Non-Invasive IED Prediction for Pulsed DC and Low Frequency Applications

Abstract

The RF power generation system includes a power supply configured to generate a periodic waveform applied to a load, and a controller configured to receive at least one of a voltage signal or a current signal indicative of a voltage and a current applied to an electrode of the load, respectively. The controller determines a surface potential of a workpiece at the load according to the at least one of the voltage signal or the current signal and a series capacitance of the electrode. The controller further determines an ion potential by approximating the surface potential. The periodic waveform can be one of a pulsed DC waveform, an RF waveform, or a pulsed RF waveform.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Patent Application No. 18 / 158,164, filed January 23, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] Field The present disclosure relates to RF generator systems and to controlling RF generators. [Background technology]

[0003] background Plasma processing is commonly used in semiconductor manufacturing. In plasma processing, ions are accelerated by an electric field to etch material from or deposit material onto the surface of a substrate. In one basic embodiment, the electric field is generated based on a radio frequency (RF) or direct current (DC) power signal generated by a respective RF or DC generator in a power delivery system. The power signal generated by the generator must be precisely controlled to effectively perform plasma etching.

[0004] The background description set forth herein is provided for the purpose of generally providing a context for the present disclosure. To the extent that work by currently named inventors is described in this background section, aspects of the description that may not qualify as prior art at the time of filing are not admitted expressly or impliedly as prior art to the present disclosure. Summary of the Invention

[0005] overview A system comprising one or more computers may be configured to perform a particular operation or function by installing software, firmware, hardware, or a combination thereof on the system and causing the system to perform the operation during operation. One or more computer programs may be configured to perform a particular operation or function by including instructions that, when executed by a data processing device, cause the device to perform the operation. One general aspect includes an RF power generation system including a power supply configured to generate a periodic waveform applied to a load. The system also includes a controller configured to receive at least one of a voltage signal or a current signal indicative of a voltage and a current, respectively, applied to an electrode of the load, determine a surface potential of a workpiece at the load according to the at least one of the voltage signal or the current signal and a series capacitance of the electrode, and determine an ion potential from the surface potential. In the system, the periodic waveform is one of a non-sinusoidal waveform, an RF waveform, or a pulsed RF waveform. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the operations of the method.

[0006] Embodiments may include one or more of the following features: In the RF power generation system, the electrode is represented as a series capacitance between the power source and the surface potential; The RF power generation system may further include a differentiation module configured to receive the voltage signal and generate a derivative of the voltage signal; The RF power generation system may include a voltage generation module configured to receive the current signal and the series capacitance of the electrode and generate a determined voltage signal according to the current signal and the series capacitance; The RF power generation system may include a differentiation module configured to receive the voltage signal and generate a derivative of the voltage signal; The RF power generation system may include an integration module configured to receive the derivative of the voltage signal and the determined voltage signal and generate an integral of the voltage signal and the determined voltage signal; At least one of the voltage signal or the current signal is received from a sensor preceding a matching network, or at least one of the voltage signal or the current signal is received from a sensor following the matching network. The at least one of the voltage signal or the current signal received from a sensor preceding a matching network is processed to remove components of the voltage signal or the current signal introduced by the matching network. The RF power generation system may include a high-frequency power supply configured to generate a high-frequency periodic waveform applied to the load. The power supply is configured to generate the periodic waveform at a frequency less than 5 MHz. The power supply is a bias power supply for the load, and the load is configured to generate a plasma. The power supply is configured to generate the periodic waveform for a duration equal to or less than an ion transit time through a plasma sheath surrounded by the load. The power supplies include a low-frequency power supply configured to generate a low-period waveform at a low frequency and a high-frequency power supply configured to generate a high-period waveform at a high frequency, the low-period waveform and the high-period waveform being combined to output the periodic waveform applied to the load. Embodiments of the described techniques may include hardware, methods or processes, and computer software on a computer-accessible medium.

[0007] One general aspect includes a control system for a power supply configured to generate a periodic waveform applied to a load. The control system also includes a differentiation module configured to receive a voltage signal that varies in response to a sensed voltage at the load, the differentiation module generating a voltage differentiation signal. The system also includes a voltage generation module configured to receive a current signal that varies in response to a sensed current at the load and a series capacitance of an electrode supporting a workpiece in the load, the voltage generation module generating a voltage signal determined in response to the current signal and the series capacitance. The system also includes an integration module configured to receive the voltage differentiation signal and the determined voltage signal and generate an integral of the voltage differentiation signal and the determined voltage signal. In the system, a surface potential of a workpiece at the load varies in response to the sensed voltage, the sensed current, and the series capacitance of the electrode, and an ion potential of a plasma sheath surrounding the load varies in response to the surface potential. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the operations of the method.

[0008] Embodiments may include one or more of the following features: In the control system, the periodic waveform is one of a non-sinusoidal waveform, an RF waveform, or a pulsed RF waveform; At least one of the voltage signal or the current signal is received from a sensor preceding a matching network, or at least one of the voltage signal or the current signal is received from a sensor following the matching network; The at least one of the voltage signal or the current signal received from the sensor preceding the matching network is processed to remove components of the voltage signal or the current signal introduced by the matching network; The high frequency is higher than a frequency of the periodic waveform; The power supply is configured to generate the periodic waveform at a frequency less than 5 MHz; The power supply is a bias power supply for the load, the load being configured to generate a plasma; The power supply is configured to generate the periodic waveform for a duration equal to or less than an ion transit time through a plasma sheath surrounded by the load. The power source includes a low frequency power source configured to generate a low periodic waveform at a low frequency and a high frequency power source configured to generate a high periodic waveform at a high frequency, the low periodic waveform and the high periodic waveform being combined to output the periodic waveform that is applied to the load. Embodiments of the described techniques may include hardware, methods or processes, and computer software on a computer-accessible medium.

[0009] One general aspect includes a non-transitory computer-readable medium having instructions recorded thereon, the non-transitory computer-readable medium having instructions recorded thereon including generating a waveform to be applied to a load, the instructions including receiving at least one of a voltage signal or a current signal indicative of a voltage and a current to be applied to the load, respectively, the instructions including determining a surface potential of a workpiece at the load according to the at least one of the voltage signal or the current signal and a series capacitance of the electrode, and the instructions including determining an ionic potential by approximation from the surface potential. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the operations of the method.

[0010] Embodiments may include one or more of the following features: In a non-transitory computer-readable medium having stored thereon instructions, the periodic waveform is one of a non-sinusoidal waveform, an RF waveform, or a pulsed RF waveform; the electrode is represented as a series capacitance between a power source generating the periodic waveform and the surface potential; In the non-transitory computer-readable medium having stored thereon instructions, the instructions may include receiving the voltage signal and generating a derivative of the voltage signal; at least one of the voltage signal or the current signal is received from a sensor preceding a matching network, or at least one of the voltage signal or the current signal is received from a sensor following the matching network; the at least one of the voltage signal or the current signal received from a sensor preceding a matching network is processed to remove a component of the voltage signal or the current signal introduced by the matching network; In the non-transitory computer-readable medium having stored thereon instructions, the instructions may include receiving the current signal and a series capacitance of the electrode, and generating a determined voltage signal according to the current signal and the series capacitance of the electrode. The non-transitory computer-readable medium having stored thereon instructions may include receiving the voltage signal and generating a derivative of the voltage signal. The non-transitory computer-readable medium having stored thereon instructions may include receiving the derivative of the voltage signal and the determined voltage signal and generating an integral of the voltage signal and the determined voltage signal. The non-transitory computer-readable medium having stored thereon instructions may include a high frequency power supply configured to generate a high frequency periodic waveform applied to the load. The non-transitory computer-readable medium having stored thereon instructions may include generating the waveform at a frequency less than 5 MHz. The power supply is a bias power supply that generates the periodic waveform and applies power to the load, the load being configured to generate a plasma. The non-transitory computer-readable medium having stored thereon instructions may include generating the periodic waveform for a duration less than or equal to an ion transit time through a plasma sheath surrounded by the load.The non-transitory computer-readable medium having stored thereon instructions may include generating a low-period waveform at a low frequency and generating a high-period waveform at a high frequency, the low-period waveform and the high-period waveform being combined to output the periodic waveform that is applied to the load. Embodiments of the described techniques may include hardware, a method or process, and computer software on a computer-accessible medium.

[0011] Further scope 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 explanation of the drawings]

[0012] BRIEF DESCRIPTION OF THE DRAWINGS The present disclosure will become more fully understood from the detailed description and the accompanying drawings.

[0013] [Figure 1] FIG. 1 shows one representation of an inductively coupled plasma processing system.

[0014] [Figure 2] FIG. 2 shows one representation of a capacitively coupled plasma processing system.

[0015] [Figure 3] FIG. 3 is a schematic block diagram of a power transfer system having multiple power supplies arranged according to various configurations of the present disclosure.

[0016] [Figure 4] FIG. 4 shows the waveform of an RF signal and the pulses that modulate the RF signal to illustrate the pulsed mode of operation.

[0017] [Figure 5] FIG. 5 is a schematic block diagram of a power supply that provides power to a load.

[0018] [Figure 6] FIG. 6 is an electrical representation of the electrodes of the load.

[0019] [Figure 7] FIG. 7 is a block diagram of a module for determining the surface potential of the electrodes of a load.

[0020] [Figure 8] FIG. 8 shows a functional block diagram of example control modules arranged in various configurations.

[0021] [Figure 9] FIG. 9 illustrates a flow chart of the operation of a control system arranged in accordance with the principles of the present disclosure.

[0022] In the drawings, reference numbers may be reused to identify similar and / or identical elements. DETAILED DESCRIPTION OF THE INVENTION

[0023] Detailed Description A power system may include a DC or RF power generator or generator, a matching network, and a load (such as a process chamber, plasma chamber, or reactor with fixed or variable impedance). The power generator generates a DC or RF power signal, which is received by a matching network or an impedance optimization controller or circuit. The matching network or impedance optimization controller or circuit transforms the load impedance to the characteristic impedance of the transmission line between the power generator and the matching network. Impedance matching serves to maximize the amount of power delivered to the load ("forward power") and minimize the amount of power reflected back from the load to the power generator ("reverse power" or "reflected power"). When the input impedance of the matching network matches the characteristic impedance of the transmission line and the generator, the power delivered to the load can be maximized by minimizing the reflected power.

[0024] In the field of power supplies or power delivery, there are typically two approaches to applying a power signal to a load. The first, more traditional approach is to apply a continuous power signal to the load. In continuous mode or continuous wave mode, the continuous power signal is typically a constant DC power signal or a sinusoidal RF power signal that is continuously output by the power supply to the load. In the continuous mode approach, the power signal exhibits a constant DC or sinusoidal output, and the amplitude and / or frequency (for RF power signals) of the power signal can be varied to vary the output power applied to the load.

[0025] A second approach to applying a power signal to a load is to pulse the RF signal rather than applying a continuous RF signal to the load. In a pulsed or pulsed mode of operation, the RF signal is modulated by a modulation signal to define an envelope for the modulated power signal. The RF signal can be, for example, a sinusoidal RF signal or other time-varying signal. The power delivered to the load is typically varied by varying the modulation signal.

[0026] In a typical power supply configuration, the output power delivered to a load is determined using sensors that measure the forward and reflected power or the voltage and current of the RF signal delivered to the load. These signal pairs are analyzed in a control loop. This analysis typically determines a power value that is used to adjust the output of the power supply to vary the power delivered to the load. In a power delivery system where the load is a process chamber or other nonlinear or time-varying load, the delivered power is, in part, a function of the impedance of the load, so that changes in the impedance of the load cause a corresponding change in the power delivered to the load.

[0027] In systems where the fabrication of various devices relies on introducing power to a load to control the fabrication process, power is typically delivered in one of two configurations. In the first configuration, power is capacitively coupled to the load. Such systems are called capacitively coupled plasma (CCP) systems. In the second configuration, power is inductively coupled to the load. Such systems are typically called inductively coupled plasma (ICP) systems. Power coupling to the plasma can also be achieved via wave coupling at microwave frequencies. Such approaches typically use electron cyclotron resonance (ECR) or microwave sources. Helicon sources are another form of wave-coupled source and typically operate at RF frequencies similar to conventional ICP and CCP systems. The power delivery system can include at least one bias power and / or source power applied to one or more electrodes of the load. The source power typically generates the plasma and controls the plasma density. The bias power modulates ions in the sheath formation. The bias and source may share the same electrode or use separate electrodes, depending on various design considerations.

[0028] When a power delivery system drives a time-varying or nonlinear load, such as a process chamber or plasma chamber, the power absorbed by the bulk plasma and plasma sheath produces an ion density over a range of ion energies. One characteristic measure of ion energy is the ion energy distribution function (IEDF). The ion energy distribution function (IEDF) can be controlled by bias power. For systems in which multiple RF power signals are applied to a load, one method of controlling the IEDF is to vary the multiple RF signals, which are related by at least one of amplitude, frequency, and phase. The related at least one of amplitude, frequency, and phase of the multiple RF power signals may also be related by a Fourier series and associated coefficients. The frequencies between the multiple RF power signals may be locked, and the relative phases between the multiple RF power signals may also be locked. Examples of such systems can be found in U.S. Pat. Nos. 7,602,127, 8,110,991, and 8,395,322. All of these patents are assigned to the assignee of the present application and are incorporated herein by reference.

[0029] Time-varying or nonlinear loads may exist in various applications. In some applications, a plasma processing system may also include components for generating and controlling a plasma. One such component is a nonlinear load embodied as a process chamber, such as a plasma chamber or reactor. As an example, a typical plasma chamber or reactor used in a plasma processing system for thin film manufacturing may utilize a dual power system. One power generator (source) controls the generation of the plasma, and another power generator (bias) controls ion energy. Examples of dual power systems include those described in the above-referenced U.S. Pat. Nos. 7,602,127, 8,110,991, and 8,395,322. The dual power systems described in these patents adapt power supply operation to control ion density and its corresponding ion energy distribution function (IEDF) using a closed-loop control system.

[0030] For example, there are several approaches to controlling a process chamber that can be used to generate a plasma. For example, in an RF power transmission system, the phase and frequency of multiple driving RF signals operating at the same or nearly the same frequency can be used to control the generation of the plasma. For RF-driven plasma sources, periodic waveforms that affect the plasma sheath dynamics and corresponding ion energy are generally known and controlled by the frequency and associated phase interactions of the periodic waveforms. Another approach in RF power transmission systems involves dual frequency control. That is, two RF frequency sources operating at different frequencies are used to power the plasma chamber to provide substantially independent control of ion and electron densities.

[0031] Another approach utilizes a broadband RF power source to drive the plasma chamber. The broadband approach presents several challenges. One challenge is coupling the power to the electrodes. A second challenge is that the transfer function from the generated waveform for the desired IEDF to the actual sheath voltage must be formulated for a wide process space to support the material surface interaction. One approach to addressing this in an inductively coupled plasma system is to control the plasma density by controlling the power applied to the source electrode, while controlling the IEDF by controlling the power applied to the bias electrode to modulate the ions to control the etch rate and etch feature profile. Control of the source and bias electrodes is used to control the etch rate and various other etch characteristics via ion density and energy.

[0032] As the fabrication of integrated circuits and integrated devices continues to evolve, so too do the power requirements for controlling the fabrication processes. For example, in the fabrication of memory devices, the requirements for bias power continue to increase. Increased power generates more ions with higher energy for more directional or anisotropic etch feature profiles and faster surface interactions, thereby increasing etch rates and enabling etching of features with higher aspect ratios. In RF systems, increased ion energy can sometimes be accompanied by a decrease in bias frequency requirements, along with an increase in the power and number of bias supplies coupled to the plasma sheath generated in the plasma chamber. Increased power at low bias frequencies and an increase in the number of bias supplies results in intermodulation distortion (IMD) from sheath modulation. IMD emissions can significantly reduce the power supplied by the source where plasma generation occurs. U.S. Patent No. 10,821,542, entitled "Pulse Synchronization by Monitoring Power in Another Frequency Band," issued on November 3, 2020, and assigned to the assignee of the present application, and is incorporated herein by reference, describes a method for pulse synchronization by monitoring power in another frequency band. In this U.S. patent application, pulse generation of a second RF generator is controlled in response to detection by the second RF generator of pulse generation of a first RF generator, thereby synchronizing pulse generation between the two RF generators.

[0033] Previous methods for calculating or predicting ion energy distributions are described in U.S. patent application Ser. No. 17 / 715,672, filed April 7, 2022, and assigned to the assignee of the present application, entitled "Real-Time Non-Invasive IEDF Plasma Sensor." This patent application is incorporated herein by reference. The system and method described in this application require significant computing power and accurate electrical representations of the plasma reactor, its parasitic elements, and its various sheaths. These requirements make the system and method described in this application difficult to implement in a production system. This limits the applicability of the system and method described in this application to use during manufacturing so that the process can be adjusted in real time.

[0034] FIG. 1 shows one representation of an inductively coupled plasma (ICP) system 110. The ICP system 110 includes a nonlinear load, such as a reactor, plasma reactor, or plasma chamber 112 (used interchangeably herein) for generating a plasma 114. Power in the form of voltage or current is applied to the plasma chamber 112 via a pair of coils, including a coil assembly that includes one or more coils arranged in various configurations. In one non-limiting configuration shown in FIG. 1, the plasma chamber 112 includes one or both of a first coil 116 and a second coil 118. In various configurations, the multiple coils may be arranged in a concentric, intertwined, or spiral configuration. Power is applied to the first coil 116 via an RF power generator or power supply 120, and power is applied to the second coil 118 via an RF power generator or power supply 122. The coils 116 and 118 are arranged to provide power to the plasma chamber 112. The dielectric window 124 allows power to be coupled to the plasma while providing a vacuum seal. A substrate 126 is located within the plasma chamber 112, which typically forms the workpiece that is subjected to plasma processing. An RF power generator, power supply, or power source 128 (these terms may be used interchangeably herein) applies power to the plasma chamber 112 through the substrate 126.

[0035] In various configurations, the power supplies 120, 122 provide a source voltage or current to ignite or generate the plasma 114 and control the plasma density. Also, in various configurations, the power supply 128 provides a bias voltage or current to modulate ions to control the ion potential or ion energy of the plasma 114. In various configurations, the power supplies 120, 122 are locked to operate at the same frequency, voltage, and current, with a fixed or variable relative phase. In other various configurations, the power supplies 120, 122 can operate at different frequencies, voltages, and currents, and relative phases.

[0036] FIG. 2 shows one representation of a capacitively coupled plasma (CCP) system 210. The CCP system 210 includes a plasma chamber 212 for generating a plasma 214. A pair of electrodes 216, 218 disposed within the plasma chamber 212 are connected to DC (ω=0) or RF power generators or sources 220, 228, respectively. In various configurations, the source 220 provides a source voltage or current to ignite or generate the plasma 214 or to control the plasma density, although a bias power supply may also be used to ignite the plasma. In various configurations, the source 228 provides a bias voltage or current to modulate ions within the plasma to control the ion potential, ion energy, or ion density of the plasma 214. In various CCP configurations, bias power and source power may be applied to an upper electrode, such as electrode 216, and a lower electrode, such as electrode 226, in various combinations. In another non-limiting example, bias power and source power may be applied to a lower electrode, such as electrode 226, while an upper electrode, such as electrode 216, is grounded or floating. In various RF configurations, the power supplies 220, 228 operate in relative phase when the power supplies are harmonically related. In other various configurations, the power supplies 220, 228 operate at different frequencies, voltages, and currents, with fixed or variable relative phase. Also, in various configurations, the power supplies 220, 228 may be connected to the same electrode, but with opposing electrodes or further connected to a third DC (ω=0) or RF power generator (not shown). In addition to sinusoidal bias waveforms, non-sinusoidal bias waveforms may also control ion energy in various configurations. As a non-limiting example, the bias waveform may be a pulsed rectangular waveform or a piecewise linear waveform as described in U.S. Patent No. 10,396,601, entitled "Piecewise RF Power System and Method for Supplying a Pre-Distorted RF Bias Voltage Signal to an Electrode in a Process Chamber," which issued on August 27, 2019, and is assigned to the assignee of the present application, and which is incorporated herein by reference.

[0037] 1 and 2 illustrate conventional single bias electrode systems in which each bias electrode 126, 226 is configured as a single electrode rather than multiple electrodes. In conventional single bias electrode systems, plasmas 114, 214 may be formed as bulk plasmas. The respective bulk plasmas result in plasma sheaths 130, 230 surrounding the respective loads or plasma chambers 112, 212.

[0038] FIG. 3 illustrates an RF generator or power supply system 310. The power supply system 310 includes a pair of radio frequency (RF) generators or power supplies 312a, 312b, matching networks 318a, 318b, and a load 332, such as a nonlinear load, which may be a plasma chamber, a plasma reactor, a process chamber, or the like. In various configurations, the RF generator 312a is referred to as a source RF generator or power supply, and the matching network 318a is referred to as a source matching network. In various configurations, the RF generator 312b is referred to as a bias RF generator or power supply, and the matching network 318b is referred to as a bias matching network. It will be appreciated that reference numbers with or without subscripts or primes may be used to refer to individual components. In various configurations, one or both of the matching networks 318a, 318b may be implemented as an RF blocking filter rather than impedance matching, as may be the case for matching networks receiving pulsed DC or non-sinusoidal signals, for example. In various other configurations, one or both of the matching networks 318a, 318b may be omitted.

[0039] In various configurations, the source RF generator 312a receives a control signal 330 from the matching network 318b, the generator 312b, or a signal 330' from the bias RF generator 312b. The synchronization or trigger signal 330 or 330' represents an input signal to the source RF generator 312a that represents one or more operating characteristics or parameters of the bias RF generator 312b. In various configurations, a synchronization bias detector 334 detects the RF signal output from the matching network 318b to the load 332 and outputs the synchronization or trigger signal 330 to the source RF generator 312a. In various configurations, a synchronization or trigger signal 330', rather than the trigger signal 330, may be output from the bias RF generator 312b to the source RF generator 312a. The difference between the trigger or synchronization signals 330, 330' may result from the effect of the matching network 318b, which may adjust the phase between the input signal to the matching network and the output signal from the matching network. Signals 330, 330' contain information about the operation of bias RF generator 312b that, in various configurations, enables a predictable response to counteract periodic variations in impedance caused by bias RF generator 312b in plasma chamber 332. In the absence of control signals 330 or 330', RF generators 312a, 312b operate autonomously.

[0040] The RF generators 312a and 312b each include an RF power supply or amplifier 314a and 314b, a sensor 316a and 316b, and a processor, controller, or control module 320a and 320b, respectively. The RF power supplies 314a and 314b generate RF power signals 322a and 322b that are output to the sensors 316a and 316b, respectively. The RF power signals 322a and 322b pass through the sensors 316a and 316b and are provided to matching networks 318a and 318b as RF power signals f1 and f2, respectively. The sensors 316a and 316b output signals that vary in response to various parameters sensed from the load 332. While the sensors 316a and 316b are shown within the respective RF generators 312a and 312b, the sensors 316a and 316b may also be located external to the RF generators 312a and 312b. Such external sensing can be performed at the output of the RF generator, at the input of an impedance matching device located between the RF generator and the load, or between the output of the impedance matching device (including inside the impedance matching device) and the load.

[0041] The sensors 316a, 316b detect various operating parameters and output signals X and Y. The sensors 316a, 316b may include voltage sensors, current sensors, and / or directional coupler sensors. The sensors 316a, 316b measure (i) the voltage V and current I and / or (ii) the forward power P output from the respective power amplifiers 314a, 314b and / or RF generators 312a, 312b. FWD and the reverse or reflected power P received from the respective matching networks 318a, 318b or loads 332 connected to the respective sensors 316a, 316b. REV It can detect voltage V, current I, forward power P FWD , and reverse power P REVmay be scaled, filtered, or scaled and filtered versions of the actual voltage, current, forward power, and reverse power associated with the respective power sources 314a, 314b. The sensors 316a, 316b may be analog or digital sensors, or a combination thereof. In digital implementations, the sensors 316a, 316b may include an analog-to-digital (A / D) converter and signal sampling components with a corresponding sampling rate. The signals X and Y may represent the voltage V and current I or forward (or source) power P FWD and reverse (or reflected) power P REV It can represent either

[0042] The sensors 316a, 316b generate sensor signals X, Y, which are received by respective controllers or control modules 320a, 320b. The control modules 320a, 320b process the respective X and Y signals 324a, 326a and 324b, 326b and generate one or more feedforward or feedback control signals 328a, 328b for the respective power supplies 314a, 314b. The power supplies 314a, 314b adjust the RF power signals 322a, 322b based on the received one or more feedforward or feedback control signals. In various configurations, the power control modules 320a, 320b may control the matching networks 318a, 318b via control signals 329a, 329b, respectively, based on, for example, the X and Y signals 324a, 326a and 324b, 326b. Power control modules 320a, 320b may include any of the various components described below in connection with one or more proportional-integral (PI), proportional-integral-derivative (PID), linear quadratic regulator (LQR) controllers or subsets thereof and / or one or more direct digital synthesis (DDS) components and / or modules.

[0043] In various configurations, the power control modules 320a, 320b may include multiple functions, multiple processes, multiple processors, or multiple sub-modules. The control signals 328a, 328b may be control or actuator drive signals and may communicate DC offset or rail voltages, voltage or current values, frequency and phase components, etc. In various configurations, the feedback control signals 328a, 328b may be used as inputs to one or more control loops. In various configurations, the multiple control loops may include proportional-integral (PI), proportional-integral-derivative (PID) controllers for the RF drive and rail voltages, linear quadratic regulator (LQR) control loops, or a subset thereof. In various configurations, the control signals 328a, 328b may be used in either or both single-input, single-output (SISO) or multiple-input, multiple-output (MIMO) control schemes. An example of a MIMO control scheme can be found by reference to U.S. Patent No. 10,546,724, entitled "Pulsed Bidirectional Radio Frequency Source / Load," issued on January 28, 2020, and assigned to the assignee of the present application, which is incorporated herein by reference. In another configuration, signals 328a, 328b can provide feedforward control as described in U.S. Patent No. 10,049,857, entitled "Adaptive Periodic Waveform Controller," issued on April 14, 2018, and assigned to the assignee of the present application, which is incorporated herein by reference.

[0044] In various configurations, the power supply system 310 can include a controller 320'. The controller 320' can be located external to either or both of the RF generators 312a, 312b and may be referred to as an external or common controller 320'. In various configurations, the controller 320' can implement one or more functions, processes, or algorithms described herein with respect to either or both of the controllers 320a, 320b. As such, the controller 320' communicates with each of the RF generators 312a, 312b via a pair of links 336, 338 that enable the exchange of data and control signals, as appropriate, between the controller 320' and the RF generators 312a, 312b. For various configurations, the controllers 320a, 320b, 320' can perform distributed and collaborative analysis and control of the RF generators 312a, 312b. In various other configurations, the controller 320' can control the RF generators 312a, 312b, eliminating the need for respective local controllers 320a, 320b.

[0045] In various configurations, the RF power supply 314a, the sensor 316a, the controller 320a, and the matching network 318a can be referred to as the source RF power supply 314a, the source sensor 316a, the source controller 320a, and the source matching network 318a, respectively. Similarly, in various configurations, the RF power supply 314b, the sensor 316b, the controller 320b, and the matching network 318b can be referred to as the bias RF power supply 314b, the bias sensor 316b, the bias controller 320b, and the bias matching network 318b, respectively. As noted above, in various configurations, the term source refers to an RF generator that generates a plasma, and the term bias refers to an RF generator that adjusts the ion potential and ion energy distribution function (IEDF) of the plasma. In various configurations, the source and bias RF power supplies operate at different frequencies. In various configurations, the source RF power supply operates at a higher frequency than the bias RF power supply. In various configurations, the source and bias RF power supplies operate at the same frequency or substantially the same frequency.

[0046] According to various configurations, the source RF generator 312a and the bias RF generator 312b include multiple ports for communicating with the outside world. The source RF generator 312a includes a pulse synchronization output port 340, a digital communication port 342, an RF output port 344, and a control signal port 360. The bias RF generator 312b includes an RF input port 348, a digital communication port 350, and a pulse synchronization input port 352. The pulse synchronization output port 340 outputs a pulse synchronization signal 356 to the pulse synchronization input port 352 of the bias RF generator 312b. The digital communication port 342 of the source RF generator 312a and the digital communication port 350 of the bias RF generator 312b communicate via a digital communication link 357. The control signal port 360 of the source RF generator 312a receives one or both of the control signals 330 and 330′. The RF output port 344 generates an RF control signal 358 that is input to the RF input port 348. In various configurations, RF control signal 358 is substantially identical to the RF control signal controlling source RF generator 312a. In various other configurations, RF control signal 358 is identical to the RF control signal controlling source RF generator 312a, but is phase shifted within source RF generator 312a by a desired phase shift produced by bias RF generator 312b. Thus, in various configurations, source RF generator 312a and bias RF generator 412b are driven by substantially identical RF control signals or by substantially identical RF control signals phase shifted by a predetermined amount.

[0047] In various configurations, the power supply system 310 may include multiple RF source generators 312 a and multiple RF bias generators 312 b. As a non-limiting example, multiple source RF generators 312 a, 312 a′, 312 a″, . . . , 312 a may be used to provide multiple output power signals to one or more source electrodes of the load 332. n Similarly, multiple bias RF generators 312b, 312b', 312b'', ..., 312b may be arranged to provide multiple output power signals to multiple bias electrodes of the load 332. nmay be arranged. When the source RF generator 312a and the bias RF generator 312b are configured to include multiple source RF generators or bias RF generators, each RF generator outputs a separate signal to a corresponding plurality of matching networks 318a, 318b, which are configured to operate as described above in a one-to-one correspondence. In various other configurations, there may not be a one-to-one correspondence between each RF generator and matching network. In various configurations, multiple source electrodes may refer to multiple electrodes that cooperate to define a composite source electrode. Similarly, multiple bias electrodes may refer to multiple connections to multiple electrodes that cooperate to define a composite bias electrode.

[0048] FIG. 4 is a plot of voltage versus time illustrating a pulse or pulsed mode of operation for delivering power to a load, such as load 332 in FIG. 3 . More specifically, FIG. 4 shows two multi-state pulses P1 and P2 of a pulse signal 412 having multiple states S1-S4 and S1-S3. In FIG. 4 , an RF signal 410 is modulated by pulses P1 and P2. When the pulse is ON, as shown in states S1-S3 of P1 and states S1-S2 of P2, the RF generator 312 outputs an RF signal 410 having an amplitude defined by the pulse value in each state. Conversely, during state S4 of P1 and state S3 of P2, the pulse is OFF, and the RF generator 312 does not output an RF signal 410. Pulses P1 and P2 can repeat with a constant duty cycle or a variable duty cycle, and states S1-S4 and S1-S3 of each pulse P1 and P2 can have the same or variable amplitude and width.

[0049] In various configurations, the RF signal 410 need not be implemented as a sinusoidal waveform as shown in FIG. 4 . As referenced above with respect to FIG. 2 , in addition to a sinusoidal waveform, in various configurations, the signal 410 may be a non-sinusoidal waveform. By way of non-limiting example, the waveform 410 may be a repetitively or intermittently pulsed square waveform or a piecewise linear waveform as described in U.S. Pat. No. 10,396,601. In various configurations, the pulse signal 412 may be other than a square wave as shown in FIG. 4 . Further, by way of non-limiting example, the envelope of the pulse signal 412 may be rectangular, trapezoidal, triangular, sawtooth, Gaussian, or other shape that defines the envelope or modulation envelope of the underlying modulated RF signal. In various configurations, the pulse signal may occur or reoccur within a fixed or variable period or time. In various other configurations, the pulse signal may change shape between each occurrence. In various other configurations, the pulse signal may occur or reoccur within a fixed or variable time and may change shape between each occurrence. Furthermore, pulses P1, P2 can have multiple states S1, ..., Sn that vary in amplitude, duration, and shape. States S1, ..., Sn may repeat within a fixed or variable period and may include all or some of the various shapes described above. Also, as shown in Figure 4, RF signal 410 may operate at a frequency that varies between states or within a state.

[0050] FIG. 5 shows, by way of non-limiting example, a representation of a portion of an RF plasma generation system 510, such as for a bias portion of an RF power supply system. The RF plasma generation system 510 includes a pair of RF power generators 530a, 530b implemented as a pair of bias RF power generators. The RF power generator 530a represents a high-frequency RF power generator that supplies high-frequency bias power, and the RF power generator 530b represents a low-frequency RF power generator that supplies low-frequency bias power. Each RF power generator 530a, 530b can operate to provide a desired ion potential and corresponding IED according to various design considerations. Each RF power generator 530a, 530b outputs RF power to a respective transmission line 532a, 532b. The output from each transmission line 532a, 532b is input to a matching network 534.

[0051] The matching network 534 combines the respective RF powers and outputs a signal to the sensor 550. The sensor 550 may be implemented as any of the sensors described above, including a V / I sensor or a directional coupler. The sensor 550 detects one or more preselected parameters at the input to the plasma chamber 538, from which an approximation of the ion energy in the plasma chamber can be determined as described herein. The sensor 550 outputs one or more sensed values ​​that vary depending on the plasma conditions. The RF powers input to the sensor 550 are combined and passed through the sensor 550 to the electrode 536.

[0052] In various configurations, the matching network 534 and the sensor 550 may be sequentially arranged such that the sensor 550 precedes the matching network 534. In such a configuration, the sensor 550 receives and combines the outputs from the RF power generators 530a and 530b and outputs a sensor value or signal according to the combined RF power received from the RF power generators 530a and 530b via their respective transmission lines 530a and 530b. The sensor 550 also provides a matching function and outputs a power signal to the matching network 534, which outputs the matching signal to the electrode 536. In such a configuration, a preselected parameter sensed by the sensor 550 represents a sensed value or signal. The sensed value or signal may be processed to remove the component portion of the signal introduced by the matching network 534.

[0053] In various configurations, the electrode 536 may be implemented as an electrostatic chuck (ESC) or an electrode keyed to a supported workpiece. Electrode 536 may be referred to herein as an electrode, an electrostatic chuck, or an ESC. In various configurations, the electrode or the electrostatic chuck may be implemented as a series capacitor ESC s and parallel capacitor ESC p The series capacitor ESC can be represented as a pair of capacitors including s is connected to a power application or electrode side sheath, represented as power application or electrode side sheath 546. The potential on the surface of the ESC, shown at the node connecting the electrostatic chuck 536 and the power application or electrode side sheath 546, is V S is shown as:

[0054] A power or electrode side sheath 546 is connected to the wall sheath 544, and the node between the power or electrode side sheath 546 and the wall sheath 544 is at a plasma potential V P The wall sheath 544 is also expressed as a wall potential V WThe power supply is connected to ground through a capacitor 552 at a node having a voltage I. In various configurations, the capacitor 552 may be omitted, implying that the reactor has a conductive wall in contact with the plasma. The current flowing through the power supply sheath electrode sheath 546, the wall sheath 544, and the capacitor 552 is I. P is shown as:

[0055] 5 shows one pair of sheath voltages or potentials, it should be understood that the electrical representation may be constructed using more than one sheath potential. A larger number of sheath potentials in the electrical representation increases the accuracy of the electrical representation but requires additional computational overhead.

[0056] In various configurations, IED can be predicted using electrical parameters selected to characterize the system. In various configurations, at drive frequencies less than or close to the ion sheath transit time, ions can cross the sheath at approximately the waveform's maximum value during one waveform period. Therefore, the ion potential can track the sheath potential waveform. In other words, ions crossing the sheath without collisions can be assumed to gain energy approximately equal to the magnitude of the sheath potential waveform. The ion potential at the electrode surface (which is also the ion potential at the substrate or workpiece) has similar characteristics and values ​​to the sheath potential, albeit with an offset. In other words, the time derivative of the surface potential and the time derivative of the sheath potential are essentially equal. The ion potential differs from conventional RF drive waveforms typically measured at the chamber input. The ion potential is a virtual potential calculated to represent the energy ions gain as they cross the sheath and to facilitate the generation of ion energy distributions. Alternative methods for measuring ion energy require invasive measurement hardware, which is typically unavailable and undesirable in production plasma reactors. However, as described herein, parameters measured by the sensor 550, such as voltage and current waveforms, can be used to determine the ionic potential.

[0057] Many production plasma processing equipment use electrodes implemented as ESCs to grip a substrate, and if the ESC has a fixed series capacitance, the potential on its surface can be determined using the voltage and current relationship of a capacitor in series with the power delivery sheath. In various configurations, the series capacitance can be characterized before or during the production process. Below are mathematical descriptions and block diagrams of such implementations.

[0058] The current I at the input to the plasma chamber or reactor 538 M (t) is defined by equation (1).

number

number

number

number

number

[0059] Referring to FIG. 6, the electrical representation of electrode 610 is a voltage V ESC and has a capacitance C ESC The voltage V input to the reactor 538 is M and current I M is applied to electrode 610. Ionic potential V ION (t) is the surface potential V of the electrode 610 as shown in equation (6). S can be approximated according to

number

[0060] FIG. 7 shows the surface potential V S 7 shows a block diagram 710 of one method for determining the voltage signal V. M (t) is input to the derivative module 712, which applies a constant to dV M Determine the derivative of the input voltage, i.e., (t) / dt. M (t) and electrode capacitance C ESCis input to a divider or voltage generation module 714. The divider or voltage generation module 714 divides the current signal I M (t) and electrode capacitance C ESC The derivative module 712 and the divider or voltage generation module 714 output their respective derivative and quotient values ​​or signals to a combiner module 716. The combiner module 716 combines the output from the derivative module 712 and the output from the divider or voltage generation module 714. The combiner module 760 outputs the combined value or signal to an integrator 718. The integrator 718 integrates the combined value or signal, and calculates the integrated value or signal, the sheath potential V S The surface potential V S to the ionic potential V ION is approximated, and the ionic potential V ION The controller 720 controls various system parameters according to the ionic potential V ION In various configurations, the respective voltage signals V M (t) and current signal I M The (t) value or signal may be output by sensor 550 of Figure 5. Sensor 550 may either precede matching network 534 or follow matching network 534, as described above with respect to Figure 5.

[0061] Figure 8 encompasses various components of Figures 1-7. Control module 810 can include an amplitude control module 812, a frequency control module 814, an ion energy determination module 816, and an impedance matching module 818. Amplitude control module 812 includes an amplitude adjustment module 820 and an amplitude update module 822. Similarly, frequency control module 814 includes a frequency adjustment module 824 and a frequency update module 826. In various configurations, control module 810 includes one or more processors that execute code associated with module portions or modules 810, 812, 814, 816, 818, 820, 822, 824, and 826. The operation of module portions or modules 810, 812, 814, 816, 818, 820, 822, 824, and 826 is described below with respect to the method of Figure 9.

[0062] For more detailed structure of controllers 320a, 320b, 320' of FIG. 3, see the flowchart of FIG. 9 below and the definition of the term "module" below. The system disclosed herein can be operated in numerous ways, examples of which are shown in FIG. 3, illustrating various control system methods. While the following operations are primarily described with respect to the embodiment of FIG. 3, these operations can be easily modified to apply to other embodiments of the present disclosure. These operations may be performed iteratively. While the following operations are shown and primarily described as occurring continuously, one or more of the following operations may occur while one or more of the other operations are occurring.

[0063] 9 illustrates a flow chart of a control system 910 for controlling the power transfer system of FIG. 3, for example. Control begins at block 920 and proceeds to block 922. In block 922, one or more electrical parameters, such as the voltage and current input to reactor 538, are measured. The one or more electrical parameters are output to respective blocks 924 and 928. In various configurations, a first electrical parameter, such as the voltage input to reactor 538, is input to block 924. In block 924, a first value or signal is generated based on the first electrical parameter. In various configurations, the first value or signal can be a derivative of the first electrical parameter, such as a derivative of the voltage input to reactor 538.

[0064] In various configurations, a second electrical parameter, such as the current input to reactor 538, is input to block 928. Block 928 also receives a component value, such as the capacitance of electrode 610. In block 928, a second value is generated based on the second electrical parameter and the component value. In various configurations, the second value can be a quotient of the component value and the second electrical parameter.

[0065] In various configurations, the first and second values ​​are output from respective blocks 924 and 928 and input to block 930. In block 930, the first and second values ​​are combined and the combined value is output to block 932. In block 932, the surface potential V of electrode 536 is calculated. S The resultant value is integrated to determine the surface potential V S to the ionic potential V ION The process may end at block 934 or may return to block 922.

[0066] The IED estimation method proposed in this disclosure provides IEDF control over a predetermined operating range of low RF frequencies, such as for bias RF generators. The systems and methods described herein utilize the capacitance of the chamber electrode or electrostatic chuck and sample voltages and currents at the chamber input, typically the chamber electrode or electrostatic chuck. The sampling occurs with reasonable accuracy and at an appropriate rate. With this information, a signal representing a predicted value of ion energy can be obtained with minimal calculations.

[0067] conclusion The above description is merely illustrative in nature and is not intended to limit the disclosure, its application, or its uses. The broad teachings of the present disclosure can be embodied in various forms. Accordingly, while the present disclosure includes specific examples, the essential scope of the disclosure should not be limited, as other variations will become apparent upon review of the drawings, the specification, and the following claims. In the written description and claims, one or more steps in a method may be executed in a different order (or simultaneously) without altering the principles of the disclosure. Similarly, one or more instructions stored in a non-transitory computer-readable medium may be executed in a different order (or simultaneously) without altering the principles of the disclosure. Unless otherwise indicated, numbering or other labeling of instructions or method steps is for convenience of reference and is not intended to indicate a fixed order.

[0068] Furthermore, although each of the embodiments is described above as having certain features, any one or more of these features described with respect to any embodiment of the present disclosure can be implemented in and / or combined with any feature of any other embodiment, even if such combination is not explicitly stated. In other words, the described embodiments are not mutually exclusive, and substituting one or more embodiments for one another is within the scope of the present disclosure.

[0069] 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," "next to," "on," "above," "below," and "disposed." Unless expressly stated as "direct," when a relationship between a first element and a second element is described in the above disclosure, the relationship may be a direct relationship where no other intervening elements exist between the first element and the second element, or it may be an indirect relationship where one or more intervening elements (spatial or functional) exist between the first element and the second element.

[0070] The phrase "at least one of A, B, and C" should be interpreted to mean a non-exclusive logical OR (A OR B OR C), and not to mean "at least one of A, at least one of B, and at least one of C." The term "set" does not necessarily exclude the empty set; in other words, a "set" may have no elements in some cases. The term "non-empty set" is sometimes used to indicate the exclusion of the empty set; in other words, a non-empty set always has one or more elements. The term "subset" does not necessarily require a proper subset. In other words, a "subset" of a first set may be coextensive with (equal to) the first set. Furthermore, the term "subset" does not necessarily exclude the empty set; in other words, a "subset" may have no elements in some cases.

[0071] In the drawings, the direction of the arrow, as indicated by the arrowhead, generally indicates the flow of information (e.g., data or instructions) that is being described. For example, an arrow may be directed from element A to element B if element A and element B exchange various information and the information communicated from element A to element B is relevant to the description. This single-headed arrow does not imply that other information is not communicated from element B to element A. Furthermore, for information sent from element A to element B, element B may send a request for that information or an acknowledgment of its receipt to element A.

[0072] For the purposes of this application, including the definitions below, the term "module" is interchangeable with the term "controller" or the term "circuitry." For the purposes of this application, the term "controller" is interchangeable with the term "module." The term "module" may mean, be a part of, or include an application-specific integrated circuit (ASIC), digital, analog, or mixed analog / digital discrete circuitry, a digital, analog, or mixed analog / digital integrated circuit, a combinational logic circuit, a field-programmable gate array (FPGA), processor hardware (shared, dedicated, or group) that executes code, memory hardware (shared, dedicated, or group) that stores code to be executed by the processor hardware, other suitable hardware components that provide the described functionality, or a combination of some or all of the above, such as in a system-on-chip.

[0073] A module may include one or more interface circuits. In some examples, the interface circuit(s) may implement a wired or wireless interface for connecting to a local area network (LAN) or a wireless personal area network (WPAN). Examples of LANs include the Institute of Electrical and Electronics Engineers (IEEE) Standard 802.11-2020 (also known as the WIFI wireless networking standard) and IEEE Standard 802.3-2018 (also known as the Ethernet wired networking standard). Examples of WPANs include the IEEE Standard 802.15.4 (including the ZIGBEE standard from the ZigBee Alliance) and the BLUETOOTH wireless networking standard from the Bluetooth Special Interest Group (SIG) (including the Bluetooth SIG Core Specification Versions 3.0, 4.0, 4.1, 4.2, 5.0, and 5.1).

[0074] Modules may communicate with other modules using interface circuit(s). While modules are sometimes depicted in this disclosure as logically communicating directly with other modules, in various embodiments, modules may actually communicate through a communications system. A communications system includes physical and / or virtual networking equipment such as hubs, switches, routers, and gateways. In some embodiments, a communications system connects to or traverses a wide area network (WAN) such as the Internet. For example, a communications system may include multiple LANs connected to each other over the Internet or point-to-point leased lines using technologies including multiprotocol label switching (MPLS) and virtual private networks (VPNs).

[0075] In various embodiments, the functionality of a module may be distributed among multiple modules connected via a communication system. For example, multiple modules may perform the same function, which is distributed by a load balancing system. In a further example, the functionality of a module may be divided between a server module (also known as remote or cloud) and a client (or user) module. For example, a client module may include a native or web application running on a client device and capable of network communication with a server module.

[0076] Some or all of the hardware features of a module may be specified using a hardware description language such as IEEE Standard 1364-2005 (commonly referred to as "Verilog") and IEEE Standard 1076-2008 (commonly referred to as "VHDL"). A hardware description language may be used to fabricate and / or program hardware circuits. In some embodiments, some or all of the features of a module may be specified in a language such as IEEE 1666-2005 (commonly referred to as "SystemC"), which includes both code and hardware descriptions, as described below.

[0077] 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. Shared processor hardware encompasses a single microprocessor that executes some or all code from multiple modules. Group processor hardware encompasses a microprocessor that executes some or all code from one or more modules in combination with additional microprocessors. References to multiple microprocessors include multiple microprocessors on separate dies, multiple microprocessors on a single die, multiple cores of a single microprocessor, multiple threads of a single microprocessor, or any combination of the above.

[0078] Memory hardware may also store data along with or separately from the code. Shared memory hardware encompasses a single memory device that stores some or all code from multiple modules. One example of memory hardware may be a level 1 cache on or near a microprocessor die, which may store code from multiple modules. Another example of shared memory hardware may be persistent storage, such as a solid-state drive (SSD), which may store code from multiple modules. Group memory hardware encompasses a memory device that stores some or all code from one or more modules in combination with other memory devices. An example of group memory hardware is a storage area network (SAN), which may store code for a particular module across multiple physical devices. Another example of group memory hardware is the random access memory of each of a set of servers, which combined store code for a particular module.

[0079] The term memory hardware is a subset of the term computer-readable medium. As used herein, the term computer-readable medium does not encompass transient electrical or electromagnetic signals propagating in a medium (e.g., on a carrier wave). Thus, the term computer-readable medium is considered to be tangible and non-transitory. Non-limiting examples of non-transitory computer-readable medium are non-volatile memory devices (such as flash memory devices, erasable programmable read-only memory devices, or mask read-only memory devices), volatile memory devices (such as static random access memory devices or dynamic random access memory devices), magnetic recording media (such as analog or digital magnetic tape or hard disk drives), and optical recording media (such as CDs, DVDs, or Blu-ray discs).

[0080] The apparatus and methods described in this application may be implemented in part or entirely by a special-purpose computer generated by configuring a general-purpose computer to perform one or more specific functions embodied in a computer program. Such apparatus and methods may be referred to as computerized apparatus and computerized methods. The functional blocks and flowchart elements described above function as software specifications, which can be converted into a computer program by the routine work of a skilled engineer or programmer.

[0081] A computer program includes processor-executable instructions stored on at least one non-transitory computer-readable medium. A computer program may include or rely on stored data. A computer program may include a basic input / output system (BIOS) that interacts with hardware in a special-purpose computer, device drivers that interact with specific devices in a special-purpose computer, one or more operating systems, user applications, background services, background applications, etc.

[0082] A computer program may include (i) parsed written text such as HTML (Hypertext Markup Language), XML (Extensible Markup Language), or JSON (JavaScript Object Notation), (ii) assembly code, (iii) object code generated from source code by a compiler, (iv) source code executed by an interpreter, (v) source code compiled and executed by a just-in-time compiler, etc. By way of example only, source code may be written using syntax from languages ​​including C, C++, C#, Objective C, Swift, Haskell, Go, SQL, R, Lisp, Java, Fortran, Perl, Pascal, Curl, OCaml, JavaScript (registered trademark), HTML5 (Hypertext Markup Language Fifth Revision), Ada, ASP (Active Server Pages), PHP (Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash (registered trademark), Visual Basic (registered trademark), Lua, MATLAB, SIMULINK, and Python (registered trademark).

Claims

1. 1. A power generation system comprising: a power supply configured to generate a waveform to be applied to a load; a controller, receiving at least one of a voltage signal or a current signal indicative of the voltage and current applied to the electrodes of the load, respectively; determining a surface potential of a workpiece at the load according to the at least one of the voltage signal or the current signal and the series capacitance of the electrode; Determine the ionic potential from the surface potential and a controller configured as A power generation system comprising:

2. The power generation system of claim 1 , wherein the electrode is represented as a series capacitance between the power source and the surface potential.

3. The power generation system of claim 1 , further comprising a derivative module configured to receive the voltage signal and generate a derivative of the voltage signal.

4. The power generation system of claim 1 , further comprising a voltage generation module configured to receive the current signal and the series capacitance of the electrode and generate a determined voltage signal according to the current signal and the series capacitance.

5. 2. The power generation system of claim 1, wherein at least one of the voltage signal or the current signal is received from a sensor preceding the matching network, or at least one of the voltage signal or the current signal is received from a sensor following the matching network.

6. 6. The power generation system of claim 5, wherein the at least one of the voltage signal or the current signal received from a sensor preceding a matching network is processed to remove components of the voltage signal or the current signal introduced by the matching network.

7. The power generation system of claim 4 , further comprising a derivative module configured to receive the voltage signal and generate a derivative of the voltage signal.

8. The power generation system of claim 7 , further comprising an integration module configured to receive the derivative of the voltage signal and the determined voltage signal and to generate an integral of the voltage signal and the determined voltage signal.

9. The power generation system of claim 1 , further comprising a high frequency power source configured to generate a high frequency waveform that is applied to the load.

10. 10. The power generation system of claim 9, wherein the power source is configured to generate the waveform at a frequency less than 5 MHz.

11. The power generation system of claim 1 , wherein the power source is a bias power source for the load, the load being configured to generate a plasma.

12. The power generation system of claim 1 , wherein the power supply is configured to generate the waveform for a duration equal to or less than an ion transit time through a plasma sheath surrounded by the load.

13. 2. The power generation system of claim 1, wherein the power source includes a low frequency power source configured to generate a low waveform at a low frequency and a high frequency power source configured to generate a high waveform at a high frequency, the low waveform and the high waveform being combined to output the waveform applied to the load.

14. 1. A control system for a power supply configured to generate a waveform to be applied to a load, comprising: a derivative module configured to receive a voltage signal that varies as a function of a sensed voltage at the load, the derivative module generating a voltage derivative signal; a voltage generation module configured to receive a current signal that varies in response to a sensed current in the load and a series capacitance of an electrode supporting a workpiece in the load, the voltage generation module generating a voltage signal that is determined in accordance with the current signal and the series capacitance; an integration module configured to receive the voltage derivative signal and the determined voltage signal and generate an integral of the voltage derivative signal and the determined voltage signal; Equipped with a surface potential of a workpiece at the load varies in response to the sense voltage, the sense current, and the series capacitance of the electrode, and an ion potential of a plasma sheath surrounded by the load varies in response to the surface potential; Control system.

15. The control system of claim 14 , wherein the waveform is one of a non-sinusoidal waveform, a waveform, or a pulse waveform.

16. 15. The control system of claim 14, wherein at least one of the voltage signal or the current signal is received from a sensor preceding the matching network, or at least one of the voltage signal or the current signal is received from a sensor following the matching network.

17. 17. The control system of claim 16, wherein the at least one of the voltage signal or the current signal received from a sensor preceding a matching network is processed to remove components of the voltage signal or the current signal introduced by the matching network.

18. The control system of claim 14 , further comprising a high frequency power supply configured to generate a high frequency waveform applied to the load, the high frequency being greater than a frequency of the waveform.

19. 20. The control system of claim 18, wherein the power supply is configured to generate the waveform at a frequency less than 5 MHz.

20. The control system of claim 14 , wherein the power supply is a bias power supply for the load, the load being configured to generate a plasma.

21. 15. The control system of claim 14, wherein the power supply is configured to generate the waveform for a duration equal to or less than an ion transit time through a plasma sheath surrounded by the load.

22. 15. The control system of claim 14, wherein the power source includes a low frequency power source configured to generate a low waveform at a low frequency and a high frequency power source configured to generate a high waveform at a high frequency, the low waveform and the high waveform being combined to output the waveform applied to the load.

23. A non-transitory computer-readable medium having instructions recorded thereon, the instructions comprising: generating a waveform to be applied to the load; receiving at least one of a voltage signal or a current signal indicative of the voltage and current applied to the load, respectively; determining a surface potential of the workpiece at the load according to the at least one of the voltage signal or the current signal and a series capacitance of an electrode supporting the workpiece; Determine the ionic potential by approximation from the surface potential A non-transitory computer-readable medium having instructions recorded thereon, including:

24. 24. The non-transitory computer-readable medium having stored thereon instructions of claim 23, wherein the waveform is one of a non-sinusoidal waveform, a sinusoidal waveform, or a pulsed waveform.

25. 24. The non-transitory computer-readable medium having stored thereon instructions of claim 23, wherein the electrode is represented as a series capacitance between a power source generating the waveform and the surface potential.

26. 24. The non-transitory computer-readable medium having stored thereon instructions of claim 23, the instructions further comprising receiving the voltage signal and generating a derivative of the voltage signal.

27. 24. The non-transitory computer-readable medium having stored thereon instructions of claim 23, wherein at least one of the voltage signal or the current signal is received from a sensor preceding the matching network or at least one of the voltage signal or the current signal is received from a sensor following the matching network.

28. 28. The non-transitory computer-readable medium having stored thereon instructions of claim 27, wherein the at least one of the voltage signal or the current signal received from a sensor preceding a matching network is processed to remove a component of the voltage signal or the current signal introduced by the matching network.

29. 24. The non-transitory computer-readable medium having stored thereon instructions of claim 23, wherein the instructions further comprise receiving the current signal and the series capacitance of the electrode, and generating a determined voltage signal according to the current signal and the series capacitance of the electrode.

30. 30. The non-transitory computer-readable medium having stored thereon instructions of claim 29, wherein the instructions further comprise receiving the voltage signal and generating a derivative of the voltage signal.

31. 31. The non-transitory computer-readable medium having stored thereon instructions of claim 30, wherein the instructions further comprise receiving the derivative of the voltage signal and the determined voltage signal, and generating an integral of the voltage signal and the determined voltage signal.

32. 24. The non-transitory computer-readable medium having stored thereon instructions of claim 23, further comprising a high frequency power supply configured to generate a high frequency waveform that is applied to the load.

33. 33. The non-transitory computer-readable medium having stored thereon instructions of claim 32, wherein the instructions further comprise generating the waveform at a frequency less than 5 MHz.

34. 24. The non-transitory computer-readable medium having stored thereon instructions of claim 23, wherein a power supply is a bias power supply that generates the waveform and applies power to the load, the load being configured to generate a plasma.

35. 24. The non-transitory computer-readable medium having stored thereon instructions of claim 23, wherein the instructions further comprise generating the waveform for a duration equal to or less than an ion transit time of a plasma sheath surrounded by the load.

36. 24. The non-transitory computer-readable medium having stored thereon instructions of claim 23, wherein the instructions further comprise generating a low waveform at a low frequency and generating a high waveform at a high frequency, the low waveform and the high waveform being combined to output the waveform applied to the load.

37. 10. The power generation system of claim 1, wherein the waveform is one of a non-sinusoidal waveform, a sinusoidal waveform, or a pulsed waveform.

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