Pulsed bidirectional RF source / load

Abstract

A pulsed bidirectional RF source / load is provided. The RF power system includes a main RF generator and an auxiliary RF generator, each of which outputs a corresponding RF signal. The main RF generator also outputs an RF control signal to the auxiliary RF generator, and the RF signal output by the auxiliary RF generator varies according to the RF control signal. The auxiliary RF generator receives a sense signal indicating electrical characteristics of the respective RF signals output by the main RF generator and the auxiliary RF generator. The auxiliary RF generator determines a phase difference between the RF signals. The sensed electrical characteristics and phase are used independently or in conjunction to control the phase and amplitude of the RF signal output by the auxiliary RF generator. The auxiliary generator includes an inductive clamp circuit that returns reflected energy from the coupling network to the variable resistive load.

Description

[0001] This application is a divisional application of a patent application entitled “Pulsed Bidirectional RF Source / Load” with application number 201880030682.7 (PCT / US2018 / 032067) filed on May 10, 2018.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to US 15 / 974,947, filed May 9, 2018, and claims the benefit of U.S. Provisional Application No. 62 / 504,197, filed May 10, 2017. The entire disclosures of the above applications are incorporated herein by reference. Technical Field

[0004] The present disclosure relates to controlling FR generators and dissipating reflected energy from variable impedance loads. Background Art

[0005] The background description provided here is for the purpose of generally presenting the context of the present disclosure. The work of the presently named inventors to the extent described in this background section, and aspects of the description that may not otherwise qualify as prior art at the time of filing, are not admitted, either explicitly or implicitly, to be prior art against the present disclosure.

[0006] Plasma etching is commonly used in semiconductor manufacturing. In plasma etching, ions are accelerated by an electric field to etch exposed surfaces on a substrate. The electric field is generated based on an RF power signal generated by an RF generator in a radio frequency (RF) power system. The RF power signal generated by the RF generator must be precisely controlled to perform plasma etching effectively.

[0007] An RF power system may include an RF generator or power supply, a matching or matching network, and a load (e.g., a plasma chamber). The RF generator generates an RF power signal that is received at the matching network. The matching network matches the input impedance of the matching network to the characteristic impedance of the transmission line between the RF generator and the matching network. This impedance matching helps maximize the amount of power sent to the matching network ("forward power") and minimize the amount of power reflected from the matching network back to the RF generator ("reverse power"). When the input impedance of the matching network matches the characteristic impedance of the transmission line, forward power can be maximized and reverse power can be minimized.

[0008] In RF power generators or power supplies, there are generally two methods for applying an RF signal to a load. The first, more traditional method, is to apply a continuous wave (CW) signal to the load. In CW mode, the CW signal is typically a sine wave that is continuously output by the power supply to the load. In this CW method, the RF signal can be a sinusoidal output, and the amplitude and / or frequency of the sine wave can be varied to change the output power applied to the load.

[0009] A second method of applying an RF signal to a load involves pulsing the RF signal rather than applying a continuous wave signal to the load. In pulsed operation, a sinusoidal RF signal is modulated by a modulation signal to define the envelope of the modulated sinusoidal signal. In conventional pulse modulation schemes, the RF sinusoidal signal is typically output at a predetermined frequency and amplitude. The frequency can be varied to improve impedance matching and provide agile frequency adjustment. The amplitude can be varied to change the power of the RF signal. In addition to varying the sinusoidal RF signal, or leaving it unchanged, the power delivered to the load can also be controlled by varying the modulation signal.

[0010] In a typical RF power generator configuration, the output power applied to the load is determined using sensors that measure the forward and reflected power, or voltage and current, of the RF signal applied to the load. Any combination of these signals is analyzed to determine parameters or electrical characteristics of the power applied to the load. Parameters may include, for example, voltage, current, frequency, and phase. This analysis can determine a power value that is used to adjust the output of the RF power supply in order to vary the power applied to the load. In an RF power delivery system (where the load is a plasma chamber), a varying impedance of the load results in a corresponding varying power applied to the load, as the applied power is, in part, a function of the load's impedance. Therefore, varying impedance may require changes in the parameters of the power applied to the load in order to maintain optimal application of power from the RF power supply to the load.

[0011] In plasma systems, power is typically delivered in one of two configurations. In the first configuration, power is capacitively coupled to the plasma chamber. Such systems are referred to as capacitively coupled plasma (CCP) systems. In the second configuration, power is inductively coupled to the plasma chamber. Such systems are referred to as inductively coupled plasma (ICP) systems. Plasma delivery systems typically include a bias and source that apply corresponding bias and source powers to one or more electrodes. The source power typically generates the plasma within the plasma chamber, and the bias power adjusts the plasma to an energy relative to the bias RF power supply. Depending on various design considerations, the bias and source may share the same electrode or may use separate electrodes.

[0012] When an RF power delivery system drives a load in the form of a plasma chamber, the electric field generated by the power delivered to the plasma chamber produces ion energy within the chamber. One characteristic measure of ion energy is the ion energy distribution function (IEDF). The ion energy distribution function (IEDF) can be controlled using an RF waveform. One way to control the IEDF of a system (in which multiple RF power signals are applied to the load) occurs by varying multiple RF signals that are related by frequency and phase. The frequencies between the multiple RF power signals are locked, and the relative phases between the multiple RF signals are also locked. Examples of such systems can be found in U.S. Patent Nos. 7,602,127, 8,110,991, 8,395,322, and 9,336,995, assigned to the assignee of the present invention and incorporated herein by reference.

[0013] RF plasma processing systems include components for plasma generation and control. One such component is referred to as a plasma chamber or reactor. For example, a general plasma chamber or reactor utilized in an RF plasma processing system for thin film manufacturing utilizes a dual-frequency system. One frequency (source) of the dual-frequency system controls the generation of plasma, while the other frequency (bias) of the dual-frequency system controls ion energy. Examples of dual-frequency systems include systems described in the above-mentioned U.S. Patent No. 7,602,127, U.S. Patent No. 8,110,991, U.S. Patent No. 8,395,322, and U.S. Patent No. 9,336,995. The dual-frequency systems described in the above-mentioned patents include closed-loop control systems that adapt RF power supply operation for the purpose of controlling ion density and its corresponding IEDF.

[0014] The requirements for plasma processing accuracy continue to increase. Plasma-based manufacturing systems require tighter tolerances, including reducing component size and increasing density, both of which require higher accuracy from plasma-based manufacturing processes. There are additional challenges with respect to three-dimensional integrated circuit and memory manufacturing processes. One way to significantly increase the density of memory components is to manufacture memory components in a three-dimensional structure. Three-dimensional etching requires tight tolerances to guide ions to perform the manufacturing process. Some three-dimensional etching processes require an aspect ratio of 40:1 or greater. In other words, the etched channel hole can be at least 40 times higher than the width. In order to properly etch to these tolerances, ions must be guided in a substantially orthogonal direction at the wafer being manufactured or directly at the workpiece wafer being manufactured to provide sufficient yield. Other applications that require ions to have similarly accurate directionality at a direction substantially orthogonal to the wafer include solar or flat panel display manufacturing and multiple electrode plasma manufacturing systems.

[0015] Further complicating the plasma-based manufacturing process is that the distribution of electric power across the surface of the wafer may not be uniform. The electric field or electric power near the edge of the workpiece or wafer may change relative to the electric power or field away from the edge of the wafer. This change can cause the ions to move in a direction that is less orthogonal to the wafer or more transverse to the wafer, making it difficult to meet the tolerances required for efficient manufacturing, such as for three-dimensional structures. One way to improve the directionality of ions near the edge of the wafer is to place a secondary electrode (sometimes referred to as an auxiliary electrode) near the edge of the wafer to provide a supplemental electric field near the edge of the wafer. The secondary electrode can be independently powered by a separate RF generator and enables adjustment of the electric power and field near the edge of the wafer, thereby enabling increased control over the angle of incidence of the ions on the wafer.

[0016] Current methods of providing RF power to the auxiliary electrode include passive reactive termination of the auxiliary electrode, such as with a variable capacitor. Other methods include using a slave or secondary RF generator operating in a phase-locked loop relative to a master or primary RF generator. However, in pulsed implementations, these methods may not provide the desired ion directionality in plasma-based manufacturing systems. Summary of the Invention

[0017] The RF system includes a first RF generator connected to a first electrode of a load and generating a first RF signal to the first electrode, and a second RF generator connected to a second electrode of the load and generating a second RF signal to the second electrode. The first RF generator and the second RF generator provide corresponding RF voltages to the first and second electrodes. A controller controls the second RF generator. The controller generates a control signal to at least one of the first RF generator and the second RF generator. Based on the RF control signal transmitted from the first RF generator to the second RF generator, the first RF generator and the second RF generator operate at substantially the same frequency.

[0018] An RF power system for supplying a first RF power to an electrode in a load includes a processor and a memory. The memory stores instructions executable by the processor and configured to determine whether a voltage of the first RF power is equal to a predetermined power setpoint. The instructions further determine whether a phase difference between the first RF power and a second RF power is equal to a predetermined phase delta, and control at least one of the phases of the first RF power based on the phase difference between the first RF power and the second RF power. The instructions further vary a DC rail voltage based on an electrical characteristic of the first RF power to control the RF voltage of the first RF power, or vary both the phase of the first RF power and the DC rail voltage based on the phase difference between the first RF power and the second RF power and the electrical characteristic of the first RF power to control the first RF power.

[0019] The RF system includes a first RF generator connected to a first electrode of a load and generating a first RF signal to the first electrode. A second RF generator is connected to a second electrode of the load and generating a second RF signal to the second electrode. A controller controls the second RF generator, and the controller generates a control signal to at least one of the first RF generator or the second RF generator. A DC power supply provides a DC rail voltage for driving a power amplifier of the second RF generator, wherein the controller varies the DC rail voltage to control the RF voltage at the second electrode. The first RF generator and the second RF generator operate at substantially the same RF frequency, and the controller is configured to at least one of: (1) vary the phase of the second RF signal based on a phase difference between the first RF signal and the second RF signal, (2) vary the DC rail voltage based on an electrical characteristic of the second RF signal to control the RF voltage at the second electrode, wherein the DC power supply provides the DC rail voltage to drive the power amplifier of the second RF generator, or (3) vary the phase of the second RF signal and the DC rail voltage based on the phase difference between the first RF signal and the second RF signal and the electrical characteristic of the second RF signal to control the RF voltage at the second electrode, wherein the DC power supply provides the DC rail voltage to drive the power amplifier of the second RF generator.

[0020] A method of operating an RF power supply system, the method comprising generating a first RF signal applied to a first electrode of a load. A second RF signal is applied to a second electrode of the load. A DC rail voltage drives a power amplifier, the power amplifier generates the second RF signal and varies the DC rail voltage to control the RF voltage at the second electrode. The method further comprises at least one of: (1) varying the phase of the second RF signal based on a phase difference between the first RF signal and the second RF signal, (2) varying the DC rail voltage based on an electrical characteristic of the second RF signal to control the RF voltage at the second electrode, wherein the DC rail voltage drives the power amplifier that generates the second RF signal, or (3) varying the phase of the second RF signal and the DC rail voltage based on the phase difference between the first RF signal and the second RF signal and the electrical characteristic of the second RF signal to control the RF voltage at the second electrode, wherein the DC rail voltage powers the power amplifier.

[0021] A radio frequency power supply system is provided, comprising a main RF generator and an auxiliary RF generator, each of which outputs a corresponding RF signal. The main RF generator also outputs an RF control signal to the auxiliary RF generator, and the RF signal output by the auxiliary RF generator is varied according to the RF control signal. The main RF generator also generates a pulse synchronization signal, which is input to the auxiliary RF generator to vary the pulsation of the RF signal output by the auxiliary RF generator.

[0022] In other features, the auxiliary RF generator receives a sense signal indicative of electrical characteristics of respective RF signals output by the primary RF generator and the auxiliary RF generator.

[0023] In other features, the auxiliary RF generator determines a phase difference between RF signals output by corresponding RF generators based on the sensed signal and generates a request to the main RF generator to change the RF control signal based on the phase difference.

[0024] In other features, the auxiliary RF generator includes a power amplifier including a voltage clamp circuit that returns energy reflected from the coupling network to a variable resistive load. The variable resistive load dissipates the reflected energy in accordance with a command signal that changes a resistance of the variable resistive load.

[0025] Further areas of applicability of the present disclosure will become apparent from the detailed description, claims and drawings.The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present disclosure will be more fully understood from the detailed description and accompanying drawings, in which:

[0027] Figure 1 is a schematic and functional block diagram of a radio frequency (RF) power supply system according to various embodiments;

[0028] Figure 2 is a schematic and functional block diagram of an auxiliary RF generator according to various embodiments;

[0029] Figure 3 is a schematic and functional block diagram of an auxiliary RF generator for operating in an auxiliary mode according to various embodiments;

[0030] Figure 4 is a block diagram of an auxiliary RF generator configured to operate in a standalone mode according to various embodiments;

[0031] Figure 5 is a diagram showing waveforms related to the operation of the RF power supply system of the present disclosure;

[0032] Figure 6 is a flow chart depicting a phase control loop of an RF control system; and

[0033] Figure 7 is a flow chart depicting a power control loop of an RF control system;

[0034] Figures 8A to 8E are waveforms depicting selected electrical characteristics of an exemplary RF power system oscillating under selected conditions;

[0035] Figures 9A to 9E are waveforms of selected electrical characteristics of an exemplary RF power system during a transition period of settings of a matching network;

[0036] FIG. 10A to FIG. 10B is a contour plot of selected electrical characteristics of the RF power system for an initial state;

[0037] Figures 11A to 11B In the RF power system from FIG. 10A to FIG. 10B Contour plots of selected electrical properties after transition from an initial state to a final state in ;

[0038] FIG. 12A to FIG. 12B is a contour plot of selected electrical characteristics of an RF power system according to various embodiments, wherein a plurality of inputs influence control of a selected output;

[0039] Figure 13 is a contour plot depicting the rail voltage contours of the output voltage under selected conditions;

[0040] Figure 14 is a functional block diagram of a control system of an RF power system according to various embodiments;

[0041] FIG. 15A to FIG. 15B is a graph of selected electrical characteristics of an RF power system operating under nominal conditions;

[0042] 16A to 16B is a plot of selected electrical characteristics of an RF power system, where the response surface is rotated under stress conditions;

[0043] 17A to 17D is a graph of selected electrical characteristics of an RF power supply system controlling a single input for a selected output operating under nominal conditions;

[0044] 18A to 18D is a graph of selected electrical characteristics of an RF power system controlling a single input for a selected output operating under stress conditions;

[0045] 19A to 19D is using Figure 14 a graph of selected electrical characteristics of the RF power system under nominal conditions controlled by the control system;

[0046] 20A to 20D is using Figure 14 a graph of selected electrical characteristics of the RF power system under nominal conditions controlled by the control system;

[0047] Figure 21 is a functional block diagram of an example control module according to an embodiment of the present disclosure; and

[0048] Figure 22is a flow chart depicting control of a multiple-input multiple-output RF power supply system.

[0049] Among the drawings, reference numerals may be repeated to identify similar and / or identical elements. DETAILED DESCRIPTION

[0050] Figure 1 A schematic and functional block diagram of an RF power system 10 is depicted. The RF power system 10 includes a main RF generator 12 and an auxiliary RF generator 14. The main RF generator 12 generates a main RF signal 18 that is input to a main matching or coupling network 20. The main matching network 20 changes the impedance between the main RF generator 12 and a coupling network 24 to achieve impedance matching between the main RF generator 12 and the coupling network 24, thereby maximizing power transfer from the main RF generator 12 to the coupling network 24. Similarly, the auxiliary RF generator 14 generates an auxiliary RF signal or output 26 to an auxiliary matching or matching network 28. The auxiliary matching network 28 changes the impedance between the auxiliary RF generator 14 and the coupling network 24 to provide impedance matching between the auxiliary RF generator 14 and the coupling network 24 to maximize power transfer from the auxiliary RF generator 14 to the coupling network 24. In various embodiments, a direct current (DC) bus 16 provides a DC voltage to one or both of the main RF generator 12 and the auxiliary RF generator 14.

[0051] The main matching network 20 outputs a main matching RF signal 22 to the coupling network 24. The auxiliary matching network 28 outputs an auxiliary matching RF signal 30 to the coupling network 24. In various embodiments, the auxiliary matching network 28 may have an external input (not shown). In various embodiments, the external input receives an external signal that controls the position of one or more capacitive components of the auxiliary matching network 28 to change the impedance of the auxiliary matching network 28. In various embodiments, the main matching RF signal 22 and the auxiliary matching RF signal 30 may communicate with the same or separate electrodes of the coupling network 24. In various embodiments, the main matching RF signal 22 is applied to the main electrode 32 of the coupling network 24, and the auxiliary matching RF signal 30 is applied to the auxiliary electrode 40 of the coupling network 24. In various embodiments, the main electrode 32 and the auxiliary electrode 40 are capacitively coupled, as indicated by the capacitor 44 shown in dashed lines to indicate the capacitive aspect of the coupling. In various embodiments, the coupling network 24 may be a plasma chamber, a plasma reactor, or other load.

[0052] Throughout the description, the RF power system 10 may be referred to as having components associated with a primary portion of the RF power system 10 and components associated with an auxiliary portion of the RF power system 10. Components associated with the primary portion may be referred to as main, primary, first, or primary components. Components associated with the auxiliary portion of the RF power system 10 may be referred to as auxiliary, slave, secondary, or second components.

[0053] The primary matching RF signal 22 and the auxiliary matching RF signal 30 cooperate to generate a reaction within the coupling network 24. In various embodiments, the primary RF generator 12 generates a 100 kHz-2 MHz RF output signal and may be generally referred to as a bias RF generator. The bias RF generator generally accelerates positive ions from the plasma to the substrate surface to control ion energy and etch anisotropy. In various embodiments, the auxiliary RF generator 14 operates at the same frequency as the primary RF generator 12. A generator (not shown) may supply RF power to the coupling network 24 via a 13 MHz-100 MHz signal and may be referred to as a source RF generator. The source RF generator provides energy to ignite the plasma in the coupling network 24.

[0054] According to various embodiments, the main RF generator 12 and the auxiliary RF generator include multiple ports for external communication. The main RF generator 12 includes a pulse synchronization output port 34, a digital communication port 36, and an RF output port 38. The auxiliary RF generator 14 includes an RF input port 42, a digital communication port 46, and a pulse synchronization input port 48. The pulse synchronization output port 34 outputs a pulse synchronization signal 50 to the pulse synchronization input port 48 of the auxiliary RF generator 14. The digital communication port 36 of the main RF generator 12 and the digital communication port 46 of the auxiliary RF generator 14 communicate via a digital communication link 52. The RF output port 38 generates an RF control signal 54 that is input to the RF input port 42. In various embodiments, the RF control signal 54 is substantially identical to the RF control signal that controls the main RF generator 12. In various other embodiments, the RF control signal 54 is identical to the RF control signal that controls the main RF generator 12, but is phase-shifted within the main RF generator 12 according to the requested phase shift generated by the auxiliary RF generator 14. Thus, in various embodiments, the primary RF generator 12 and the auxiliary RF generator 14 are driven by substantially the same RF control signal or by substantially the same RF control signal that is phase-shifted by a predetermined amount.

[0055] The auxiliary RF generator 14 also includes a pair of sensor ports: a primary sense port 60 and an auxiliary sense port 62 that receive voltage signals from respective primary voltage sensors 64 of the primary matching network 20 and auxiliary voltage sensors 66 of the auxiliary matching network 28. In various embodiments, the primary voltage sensor 64 senses the voltage of the primary matching RF signal 22 to determine the voltage of the primary matching RF signal 22 applied to the coupling network 24. Similarly, the auxiliary voltage sensor 66 senses the voltage of the auxiliary matching RF signal 30 applied to the coupling network 24.

[0056] According to various embodiments, the main voltage sensor 64 and the auxiliary voltage sensor 66 detect operating parameters of the corresponding matching RF signals 22, 30. Although described herein as voltage sensors, those skilled in the art will recognize that the main voltage sensor 64 and the auxiliary voltage sensor 66 may include voltage, current and / or directional coupler sensors to detect selected electrical characteristics. In various embodiments, the main voltage sensor 64 and the auxiliary voltage sensor 66 may detect (i) voltage v and current i and / or (ii) forward (or source) power P output from the corresponding matching RF signals 22, 30. FWD and / or the reverse (or reflected) power P of the main matching RF signal 22 and the auxiliary matching RF signal 30 REV The voltage v, current i, forward power PFWD, and reverse power PREV may be scaled and / or filtered versions of the actual voltage, current, forward power, and reverse power associated with the corresponding matched RF signals 22, 30. In various embodiments, the primary voltage sensor 64 and the auxiliary voltage sensor 66 may be analog and / or digital sensors. In a digital implementation, the primary voltage sensor 64 and the auxiliary voltage sensor 66 may include analog-to-digital (A / D) converters and signal sampling components with corresponding sampling rates.

[0057] In various embodiments, the voltage sensors 64, 66 are configured to determine the electrical characteristics of the respective main RF signals 18, 26. In various other embodiments, the voltage sensors 64, 66 are configured to determine the electrical characteristics of the respective matching RF signals 22, 30. When the voltage sensors 64, 66 are configured to detect the voltage of the respective matching RF signals 22, 30, the respective matching RF signals 22, 30 will reflect the phase shift generally introduced by the respective matching networks 20, 28. If the voltage sensors 64, 66 are configured to detect the electrical characteristics of the respective RF signals 18, 26, the sensor signals input to the respective sense ports 60, 62 will not reflect the phase shift introduced to the respective matching RF signals 22, 30 by the respective matching networks 20, 28. Therefore, in various embodiments, the signals input to the respective sense ports 60, 62 may need to be post-processed to approximate the phase shift introduced by the respective matching networks 20, 28.

[0058] Those skilled in the art will recognize that the primary matching network 20 and the auxiliary matching network 28 can be implemented as separate components or combined into a single component. In addition, those skilled in the art will recognize that the primary voltage sensor 64 and the auxiliary voltage sensor 66 can be implemented integrally with the respective matching networks 20, 28 or implemented separately from the respective matching networks 20, 28 and placed upstream or downstream of the respective matching networks 20, 28.

[0059] In operation, the main RF generator 12 generates a main RF signal 18, and the main matching network 20 introduces a matching impedance into the main RF signal 18 to produce a main matched RF signal 22. Similarly, the auxiliary RF generator 14 generates an auxiliary RF signal 26, and the auxiliary matching network 28 introduces a matching impedance into the auxiliary RF signal 26 to produce an auxiliary matched RF signal 30. The operation of the auxiliary RF generator 14 is coordinated with respect to the main RF generator 12, thereby defining a master / slave relationship. The main RF generator 12 outputs an RF control signal 54 from the RF output port 38. The RF control signal 54 is input to the RF input port 42 of the auxiliary RF generator 14. The RF control signal 54 can be a digital or analog signal and defines the RF operating frequency of the auxiliary RF generator 14. When the main RF generator 12 and the auxiliary RF generator 14 operate in a pulsed operating mode, as described above, the main RF generator 12 generates a pulsed synchronization signal 50 from the pulsed synchronization output port 34. The pulse synchronization signal 50 is input to the pulse synchronization input port 48 of the auxiliary RF generator 14. Thus, the RF frequency and pulse of the auxiliary RF generator 14 are controlled by the input from the main RF generator 12.

[0060] In various embodiments, the auxiliary RF generator 14 communicates with the primary RF generator 12 through the respective digital communication ports 36, 46 via a digital communication link 52. The digital communication link 52 enables the auxiliary RF generator 14 to communicate with the primary RF generator 12 to request adjustments to the RF control signal 54 to enable the auxiliary RF generator 14 to align the matching RF signals 22, 30 as measured by the respective voltage sensors 64, 66.

[0061] In various embodiments, the primary sense port 60 and the auxiliary sense port 62 communicate with respective voltage sensors 64, 66 to receive information about the respective matching RF signals 22, 30. The respective voltage sensors 64, 66 enable the auxiliary RF generator 14 to determine the amplitude of the respective matching RF signals 22, 30 and the phase of the respective matching RF signals 22, 30. In various embodiments, the amplitude and phase of the RF signals can be controlled for each pulse state of the respective RF generators 12, 14. The amplitude and phase data are processed by the auxiliary RF generator 14 to determine proper synchronization between the primary matching RF signal 22 and the auxiliary matching RF signal 30. Once the auxiliary RF generator 14 determines the correct adjustment to achieve proper synchronization, the auxiliary RF generator 14 communicates with the primary RF generator via the digital communication link 52 to communicate the desired phase adjustment.

[0062] The main RF generator 12 receives the adjustment request from the auxiliary RF generator 14 and adjusts the phase of the RF control signal 54 according to the adjustment request. The phase of the auxiliary matching RF signal 30 is thus phase-locked to the phase of the main matching RF signal 22. In various embodiments, the auxiliary RF generator 14 transmits other data to the main RF generator. The other data may include pulsation information.

[0063] In various embodiments, the main RF generator 12 determines the RF operating frequency of the auxiliary RF generator 14. The main RF generator 12 may implement an agile frequency tuning (AFT) method to minimize reflected power. The main RF generator 12 may also set pulse conditions based on a desired pulse repetition rate, power level, and duty cycle. In various embodiments, the auxiliary RF generator 14 generates RF power at the frequency determined by the main RF generator 12 and is phase-locked to the operation of the main RF generator 12.

[0064] Figure 2 A schematic and functional block diagram depicts an expanded view of the auxiliary RF generator 14. The auxiliary RF generator 14 includes a controller portion 100, a signal generating portion 102, a power amplifier portion 104, an energy dissipating portion 106, and a DC generating portion 108. The controller portion 100 includes a control module or controller 110, which further includes an auxiliary RF detector module 112, a main RF detector module 114, an RF actuator module 116, and a customer interface 118. The auxiliary RF generator 14 may further include a memory 122. The memory 122 may be used to store set, predetermined, and / or detected voltages, phases, and other operating parameters.

[0065] The auxiliary RF detector module 112 communicates with the primary and auxiliary sense ports 60, 62. The auxiliary RF detector module 112 receives primary and auxiliary voltage sensor signals from the corresponding primary and auxiliary voltage sensors 64, 66 via the corresponding primary and auxiliary sense ports 60, 62. The auxiliary RF detector module 112 of the controller 110 determines the amplitude and phase (relative phase or phase difference) of the corresponding primary and auxiliary RF outputs (before or after the matching network) and determines whether a phase or amplitude correction is necessary. The phase correction is communicated to the primary RF generator 12 via the digital communication link 52. The auxiliary RF detector module 112 communicates the desired phase correction via status / control lines and the communication module 126.

[0066] The controller 110 also includes a main RF detector module 114 that determines selected electrical characteristics of the RF output from the power amplifier section 104. The main RF detector module 114 communicates with the controller 110 regarding the status of the RF signal or output 26. The controller 110 also includes an RF actuator module 116. The RF actuator module 116 receives the pulse synchronization signal 50 via the pulse synchronization input port 48. The RF actuator module 116 also receives an RF detection signal from the RF synchronization module 142, as will be described in greater detail herein. The RF actuator module 116 generates control signals to control the frequency and power of the continuous wave RF signal component of the RF output 26 and the pulsed component of the RF output 26 in various modes.

[0067] The signal generation portion 102 includes an RF switch module 140 that receives an RF control signal 54 from the main RF generator 12 via the RF input port 42. The RF control signal 54 is passed to the RF switch module 140. The RF switch module 140 also receives a pulse input from the RF actuator module 116. The pulse input is generated by the RF actuator module based on a pulse synchronization signal 50 received at the pulse synchronization input port 48. The RF switch module 140 controls the generation of the pulsed sinusoidal signal, as will be described herein.

[0068] As will be described in greater detail herein, the RF synchronization module 142 enables the auxiliary RF generator 14 to operate as a slave RF generator or as an independent generator, wherein the RF sinusoidal component of the RF output signal is generated independently of the master RF generator 12. In the slave configuration of the auxiliary RF generator 14 (where the master RF generator 12 controls the operation of the auxiliary RF generator 14), the RF synchronization module 142 effectively passes the pulsed RF signal received from the slave RF switch module 140 and generates a pair of RF signals that are input to the phase shifter module 144. The phase shifter module 144 receives a pulse amplitude control signal from the RF actuator module 116. The pulse amplitude control signal determines the relative phase shift between the pair of pulsed RF signals input to the phase shifter module 144. The phase shifter module 144 generates a pair of phase-shifted signals phi1 146 and phi2 148 that are output from the signal generation portion 102.

[0069] Phase-shifted signals phi1 and phi2 are output to the power amplifier section 104. The pair of phase-shifted signals are input to a driver 152. The driver 152 generates corresponding drive signals to the power amplifiers 154 and 156. The outputs from the power amplifiers 154 and 156 are combined and input to a filter 158. In various embodiments, the filter 158 may be a harmonic filter to remove harmonics and generate a filtered signal that is input to the VI sensor 160. The VI sensor 160 may be a voltage / current sensor or a directional coupler as described above. The auxiliary RF generator 14 thus provides a pulsed RF output 26.

[0070] Phi1 provides a drive signal for power amplifier 154, and phi2 provides a drive signal for power amplifier 156. In various embodiments, power amplifiers 154, 156 are driven by the drive signals to achieve out-of-phase between power amplifiers 154, 156. Out-phasing controls the amplitude of the output signal of power amplifier section 104 by changing the phase between power amplifiers 154, 156 by varying phi1 and phi2. Those skilled in the art will recognize that various applications do not require out-of-phase signal generation, and various embodiments may use a single drive signal and power amplifier.

[0071] The VI sensor 160 can be implemented as described above with respect to a directional coupler and a VI sensor. The VI sensor 160 outputs a pair of sensor signals to an analog front end 164 of the signal generating portion 102. The analog front end 164 receives the analog signal from the VI sensor 160 and generates a digital signal that is input to the main RF detector module 114. The VI sensor 160, the analog front end 164, and the main RF detector 114 are capable of measuring various electrical characteristics of the RF output from the auxiliary RF generator 14.

[0072] In various embodiments, the power amplifiers 154, 156 are configured to include voltage clamps, such as inductive voltage clamps. Examples of such systems can be found in U.S. Patent Nos. 6,469,919, 6,618,276, 6,885,567, 7,180,758, and 7,397,676, all assigned to the assignee of the present application and incorporated herein by reference.

[0073] The power amplifiers 154, 156 receive DC power generated from the DC generation section 108. The DC generation section 108 includes an AC / DC converter that receives a three-phase AC input signal and generates a DC output signal. The AC / DC converter 170 generates an agile DC supply voltage on a voltage rail that powers the respective power amplifiers 154, 156. The AC / DC converter 170 generates a variable DC output voltage to vary the amplitude of the RF signal output by the respective power amplifiers 154, 156. The controller 110 of the control section 100 communicates with the AC / DC converter 170 via a power supply unit (PSU) interface so that the controller 110 can monitor and change the operation of the AC / DC converter 170 in order to generate the desired rail voltage to power the power amplifiers 154, 156. The DC bus 16 is shown connected to the AC / DC converter 170. Figures 2 to 4 , the DC bus 16 is shown with dashed lines to indicate that it may be connected to the respective primary and auxiliary RF generators 12, 14 in various configurations.

[0074] The DC generation section 108 communicates with the energy dissipation section 106. The energy dissipation section 106 includes a variable resistive load 172 connected to a voltage rail that connects the AC / DC converter 170 and the power amplifiers 154 and 156. The variable resistive load 172 provides a current drain or sink for power reflected from the load connected to the RF output 26. In various embodiments, the coupling network 24 reflects or transmits power back to the power amplifiers 154 and 156. The voltage clamping circuits of the power amplifiers 154 and 156 return the reflected / transmitted power to the variable resistive load 172, where the energy / power is dissipated. In various embodiments, the reflected energy / power is dissipated in the AC / DC converter 170 without the assistance of the variable resistive load 172. However, in various other embodiments, the AC / DC converter 170 is sized such that the power reflected from the coupling network 24 exceeds the power dissipation capability of the AC / DC converter 170. The variable resistive load 172 may be controlled via a load control signal from the controller 110 to vary the energy dissipated or the power reflected by the inductive clamp circuits of the power amplifiers 154, 156. The load control signal generated by the controller 110 may use a pulse width modulated or pulse density modulated signal to vary the impedance of the variable resistive load 172, thereby variably controlling the power drawn from the coupling network 24 toward the power amplifiers 154, 156.

[0075] With reference to coupling network 24, as discussed above, in various embodiments, it may be desirable to control the ion angle so that the ions are directed orthogonally at the workpiece or wafer to better control the etching process. As also discussed above, the electrical power and electric fields near the edge of the wafer often present additional challenges for accurately controlling the directionality of the ions toward the wafer. By varying the resistance of variable resistive load 172, the ions near the edge of the wafer can be better directed to effect a more accurate etching process.

[0076] The RF synchronization module 142 operates variably depending on whether the auxiliary RF generator 14 is operating in the auxiliary or master / standalone mode. The standalone mode occurs when the auxiliary RF generator 14 operates independently of the master RF generator 12. The RF synchronization module 142 receives a mode signal from the RF actuator module 116 of the controller 110 indicating whether the auxiliary RF generator 14 is operating in the auxiliary mode or the master / standalone mode.

[0077] In the slave or auxiliary mode, the signals phi1 and phi2 output by the RF actuator module 116 to the RF synchronization module 142 have no effect. The RF signal received from the RF switch module 140 passes through the RF synchronization module 142. The phase shifter module 144 generates the drive control signals phi1 and phi2 based on the pulse amplitude control signal received from the RF actuator module 116.

[0078] In master / standalone mode, the auxiliary RF generator 14 relies on the RF actuator module 116 for controlling the desired RF signal frequency. In various embodiments, in master / standalone mode, the auxiliary RF generator 14 receives a pulsed synchronization signal 50 from the pulsed synchronization input port 48. In other various embodiments, in master / standalone mode, the RF actuator module 116 determines the synchronization pulse. Also in master / standalone mode, the RF synchronization module 142 and the phase shifter module 144 operate in a pass-through mode, as the RF actuator module 116 generates the drive signals phi1 and phi2 that are passed to the driver 152. In standalone operation, the power amplifiers 154 and 156 operate out of phase to vary the phase between the power amplifiers 154 and 156 in order to control the output power of the auxiliary RF generator 14. In auxiliary mode, the variable resistive load 172 provides a dissipative load to variably dissipate power reflected from the coupling network 24.

[0079] Figure 3 Depicts a structural and functional block diagram of the auxiliary RF generator 14' of the RF power system 10 configured to operate in auxiliary or slave mode. Figure 2 Components of the auxiliary RF generator 14 are removed to provide a simplified configuration of the RF generator in the auxiliary slave mode. Figure 3 In the configuration of the auxiliary RF generator 14 'as described above Figure 1 and Figure 2 Operate as described. Figure 3 The auxiliary RF generator 14' will not operate in either the master or standalone mode.

[0080] Figure 4 Depicting the structure and functional block diagram of the auxiliary RF generator 14' of the RF power system 10 configured to operate in either a primary or standalone mode. Figure 2 The components of the auxiliary RF generator 14 are removed. In this mode, the auxiliary RF generator 14' does not require an external RF signal output to determine the frequency of the RF signal it generates. Figure 4, the pulse synchronization input port 48 receives the pulse synchronization signal 50, which is input to the RF actuator module 116 of the controller 110. The pulse synchronization signal 50 controls the pulsation of the RF output of the auxiliary RF generator 14". The RF actuator module 116 does not generate a pulse amplitude control signal to the phase shifter module 144. Instead, the RF actuator module 116 generates phi1 and phi2 signals that are input to the driver 152. Figure 4 The auxiliary RF generator 14" does not include, for example, Figure 2 and Figure 3 In various embodiments, the power amplifiers 154, 156 include inductive clamps, and the power reflected from the coupling network 24 to the auxiliary RF generator 14 can be returned to the AC / DC converter 170. Figure 4 In various other embodiments shown, the AC / DC converter 170 generally outputs higher power, so the variable resistive load 172 may be optional to dissipate the power level returned from the coupling network 24. In various other embodiments, the inductive clamps of the power amplifiers 154, 156 may return energy to the main RF generator 12 via a DC bus connection (e.g., DC bus 16), and such energy flow may be passed through the AC / DC converter or bypass the AC / DC converter 170. If the energy flow bypasses the AC / DC converter 170, the DC bus 16 may be as shown. Figure 4 Configure as shown.

[0081] In various embodiments described herein, the master and slave devices can operate at the same frequency because the drive signals originate from a common point in the system. Transient voltage spikes can occur in a phase-locked loop (PLL) implementation during rapid frequency or amplitude changes. The disclosed direct path of the phase-shifted master RF control signal 54 to the auxiliary power amplifiers 154, 156 prevents transient voltage spikes. In addition, the integrated inductive clamp and variable resistive load increase the range of voltage control at the electrodes and coupling network, which the auxiliary RF generator 14 supplies power to.

[0082] In various embodiments, the auxiliary RF generator 14 can function as the main RF generator, and the main RF generator 12 can function as the auxiliary RF generator. That is, the auxiliary RF generator 12 and the controller 110, in various embodiments, control the rail voltages to the power amplifiers 154, 156 and the phase of the RF output signal 26. In various other embodiments, the controller 110 of the auxiliary RF generator 14 also generates control signals that are input to the main RF generator 12 to control the voltage and phase of the main RF signal 18, including controlling the DC rail voltage in the main RF generator to vary the voltage of the main RF output signal 18 and controlling the phase of the main RF signal 18 to control the phase difference between the RF signals output by the respective auxiliary RF generators 14 and main RF generators 12. In various embodiments, the auxiliary RF generator 14 outputs the RF signal to the main RF generator 12 via the RF input port 42, in which case the RF input port 42 operates as an output port or an input / output port. The phase shift between the RF output signals 18, 26 (or 22, 30) can occur when the phase shifter module 144 affects the phase shift of the RF output signal 26 relative to the RF signal sent to the main RF generator 12 via the (reverse) input port 42. Alternatively, the main RF generator 12 may include a phase shifter module similar to the phase shifter module 144, and the auxiliary RF generator 14 may output the commanded phase shift to the main RF generator 12 via the digital communication port 46 for application by a phase shifter local to the main RF generator 12. Furthermore, in various embodiments, the main sense port 60 and the auxiliary sense port 62 may be configured when the main RF generator 12 is connected. In such a configuration, the main RF generator 12 and the auxiliary RF generator 14 may communicate sensed electrical characteristic information using the digital communication ports 36, 46.

[0083] Figure 5 An exemplary diagram depicts RF signals of the RF power system 10 according to various embodiments. Waveform 200 depicts an RF signal output by the main RF generator 12, such as the main matching RF signal 22. Waveform 202 depicts an RF signal output by the auxiliary RF generator 14, such as the auxiliary RF signal 26. Waveforms 200 and 202 illustrate challenges addressed by current embodiments. When waveforms 200 and 202 are compared, it can be seen that there is a phase difference between waveforms 200 and 202. Because matching networks 20 and 28 introduce different phase shifts, waveforms 200 and 202 are not phase-aligned. Waveforms 204 and 206 depict an improvement provided by embodiments of the present disclosure.

[0084] Waveform 204 represents the matched RF signal 20 output from the main matching network 20. Waveform 204 has thickness to indicate frequency content introduced into waveform 204 from other generators in the RF power system 10, such as from the source RF generator. Waveform 206 depicts an example waveform of the auxiliary matched RF signal 30 output from the auxiliary matching network 28. Waveform 206 is also depicted as having thickness to indicate high frequency content, such as from the source RF generator, although waveform 206 includes less frequency content than waveform 204. As can be seen, waveforms 204 and 206 depict phase-aligned RF signals, such as would be output by the main RF generator 12 and the auxiliary RF generator 14.

[0085] Figure 6 A flowchart 300 is depicted for adjusting the phase of an auxiliary RF generator relative to a primary RF generator. Control begins at block 302 and proceeds to block 304. Block 304 measures the phase difference between the primary and secondary RF generators. Once the phase difference is measured, control proceeds to block 306, where a determination is made as to whether the phase difference is zero. If the phase difference is zero, no adjustment is required, and control returns to block 304 to again measure the phase difference between the primary and secondary RF generators. If the phase difference is not zero, control proceeds to block 308, where the auxiliary RF generator sends a command to the primary RF generator requesting the primary RF generator to change the phase of the RF generator. Control proceeds to block 304 to again measure the phase difference between the primary and secondary RF generators.

[0086] Figure 7 A flowchart 320 is depicted for determining the voltage or power output of an auxiliary RF generator. Control begins at block 322 and proceeds to block 324. Block 324 measures the voltage of the auxiliary RF generator's RF output. Once the voltage is measured, control proceeds to block 326, where a determination is made as to whether the measured voltage is equal to a predetermined set point. If the measured voltage is equal to the predetermined set point, control proceeds to block 324 to measure the voltage of the auxiliary generator's RF output again. If the measured voltage is not equal to the predetermined set point, control proceeds to block 328. At block 328, the output of the agile DC power supply is adjusted to change the rail voltage applied to the power amplifier of the auxiliary RF generator. Control proceeds to block 324 to measure the voltage of the auxiliary RF generator's RF output again.

[0087] In various configurations, Figure 1 The RF control system is adjustable within a predetermined operating space. For example, the RF control system is typically controlled by selecting the position of the variable capacitor in the auxiliary matching network 28. Figure 1Auxiliary matching network 28. In various embodiments, the full range of positions of the variable capacitor is not always available, especially over the entire operating space. The operating space in which the variable capacitor can be located to achieve system operation is generally referred to as the adjustable operating space. Preferably, the adjustable operating space can be maximized. For example, the auxiliary matching network 28 may include a variable capacitor capable of adjusting multiple positions. However, in various embodiments, only selected positions are available within a predetermined frequency range. As a non-limiting example, if the auxiliary RF generator 14 operates at up to 400 kHz, changing between positions at frequencies greater than a predetermined frequency, such as 380 kHz, results in extended settling times and oscillations between the voltage and phase control loops of the auxiliary electrode 40 to which the RF signal is applied. When outside the adjustable operating space, control challenges include instability near the edges of the actuator range and oscillations or swings in the steady-state values of the auxiliary voltage and phase at higher frequencies.

[0088] Figures 8A to 8E instruct Figure 1 The relationship between various electrical parameters of the RF power control system 10. Figure 8A Depicts the voltage waveforms of the primary voltage 400 and the auxiliary voltage 402 at the outputs of the respective primary matching network 20 and the auxiliary matching network 28, respectively. Figure 1 The primary voltage 400 and the auxiliary voltage 402 are measured elsewhere in the circuit (including the corresponding primary electrode 32 and auxiliary electrode 40). Figure 8B A waveform 404 indicating the net power in Watts delivered by the auxiliary RF generator 14 is depicted. Figure 8C A waveform 406 is depicted indicating the phase difference in degrees between the RF signals applied to the respective primary and auxiliary electrodes 32, 40. Figure 8D Describes the indication as set by the voltage actuator Figure 2 The rail voltage of the agile DC power supply voltage V RAIL FIG8E depicts a waveform 410 indicating the relative phase set point commanded by the phase actuator of the auxiliary RF generator 14. Thus, the phase, phase set point, or phase actuator is determined by Figure 2 The desired phase is determined by the controller 110. In the case of a phase RF envelope, the waveform in FIG8 indicates the measured value for a given pulse state. For example, in the case of a pulse waveform with 4 states, there will be four measured values, one for each pulse state. Each pulse state results in a waveform indicating the corresponding value for each pulse state as shown in FIG. Figures 8A to 8E In the case of continuous wave (CW) operation, there will be a waveform similar to Figures 8A to 8EThe controller 110 processes each pulse state individually and smoothly transitions between states as they progress from 1..n and then repeat.

[0089] As in Figures 8A to 8E As can be seen in FIG, starting at time T1, adjustments to the phase and rail voltage actuators of the auxiliary RF generator 14, without considering the effects of cross-terms between the control loops, result in oscillations of waveforms 400, 402, 404, 406, 408, and 410. That is, the phase and rail voltage are adjusted independently. The phase is adjusted according to one control loop, and the rail voltage is adjusted according to a second control loop. Independent control results in Figure 8A to Figure 8E The oscillations of the waveforms in φ , ...oscillations result in corresponding instabilities that inhibit the stability of waveforms 400 - 410 .

[0090] Figures 9A to 9E Describes something similar to Figures 8A to 8E The electrical characteristics of Figure 8A Similar reference numerals to those in FIG. 8E refer to Figures 9A to 9E waveform. Figure 9E Indicates the response resulting from the transition in the variable capacitance of the auxiliary matching network 28. At time T1 (which represents the time at which the auxiliary RF generator rail voltage V RAIL and phase), the rail voltage 412 and phase 410 initially deviate from stable or steady-state values near and after time T2, as shown at respective points 412, 414. In other words, at the transition, Figure 9D The commanded rail voltage waveform 408 should increase from the rail voltage before time T1 in order to reach a stable condition at T2. However, as shown at point 412, the rail voltage V RAIL Likewise, the commanded phase at point 414 increases rather than decreases before converging to a stable value at time T3. In other words, in response to the transition, the rail voltage and phase waveforms 408, 410, respectively, initially adjust away from their final stable values.

[0091] Figure 10A and Figure 10B An example contour diagram depicting an RF system having a primary electrode and an auxiliary electrode is shown. Figure 10A Contour map of . Figure 10A The description of contour plots generally applies to contour plots described throughout the specification. Figure 10A In FIG, the x-axis represents the phase or phase set point as defined by the phase actuator. The y-axis represents the rail voltage V RAIL. The phase of the x-axis and the rail voltage of the y-axis define two inputs for varying the incremental phase defined along the z-axis in three-dimensional space. To represent the z-axis in two-dimensional space, contour lines 420a, 420b, ..., 420g define lines of constant incremental phase. Incremental phase is generally defined as the phase difference between the RF signal applied to the main electrode 32 and the RF signal applied to the auxiliary electrode 40. In various embodiments, contour line 420a corresponds to -D2, indicating a negative incremental phase or phase lag of the RF signal applied to the auxiliary electrode 40 relative to the RF signal applied to the main electrode 32. Contour line 420b corresponds to incremental phase -D1, contour line 420c corresponds to 0 incremental phase, contour line 420d corresponds to incremental phase D1, contour line 420e corresponds to incremental phase D2, contour line 420n corresponds to incremental phase D3, and contour line 420g corresponds to incremental phase D4. The area between the contour lines represents the transition in incremental phase between the corresponding contour lines, which may be gradual or abrupt.

[0092] Figure 10A Indicates the phase of the RF signal applied to the auxiliary electrode 40 and the rail voltage V of the auxiliary RF generator 14 RAIL As mentioned above, the rail voltage V RAIL represents the output of the agile DC power supply and is applied to the corresponding power amplifiers 154, 156. As a non-limiting example, Figure 10A Point 422 indicates the voltage for a given phase (x-axis) and rail voltage V RAIL (y-axis), incremental phase = 0. That is, for phase x = a and rail voltage V RAIL y=b, delta phase level=0 (z=0).

[0093] Figure 10B is the auxiliary voltage indicating the phase relative to the auxiliary RF generator 14 (x-axis) and Figure 2 The rail voltage V output of the agile DC power supply RAIL (y-axis). The auxiliary voltage is typically described as the voltage at the auxiliary electrode 40 and can be measured using peak-to-peak or root mean square (RMS) techniques. Figure 10B The contour curve of indicates the auxiliary voltage at the auxiliary electrode 40. As a non-limiting example, it is of particular interest to Figure 10B Point 424. For a given phase x=n and rail voltage V RAIL y=n,auxiliary voltage level=V R5 , as shown at point 424 .

[0094] Figure 11A and Figure 11B It is depicted from Figure 10A and Figure 10B The initial conditions represented by Figure 11A and Figure 11B For example, in various embodiments, Figure 10A and Figure 10B It can be used to express the incremental phase for RF power delivery systems with respect to the phase and rail voltage V RAIL (for Figure 10A ) and the auxiliary voltage relative to the phase and rail voltage V RAIL ( Figure 10B ), wherein the auxiliary matching network 28 is configured such that the adjustable element of the auxiliary matching network 28 is in a first position. Figure 11A and Figure 11B represents the corresponding incremental phase relative to the phase and rail voltage V when the adjustable element of the auxiliary matching network 28 is displaced to the second position RAIL ( Figure 10A ) and the auxiliary voltage relative to the phase and rail voltage V RAIL ( Figure 10B In various embodiments, the adjustable element can be adjusted from a first position to a second position.

[0095] refer to Figure 10A and Figure 11A , the selected point 422 represents phase a = rail voltage V RAIL = b, and the resulting incremental phase level = 0. Figure 10A As shown, point 422 is located at the contour increment phase = 0. After the transition, the position of the contour changes, wherein the contour values -D2, -D1, ..., D4 are Figure 10A and Figure 11A In various embodiments, it is preferred that point 422 remain on the same contour line in this non-limiting example, such as delta phase = 0. In order to remain on the same contour line, point 422 must be moved from Figure 10A Point 422 transitions to Figure 11A The transition occurs along arrow 426. To move from point 422 to point 422', the phase must be adjusted from x=a to x=a' and the rail voltage V RAIL Adjust from y=b to y=b' to maintain the position of point 422 on the contour incremental phase=0.

[0096] Likewise, in Figure 10B In the figure, point 424 is shown as phase x=m, rail voltage V RAIL =n and auxiliary voltage level = V R5 . Figure 10B and Figure 11B V in R1,...,V R7 Contour lines indicate similar values. Figure 10B Point 424 is shown along the contour line V R5 In order to maintain point 424 on the contour line V R5 superior, Figure 10B Point 424 transitions to point 424' along arrow 428 in FIG. 11B. Figure 11B As shown, the phase must be changed to x=m' and the rail voltage V RAIL Change to y=n' to maintain point 424 along the contour line V R5 , such as shown at point 424'. Figure 10A and Figure 11A Points 422 to 422' shown and Figure 10B and Figure 11B In each instance of the transition from point 424 to point 424' shown, the phase set point must be decreased and the rail voltage V RAIL Therefore, in various embodiments, Figure 10A and Figure 10B as well as Figure 11A and Figure 11B Prove that the control phase and rail voltage V RAIL is necessary in order to maintain the position along the predetermined contour.

[0097] Figure 12A and Figure 12B depiction Figure 12A The incremental phase in relation to the phase and rail voltage V RAIL and the auxiliary voltage in FIG12B relative to the phase and rail voltage V RAIL Contour map of . Figure 12A and Figure 12B Each contour plot in the Figure 12A Phase = d, rail voltage V RAIL =e and incremental phase =f and Figure 12B Point 428 where auxiliary voltage = g. Figure 12A and Figure 12B The curves 430 and 432 and the corresponding contour plots indicate the proximity of Figure 12A and Figure 12B The rail voltage V RAIL and phase solution challenges.

[0098] like Figure 12A As shown, in the area around point 428, the rail voltage V RAIL affects the incremental phase because point 428 is on a contour line roughly parallel to the rail voltage V RAIL The change of incremental phase affects the position of Figure 12BConvergence of point 428 in . In addition, as Figure 12B As shown, the auxiliary voltage contour lines V1, ..., V 12 is parallel to the phase value, so that small phase actuator changes significantly affect the voltage. Similarly, Figure 12B In the figure, the auxiliary voltage contour lines V1, ..., V 12 Roughly perpendicular to the rail voltage V RAIL Therefore, a large rail voltage V RAIL Therefore, waveforms 430 and 432 are generated by changing the phase and rail voltage V RAIL An independent control loop is used to direct the surround around the desired endpoint 428 in order to arrive at the desired set point on the selected contour line.

[0099] Figure 12A and Figure 12B Display pair Figure 1 The various configurations of RF power systems present specific challenges, where regulating a single input presents challenges for accurate control of the auxiliary voltage. It can be seen that the phase or rail voltage V RAIL A significant increase in one of the variables is necessary to change the position of a point along the contour line, such as point 428, and smaller changes in the other variables result in significant changes in the position of point 428 along the contour line. Thus, single-input systems can lead to certain challenges where a single input is changed in order to adjust a specific output.

[0100] As a comparison, Figure 13 Indicates the contour plot where the rail voltage V RAIL Can be changed to adjust the position of a point such as point 440. Figure 13 In the example, point 440 corresponds to the phase x=h, the rail voltage V RAIL y=i and thus auxiliary voltage=j. Figure 13 A condition is presented in which one of the inputs is changed, either the phase along the x-axis or the rail voltage V along the y-axis RAIL , so that along the contour line, for example along the contour line V with reasonable resolution T5 The adjustment of point 440 becomes possible. Figure 12A and Figure 12B By adjusting the phase along the x-axis or the V along the y-axis RAIL One of them cannot make such resolution possible.

[0101] Figure 14 Describes the various embodiments for controlling Figure 1-4 The auxiliary RF generator 14 is used to supply agile DC power to the actuator (rail voltage V RAIL) and a linear-quadratic-integral (LQI) control system of a phase actuator (phase). Figure 14 The LQI configuration provides optimal control, wherein the controller gains are determined based on minimization of a cost function. Such a configuration utilizes internal measurements and output feedback for controlling selected parameters of the auxiliary RF generator 14. Figure 14 The control system is inherently multiple-input, multiple-output (MIMO). In various embodiments, performance is highly tunable, including enabling separate adjustments to feedback error, state, and actuator amplitude.

[0102] exist Figure 14 In FIG, the control system 480 receives an input value r, which represents a vector or matrix, which is the set point for the auxiliary voltage and the incremental phase or phase difference between the main RF signal and the auxiliary RF signal:

[0103]

[0104] in:

[0105] r Aux representing a set point for the voltage of the RF waveform applied to the auxiliary electrode; and

[0106] r 增量相位 A set point that represents the phase difference or delta phase between the primary and secondary RF waveforms.

[0107] The set point r is compared with the system output:

[0108]

[0109] in:

[0110] y1=V Aux a measured voltage representing the RF waveform applied to the auxiliary electrode; and

[0111] y2=Δ 相位 represents the measured phase difference between the primary RF waveform and the auxiliary RF waveform.

[0112] The input r is applied to the adder 482 which determines the difference or error represented as a matrix or vector e. The matrix or vector e represents the auxiliary voltage set point r Aux and the measured auxiliary voltage set point y Aux The difference between the two and the incremental phase set point r 增量相位 and the measured incremental phase output Δ 相位 That is,

[0113]

[0114] in:

[0115] e Aux represents the error or difference between the commanded RF voltage applied to the load and the actual RF voltage applied to the load; and

[0116] e 增量相位 Represents the error or difference between the commanded phase difference and the actual phase difference between the primary and secondary RF signals.

[0117] The error e is input to the integrator and is represented by the matrix or vector x j The integrated error value represented by is applied to block 488. The matrix or vector x j It can be expressed as follows:

[0118]

[0119] in:

[0120] x3 represents the integral of the auxiliary electrode error input by integrator 486; and

[0121] x4 represents the integral of the phase difference error output by integrator 486.

[0122] Block 488 receives the integrated error value e and also receives a matrix or vector x comprising the values of the internal states output by the system block 490. The matrix or vector x is represented as follows:

[0123]

[0124] in:

[0125] x1=x 轨道 represents the measured auxiliary rail voltage state output by system 490, as will be further described below; and

[0126] x2=x 相位 represents the measured auxiliary phase state output by system 490.

[0127] Block 488 is a gain block that applies the feedback gain matrix K to generate a control matrix or vector u to the system block 490. The matrix or vector u is represented as follows:

[0128]

[0129] in:

[0130] u1 represents the command rail voltage V of the auxiliary RF generator 轨道 ;and

[0131] u2 represents the command phase of the RF waveform output by the auxiliary RF generator.

[0132] System block 490 responds to input u to regulate the auxiliary voltage output y aux and phase output y 相位 .

[0133] exist Figure 14 The LQI or state representation depicted in replaces the nth order differential equation with a single first order matrix differential equation. Figure 14 In the control system 480, u described above in equation (6) can be further described as follows:

[0134]

[0135] in:

[0136] K 11 , K 12 , K 21 and K 22 Indicates status feedback;

[0137] K 13 and K 14 Indicates the correction constant of the auxiliary voltage;

[0138] K 23 and K 24 represents the correction constant of the phase actuator; and

[0139] x1, x2, x3 and x4 are as described above.

[0140] In various embodiments, K is configured with the following understanding: 11 , K 12 , K 21 and K 22 : Because the auxiliary voltage and the phase voltage act quickly, only minimal secondary effects exist. K 11 , K 12 , K 21 and K 22 Used to approximate the gyrodynamics of the auxiliary voltage and phase. In various embodiments, the K constant is set based on predetermined contour lines used to characterize the auxiliary RF generator at the time of manufacture. The slope between the contour lines is used to determine the K value. In various embodiments, the K constant is set based on in situ measurements of the auxiliary RF generator contour lines for given operating conditions.

[0141] Figure 15A Plotting the auxiliary voltage versus phase on the x-axis and the rail voltage V on the y-axis RAIL In various embodiments, the auxiliary voltage may be represented by shading or color, or Figure 15A and Figure 15B includes a plurality of quadrants, including quadrants 500, 502, ..., 510. Similarly, Figure 15B Plot phase shift versus phase on the x-axis and rail voltage V on the y-axis RAIL The various quadrants 512 , 514 , . . . , 522 indicate the phase offset between the primary RF generator 12 and the auxiliary RF generator 14 .

[0142] Figure 16A and Figure 16B Corresponding to the corresponding Figure 15A and Figure 15B , Figure 16A and Figure 16B In response to when the contour lines are arranged so that the RF power system can oscillate when converging to a solution, the corresponding auxiliary voltage and phase offset are indicated, e.g. Figure 12A and Figure 12B Therefore, in Figure 16A The quadrants 500', 502', ..., 510' in FIG. 5 indicate the convergence challenge conditions under such conditions. Figure 15A The positions of quadrants 500, ..., 510. Figure 16A As can be seen, from Figure 15A The shape of the auxiliary voltage is reflected around a 45-degree angle line. Similarly, Figure 15B The curve is shifted so that the position of the contour line is similarly reflected around the approximately 45-degree angle line. The position of the corresponding points 512', 514', ..., 518' indicates Figure 15B Reflection of the corresponding quadrant.

[0143] 17A to 17D Depicts various corresponding electrical parameters versus time using proportional-integral control according to various embodiments, under conditions when the contour lines are arranged in a configuration that facilitates convergence to a predetermined auxiliary voltage and incremental voltage solution. Figure 17A Waveform 540 indicates the rail voltage set point. Figure 17B A waveform 542 is indicative of an auxiliary voltage. Figure 17C Waveform 544 indicates the phase set point. Figure 17D Waveform 546 indicates the delta phase between the main RF generator 12 and the auxiliary RF generator 14. As can be seen at time T1, when the RF generator moves into closed-loop operation after power-up, the auxiliary voltage increases and the delta phase decreases accordingly. Both the auxiliary voltage 542 and the delta phase 546 stabilize almost immediately.

[0144] 18A to 18D Depict corresponding to the 17A to 17D The waveform of the electrical characteristics. Figure 18A to Figure 18D, the auxiliary voltage contours and / or incremental phase contours are arranged so that convergence to a predetermined solution results in searching or hunting around the desired solution endpoints. Waveform 540 ' corresponds to the rail voltage V RAIL , waveform 542' corresponds to the auxiliary voltage, waveform 544' corresponds to the phase set point, and waveform 546' corresponds to the incremental phase. At time T1, the RF generator output is powered up in open loop mode to a predetermined starting point for the rail voltage and phase actuator. At time T2, the RF generator enters closed loop operation. It is seen that the rail voltage 540' and the auxiliary voltage 542' exhibit instability at T2, and to a lesser extent, the phase set point 544' and the incremental phase 546' also exhibit instability. At T3, the RF generator output is disabled before shutting down. As in 18A to 18D As can be seen in Figure 3, under the selected conditions, the rail voltage and phase actuator system tend to oscillate.

[0145] Figures 19 and 20 depict 19A to 19D and 20A to 20D The waveform depicted is the same as the corresponding 17A to 17D and / or 18A to 18D The waveform has similar electrical characteristics. However, 19A to 19D and 20A to 20D Instructions for use Figure 14 The waveform 560 depicts the rail voltage V of the auxiliary RF generator 14. RAIL , waveform 562 depicts the auxiliary voltage applied to the auxiliary electrode 40 of the coupling network 24, waveform 564 depicts the phase set point of the auxiliary RF generator 14, and waveform 566 depicts the incremental phase between the RF signals applied to the respective main and auxiliary electrodes 32, 40. Waveforms 560', 562', 564', and 566' depict waveforms of similar electrical characteristics.

[0146] 19A to 19D Depicts a waveform where the contour plot of the RF system is arranged to facilitate convergence to a predetermined point. 19A to 19D The waveform represents the use of Figure 14 The control model provides the implementation of the control.

[0147] 20A to 20D Depicted by Figure 14 The control support system is a control implemented in a configuration in which the incremental phase and auxiliary voltage contours are arranged so that the rail voltage V RAIL and / or phase setpoints can be searched for solutions. 19A to 19D and 20A to 20D As shown, using Figure 14The control indication provided in FIG: The waveforms 560 ′, 562 ′, 564 ′, 566 ′ converge to stability relatively quickly relative to the waveforms 560 , 562 , 564 , 566 of the nominal condition. 19A to 19D and 20A to 20D As can be seen in Figure 1, at time T1, the controller enters the learning phase. The actuator is manipulated using a predetermined sequence and auxiliary voltage, and the incremental phase output is recorded. Using this information, the slopes of the contours for the current operating conditions are calculated. These are then used to update the K matrix of controller gains. At time T2, the RF generator enters closed-loop operation using these updated gain parameters. 19A to 19D and 20A to 20D The system converges relatively quickly to stability with minimal oscillations. It can be seen that regardless of the configuration of the contours of the incremental phase and / or auxiliary voltage, Figure 14 The system provides convergence.

[0148] Figure 21 A control module 569 is shown. Figures 2 to 4 The control module or controller 110 may be implemented as a control module 569. The control module 569 may include an auxiliary RF voltage module 568, a phase difference module 570, a voltage comparison module 572, a phase comparison module 574, a DC voltage module 576, and a phase output module 578. In various embodiments, the control module 569 includes a processor that executes code associated with the modules 568, 570, 572, 574, 576, and 578. Figure 22 The operations of modules 568, 570, 572, 574, 576, and 578 are described below.

[0149] for Figures 2 to 4 For further definition of the structure of the control module, see the following Figure 22 The method and the definition of the term "module" are provided below. Many methods can be used to operate the system disclosed herein, among which the example RF control system method is in Figure 22 Although Figures 2 to 4 The following operations are primarily described for implementations of the present disclosure, but the operations can be easily modified to apply to other implementations of the present disclosure. The operations can be performed repeatedly. Although the following operations are shown and primarily described as being performed sequentially, one or more of the following operations can be performed while performing one or more of the other operations.

[0150] As a non-limiting example, Figure 22 Depicts used for control Figure 1FIGURE 58 is a flow chart diagram of a multi-input multi-output control system for the auxiliary RF generator 14 of the RF power system 10 of FIGURE 58. The method begins at a start block 582 and proceeds to blocks 584 and 586. At block 584, the auxiliary RF voltage module 568 of the control module 569 measures the voltage output of the auxiliary RF generator 14, for example, via the auxiliary voltage sensor 66. At block 586, the phase difference module 570 of the control module 569 measures the phase difference between the respective RF output signals of the main RF generator 12 and the auxiliary RF generator 14. It should be noted that blocks 584 and 586 may be used in various embodiments as shown in FIGURE 58. Figure 22 The steps are shown as being performed in parallel, or may be performed sequentially in various other implementations.

[0151] Once the output voltage of the auxiliary RF generator 14 and the phase difference between the auxiliary RF generator 14 and the main RF generator 12 have been determined, control proceeds to decision block 588. At decision block 588, two separate decision inputs are considered. At block 590, the voltage comparison module 572 of the control module 569 determines whether the measured output voltage is within a range of, or equal to, a predetermined set point. At block 592, the phase comparison module 574 of the control module 569 determines whether the phase difference is within a range of, or equal to, a predetermined value (increment). As shown at block 588, if the voltage is equal to the predetermined set point and the phase difference is equal to the predetermined difference increment, control proceeds back to blocks 584 and 586. In other words, no adjustment of the output voltage or phase difference is required. Further at block 588, if the voltage is not equal to the predetermined set point or the phase difference is not equal to the predetermined difference increment, control proceeds to block 594.

[0152] Block 594 implements multi-input multi-output control of the voltage set point of the auxiliary voltage and the phase difference between the main RF generator 12 and the auxiliary RF generator 14. Thus, both inputs can be adjusted or controlled in response to one or both of the auxiliary voltages not being at a predetermined set point or the phase difference not being at a predetermined value increment. At block 596, the DC voltage module 576 of the control module 569 generates a control signal to adjust the output of the agile DC power supply, for example, Figure 2 170 of the control module 569 to change the output voltage of the auxiliary RF generator 14. At block 598, the phase output module 578 of the control module 569 determines a phase set point for the auxiliary RF generator to adjust the phase difference to a predetermined value increment. At block 598, the phase output module 578 causes the auxiliary RF generator 14 to generate a request to the main RF generator 12 to affect a corresponding adjustment to the phase of the auxiliary RF generator 14.

[0153] Block 594 is configured to demonstrate the process of regulating the output of the agile DC power supply to vary the rail voltage V RAILand adjust the phase of the auxiliary RF generator 14. Link 600 indicates the communication between the corresponding blocks 596, 598. That is, the DC voltage module 576 and the phase output module 578 communicate. Thus, block 594 indicates, for example, Figure 14 Thus, flow chart 580 illustrates the implementation of control by regulating Figure 2 The rail voltage of the DC power supply 170 V RAIL Multiple-input, multiple-output control and phase control provided, for example, by an RF control signal.

[0154] The foregoing description is merely illustrative in nature and is in no way intended to limit the present disclosure, its application or use. The broad teachings of the present disclosure can be implemented in various forms. Therefore, although the present disclosure includes specific examples, the true scope of the present disclosure should not be so limited, because other modifications will become apparent when studying the drawings, description and subsequent claims. It should be understood that one or more steps within the method can be performed in different orders (or simultaneously) without changing the principles of the present disclosure. In addition, although each embodiment is described above as having certain features, any one or more of those features described in any embodiment of the present disclosure can be implemented in any other embodiment and / or combined with the features of any other embodiment, even if the combination is not explicitly described. In other words, the embodiments are not mutually exclusive, and the arrangement of one or more embodiments to each other is still within the scope of the present disclosure.

[0155] Spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including "connected," "engaged," "coupled," "adjacent," "near," "on top of," "above," "below," and "arranged." Unless explicitly described as "directly," when describing a relationship between a first element and a second element in the above disclosure, the relationship can be a direct relationship, in which there are no other intervening elements between the first element and the second element, but can also be an indirect relationship, in which there are one or more intervening elements (spatially or functionally) between the first element and the second element. As used herein, the phrase "at least one of A, B, and C" should be construed to mean a logical (A or B or C), using a non-exclusive logical OR, and should not be construed to mean "at least one of A, at least one of B, and at least one of C."

[0156] In the accompanying drawings, the direction of the arrow, as indicated by an arrow, generally indicates the flow of information (e.g., data or instructions) of interest to the diagram. For example, when component A and component B exchange various information, but the information transmitted from component A to component B is relevant to the diagram, an arrow may be directed from component A to component B. This unidirectional arrow does not mean that no other information is transmitted from component B to component A. In addition, for information transmitted from component A to component B, component B may send a request for the information or an acknowledgment of receipt of the information to component A.

[0157] In this application (including the definitions below), the term "module" or the term "controller" may be replaced with the term "circuit". The term "module" may refer to, be part of, or include the following: an application-specific integrated circuit (ASIC); a digital, analog, or mixed analog / digital discrete circuit; a digital, analog, or mixed analog / digital integrated circuit; a combinational logic circuit; a field-programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) that executes code; a memory circuit (shared, dedicated, or group) that stores code executed by the processor circuit; other appropriate hardware components that provide the functionality; or a combination of some or all of the above, such as in a system-on-chip.

[0158] A module may include one or more interface circuits. In some examples, the interface circuit may include a wired or wireless interface connected to a local area network (LAN), the Internet, a wide area network (WAN), or a combination thereof. The functionality of any given module of the present disclosure may be distributed among multiple modules connected by the interface circuits. For example, multiple modules may allow for load balancing. In another example, a server (also referred to as a remote or cloud) module may implement some functionality on behalf of a client module.

[0159] The term "code" as used above may include software, firmware and / or microcode, and may refer to programs, routines, functions, classes, data structures and / or objects. The term "shared processor circuitry" includes a single processor circuit that executes some or all code from multiple modules. The term "group processor circuitry" includes a processor circuit that, in conjunction with additional processor circuitry, executes some or all code from one or more modules. References to multiple processor circuits include multiple processor circuits on discrete dies, multiple processor circuits on a single die, multiple cores of a single processor circuit, multiple threads of a single processor circuit, or a combination of the foregoing. The term "shared memory circuitry" includes a single memory circuit that stores some or all code from multiple modules. The term "group memory circuitry" includes a memory circuit that, in conjunction with additional memory, stores some or all code from one or more modules.

[0160] The term "memory circuit" is a subset of the term "computer-readable medium." As used herein, the term "computer-readable medium" does not include transitory electrical or electromagnetic signals propagated through a medium (e.g., on a carrier wave); thus, the term "computer-readable medium" may be considered to be both tangible and non-transitory. Non-limiting examples of non-transitory, tangible computer-readable media are non-volatile memory circuits (e.g., flash memory circuits, erasable programmable read-only memory circuits, or mask read-only memory circuits), volatile memory circuits (e.g., static random access memory circuits or dynamic random access memory circuits), magnetic storage media (e.g., analog or digital magnetic tape or hard drives), and optical storage media (e.g., CDs, DVDs, or Blu-ray discs).

[0161] The apparatus and methods described herein may be implemented partially or entirely by a special-purpose computer, which is created by configuring a general-purpose computer to perform one or more specific functions embodied in a computer program. The functional blocks, flow chart components, and other elements described above serve as software specifications that can be translated into a computer program by routine work by a skilled technician or programmer.

[0162] The computer program includes processor-executable instructions stored on at least one non-transitory tangible computer-readable medium. The computer program may also include or rely on stored data. The computer program may include a basic input / output system (BIOS) that interacts with the hardware of the special-purpose computer, device drivers that interact with specific devices of the special-purpose computer, one or more operating systems, user applications, background services, background applications, etc.

[0163] Computer programs may include: (i) descriptive text to be parsed, such as HTML (Hypertext Markup Language), XML (Extensible Markup Language), or JSON (JavaScript Object Notation), (ii) assembly code, (iii) object code generated by a compiler from source code, (iv) source code for execution by an interpreter, (v) source code for compilation and execution by a just-in-time compiler, etc. By way of example only, languages including C, C++, C#, Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Fortran, Perl, Pascal, Curl, OCaml, HTML5 (Hypertext Markup Language 5th Revision), Ada, ASP (Active Server Pages), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Visual Lua, MATLAB, SIMULINK, and The syntax of the language is used to write source code.

[0164] None of the elements recited in a claim are means-plus-function elements within the meaning of 35 USC §112(f) unless the element is expressly recited using the phrase “means for” or in the case of a method claim using the phrase “operation of” or “step of”.

Claims

1. An RF system comprising: a first RF generator connected to a first electrode of the load, the first RF generator being configured to generate a first RF signal to the first electrode; a second RF generator connected to a second electrode of the load, the second RF generator configured to generate a second RF signal to the second electrode, wherein the first RF generator and the second RF generator provide corresponding RF voltages to the first electrode and the second electrode; as well as a controller configured to control the second RF generator, the controller generating a control signal to at least one of the first RF generator and the second RF generator, wherein the first RF generator and the second RF generator are configured to operate at the same frequency according to an RF control signal transmitted from the first RF generator to the second RF generator, wherein the second RF generator is configured to transmit a request to the first RF generator via the second digital communication port to request adjustment of the pulsation of the second RF signal, and the first RF generator is configured to change the pulse control signal applied to the second RF generator to adjust the pulsation of the second RF signal, and wherein the second RF generator further comprises: a first sensor configured to detect at least one first electrical characteristic of the first RF signal and generate a first sensor output signal based on the at least one first electrical characteristic; power amplifiers; and a DC generator configured to output a DC voltage to the power amplifier, wherein the controller is configured to receive the at least one first electrical characteristic, the controller is configured to determine a set point for the DC generator, and the controller is configured to generate a DC control signal that varies according to the set point and transmit the DC control signal to the DC generator to vary the DC voltage.

2. The RF system of claim 1 , further comprising a DC power supply configured to provide a DC rail voltage for driving a power amplifier of the second RF generator, wherein the controller varies the DC rail voltage to control the RF voltage at the second electrode.

3. The RF system of claim 2 , wherein the controller is configured to determine a phase of the first RF signal and a phase of the second RF signal and to control a phase difference between the first RF signal and the second RF signal, wherein the controller is configured to change the phase of the second RF signal according to the phase difference.

4. The RF system of claim 1 , wherein the first RF generator and the second RF generator are configured to operate in one of a continuous wave operation mode and a pulsed operation mode. The RF system of claim 1 , wherein the adjustment is one of an amplitude and a phase of the second RF signal.

6. The RF system of claim 1 , wherein the second RF generator is configured to transmit a request to the first RF generator via the second digital communication port to request adjustment of the pulsation of the second RF signal, and the first RF generator changes a pulse control signal applied to the second RF generator to adjust the pulsation of the second RF signal.

7. The RF system of claim 6, wherein the adjustment is one of a pulse repetition rate, a power level, and a duty cycle.

8. The RF system of claim 1 , wherein the second RF generator further comprises: an inductive clamping circuit, arranged in the power amplifier; as well as A variable resistor is configured to communicate with the power amplifier, the variable resistor being configured to dissipate energy transferred by the inductive clamp circuit.

9. An RF system comprising: a first RF generator connected to a first electrode of the load, the first RF generator being configured to generate a first RF signal to the first electrode; a second RF generator connected to a second electrode of the load, the second RF generator configured to generate a second RF signal to the second electrode, wherein the first RF generator and the second RF generator provide corresponding RF voltages to the first electrode and the second electrode; as well as a controller configured to control the second RF generator, the controller generating a control signal to at least one of the first RF generator and the second RF generator, wherein the first RF generator and the second RF generator are configured to operate at the same frequency according to an RF control signal transmitted from the first RF generator to the second RF generator, wherein the second RF generator is configured to transmit a request to the first RF generator via the second digital communication port to request adjustment of the pulsation of the second RF signal, and the first RF generator is configured to change the pulse control signal applied to the second RF generator to adjust the pulsation of the second RF signal, and The controller is configured to at least one of the following: changing the phase of the second RF signal according to a phase difference between the first RF signal and the second RF signal, varying a DC rail voltage in accordance with an electrical characteristic of the second RF signal to control the RF voltage at the second electrode, wherein a DC power supply provides the DC rail voltage for driving a power amplifier of the second RF generator, and The phase of the second RF signal and the DC rail voltage are varied as a function of both the phase difference between the first RF signal and the second RF signal and the electrical characteristic of the second RF signal to control the RF voltage at the second electrode, wherein a DC power supply provides the DC rail voltage for driving the power amplifier of the second RF generator.

10. The RF system of claim 9, further comprising a DC power supply configured to provide a DC rail voltage for driving a power amplifier of the second RF generator, wherein the controller varies the DC rail voltage to control the RF voltage at the second electrode.

11. The RF system of claim 10 , wherein the controller is configured to determine a phase of the first RF signal and a phase of the second RF signal and to control a phase difference between the first RF signal and the second RF signal, wherein the controller is configured to change the phase of the second RF signal according to the phase difference.

12. The RF system of claim 9, wherein the first RF generator and the second RF generator are configured to operate in one of a continuous wave operation mode and a pulsed operation mode.

13. The RF system of claim 9, wherein the adjustment is one of an amplitude and a phase of the second RF signal.

14. The RF system of claim 9 , wherein the second RF generator is configured to transmit a request to the first RF generator via the second digital communication port to request adjustment of the pulsation of the second RF signal, and the first RF generator changes a pulse control signal applied to the second RF generator to adjust the pulsation of the second RF signal.

15. The RF system of claim 14, wherein the adjustment is one of a pulse repetition rate, a power level, and a duty cycle.

16. An RF power supply system for supplying a first RF power to an electrode in a load, comprising: processor; as well as a memory, wherein the memory stores instructions executable by the processor and configured to: determining whether the voltage of the first RF power is equal to a predetermined power set point, determining whether a phase difference between the first RF power and the second RF power is equal to a predetermined phase increment, and A first power supply controller for the first RF power generates a request to a second power supply controller for the second RF power to adjust a parameter of the first RF power to perform at least one of the following controls: controlling the phase of the first RF power according to the phase difference between the first RF power and the second RF power, varying a DC rail voltage according to electrical characteristics of the first RF power to control an RF voltage of the first RF power, and The phase and DC rail voltage of the first RF power are varied according to both the phase difference between the first RF power and the second RF power and the electrical characteristics of the first RF power to control the first RF power.

17. The RF power system of claim 16, wherein a DC power supply provides the DC rail voltage for driving a power amplifier that generates the first RF power.

18. The RF power supply system of claim 16, wherein the second RF power is changed according to a control signal of the first RF power.

19. The RF power system of claim 16, wherein the instructions are further configured to generate a control signal to a variable DC power supply that provides the DC rail voltage.

20. The RF power supply system of claim 19, wherein the DC rail voltage varies in accordance with the control.

21. A method of operating an RF power system, the method comprising: generating a first RF signal applied to a first electrode of a load; generating a second RF signal applied to a second electrode of the load; providing a DC rail voltage for driving a power amplifier that generates the second RF signal and varies the DC rail voltage to control the RF voltage at the second electrode; communicating a request for the second RF signal to a controller of the first RF signal, wherein the controller of the first RF signal generates a control signal to change the second RF signal; and At least one of the following: changing the phase of the second RF signal according to a phase difference between the first RF signal and the second RF signal, varying a DC rail voltage to control the RF voltage at the second electrode based on an electrical characteristic of the second RF signal, wherein the DC rail voltage drives a power amplifier that generates the second RF signal, and The phase of the second RF signal and the DC rail voltage are varied based on both the phase difference between the first RF signal and the second RF signal and the electrical characteristics of the second RF signal to control the RF voltage at the second electrode, wherein the DC rail voltage powers the power amplifier.

22. The method of claim 21, further comprising generating the second RF signal in one of a continuous wave mode of operation and a pulsed mode of operation.

23. The method of claim 21, further comprising pulsing the second RF signal according to a pulse control signal to adjust the pulsation of the second RF signal.

24. The method of claim 21, further comprising: detecting at least one first electrical characteristic of the first RF signal and generating a first sensor output signal based on the at least one first electrical characteristic; detecting at least one second electrical characteristic of the second RF signal and generating a second sensor output signal based on the at least one second electrical characteristic; as well as A determination is made as to whether at least one of the second RF signal and the ripple of the second RF signal requires adjustment, and the requested adjustment is communicated to the first RF generator.

25. The method of claim 21, further comprising: providing an inductive clamp circuit disposed in the power amplifier generating the second RF signal; as well as A variable resistor is provided in communication with the power amplifier, the variable resistor dissipating energy transferred by the inductive clamp circuit.

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