance elements) of an impedance matching network. In such cases, aspects of the present disclosure may or may not be used for control of the RF supply to the impedance matching network as part of the overall power delivery system. The controller may reside in any portion of the power delivery system (e.g., in the generator or matching network), and may or may not receive information from and control other portions of the power delivery system. For example, a controller residing in the generator may control the generator and the match as part of the power delivery system using information obtained only from the generator, only from the match, or from both the generator and the match. The controller and control schemes discussed herein may also be used in other systems with or without power in a plasma power delivery environment.

Fig. 1A (prior art) shows a simple analog in-cycle control system that can be used to control the plasma power delivery system, and fig. 1B (prior art) shows a simple digital in-cycle control system that can be used to control the plasma power delivery system. In fig. 1A, the difference between input 101 and output 106 produces an error signal 102, which error signal 102 is used by controller 103 to produce a control input 104 to device 105. In this figure, the controller is a simple integrator with a gain of k. In a practical implementation, the control input 104c may be a drive level of a power amplifier, and the device 105P may be a power amplifier. To illustrate the performance difference between this controller and the disclosed inter-cycle controller, the device 105P is a unity gain block, i.e., y ═ c. According to these assumptions, the loop gain has unity gain at k rad/s or k/(2 π) Hz, the time constant of the system step response is 1/k s, and the integral of the system impulse response reaches 63.2% (1-1/e) within 1/k s. In FIG. 1B, input 151 is at 1/T_sIs sampled and digitized by sampler 157. (in some applications the input is already a digital data stream and sampler 157 is not present in the system.) output 156 is sampled and digitized by sampler 159 and the difference between the input and output produces an error signal 152, which error signal 152 is used by controller 153 to produce a control input 154, which control input 154 is converted by digital-to-analog converter 158 to an analog control signal, which is fed to device 155. For fig. 1A, to illustrate the performance difference between this controller and the disclosed inter-cycle controller, the device 105P is a unity gain block. With respect to k and unity gain frequency and response timeThe same statement of relationship between is the same for the analog controller of FIG. 1, assuming k is much less than 2 π/T_sIf so.

FIG. 2A (Prior Art) shows a simple intra-cycle controller pair such as that shown in FIG. 1A or FIG. 1B having a period T _p205, 200, in response to the periodic input. In this example, a set of different set points (e.g., set point power of 1, then 2, then 5, ramping to 3) defines one cycle of input. Output 202 follows input 201 with visible inaccuracies (where the output does not match the input set point). The closed loop response time constant of this figure is 10 mus. The output at a given point a, 203 can be obtained by multiplying the time-shifted time-reversed impulse response of the system by the input and integrating. The normalized time-shifted time-reversed impulse response of unit 204 shows that the output of point a 203 is severely affected by the very recent past (within one time constant or 10 μ s before point a) and is almost completely unaffected by events that occurred 10 time constants before point a. In order to accommodate the changing set point in the pulse, conventional controllers must be very fast. As shown in fig. 2B (prior art), speeding up the controller improves the ability of the output to accurately follow the input. The closed loop response time constant of this figure is 5 mus. Response 250 shows that output 252 more closely follows input 251. The normalized time-shifted time-reversed impulse response 254 shows that point a 253 is now more affected by inputs in the very near past.

In these conventional in-cycle controllers, error control is based on measurements of the current output (in cycles) relative to a set point. Thus, for example, referring to FIG. 2A, a measured value of the output at time 1.5ms is compared to a set point value at the same time to generate an error signal. In other words, the set point is compared to the measured value during the current cycle to generate an error signal for the controller during the regular cycle. Instead, the inter-cycle controller compares measurements of the output over one or more past cycles for a given set point and uses the past measurements at the set point to generate the current error signal and controller output. Referring again to fig. 2A, for example, at time 1.5ms (setpoint of 3), a measurement at time 0.94ms at setpoint of 3 (which is one waveform repetition period of 0.56ms, or the portion of the previous pulse associated with time 1.5 ms) will be used by the controller to generate an error and output, which is different from the measurement in the inter-pulse at 1.5 ms. It is worth noting that the inter-cycle controller need not be as fast as it relies on measurements of the past cycle rather than the immediate values in the pulse.

In some examples, a pulse (e.g., a pulse over period Tp) is divided into multiple time periods, and the corresponding (same) output value in the same time period of the previous pulse is used for the error signal. Referring again to the example above, i.e. using the measurement at time 0.94ms for the first pulse for error correction at time 1.5ms for the subsequent second pulse, the time period will contain a certain value of 0.56ms within a certain range. In one example, the time period through which the pulses are divided is such that any given time period does not include a different set point, except for ramped set point transitions.

In various embodiments, the inter-period pulse information is stored in some form of memory so that the controller can access the inter-period pulse information and use it for error feedback for subsequent pulses. Complex pulses (e.g., set point transitions with ramping) and other different set points may benefit from a relatively small time period subdivision of the pulses, and thus may require relatively larger and faster memories. In a particular example, a pulse having a period Tp between 100ms and 10 μ s may be subdivided into 1024 time slices, and the output value for each slice is stored for comparison with the measured values in the same time slice of the subsequent pulse.

In some applications, no error signal is generated. In impedance matching applications using a cycle-duration control scheme, impedance information T about one or more cycles presented to a generator in the past_p205 may be used to adjust the variable impedance element within the matching network at the current time. This information can be used to calculate adjustments to the variable impedance matching element without first generating an error signal. In impedance matching applications, the set point (e.g., 101, 151, 303, 351, 501) is typicallyIs constant but there is a periodic disturbance of the load impedance that must be matched to the desired input impedance. Such periodic perturbations may be caused, for example, by delivering power to the plasma load in a predetermined output pattern versus time, where the pattern repeats at a repeating cycle. In this case, a synchronization signal from, for example, a power supply providing a prescribed power pattern, may be provided to the matching network to help the matching network synchronize with the repeating waveform of the disturbance.

Fig. 3A illustrates a block diagram of one example of an inter-cycle controller 300 that can be implemented in a plasma power delivery system, according to one embodiment of the present disclosure. Fig. 3A illustrates a block diagram of an alternative example implementation of an inter-cycle controller 350 that may be implemented in a plasma power delivery system, according to another embodiment of the present disclosure. Some embodiments of the inter-cycle controller described herein may be considered a multiple-input multiple-output (MIMO) controller. The controller or more generally the control elements may be implemented in hardware and software, as well as in various possible combinations thereof. The control element may be integrated with the generator or other device, or may be a separate component. In some applications, the inter-cycle controller may reside in a different piece of equipment than is being controlled. As an example, a controller connected to the impedance matching network may reside in the generator, but control the variable impedance elements in the impedance matching network. In such applications, the forward and reflected signals from the coupler may be obtained from a coupler resident in the generator, analog filtered, digitized in an analog-to-digital converter, and processed to extract an operating software program or digital logic circuit operating, for example, in an FPGA by matching the impedance provided to the generator by the microprocessor. The measurements may be stored in memory by a microprocessor or reconfigurable digital circuitry residing in the FPGA. The memory containing the impedance measurement samples at different times can be processed using software running in a microprocessor or an FPGA. The software or FPGA may in the past implement an inter-cycle control scheme using one or more samples of the waveform repetition period. To implement such a scheme, a method of matching can also be usedInformation of past values of the variable impedance element. The controller may then send a control signal to the match to change the variable impedance element in the match. FIG. 3A implements an inter-cycle controller (providing an interleaved scheme) as N controllers, each with an input repetition period T_pAnd (5) operating. Block 301 shows a first such controller and block 302 shows an nth such controller. Input 303 is converted by analog-to-digital converter 304 at 1/T_sIs sampled and digitized. (the input may already exist as a data stream, in which case converter 304 is not used.) the sampled input is then switched or routed by switch 305 to the controllers, such that each controller is at 1/T_pReceives updated input. The output of the controller is routed through switch 306 to a common control input c. The control input is converted to an analog signal by digital-to-analog converter 307 and applied to the control input of device P308. The output y 309 of each controller is sampled by a sampler (313 of controller 301) at 1/T_pIs sampled at the rate of (c).

Each controller creates an error function (310 for controller 301) by subtracting the input from the sampled output. (due to the sampled output being delayed by the waveform period T_pThus, an inter-cycle controller is implemented. ) The error function is integrated (311 for controller 301) and an output is generated (312 for controller 301). Adjusting the number N of controllers and the sampling period T_sSo that NT is_s＝T_p. To accommodate the repetition period T of the input_pSeveral sampling periods may be varied and additional controllers may be used. For example, there may be N +3 controllers to handle T that can vary by three sample periods_p. When the ratio is less than the maximum T_pWithout updating the additional control section, the state of the last updated controller may be copied to the additional control section.

Fig. 3B illustrates an alternative implementation of an inter-cycle controller 350 according to an embodiment of the present disclosure. Input 351 is provided at 1/T by analog-to-digital converter 352_sIs sampled and digitized. (the input may already be present as a data stream, in which case converter 352 is not used.) output 358 is taken by analog-to-digital converter 359And sampled and digitized. (the output may be a digital data stream derived from measurements of the output, in which case an analog-to-digital converter may not be implemented as shown.) the error function 353 is obtained by subtracting the input from the output. Controller 354 for one period T based on the input_PThe previous control input to the value of device c 355, and the error function e 353, to generate the control input to device c 355. This is clearly different from conventional in-cycle controllers, as shown below. The control input to the device is converted to an analog signal by a digital to analog converter 356 and applied to a device 357. For the controller 300, the following may be handled: repetition period T of input_pThe case of several sampling periods may be changed. In this case, allowing N to be based on the appropriate input T_pOf the previous period T_sAnd the number of the same.

Fig. 4A-4D illustrate the response of an inter-period controller to a periodic control input that can be implemented in a plasma power delivery system according to one embodiment of the present disclosure. In fig. 4A and 4B, a response 400 of an output 402 to a periodic input 401 is shown. As shown in response 400, the output converges slowly to the input (fig. 4A), but after about 30 cycles of the input (fig. 4B), output 404 follows input 403 with little perceptible error. FIG. 4C shows point A451 on response 450 and the points that affect point A. Note that for the weekly controller, point a 451 is still significantly affected by the past 5ms input. Thus, even if each portion of the output approaches the input with a time constant on the order of 5 milliseconds, the output follows the input after a few cycles with little perceived error. For a conventional in-cycle controller, the output will not follow the input with this accuracy, even if a time constant of 5 mus is used.

Fig. 5 illustrates a block diagram of an exemplary cycle duration and duration combination controller 500, which may be implemented in a plasma power delivery system, according to one embodiment of the present disclosure. Input 501 is converted by analog-to-digital converter 502 at 1/T_sIs sampled and digitized. (the input may already be present as a data stream, in which case the converter 5 is not used02. ) The output 509 is sampled and digitized by an analog-to-digital converter 510. (the output may be a digital data stream derived from measurements of the output, in which case an analog-to-digital converter may not be implemented as shown.) the error function 503 is obtained by subtracting the input from the output. A controller 504 for controlling the operation of the motor according to the input one period T_PBefore and one sampling period T_sThe previous control input to the value of device c 506, and the error function e 353 generate the control input to device c 355. Selection of N and T_sTo satisfy T_p＝NT_s. The control input c 506 is a weighted average of values based on a sampling period T_sA preceding and an input period T_pThe previous value. This weighting may be more clearly illustrated in the sequence (sample time) domain shown in equation 505. In 504 and 505, W_eIs a real number between 0 and 1, and W_a＝1–W_e. If W is_e1, the controller is a pure inter-period controller if W_eAnd 0, the controller is a conventional periodic controller. The control input to device c 506 is converted to an analog signal by a digital-to-analog converter 507 and applied to device 508. The following can be handled: repetition period T of input_pThe case of several sampling periods may be changed. In this case, allowing N to be based on the appropriate input T_pOf the previous period T_sAnd the number of the same. In this case, if the portion near the end of the iteration has not been updated recently, rather than duplicating the state of the previous sample, the weights may be changed to run the pure in-cycle controller (W)_e0) until the time to start the next input cycle. The exemplary inter-cycle and intra-cycle combination controller 500 has the additional advantage that it can easily transition from operating with periodic inputs to operating with non-repetitive inputs 501.

Fig. 6A, 6B, 6C, and 6D illustrate an exemplary periodic controller (e.g., 300, 350, or 500 (where W is W) that can be implemented in a plasma power delivery system according to one embodiment of the present disclosure_e1) of the test piece. For ease of illustration, in FIG. 6, device P308. 357 or 506 is a simple unity gain block, sample period T _s1 mus, repeat period T_p1ms, so N Tp/Ts 1000, and k (k in 500)_e) 62.83. A bode plot of the loop gain of the inter-cycle controller is shown in fig. 6A. The loop gain is very different from a conventional in-cycle controller. E.g. for gain k (k in 500)_e) It is expected that at 10Hz there is a first gain crossover frequency, as at 62.83-2 pi 10, but the magnitude of the gain is at the input harmonic (1/T)_pMultiple of) returns infinity; the unique nature of the cycle period controller allows it to track cycle inputs with unprecedented precision. Fig. 6B shows a nyquist plot of the loop gain. For ease of explanation of the Nyquist plot, the magnitude of the loop gain is log₂(1+log₂(1 +. cndot.)) scaling. This mapping maps 0 to 0, 1 to 1 and is monotonically increasing, so we can still verify that point-1 + j0 in the complex plane is not wrapped around. Although there are multiple gain crossover points in the bode plot, the nyquist plot indicates that the system is stable. Fig. 6C shows the magnitude and phase of the closed loop response of the system. FIG. 6D shows the magnitude and phase of the closed loop response of the system only at the harmonics of the input and +/-1Hz from the harmonics of the input. FIG. 6D shows that the gain at the harmonic is unity, confirming that it will accurately follow a signal having a period T_pIs input periodically. In FIG. 6D, the points with exactly 0dB gain and 0 phase (unity gain) are exactly at the input harmonics, and the points with-0.04 dB gain and +/-5 degrees phase are 1Hz above and below the input harmonics.

Fig. 7A, 7B, 7C, and 7D illustrate a W that may be implemented in a plasma power delivery system according to one embodiment of the present disclosure_eAn exemplary set of 0.1 characteristics of the inter-cycle controller and the intra-cycle controller 500. For ease of illustration, in FIG. 7, device P506 is a simple unity gain block, sample period T _s1 mus, repeat period T_P1ms and thus N1000 Tp/Ts, K_e62.83, and k_a62830. A bode plot of the loop gain of the combined controller during and during a cycle is shown in fig. 7A. Loop gain and conventional cyclic inner controlThe mechanisms are very different. At 100Hz there is a first gain crossover frequency for W at 10Hz_eCrossover frequency of 1 with 10kHz for W_eBetween intersections of 0. At harmonics of the input (1/T)_pMultiple of) gain, the magnitude of the gain returns to a higher finite value; the unique attributes of the controller during and within the combined cycle. Fig. 7B shows a nyquist plot of the loop gain. For ease of explanation of the Nyquist plot, the magnitude of the loop gain is log₂(1+log₂(1 +. cndot.)) scaling. This mapping maps 0 to 0, 1 to 1 and is monotonically increasing, so we can still verify that point-1 + j0 in the complex plane is not wrapped around. Although there are multiple gain crossover points in the bode plot, the nyquist plot indicates that the system is stable. Fig. 7C shows the magnitude and phase of the closed loop response of the system. FIG. 7D shows the magnitude and phase of the closed loop response of the system only at the harmonics of the input and +/-1Hz from the harmonics of the input. Fig. 7D shows that the gain at the first few harmonics of the input is close to unity, which indicates that the first few harmonic components of the input will be followed with good accuracy.

Fig. 8A, 8B, 8C, and 8D illustrate a W that may be implemented in a plasma power delivery system according to one embodiment of the present disclosure_eAn exemplary set of 0.01 characteristics of the inter-cycle controller and the intra-cycle controller 500. In FIG. 8, device P506 is a simple unity gain block, sample period T _s1 mus, repeat period T_P1ms and thus N1000 Tp/Ts, K_e62.83, and k_a62830. A bode plot of the loop gain of the combined controller during and during a cycle is shown in fig. 8A. The loop gain is close to the gain of a conventional in-cycle controller. At 9.1kHz there is a first gain crossover frequency for W at 10Hz_eCrossover frequency of 1 with 10kHz for W_eBetween intersections of 0. As the frequency increases, the magnitude of the gain will return to a value that is more than twice unity. Fig. 8B shows a nyquist plot of the loop gain. For ease of explanation of the Nyquist plot, the magnitude of the loop gain is log₂(1+log₂(1 +. cndot.)) scaling. This mapping maps 0 to 0, 1 to 1 and is monotonically increasing, thusWe can still verify that point-1 + j0 in the complex plane is not wrapped around. Although there are multiple gain crossover points in the bode plot, the nyquist plot indicates that the system is stable. Fig. 8C shows the magnitude and phase of the closed loop response of the system. FIG. 7D shows the magnitude and phase of the closed loop response of the system only at the harmonics of the input and +/-1Hz from the harmonics of the input. Fig. 7D shows that the gain at the first few harmonics of the input is close to unity, which indicates that the first few harmonic components of the input will be followed with good accuracy. The controller crossed the frequency with a gain of 10kHz, approximating the performance of the controller over the period.

Fig. 9 illustrates a block diagram of a multiple-input, multiple-output version of an exemplary cycle-in-cycle and cycle combination controller 900, which may be implemented in a plasma power delivery system, according to one embodiment of the present disclosure. Input 901 is converted by analog-to-digital converter 902 at 1/T_sIs sampled and digitized. (the input may already be present as a data stream, in which case the converter 902 is not used.) the input is multidimensional and may for example contain inputs for output power and generator source impedance. Output 907 is sampled and digitized by analog-to-digital converter 909. (the output may be a digital data stream derived from measurements of the output, in which case the analog-to-digital converter may not be implemented as shown.) the output is multidimensional and may, for example, include measurements of the output power and impedance presented to the generator. The dimensions of input 901 and output 907 do not necessarily coincide. This is because the elements of the output may contain some measure of something that is minimized or maximized, and therefore no input is required (e.g., mismatch of load impedance provided to the generator and desired load impedance). Also, the input elements may not require a corresponding measurement if the values can be set simply and no corresponding measurement is needed (e.g., setting the generator source impedance). The measurements of the input 901, control input 904, disturbance 908, and output 907 are stored in memory 910. The controller 903 is operated according to an input period T stored in the memory_pA preceding and a sampling period T_sThe previous value generates a control input c904 to the device. Selection of N and T_sTo satisfy T_p＝NT_s。

In addition to calculating values for controls input to the device 904, the controller may also generate a disturbance 908 that is added to the calculated controls. The control input 904 of the device added to the disturbance 908 is converted to an analog signal by a digital-to-analog converter 905 and applied to the device 906. The perturbation 908 may be used to extract the correlation between the control input 904 and the output 907. For example, perturbing a control element that primarily controls the output power (e.g., the drive level of the power amplifier) and observing changes in the output power and impedance produced by the generator by the plasma load and then perturbing a control element that primarily controls the impedance presented to the generator (e.g., the generator frequency) and observing the output power and impedance presented to the generator by the plasma load allows the controller to extract the correlation between the control input 904 and the output 907 at 904. If the input is modulated periodically, the correlation between the control input 904 and the output 907 is also modulated (assuming the load is non-linear, as is the case for most plasma loads). The cycle duration controller may associate a control input 904 and an output 907 for each particular time period in the repeating input cycle. For example, for T_p1ms and T_sFor example, for each of 1000 time periods in the input, the controller may maintain 1000 matrices 904 associated with 907 for 1 μ s. In addition to extracting the correlation between elements of the control input 904 and elements of the output 907 for each particular time period, the correlation between different time periods may also be extracted. For example, the controller may determine how changes in control input elements over one time period affect the output over successive time periods.

A simple example illustrates the benefit of knowing these correlations. Consider a decision on how to update the two-dimensional control vector (e.g., drive and frequency) and the two-dimensional output (e.g., output power and load resistance) within the 7 th time period of the periodic input. Let the desired change in output for the 7 th time period be:

assuming that by perturbation, the correlation between the output in the 7 th time period and the control input in the 6 th and 7 th time periods can be estimated:

this gives (approximately):

when the input for 7 time periods needs to be adjusted, a change to the input for the 6 th time period has been made, so:

are known, and therefore:

this simple example uses two inputs (driver and frequency) and two outputs (output power and load resistance) of the device. The output impedance is only a component of the load impedance. In practical applications, it is the load impedance that is important, not just the resistive part of the load impedance. In this case, a third input (e.g., a variable reactance element in the matching network) must be used, or an optimization technique may be employed to control the three outputs using only two inputs, rather than the simple calculations in the example to find the best solution.

Multiple input multiple output control combined with inter-cycle control allows multiple parameters to be controlled in one control loop. This avoids the problem of interfering with the control loop, which typically requires the use of widely different speeds for different control loops in the same plasma power delivery system.

Cycle control allows singletonThe controller more easily controls multiple generators delivering power to the same plasma system. The data rate of the controller is the same during a cycle and during a cycle because the control input to the device is at a sampling rate of 1/T_sAnd (6) updating. However, the in-cycle controller needs to come from an earlier one sample period T_STo update the current control input into the device, while the inter-cycle controller requires an input cycle T from an earlier one_PTo update the control input into the device. Since in most cases T is_pRatio T_sMany times longer and therefore it is much easier to obtain information from and into the controller before the controller needs it during the period. The periodic controller can thus more easily take into account the interaction between the different generators to improve overall control of all generators delivering power to the same plasma system.

In the given example of an inter-cycle controller and an intra-cycle controller and a hybrid controller, the controller uses the past sampling period T_sOr a repetition period T_pOf the signal. Of course, the controller may also use signal samples over the past multiple sampling periods or repetition periods.

The claims (modification according to treaty clause 19)

1. A power delivery system, comprising:

a generator that generates a repetitive output pattern; and

a control element that controls the repetitive pattern based on a measurement of a value of the repetitive pattern taken at a period prior to a current period.

2. The power delivery system of claim 1, wherein: the control element also controls the repeated output pattern based on a combination of measurements of the repeated pattern taken at a period prior to the current period and measurements of values of the repeated pattern during the current period.

3. The power delivery system of claim 1, wherein the repeated output pattern follows a prescribed pattern of output versus time, wherein the prescribed pattern repeats at a repeating cycle, and wherein the measurements of the values of the repeated pattern taken over a cycle prior to the current cycle occur over one or more repeating cycles in the past.

4. The power delivery system of claim 3, further comprising: a device that receives a multi-dimensional input and produces a multi-dimensional output, wherein a correlation between an element of a control input to the device within a particular time period in the pattern and an element of an output from the device within the same particular time period is determined and used by the control element.

5. The power delivery system of claim 4, wherein the correlation between elements of the control input and elements of the output is determined by perturbing the control input and observing a response to the perturbation.

6. A power delivery system according to claim 4, wherein the control input to the device and the output from the device are multidimensional, and wherein the correlation between elements of the control input and elements of the output from the device within a particular time period in a periodic pattern and within time periods adjacent to the particular time period is determined and used by the control unit.

7. The power delivery system of claim 6, wherein the correlation between elements of the control input and elements of the output is determined by perturbing the control input and observing the response to the perturbation.

8. The power delivery system of claim 1, wherein the generator is one of a single radio frequency generator or a direct current generator, and the output is at least one of a voltage, a current, and a power.

9. A power delivery system according to claim 1, wherein the generator comprises a plurality of radio frequency generators, or a plurality of direct current generators, or a combination of radio frequency generators and direct current generators, and the output is at least one of voltage, current and power delivered to the plasma system.

10. A power delivery system according to claim 4, wherein one element of the output is one or a combination of voltage, current and power and another element of the output is one of an impedance presented to the generator and a source impedance of the generator.

11. A power delivery system according to claim 6, wherein one element of the output is one or a combination of voltage, current and power and another element of the output is one of an impedance presented to the generator and a source impedance of the generator.

12. A power delivery system, comprising:

a control system in communication with the memory for generating an output following a prescribed pattern of output versus time, wherein the prescribed pattern is repeated at a repetition period by controlling repetition of the prescribed pattern based on measurements of the output stored in the memory, the output stored in the memory being taken from one or more previous repetitions of the prescribed pattern of output versus time.

13. A power delivery system according to claim 12, wherein the control system combines measurements taken from one or more previous repetitions with measurements taken from a current repetition.

14. The power delivery system of claim 12, wherein a control input to a device of the plasma power delivery system and an output of the plasma power delivery system are multi-dimensional, wherein correlations between a plurality of control input elements of the control input at one time relative to a start of the repetition of the prescribed pattern and a plurality of output elements of the output at a same time relative to the start of the repetition period are determined and used by the control system.

15. The power delivery system of claim 14, wherein the correlation between the control input element of the control input and the output element of the output is determined by perturbing the control input and measuring a response to the perturbation.

16. A power delivery system according to claim 13, wherein the control input and the output to the device are multidimensional, wherein the correlation between a plurality of control input elements of the control input at one time relative to the start of the repeating cycle and a time adjacent to the one time and a plurality of output elements of the output at the one time relative to the start of the repeating cycle is determined and used by the control system.

17. The power delivery system of claim 16, wherein the correlation between the control input element of the control input and the output element of the output is determined by perturbing the control input and measuring a response to the perturbation.

18. A power delivery system in accordance with claim 12, wherein the power delivery system comprises a single Radio Frequency (RF) generator or a Direct Current (DC) generator, and the element of the output comprises at least one of a voltage, a current, and a power level delivered to a plasma system.

19. The power delivery system of claim 18, further comprising a plurality of generators, the plurality of generators comprising an RF generator, a DC generator, or a combination of an RF generator and a DC generator, and the elements of each of the outputs of the generators comprising at least one of a voltage, a current, and a power level.

20. A power delivery system according to claim 14, wherein one of the output elements of the output comprises at least one of a voltage, a current and a power, wherein another output element of the output comprises at least one of a load impedance presented to a generator and a source impedance of the generator.

21. A power delivery system according to claim 16, wherein one output element of the output comprises at least one of a voltage, a current, and a power level, wherein another output element of the output comprises at least one of a load impedance presented to a generator and a source impedance of the generator.

22. A power delivery system, comprising:

a controller for generating an output, the controller being subject to a periodic disturbance, wherein the periodic disturbance is caused to repeat with a repetition period by controlling the output based on measurements of values of the output taken over one or more repetition periods in the past.

23. The power delivery system of claim 22, wherein the plasma power delivery system receives a signal synchronized with the periodic disturbance.

24. A plasma power delivery system, comprising:

an impedance matching network that matches a load impedance to a desired impedance, wherein the load impedance is subject to a periodic modulation pattern that repeats with a repeating cycle; and

a control element operatively associated with the impedance matching network, the control element controlling a variable impedance element in the impedance matching network based on measurements of the value of the load impedance taken over one or more past repeating cycles.

25. The plasma power delivery system of claim 24 wherein the control unit controls a variable impedance element in the impedance matching network based on a combination of measurements of the value of the load impedance taken over one or more past repeating cycles and measurements of the value of the load impedance taken over less than past repeating cycles.