TW202304259A - Inter-period control for passive power distribution of multiple electrode inductive plasma source - Google Patents

Abstract

A generator produces output such as delivered power, voltage, current, forward power etc. that follows a prescribed pattern of output versus time where the pattern repeats with a repetition period by controlling sections of the pattern based on measurements taken one or more repetition periods in the past. A variable impedance match network may control the impedance presented to a radio frequency generator while the generator produces the output that follows the prescribed pattern of output versus time where the pattern repeats with a repetition period by controlling variable impedance elements in the match during sections of the pattern based on measurements taken one or more repetition periods in the past.

Description

Intercycle Control of Passive Power Distribution for Multi-Electrode Inductive Plasma Sources

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.

This patent application is a continuation in part of the pending patent application No. 17/113,088 filed on December 6, 2020, entitled "INTER-PERIOD CONTROL SYSTEM FOR PLASMA POWER DELIVERY SYSTEM AND METHOD OF OPERATING THE SAME" application, the pending patent application was filed on July 5, 2018 and issued on December 8, 2020 as U.S. Patent No. 10,861,677 entitled "INTER-PERIOD CONTROL SYSTEM FOR PLASMA POWER DELIVERY Continuation of Patent Application No. 16/028,131, filed under 35 U.S.C. § 119(e), entitled "INTER-PERIOD CONTROL SYSTEM FOR PLASMA" filed on July 7, 2017, for SYSTEM AND METHOD OF OPERATING THE SAME POWER DELIVERY SYSTEM AND METHOD OF OPERATING THE SAME" US Patent Application No. 62/529,963 priority. These applications and patents are assigned to the assignee and are hereby expressly incorporated herein by reference.

Plasma processing systems are used to deposit thin films on substrates using processes such as chemical vapor deposition (CVD) and physical vapor deposition (PVD), and also to remove films from substrates using etching processes. Plasma is typically generated by coupling a radio frequency (RF) or direct current (DC) generator to a plasma chamber filled with gas injected into the plasma chamber at low pressure. In some cases, the RF generator is coupled to a variable impedance matching network that can match the plasma impedance to a desired impedance, typically 50Ω, at the output of the generator. Typically, a generator delivers RF power to an antenna or electrode in the plasma chamber, and the power delivered at the antenna ignites and sustains the plasma. In some implementations, an induction coil antenna is wrapped around the reaction chamber and is actively driven by RF power to facilitate ignition (and maintenance) of the plasma in the chamber. Systems have been developed that utilize a single generator to drive two coil antennas. In these systems, a generator is typically coupled (e.g., via RF matching) to a first coil and a series capacitor couples the first coil to a second coil such that both coils are actively driven by the generator (e.g., actively driven via RF impedance matching). Generators alone or in combination with other pieces of equipment such as impedance matching networks, other generators coupled to the same plasma, cables, etc. constitute a plasma power delivery system.

It is often desirable to modulate the power delivered to the plasma system. Most modulation schemes are repeated, that is, the same modulated waveform is repeated at the waveform repetition rate. The associated waveform repetition period is equal to one divided by the waveform repetition rate. The ability to follow a prescribed modulated waveform using conventional control schemes requires high bandwidth from the controller and ultimately from the measurement system. Many plasma systems have power applied to the plasma at different frequencies. The nonlinear nature of the plasma load produces intermodulation products that can interfere with the generator's measurement system. Therefore, it is sometimes advantageous to use narrowband measurement systems 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 presented by the plasma load to the generator can 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 can also be controlled. Based on the above-mentioned problems, tracking and controlling power presents greater control challenges.

With the above observations in mind, an aspect of this disclosure is conceived.

Exemplary embodiments of the invention shown in the drawings are summarized below. These and other embodiments are described more fully in the Embodiments section. It should be understood, however, that there is no intention to limit the invention to the forms described in this Summary or Examples. Those skilled in the art will recognize that there are many modifications, equivalents and alternative constructions that fall within the spirit and scope of the invention as expressed in the claims.

According to one embodiment, a generator produces an output such as delivered power, voltage, current, forward power, etc. that follows a prescribed pattern of output versus time, wherein the pattern is determined by Measurements are made to control segments of the pattern to repeat with a repetition period. In one example, a power delivery system involves a generator that produces a repetitive output pattern, and a control element controls the Repeat pattern. The control element may further control the repeating output pattern based on the measurement of the repeating pattern taken in a cycle preceding the current cycle in combination with a measurement of a value of the repeating pattern during a current cycle . The repeating output pattern may follow a prescribed pattern of output versus time, wherein the prescribed pattern repeats at a repeating period, and wherein the value of the repeating pattern for a period preceding the current period Measurements occurred over one or more repetition periods in the past.

According to yet another embodiment, a variable impedance matching network controls the impedance presented to an RF generator while the generator generates power such as delivered power, voltage, current, forward power, etc. following a prescribed pattern of output versus time. etc., wherein the pattern is repeated for a repetition period by controlling the variable impedance elements in matching during segments of the pattern based on measurements made over one or more past repetition periods. In various possible embodiments, the generator may provide the delivered power, voltage, current, forward power, etc. to a plasma system in order to ignite and maintain a plasma.

According to yet another embodiment, a generator produces an output that follows a prescribed pattern of output versus time, wherein the pattern is controlled by a region of the pattern based on measurements made over one or more past repetitions. segment and repeats with a repeating period by combining the controller with an inter-period controller that calculates the control output based on measurements taken in the past less than one repeating period.

According to yet another embodiment, a variable impedance matching network controls the impedance presented to an RF generator while the generator generates power such as delivered power, voltage, current, forward power, etc. following a prescribed pattern of output versus time. etc., wherein the pattern is controlled by controlling a variable impedance element in matching during a segment of the pattern based on measurements made over one or more past repetitions and combining the controller with a cycle The inner controller is combined to repeat with a repetition period in which the controller calculates the control of the variable impedance elements in the matching based on measurements taken in the past less than one repetition period.

According to another embodiment, a generator produces output that follows a prescribed pattern of output versus time, wherein the pattern repeats in a repetition period by: based on the amount performed over one or more repetition periods in the past control a segment of the pattern by measuring it while adjusting another parameter such as the generator output frequency or control in or coupled to the generator based on measurements made over one or more past repetitions A variable impedance element contained in a variable impedance matching network to the plasma where control inputs such as power control and generator frequency are presented to the generator in relation to control outputs such as delivered power and impedance Correlations between are determined and used by the control system.

According to yet another embodiment, a generator produces output that follows a prescribed pattern of output versus time, wherein the pattern repeats at a repetition period by: and controlling a measurement made by a segment of the same segment; and compensating for coupling between adjacent or closely located segments in the waveform by perturbing the control input, determining the response to the perturbation, and using the response to the perturbation. Such measurements for other segments in the model are then controlled.

One embodiment of the present disclosure may be characterized as a system for controlling the spatial distribution of plasma in a processing chamber. In this embodiment, the system includes: a primary inductor positioned to excite the plasma when power is actively applied to the primary inductor; at least one secondary inductor positioned proximate to the primary inductor to such that substantially all of the current passing through the secondary inductor is generated by mutual inductance through the plasma with the primary inductor; and at least one termination element coupled to the at least one secondary inductor, the at least one terminal A connecting element affects the current through the at least one secondary inductor to affect the spatial distribution of the plasma.

Another embodiment may be characterized as a method for controlling a spatial distribution of plasma in a processing chamber comprising a primary inductor and N secondary inductors. The method includes: exciting the plasma in the processing chamber with the primary inductor; inductively coupling the primary inductor to each of N secondary inductors via the plasma, where N equal to or greater than one; and terminating each of the N secondary inductors such that substantially all current through each of the N secondary inductors is routed through the plasma and the primary inductor Generated by mutual inductance of the inductors, the current through each of the N secondary inductors affects the spatial distribution of the plasma.

Yet another embodiment of the present disclosure can be characterized as an apparatus for controlling the spatial distribution of plasma in a processing chamber. The apparatus includes: a primary terminal configured to couple to a primary inductor of the plasma processing chamber and actively apply power to the primary inductor; a secondary terminal configured to couple to to a corresponding secondary inductor of the plasma processing chamber; and a terminating element coupled to the secondary terminal, the terminating element being arranged to provide a path for current to flow through the secondary inductive component, wherein the Substantially all of the current through the secondary inductor and the terminating element is generated by mutual inductance through the plasma and the primary inductor.

Periodic Control of Distributed Sensing Electrodes

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 prescribed profile of output versus time, wherein the profile is obtained by or multiple repetition periods other than the measurements made during the current period to control the segment of the pattern to repeat with a repetition period. Such inter-cycle controllers can utilize lower bandwidth measurement and control systems to more accurately reproduce the output than conventional controllers. The benefits provided by the inter-cycle controller may be beneficial in various circumstances, including in the presence of plasma-generated mixing and intermodulation products. In additional embodiments, the inter-cycle controller may be combined with conventional in-cycle controllers. In additional embodiments, parameters such as generator output frequency can be adjusted along with the main output based on measurements taken over one or more past repetitions, where control inputs such as power control and generator frequency are correlated with parameters such as presenting Correlations between control outputs such as delivered power and impedance to the generator are determined and used by the control system. In an additional embodiment, the generator produces an output that follows a prescribed pattern of output versus time, wherein the pattern repeats in a repetition period by: based on a segment of the pattern in the past for one or more repetition periods and control the same segment by perturbing the control input, determining the response to the perturbation, and using the response to the perturbation to compensate for coupling between adjacent or closely located periods in the waveform. Such measurements for other segments in the model.

Although described primarily with reference to controllers for generators, aspects of the present disclosure are applicable to switched mode power supplies and their controllers, which may be used in eV source applications to provide a bias voltage to a substrate as the overall power part of the delivery system as well as other substrate biasing schemes. The controllers and control schemes discussed herein may also be used to control variable impedance elements of impedance matching networks, such as vacuum variable capacitors or switched varactor elements. In such cases, aspects of the present disclosure may or may not also be used in the RF supplier's control of the impedance matching network as part of the overall power delivery system. The controller may reside in any part of the power delivery system (eg, in the generator or matching network), and may or may not need to receive information from and control other parts of the power delivery system. For example, a controller resident in a generator may control both the generator and the matching as part of a power delivery system with only the self-generator, only the self-matching, or both the self-generator and the matching information obtained. The controllers and control schemes discussed herein may also be used in other systems with or without delivered power in a plasma power delivery environment.

Figure 1A (prior art) shows a simple analog intra-cycle control system that can be used to control a plasma power delivery system, and Figure IB (prior art) shows a simple digital intra-cycle control system that can be used to control a plasma power delivery system. In FIG. 1A , the difference between an input 101 and an output 106 generates a controller 103 for generating an error signal 102 to a device 105 that controls an input 104 . In this scheme, the controller is a simple integrator with a gain of k. In a practical implementation, the control input 104c may be the drive level of a power amplifier, and the device 105P is a power amplifier. To illustrate the difference in performance between this controller and the disclosed cycle-by-cycle controller, device 105 P is a unity gain block, ie y = c . Under these assumptions, the loop gain has unity gain at k rad/s or k/(2π) Hz, the time constant of the system step response is 1/ks and the integral of the system's impulse response reaches 63.2% in 1/ks ( 1-1/e). In FIG. 1B , input 151 is sampled at a sampling rate of 1/T _s 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 the controller 153 is used to generate an error signal 152 for a control input 154 , which is converted by a digital-to-analog converter 158 into an analog control signal fed to device 155 . For FIG. 1A , to illustrate the difference in performance between this controller and the disclosed cycle-to-cycle controller, device 105P is a unity gain block. The same statement about the relationship between k and unity gain frequency and response time holds for an analog controller like Fig. 1A, with the constraint that k is much smaller than 2π/ _Ts .

FIG. 2A (prior art) shows the response 200 of a simple intra-cycle controller such as that shown in FIG. 1A or FIG. 1B to a periodic input having a period _Tp 205'. In this example, a number of different setpoints (eg, setpoint power of 1, then 2, then 5 with a ramp of 3) define one cycle of the input. The output 202 follows the input 201 with visible inaccuracies (where the output does not match the input setpoint). The time constant of the closed loop response for this diagram is 10 µs. The output at a given point A 203 can be obtained by multiplying and integrating the time-shifted time-reversed impulse response of the system with the input. The normalized time-shifted time-reversed impulse response of unit 204 shows that at point A, the output at 203 is largely influenced by the recent past (within one time constant or 10 µs before point A) and is almost completely independent of Affected by events occurring earlier than 10 time constants before point A. In order to adapt to the changing set point within the pulse, conventional controllers must be very fast. As shown in Figure 2B (prior art), speeding up the controller improves the ability of the output to accurately follow the input. The time constant of the closed loop response for this diagram is 5 µs. Response 250 shows that output 252 follows input 251 more closely. The normalized time-shifted time-reversed impulse response 254 shows that point A 253 is now even more affected by inputs in the recent past.

In these conventional cycle controllers, the error control is based on the measurement of the current output (in cycle) relative to the set point. Thus, referring to FIG. 2A , for example, the measured value of the output at time 1.5 ms is compared with the set point value at the same time to generate an error signal. In other words, the set point value is compared to the measured value during the current cycle to generate an error signal for the controller during the known cycle. In contrast, an inter-cycle controller compares measurements of the output over the past one or more cycles for a given setpoint, and uses the past measurements at the setpoint to generate the current error signal and controller output. For example, referring again to Figure 2A, the controller would use a setpoint of 3 at time 1.5 ms, at time 0.94 ms (which is the previous 0.56 ms of one waveform repetition period or the portion of the preceding pulse relative to time 1.5 ms ) at the same set point as 3 to generate the error and output, rather than the measured value within a pulse of time 1.5 ms. It is worth noting that the controller does not have to be nearly as fast cycle-to-cycle because it relies on measurements from the past cycle rather than immediately adjacent values within a pulse.

In some examples, a pulse (eg, a pulse within period _Tp ) is divided into periods, and the corresponding (same) output value in the same period of the previous pulse is used for the error signal. Next referring again to the above example, referring to using the measured value at the time of the first pulse at 0.94 ms for error correction at the time of the subsequent second pulse at 1.5 ms, the time period will cover a certain value of 0.56 ms within some range. In one example, except for ramped setpoint transitions, the periods of the pulses are divided such that no given period covers a different setpoint.

In various implementations, the inter-cycle pulse information is stored in some form of memory such that the controller can access and use the inter-cycle pulse information for error feedback of subsequent pulses. Complex pulses such as with ramped setpoint transitions and other different setpoints may benefit from relatively small period divisions of pulses, and thus may require relatively larger and faster memory. In a specific example, a pulse with a period T _p between 100 ms and 10 µs can be subdivided into 1024 time slices, and the output value of each slice is stored for measurement in the same time slice as the subsequent pulse Compare.

In some applications, no error signal is generated. In impedance matching applications using an inter-cycle control scheme, information about the impedance presented to the generator over the past one or more cycles _Tp 205 can be used to adjust the variable impedance elements present in the matching network. The 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 points (such as 101, 151, 303, 351, 501) are usually constant, but there are periodic disturbances of the load impedance that must match the desired input impedance. Such periodic disturbances may result, for example, from delivering power to the plasma load that follows a prescribed pattern of output versus time, where the pattern repeats with a repeating period. In this case, a synchronization signal from, for example, a power supply of a prescribed pattern providing power may be provided to the matching network to assist the matching network in synchronizing with the interfering repetitive waveform.

FIG. 3A shows a block diagram of one example of an inter-cycle controller 300 that may be implemented in a plasma power delivery system, according to one embodiment of the present disclosure. 3B shows a block diagram of an alternate 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 implementations of the cycle-to-cycle controllers described herein may be considered as multiple-input multiple-output (MIMO) controllers. A controller or more generally a control element can be implemented in hardware as well as in software, with 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 the equipment 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 this application, the forward and reflected signals from the coupler can be obtained from the coupler resident in the generator, filtered in analog, digitized in an analog-to-digital converter, and processed to operate by The impedance presented to the generator is extracted by a software programmed microprocessor or by matching performed by a digital logic circuit implemented, for example, in an FPGA. Measurements can be stored in memory by a microprocessor resident in the FPGA or by a reconfigurable digital circuit. A memory containing samples of impedance measurements at different times can be processed using software running in a microprocessor or by an FPGA. Software or an FPGA can use samples over the past one or more waveform repetition cycles to implement a cycle-by-cycle control scheme. To implement this approach, information about the past values of the variable impedance elements being matched can also be used. The controller can then send control signals to the match to change the variable impedance elements in the match. Figure 3A implements an inter-cycle controller (providing an interleaving scheme) as a number N of controllers, each operating at an input repetition period _Tp . Block 301 shows a first such controller and block 302 shows an Nth such controller. The input 303 is sampled and digitized by an analog-to-digital converter 304 at a sampling rate of 1/T _s . (The input may already exist as a data stream, in which case converter 304 is not used.) The sampled input is in turn switched or routed to the controllers by switch 305 such that each controller receives updated at a rate of 1/ _Tp enter. The output of the controller is routed by switch 306 to a common control input c. The control input is converted to analog by a digital-to-analog converter 307 and applied to the control input of device P 308 . Output y 309 is sampled by each controller at a rate of 1/ _Tp by samplers (313 of controller 301).

Each controller generates an error function by subtracting the input from the sampled output (controllers 301 - 310). (Since the sampled output is delayed by the waveform period _Tp , an inter-cycle controller is implemented.) The error function is integrated (by controller 301 of 311) to produce the output (controller 301 of 312). Adjust the number N of controllers and the sampling period T _s so that NT _s =T _p . To cater for cases where the input repetition period _Tp can vary by some sampling periods, an additional controller can be utilized. For example, there may be N+3 controllers to handle _Tp which may vary by three sampling periods. When the additional control section is not updated due to being shorter than the maximum _Tp , the state of the last updated controller may be copied to the additional control section.

FIG. 3B shows an alternate implementation of an inter-cycle controller 350 according to an embodiment of the disclosure. The input 351 is sampled and digitized by an analog-to-digital converter 352 at a sampling rate of 1/T _s . (The input may already exist as a data stream, in which case converter 352 is not used.) Output 358 is sampled and digitized by analog-to-digital converter 359 . (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 error function 353 is obtained by subtracting the input from the output. The controller 354 generates the control input to the device c 355 one period T _p before the input according to the value of the control input to the device c 355 and the error function e 353 . This is significantly different from conventional cycle controllers as will be shown below. The control input to the device is converted to an analog signal by a digital-to-analog converter 356 and applied to device 357 . For the controller 300, provision can be made to handle the case where the input repetition period _Tp can vary by some sampling periods. In this case, N is allowed to vary based on the number of sampling periods _Ts in the previous period _Tp of the fitted input.

4A-4D show the response of an inter-cycle controller to a periodic control input that may be implemented in a plasma power delivery system, according to one embodiment of the present disclosure. In FIGS. 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), the output 404 follows the input 403 with little perceptible error. FIG. 4C shows point A 451 on response 450 and the points that affect point A. FIG. It should be noted that for an inter-cycle controller, point A 451 is still significantly affected by the input for the past 5 ms. Thus, even though each segment of the output is close to the input's time constant of about 5 ms, after a few cycles of the input the output can follow the input with almost imperceptible error. For a conventional in-cycle controller, even with a 5 µs time constant, the output does not follow the input with this accuracy.

FIG. 5 shows a block diagram of an example combined inter-cycle and intra-cycle controller 500 that may be implemented in a plasma power delivery system, according to one embodiment of the present disclosure. The input 501 is sampled and digitized by an analog-to-digital converter 502 at a sampling rate of 1/T _s . (The input may already exist as a data stream, in which case converter 502 is not used.) Output 509 is sampled by analog-to-digital converter 510 and digitized. (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 error function 503 is obtained by subtracting the input from the output. The controller 504 generates the control input to device c 506 one period _Tp before the input and one sampling period _Ts before according to the value of the control input to device c506 and the error function e503 . N and T _s are chosen to satisfy T _p =NT _s . The control input c 506 is based on a weighted average of the values one sample period T _s ago and the input one period T _p ago. This weighting can be more clearly illustrated in the sequence (sampled time) domain shown in equation 505 . In 504 and 505, W _e is a real number between 0 and 1 and W _a =1-W _e . If W _e =1, then the controller is a pure inter-periodic controller, and if W _e =0, then the controller is a conventional intra-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 . Provision can be made to handle the case where the input repetition period _Tp can vary by some sampling periods. In this case, N is allowed to vary based on the number of sampling periods _Ts in the previous period _Tp of the fitted input. In this case, if the segment towards the end of the repetition has not been updated recently, instead of copying the state from the previous sample, the weights can be changed to run a purely intraperiodic controller (W _e =0) until the next period of the input until the beginning. This example combined inter-cycle and intra-cycle controller 500 has the additional advantage that it can be easily switched from operation with a periodic input to operation with a non-repetitive input 501 .

6A, 6B, 6C, and 6D illustrate example inter-cycle controls such as 300, 350, or 500 (where _We = 1) that may be implemented in a plasma power delivery system according to one embodiment of the present disclosure. properties of the device. For ease of illustration, in Fig. 6, device P 308, 357 or 506 is a simple unity gain block with sample period T _s =1 µs, repetition period T _p =1 ms, and thus N=Tp/Ts=1000, And k (k _e in 500) = 62.83. A Bode curve for the loop gain of the controller during cycle is shown in Figure 6A. Loop gain is very different from traditional in-cycle controllers. As expected for the gain, there is a first gain crossover frequency at 10 Hz, k (k _e in 500) = 62.83 = 2π10, but the magnitude of the gain returns to infinity at harmonics of the input (1/T _p multiples of ); a unique property of the inter-cycle controller that allows it to follow a periodic input with unprecedented accuracy. Figure 6B shows the Nyquis curve of the loop gain. To facilitate the interpretation of the Nyquis curve, the magnitude of the loop gain is scaled by log ₂ (1+log ₂ (1+●)). This mapping maps 0 to 0 and 1 to 1 and is monotonically increasing, so we can still verify that the point -1+j0 in the complex plane is not surrounded. Although there are multiple gain crossing points in the Bode curve, the Nyquist curve shows that the system is stable. Figure 6C shows the magnitude and phase of the closed loop response of the system. Figure 6D shows the magnitude and phase of the closed loop response of the system at harmonics of the input only and +/- 1 Hz from the input. Figure 6D shows that the gain at the harmonics is unity gain, confirming that a periodic input with period _Tp will be followed exactly. In Figure 6D, the point with exactly 0 dB gain and 0 phase (unity gain) is just at the harmonic of the input, and the point with -0.04 dB gain and +/-5 degrees of phase is above the harmonic of the input and below 1 Hz.

7A, 7B, 7C, and 7D illustrate an example combined inter-cycle controller and properties of an intra-cycle controller 500 that may be implemented in a plasma power delivery system, according to one embodiment of the present disclosure, where W _e =0.1. For ease of illustration, in Figure 7, device P 506 is a simple unity-gain block with sample period T _s =1 µs, repetition period T _p =1 ms, and thus N=Tp/Ts=1000, k _e =62.83 And k _a =62830. Bode curves for the loop gain of the combined cycle-to-cycle and cycle-to-cycle controllers are shown in FIG. 7A. Loop gain is very different from traditional in-cycle controllers. There is a first gain crossover frequency at 100 Hz, which is between the crossover frequency for We ₌ 1 at 10 Hz and the crossover for _We = 0 at 10 kHz. The magnitude of the gain returns to high but finite values at harmonics of the input (multiples of 1/T _p ); unique properties of combined cycle-cycle and cycle-cycle controllers. Figure 7B shows the Nyquis curve of the loop gain. To facilitate the interpretation of the Nyquis curve, the magnitude of the loop gain is scaled by log ₂ (1+log ₂ (1+●)). This mapping maps 0 to 0 and 1 to 1 and is monotonically increasing, so we can still verify that the point -1+j0 in the complex plane is not surrounded. Although there are multiple gain crossing points in the Bode curve, the Nyquist curve shows that the system is stable. Figure 7C shows the magnitude and phase of the closed loop response of the system. Figure 7D shows the magnitude and phase of the closed loop response of the system at harmonics of the input only and +/- 1 Hz from the input. Figure 7D shows that the gain at the first few harmonics of the input is close to unity gain, showing that the first few harmonic components of the input will be followed with good accuracy.

8A, 8B, 8C, and 8D illustrate an example combined inter-cycle controller and properties of an intra-cycle controller 500 that may be implemented in a plasma power delivery system, according to one embodiment of the present disclosure, where W _e =0.01. In Fig. 8, device P 506 is a simple unity gain block with sample period T _s =1 µs, repetition period T _p =1 ms, and thus N=Tp/Ts=1000, k _e =62.83 and k _a = 62830. Bode curves for the loop gain of the combined cycle-to-cycle and cycle-to-cycle controllers are shown in FIG. 8A. This loop gain is close to the loop gain of a conventional cycle-by-cycle controller. There is a first gain crossover frequency at 9.1 kHz, which is between the crossover frequency for We ₌ 1 at 10 Hz and the crossover for _We = 0 at 10 kHz. As frequency increases, the magnitude of the gain returns to a value more than twice above unity. Figure 8B shows the Nyquis curve of the loop gain. To facilitate the interpretation of the Nyquis curve, the magnitude of the loop gain is scaled by log ₂ (1+log ₂ (1+●)). This mapping maps 0 to 0 and 1 to 1 and is monotonically increasing, so we can still verify that the point -1+j0 in the complex plane is not surrounded. Although there are multiple gain crossing points in the Bode curve, the Nyquist curve shows that the system is stable. Figure 8C shows the magnitude and phase of the closed loop response of the system. Figure 7D shows the magnitude and phase of the closed loop response of the system at harmonics of the input only and +/- 1 Hz from the input. Figure 7D shows that the gain at the first few harmonics of the input is close to unity gain, showing that the first few harmonic components of the input will be followed with good precision. This controller approaches the performance of an in-cycle controller with a gain crossover frequency of 10 kHz.

FIG. 9 shows a block diagram of an example combined inter-cycle and MIMO version of an intra-cycle controller 900 that may be implemented in a plasma power delivery system, according to one embodiment of the present disclosure. The input 901 is sampled and digitized by an analog-to-digital converter 902 at a sampling rate of 1/T _s . (The input may already exist as a data stream, in which case converter 902 is not used.) The input is multi-dimensional and may include, for example, inputs for output power and generator source impedance. The output 907 is sampled and digitized by an analog-to-digital converter 909 . (The output may be a digital data stream derived from the output's measurements, in which case the analog-to-digital converter may not be implemented as shown). The output is multidimensional and may include, for example, measurements of output power and impedance presented to the generator. The dimensions of input 901 and output 907 do not have to be identical. This is because an element of the output may contain a measure of something that is minimized or maximized, and therefore does not require an input (eg, a mismatch between the load impedance presented to the generator and the desired load impedance). Furthermore, elements of an input may not require a corresponding measurement if only a value can be set and no corresponding measurement is required (eg, setting generator source impedance). The measurements of input 901 , control input 904 , disturbance 908 and output 907 are stored in memory 910 . The controller 903 generates the control input to the device c 904 one period _Tp before the input and one sample period _Ts before according to the value stored in memory. N and T _s are chosen to satisfy T _p =NT _s .

In addition to calculating the value of the control input to the device 904, the controller may also generate a disturbance 908 that is added to the calculated control. 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 . Perturbation 908 may be used to extract the correlation between control input 904 and output 907 . For example, the control element in disturbance 904 primarily controls the output power (e.g., the drive level of a power amplifier) and observes changes in both output power and impedance presented to the generator by the plasma load, and then the disturbance control element primarily Controlling the impedance presented to the generator (eg, generator frequency) and observing both the output power and impedance presented to the generator by the plasma load allows the controller to extract the correlation between control input 904 and output 907 . If the input is modulated periodically, the dependency between the control input 904 and output 907 is also modulated (assuming the load is non-linear, as is the case with most plasma loads). A cycle-by-cycle controller may correlate control input 904 and output 907 for each specific period of time within a repeating input cycle. For example, for _Tp = 1 ms and _Ts = 1 μs, the controller may maintain 1000 matrices correlating 904 and 907 for each of the 1000 time periods in the input. In addition to extracting correlations between elements of the control input 904 and elements of the output 907 for each specific time period, correlations may also be extracted between different time periods. For example, a controller may determine how a change in an element of a control input in one period of time affects the output in successive periods of time.

假設經由擾動評估第7時段中之輸出與第6及第7時段中之控制輸入之間的相關性：

由此得出（大致）：

當需要調整第7時段之輸入時，已對第6時段之輸入做出更改，因此：

係已知的且由此得出：

Simple examples illustrate the advantages of understanding these dependencies. Consider the decision on how to update the 2D control vector (eg, drive and frequency) and 2D output (eg, output power and load resistance) of period 7 in periodic inputs. Make the desired change in the output of the 7th period as:

Assume that the correlation between the output in period 7 and the control inputs in periods 6 and 7 is evaluated via perturbation:

From this it follows (roughly):

When the input for period 7 needed to be adjusted, a change was made to the input for period 6, so:

is known and thus follows:

The simple example uses two inputs (drive and frequency) and two outputs (output power and load resistance) to the device. Output resistance is only one component of load impedance. In practical applications, the load impedance is very important, not just the resistive part of the load impedance. In this case, a third input will have to be utilized (for example, a variable reactive element in a matching network), or optimization techniques can be employed to use only two inputs controlling three outputs instead of the simple calculations to find the optimal solution.

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

In-cycle control allows a single controller to more easily control multiple generators delivering power to the same plasma system. The data rate of the controller is the same between cycle and cycle because the control input to the device is updated at the sample rate 1/T _s . However, the intra-cycle controller needs information from one sampling period T _s earlier to update the current control input to the device, whereas the inter-cycle controller needs information from an input cycle T _p earlier to update the control input to the device. Since _Tp is many times longer than _Ts in most cases, it is easier to obtain information to and from the controller before the controller needs it during the cycle. Thus, the inter-cycle controller can more easily take into account the interaction between the different generators to improve the overall control of all generators delivering power to the same plasma system.

In a given instance of an inter-cycle and hybrid inter-cycle and intra-cycle controller, the controller uses samples of the signal in the past one sampling period _Ts or one repetition period _Tp . Of course, the controller can also use samples of the signal over multiple sampling periods or repetition periods in the past. Passive Power Distribution for Multi-Electrode Induced Plasma Sources

10 shows an inductively coupled plasma processing system 1000 comprising a primary coil 1002 actively driven (via matching 1006 ) by a generator 1004 to ignite and maintain a plasma 1008 in a plasma processing chamber 1010 . As depicted, exemplary system 1000 includes N secondary coils L ₁ through L _N inductively coupled to plasma 1008 , and plasma 1008 is inductively coupled to primary coil 1002 . Accordingly, the secondary coils L ₁ through L _N are inductively coupled to the primary coil 1002 via the plasma 1008 such that power is applied to the secondary coils L ₁ through L _N through the plasma 1008 . In some embodiments, generator 1004 may be an instance of device 308 in FIG. 3A , device 357 in FIG. 3B , device 508 in FIG. 5 , or device 906 in FIG. 9 .

As depicted, a corresponding one of the N passive elements ₁₀₁₂₁ through _1012N is coupled to each of the N secondary coils _L1 through _LN , the passive elements passively terminating the N secondary coils Each of _L1 through _LN . This architecture is very different from known techniques which rely on actively driving each second coil _L1 to _LN . Advantageously, since the secondary inductor is not actively driven, it is easier to place the secondary coil around the chamber 1010 and achieve plasma spatial uniformity control more easily because the secondary inductor L ₁ through L _N are driven by mutual coupling with the primary coil 1002 via the plasma 1008 and, thus, lack the need for direct power feed. Due to the inherent complexity and cost of additional power feeds, multiple secondary coils can be added in ways beyond what is practical for adding multiple directional powered secondary coils. Therefore, the plasma density can be manipulated in a more cost-effective manner.

In operation, power is applied via matching 1006 to primary coil 1002, which effectively applies power to chamber 1010, and once ignited, plasma 1008 effectively operates as the secondary of a transformer, and the plasma 1008 The induced current induces a current in the secondary coils _L1 to _LN . In turn, the current induced in the secondary coils L ₁ through L _N induces a current in the plasma 1008 and affects the density of the plasma 1008 in a region close to each of the secondary coils L ₁ through L _N .

The N passive elements 1012 ₁ to 1012 _N , depicted in the exemplary embodiment as variable capacitors, enable adjustment of the current through each of the N coils L ₁ to L _N ; thus enabling adjustment of the primary coil 1002 The ratio of the current to the N secondary coils L ₁ to L _N. Accordingly, the plasma density in regions close to each of the primary coil 1002 and secondary coils L ₁ -L _N can be adjusted.

Generator 1004 may be a 13.56 MHz generator, although this is of course not required and other frequencies are of course encompassed. And the matching 1006 can be implemented by various matching network architectures. As will be appreciated by those of ordinary skill in the art, matching 1006 is used to match the load of plasma 1008 to generator 1004 . With proper design of the matching network 1006 (inside the generator or externally as shown in FIG. 10 ), it is possible to transform the impedance of the load to a value close to the desired load impedance of the generator 1004 .

The currents in primary coil 1002 and/or secondary coils L ₁ -L _N may be non-limiting examples of outputs considered by the MIMO controllers mentioned above. Plasma density or measurements indicative of local plasma density such as current in secondary coils L ₁ -L _N are other non-limiting examples of outputs that may be considered by a MIMO controller. Inputs that may be considered by the MIMO controller include, but are not limited to, generator 1004 settings, matching 1006 settings, and N passive elements 1012 ₁ through 1012 _N settings.

Although not shown, one _or more in-cycle controllers, such as 300, 350, or 500, may provide _one or more control.

Referring next to FIG. 11A , an exemplary embodiment is shown in which the passive element 1112a (eg, a variable capacitor) and matching 1106a are both positioned within the same housing 1120 . As shown, primary terminal 1121 is at or near housing 1120 coupled to first output conductor 1122 , which couples generator 1104 (via matching 1106a and primary terminal 1121 ) to primary coil 1102 . And a secondary terminal 1123 located at or near housing 1120 is coupled to a second output conductor 1124 that couples passive termination element 1112 and secondary terminal 1123 to secondary coil 1113 . Additionally, a control portion 1126 (also referred to herein as a controller), such as an inter-cycle controller as described in FIGS. 3-9 , is arranged to receive signals 1128 , 1130 respectively indicative of The current level in the first output conductor 1122 and the second output conductor 1124 of the detector 1132 and the second sensor 1134 (e.g., a current transducer), which is indicative of the plasma in the area close to the coils 1102, 1113 1108 density). And the control portion 1126 is also configured to control the value (eg, capacitance) of the passive element 1112a (eg, a variable capacitor).

In variations of the embodiment depicted in FIG. 11A , instead of (or in addition to) current sensors 1132, 1134, other sensing components (inside or outside of housing 1120) may be used to provide An indication of the density of the plasma in close proximity to the coil 1113. For example, an optical sensor can be used to sense plasma properties such as plasma density, or an eV source that provides substrate bias to chamber 1110 can be used to sense plasma properties such as plasma density and ion density. current).

It should be appreciated that the components depicted in FIG. 11A are logical and are not intended to form a hardware diagram. For example, the control part 1126 and the sensors 1132, 1134 can each be implemented by distributed components, and can be implemented by hardware, firmware, software or a combination thereof. In many variations of the embodiment depicted in FIG. 11A, the sensed current level is converted to a digital representation, and the digital representation of the current signals 1128, 1130 is used by the controller 1126 to generate a control signal 1135 to drive the passive element 1112a. Additionally, matching 1106a may be controlled by control portion 1126 or may be separately controlled.

It should also be appreciated that, for simplicity, only one secondary coil 1113 and one passive terminating element 1112a are depicted, but it is of course contemplated that two or more passive terminating elements 1112a may be combined (e.g., housed in housing 1120 Two or more passive termination elements within) to implement two or more secondary coils 1113.

In operation, generator 1104 applies power to primary coil 1102 via matching 1106a and current in primary coil 1102 (which is sensed by first sensor 1132) induces a current in plasma 1108, which in turn induces a secondary Current in coil 1113. And the second sensor 1134 senses the current flowing through the secondary coil 1113 and thus through the second output conductor 1124 and the secondary terminal 1123 . As discussed with reference to FIG. 10 , unlike prior art implementations, the power applied by the secondary coil 1113 to the plasma 1108 is derived from the current flowing through the primary coil 1102 . More specifically, secondary coil 1113 receives power from primary coil 1102 via plasma 1108 . In other words, there is no direct power source for the secondary coil 1113 other than the mutual inductance via the plasma 1108 .

Control portion 1126, sensors 1132, 1134, and passive element 1112a together form a control system to control the state of plasma 1108 (eg, the spatial distribution and density of plasma 1108). In response to the relative current levels in the primary coil 1102 and the secondary coil 1113, the control portion 1126 in this embodiment is configured to change the value (eg, capacitance) of the passive element 1112a (eg, a variable capacitor) such that the primary The ratio of current between coil 1102 and secondary coil 1113 is at a value corresponding to a desired plasma density profile within chamber 1110 . Although not shown, the control portion 1126 may include a human interface (eg, a display and input controls) to enable a user to receive feedback and facilitate control of the plasma 1108 .

The currents in primary coil 1102 and/or secondary coil 1113 are exemplary outputs of the MIMO controllers mentioned above. Plasma density or measurements indicative of local plasma density such as current at sensors 1132, 1134 are other examples of outputs that may be considered by a MIMO controller. Inputs to the MIMO controller may include, but are not limited to, settings for generator 1104, settings for matching 1106a, and settings for passive element 1112a.

Although not shown, one or more in-cycle controllers, such as 300, 350, or 500, may provide control of one or more of generator 1104, match 1106a, and/or passive elements such as passive element 1113 .

Referring next to FIG. 11B , another embodiment is shown in which the passive termination element 1112b is implemented in a separate housing (separate from the mating 1106b and controller) in close proximity to the chamber. The components in this embodiment operate in a substantially similar manner to the components depicted in FIG. 11A , although the passive element 1112b may be implemented as a separate appliance or may be integrated with the chamber.

The current in the primary coil and/or the secondary coil may be an output considered by the MIMO controller mentioned above. Plasma density or measurements indicative of local plasma density such as current in the secondary coil are other examples of outputs that may be considered by a MIMO controller. Inputs that may be considered by the MIMO controller include, but are not limited to, generator settings, settings for variable capacitors in matching 1106b, and settings for passive element 1112b.

Although not shown, one or more in-cycle controllers, such as 300, 350, or 500, may provide control of one or more of the generator, the variable capacitor matching 1106b, and/or the passive element 1112b.

Referring next to FIG. 12, which is a flowchart depicting the steps that may be studied in detail in conjunction with the embodiments described with reference to FIGS. space allocation. As depicted, when power is applied (e.g., directly from the generator 1004, 1104 via matching) to the primary inductor (e.g., the primary coil 1002, 1102), the plasma in the chamber is excited (block 1202) . In addition, the primary inductor is inductively coupled to each of N (N is equal to or greater than one) secondary conductors (eg, secondary coils L ₁ through L _N or L _secondary ) via the plasma (block 1204 ), and each of the N secondary inductors is terminated such that substantially all of the current through each of the N secondary inductors results from the mutual inductance through the plasma and the primary inductor (region block 1206). As previously discussed, the current through each of the N secondary inductors affects the spatial distribution of the plasma. Although not required, in some variations the current through the N secondary inductors is adjusted in order to adjust the spatial distribution of the plasma (block 1208 ). For example, the secondary inductor may be terminated via one or more variable elements, such as variable reactive elements, such as variable capacitors. By adjusting the termination (e.g., the capacitance between the secondary inductors and ground), the method 1200 can locally control the plasma with greater resolution or granularity of control achieved using a larger number of secondary inductors density.

In some embodiments, control of method 1200 may utilize a MIMO controller, eg, using generators, matching, and passive element settings as inputs and related to outputs such as current in the primary coil and current in the secondary coil. alternative embodiment

In one embodiment, a power delivery system is disclosed that includes a generator and a controller. The generator can be configured to generate a power signal comprising a periodically repeating pattern generated over a period comprising a period of the power signal. The controller can be configured to base on measurements of the periodically repeating pattern in a period of the power signal prior to the current period of the power signal and a relationship between elements of multidimensional control input values and elements of multidimensional output values The current cycle of the periodically repeating pattern is controlled by a plurality of dependencies among them. The power signal can be configured to excite the plasma in the processing chamber via the primary inductor. The power delivery system may further include means for inductively coupling a primary inductor to each of N secondary inductors via a plasma, where N is equal to or greater than one, and where N passes through The current of each of the stage inductors is configured to affect the spatial distribution of the plasma.

The controller can be configured to control the periodically repeating pattern based on measurements of the periodically repeating pattern made in a cycle preceding the current cycle in combination with measurements of the periodically repeating pattern during the current cycle.

The generator can be configured to generate a periodically repeating pattern of a prescribed pattern, wherein the prescribed pattern repeats at a repeating period, and wherein measurements of the periodically repeating pattern taken in a period preceding the current period occur One or more recurrences in the past. The controller can also be configured to determine and use correlations between elements of the multidimensional control input values for specific periods of time and elements of the multidimensional output values for the same specific time periods in a periodically repeating pattern. The controller can also be configured to perturb the control input to obtain a correlation between elements of the multidimensional control input value and elements of the multidimensional output value. Correlations between elements of the multidimensional control input value for a particular time period and periods adjacent to the particular time period in the periodically repeating pattern and elements of the multidimensional output value for the particular time period can be determined and used by the controller. The correlation between elements of the multidimensional control input value and elements of the multidimensional output value can be determined by perturbing the control input and observing the response to the perturbation. One element of the periodically repeating pattern may be one or a combination of voltage, current, and power, and the other element of the periodically repeating pattern may be one of the impedance presented to the generator and the source impedance of the generator one. One element of the periodically repeating pattern may be one or a combination of voltage, current, and power, and the other element of the periodically repeating pattern is one of the impedance presented to the generator and the source impedance of the generator By.

The generator can be one of a single radio frequency generator or a direct current generator, and the periodically repeating pattern is at least one of voltage, current and power.

The generator may comprise 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 periodically repeating pattern is at least one of voltage, current and power delivered to the plasma system .

In another embodiment, a power delivery system is disclosed having a generator, a controller, a primary inductor, and N secondary inductors. The generator can be configured to generate a power signal comprising a periodically repeating pattern generated over a period that includes the period of the power signal, the power signal configured to excite a process chamber via a primary inductor The plasma. The controller can be configured to control a current period of a periodically repeating pattern based on a plurality of correlations between elements of multidimensional control input values and elements of multidimensional output values, wherein the output values precede the current period The period measurement of the power signal. The N secondary inductors may have currents configured to spatially affect the distribution of the plasma. The power applied by the N secondary inductors can be derived substantially from the current flowing through the primary coil.

The control system can be configured to combine measurements taken from one or more previous iterations with measurements taken from the current iteration. The control system can be configured to generate and use a plurality of control input elements of a multidimensional control input value at one time relative to the start of the repeat period and a plurality of outputs of the multidimensional output value at the same time relative to the start of the repeat period Dependencies between elements. The control system can be configured to perturb the control input and measure the response to the perturbation to generate correlations between control input elements of multidimensional control input values and output elements of multidimensional output values. The control system is configured to determine and use a plurality of control input elements of multidimensional control input values at a time relative to the beginning of the repeating period and at times adjacent to the one time and a value at a time relative to the beginning of the repeating period Correlation between output elements of multidimensional output values. A control system can be configured to generate a correlation between a control input element of a multidimensional control input value and an output element of a multidimensional output value by perturbing a control input and measuring the response to the disturbance. The power delivery system may include a single radio frequency (RF) or direct current (DC) generator, and elements of the output include at least one of voltage, current, and power level delivered to the plasma system. The power delivery system may include a plurality of generators each including an RF generator, a DC generator, or a combination of RF and DC generators, and elements of the output of each of the plurality of generators include voltage, current, and power voltage. At least one of the average. One of the output elements of the output may comprise at least one of voltage, current and power, wherein another output element of the output may comprise at least one of a load impedance presented to the generator and a source impedance of the generator By. One output element of the output may comprise at least one of voltage, current, and power level, wherein another output element of the output may comprise at least one of a load impedance presented to the generator and a source impedance of the generator .

In one embodiment, a system for controlling spatial distribution of plasma in a processing chamber is disclosed. The system may include primary terminals, secondary terminals and a controller. The primary terminal can be configured to couple to and actively apply power to a primary inductor of a plasma processing chamber. The secondary terminals can be configured to couple to corresponding secondary inductors of the plasma processing chamber. Substantially all of the current through the secondary inductor results from mutual inductance through the plasma and the primary inductor. The controller can be configured to control the current period of the periodically repeating pattern of the power signal delivered to the primary terminal. The control may be based on complex correlations between elements of multidimensional control input values and elements of multidimensional output values measured in periods of the power signal preceding the current period. In an embodiment, the secondary terminals may be coupled to a terminating element, such as a variable capacitor or some other variable reactive element.

In another embodiment, a method for controlling spatial distribution of plasma in a processing chamber including a primary inductor and N secondary inductors is disclosed. The method may include: exciting a plasma in the processing chamber with a primary inductor; inductively coupling the primary inductor to each of N secondary inductors via the plasma, where N is equal to or greater than one; and terminating each of the N secondary inductors such that substantially all of the current through each of the N secondary inductors results from mutual inductance through the plasma and the primary inductor , the current through each of the N secondary inductors affects the spatial distribution of the plasma.

The termination may include passively terminating each of the N secondary inductors. The method may further include adjusting the current through the N secondary inductors to adjust the spatial distribution of the plasma. The method may further include terminating each of the N secondary inductors by an impedance-tunable termination element, and adjusting the current through the N secondary inductors includes adjusting the impedance-tunable terminations The impedance of each of the connecting elements is used to adjust the current. The method can also sense at least one parameter indicative of plasma density in a region proximate to the N secondary inductors, and adjust the impedance of the impedance-tunable terminating element in response to the sensing. The method can also sense the current in each of the N secondary inductors and adjust the impedance of the impedance-adjustable termination element by adjusting the capacitance of the impedance-adjustable termination element.

Another embodiment of the present disclosure may be described as an apparatus for controlling the spatial distribution of a plasma in a processing chamber, the apparatus including a primary terminal, a secondary terminal, and a termination element coupled to the secondary terminal. The primary terminal can be configured to couple to and actively apply power to a primary inductor of a plasma processing chamber. The secondary terminals can be configured to couple to corresponding secondary inductors of the plasma processing chamber. The terminating element may be positioned to provide a path for current to flow through the secondary inductive component, wherein substantially all of the current through the secondary inductor and terminating element is generated by mutual inductance through the plasma and primary inductor.

In summary, the present disclosure provides, inter alia, a method, system, and apparatus for achieving controllable plasma density by actively driving a coil and one or more passively terminated inductors using MIMO control. Those of ordinary skill in the art can readily recognize that numerous changes and substitutions can be made in the present disclosure, its use, and its configuration to achieve substantially the same results as those achieved by the embodiments described herein. the result of. Accordingly, there is no intention to limit the disclosure to the exemplary forms disclosed. Many variations, modifications and alternative constructions are within the scope and spirit of the disclosure.

101: Input/Setpoint 102: Error Signal 103: Controller 104: Control Input 105: Device 106: Output 151: Input/Setpoint 152: Error Signal 153: Controller 154: Control Input 155: Device 156: Output 157: Sampler 158: DAC 159: Sampler 200: Response 201: Input 202: Output 203: Set Point A/Point A 204: Unit 205: Period 250: Response 251: Input 252: Output 253: Point A 254 : Normalized Time-Shifted Time-Reversed Impulse Response 300: Periodic Controller/Controller/Intra-Cycle Controller 301: Block/Controller 302: Block 303: Setpoint/Input 304: Analog-to-Digital Converter/ Converter 305: Switch 306: Switch 307: Digital to Analog Converter 308: Device 309: Output 310: Error Function 311: Error Function 312: Output 313: Sampler 350: Intercycle Controller/Intracycle Controller 351: Setting Points/Inputs 352: Analog to Digital Converter/Converter 353: Error Function 354: Controller 355: Device 356: Digital to Analog Converter 357: Device 358: Output 359: Analog to Digital Converter 400: Response 401: Period Sexual input 402: output 403: input 404: output 450: response 451: point A 500: combined inter-cycle and intra-cycle controller / inter-cycle controller / intra-cycle controller / combined inter-cycle controller and intra-cycle controller 501 : Setpoint/Input 502: Analog to Digital Converter/Converter 503: Error Function 504: Controller 505: Equation 506: Device/Control Input 507: Digital to Analog Converter 508: Device 509: Output 510: Analog to Digitizer 900: Combined Intercycle and Intercycle Controller 901: Input 902: Analog to Digital Converter/Converter 903: Controller 904: Control Input/Device 905: Digital to Analog Converter 906: Device 907: Output 908 : Perturbation 909 : Analog-to-Digital Converter 910 : Memory 1000 : Inductively Coupled Plasma Processing System 1002 : Primary Coil 1004 : Generator 1006 : Matching/Matching Network 1008 : Plasma 1010 : Plasma Processing Chamber Chamber/chamber 1012 ₁ : passive element 1012 ₂ : passive element 1012 ₃ : passive element 1102: primary coil/coil 1104: generator 1106a: matching 1106b: matching 1108: plasma 1110: chamber 1112a: passive element/passive end Connecting element 1112b: passive element/passive termination element 1113: secondary coil/coil 1120: housing 1121: primary terminal 1122: first output conductor 1123: secondary terminal 1124 second output conductor 1126: control section/controller 1128: Signal/Current Signal 1130: Letter Number/Current Signal 1132: First Sensor/Current Sensor/Sensor 1134: Second Sensor/Current Sensor/Sensor 1135: Control Signal 1202: Block 1204: Block 1206: Block 1208: Block c: Control Input/Device e: Error Function _L1 : Secondary Coil/Coil/Secondary Inductor _L2 : Secondary Coil/Coil/Secondary Inductor _LN : Secondary Coil/Coil /secondary inductor L _secondary :secondary coil P:device T _p :period/repetitive period/waveform period/input period T _s :sampling period/sample period y:output

Various features and advantages of the techniques of this disclosure will be apparent from the following descriptions of specific embodiments of these techniques, as illustrated in the accompanying drawings. It should be noted that the drawings are not necessarily to scale; however, emphasis is instead placed upon illustrating the principles of technical concepts. In addition, in the drawings, the same reference numerals may refer to the same components in different views. The drawings depict only typical embodiments of the disclosure, and therefore should not be considered limiting in scope.

[FIG. 1A] A simple analog intra-cycle control system that can be used to control a plasma power delivery system is shown.

[ FIG. 1B ] shows a simple digital 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.

[FIG. 2B] shows the response of the control system to a periodic input in a relatively fast period.

[ FIG. 3A ] and [ FIG. 3B ] depict block diagrams of example cycle-to-cycle controllers that may be implemented in a plasma power delivery system according to embodiments of the present disclosure.

[FIG. 4A] to [FIG. 4D] illustrate the controller's response to periodic input during example cycles.

[ FIG. 5 ] A block diagram illustrating an example combined inter-cycle and intra-cycle controller that 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 of an example pure periodic controller.

[ FIG. 6B ] shows a Nyquist curve of the loop gain of the cycle-to-cycle controller used to generate the loop gain of FIG. 6A .

[FIG. 6C] shows the closed loop response as a function of the frequency of the controller during the cycle that produces the loop gain of FIG. 6A.

[FIG. 6D] Shows the closed loop response as a function of frequency at and near harmonics of the controller's input waveform during pure cycles.

[ FIG. 7A ] Shows the loop gain as a function of the frequency of the inter-cycle and intra-cycle controllers for an example combination with 0.1 weighting for the inter-cycle component and 0.9 weighting for the in-cycle component.

[FIG. 7B] shows the Nyquis curve of the loop gain related to FIG. 7A.

[FIG. 7C] Shows the closed loop response as a function of frequency for the example combined controller associated with FIG. 7A.

[ FIG. 7D ] Shows the closed loop response as a function of frequency at and near harmonics of the controller's input waveform during and during the combined cycle associated with FIG. 7A .

[ FIG. 8A ] Shows the loop gain as a function of the frequency of the inter-cycle and intra-cycle controllers for an example combination with a weight of 0.01 for the inter-cycle component and a 0.99 weight for the in-cycle component.

[FIG. 8B] A Nyquis curve showing the loop gain of the combined controller associated with FIG. 8A.

[FIG. 8C] shows the closed loop response as a function of frequency of the combined controller associated with FIG. 8A.

[ FIG. 8D ] Shows the closed loop response as a function of frequency at and near harmonics of the controller's input waveform during and around the same combined cycle associated with FIG. 8A .

[ FIG. 9 ] Illustrates a block diagram of a MIMO version of a combined inter-cycle and intra-cycle controller according to one embodiment of the present disclosure.

[ FIG. 10 ] is a block diagram depicting an exemplary embodiment of the present disclosure.

[ FIG. 11A ] is a block diagram depicting another exemplary embodiment of the present disclosure.

[ FIG. 11B ] is a block diagram depicting yet another embodiment of the present disclosure.

[ FIG. 12 ] is a flowchart depicting a method that can be studied in detail in conjunction with the embodiments described with reference to FIGS. 10 to 11 .

1102: primary coil/coil

1104: generator

1106a: match

1108: Plasma

1110: chamber

1112a: Passive components/passive termination components

1113: Secondary coil/coil

1120: shell

1121: primary terminal

1122: first output conductor

1123: Secondary terminal

1124: second output conductor

1126: Control part/controller

1128: signal/current signal

1130: signal/current signal

1132: first sensor/current sensor/sensor

1134: second sensor/current sensor/sensor

1135: control signal

Claims (20)

A system for controlling spatial distribution of a plasma in a processing chamber comprising: a control system; a memory in communication with the control system; a primary inductor and N secondary inductors configured to be spaced apart by the plasma; where the control system is configured to: storing a plurality of correlations between elements of the multidimensional control input value and elements of the multidimensional output value; The current in the primary inductor is controlled based on the plurality of stored correlations between the elements of the multidimensional control input value and the elements of the multidimensional output value, wherein the plurality of correlations are obtained from the primary One or more previous cycle acquisitions of the current in the inductor, wherein the current in the primary inductor induces substantially all current in the N secondary inductors, and wherein the current in the N secondary inductors is configured to spatially affect the distribution of the plasma . The system of claim 1, wherein each of the N secondary inductors is coupled to an impedance adjustable passive termination element. As the system of claim 2, it further includes: means for sensing at least one parameter indicative of plasma density in a region proximate the N secondary inductors, and means for adjusting impedance of the impedance-tunable passive termination elements in response to the sensing . The system of claim 1, further comprising means for sensing current in each of the N secondary inductors, and means for adjusting capacitance of the impedance adjustable passive termination elements. A system for controlling spatial distribution of a plasma in a processing chamber comprising: a primary inductor configured to receive a power signal comprising a periodically repeating pattern generated during a period comprising a period of the power signal via configured to excite the plasma in the processing chamber via the primary inductor; A controller configured to control a current period of the periodically repeating pattern based on a plurality of correlations between elements of multidimensional control input values and elements of multidimensional output values, wherein the output values are at the measured in a cycle of the power signal preceding the current cycle; and means for inductively coupling the primary inductor to each of N secondary inductors via the plasma, where N is equal to or greater than one, and wherein passes through the N secondary inductors The current of each is configured to affect the spatial distribution of the plasma. The system of claim 5, further comprising means for terminating each of the N secondary inductors such that substantially all current passes through each of the N secondary inductors Produced by the mutual inductance through the plasma and the primary inductor. The system of claim 6, wherein the means for terminating each of the N secondary inductors comprises means for passively terminating each of the N secondary inductors. The system of claim 6, wherein the means for terminating includes an impedance-adjustable passive terminating element, so as to enable adjustment of current through the N secondary inductors. The system of claim 8, wherein the controller is configured to adjust an impedance of the impedance-tunable passive termination element in response to a signal indicative of the spatial allocation of the plasma. The system of claim 5, further comprising means for adjusting current through the N secondary inductors to adjust the spatial distribution of the plasma. The system of claim 10, wherein the means for terminating each of the N secondary inductors includes terminating one of the N secondary inductors by an impedance adjustable termination element means for each of the N secondary inductors, and the means for adjusting current through the N secondary inductors includes means for adjusting an impedance of each of the impedance-adjustable terminating elements. The system of claim 5, wherein the N secondary inductors do not have a direct power feed. The system of claim 5, wherein each of the N secondary inductors is coupled to a varactor, and adjustment of the varactor affects the spatial distribution of the plasma. The system of claim 5, wherein one of the multidimensional output values is a measure of plasma density near each of the N secondary inductors. A system for controlling spatial distribution of a plasma in a processing chamber comprising: a plasma processing chamber for containing a plasma; a generator that generates a power signal that modulates the plasma properties of the plasma by repeating a periodic modulation pattern with a repetition period; an impedance matching network coupled between the plasma processing chamber and the generator; a primary coil; and N secondary coils having currents configured to spatially affect distribution of the plasma, and wherein power applied to the plasma by the N secondary coils is substantially derived from flow through the primary coils current; and control means, operatively coupled to the impedance matching network, the control means comprising a measure and multi-dimensional information for indicating a load impedance obtained at one or more repetitions of the periodic modulation pattern in the past A means for controlling a variable impedance element in the impedance matching network by controlling a plurality of correlations between elements of the input value and elements of the multidimensional output value. The system of claim 15, further comprising a terminating element coupled to each of the N secondary coils such that substantially all current in the N secondary coils is derived from passing through the N secondary coils The mutual inductance between the plasma and the primary coil. The system according to claim 16, wherein the terminating element is an impedance-adjustable passive terminating element. The system of claim 16, wherein, The control means further includes means for controlling the impedance of the impedance-tunable passive termination element in response to at least one signal indicative of the distribution of the plasma. The system of claim 16, wherein the terminating element comprises a variable capacitor. The system according to claim 16, wherein the elements of the multidimensional output value at least include the current in the primary coil and the current in the N secondary coils.

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