Pulsed RF plasma generator with high dynamic range.

Abstract

An RF power generator having a fixed power generation section, the fixed power generation section including a first plurality of power amplifiers each configured to receive a supply voltage and output a first voltage, and the RF power generator also includes a weighted power generation section including a plurality of weighted power amplifier modules, each weighted power amplifier module including a weighted power amplifier and an associated transformer, each weighted power amplifier of the weighted power amplifier modules receiving a respective weighted supply voltage, the voltage across the transformer of each weighted power amplifier module being a fractional multiple of the first voltage.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Patent Application No. 18 / 390,694, filed December 20, 2023, and the benefit of U.S. Provisional Patent Application No. 63 / 441,616, filed January 27, 2023, the entire disclosures of which are incorporated herein by reference. [Background technology]

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

[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 generator. The RF power generator also includes a fixed power generation section including a first plurality of power amplifiers, each configured to receive a supply voltage and output a first voltage. The generator also includes a weighted power generation section including a plurality of weighted power amplifier modules, each including a weighted power amplifier and a transformer, wherein each weighted power amplifier of the plurality of weighted power amplifier modules receives a weighted supply voltage, and the voltage across the transformer of each weighted power amplifier module is a fractional multiple of the first voltage. 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 generator, at least one of the weighted power amplifiers of the weighted power amplifier modules receives a fractional multiple of the supply voltage, and the at least one of the weighted power amplifier modules is configured to output a fractional multiple of the first voltage; the at least one of the weighted power amplifier modules is configured to output a fractional multiple of the first voltage that is a different fractional multiple of the first voltage than other weighted power amplifier modules; two or more of the weighted power amplifier modules receive the same fractional multiple of the supply voltage; a transformer associated with one of the two or more of the weighted power amplifier modules has a turns ratio that is different from other weighted power amplifier modules; at least one of the weighted power amplifier modules receives the supply voltage, and the at least one of the weighted power amplifier modules is configured to output a fractional multiple of the first voltage. A transformer associated with at least one of the weighted power amplifier modules has a different turns ratio such that the at least one of the weighted power amplifier modules outputs a voltage that is a fractional multiple of the first voltage. Two or more of the weighted power amplifier modules receive the supply voltage, and the two or more of the weighted power amplifier modules are configured to output a voltage that is a fractional multiple of the first voltage. A transformer associated with two or more of the weighted power amplifier modules has a different turns ratio than others of the two or more of the weighted power amplifier modules. The weighted supply voltages are input to weighted power amplifiers of the weighted power amplifier modules. Each weighted supply voltage is input to a respective weighted power amplifier of the weighted power amplifier modules. The weighted supply voltages are one times the supply voltage divided by a power of two.The RF power generator may further include a harmonic filter configured to convert the impedance of each power amplifier to an inductive impedance. The inductive impedance is located above the horizontal axis of a Smith chart. The first plurality of power amplifiers of the fixed power generation unit are connected in series. Each of the first plurality of power amplifiers of the fixed power generation unit is configured to output the first voltage to a respective transformer, the respective transformers being connected in series. The weighted power amplifier modules of the weighted power generation unit are connected in series. Each of the weighted power amplifier modules of the weighted power generation unit is configured to output the fractional multiple of the first voltage to a respective transformer, the respective transformers being connected in series. Each power amplifier of the fixed power generation unit and each power amplifier module of the weighted power generation unit are connected in series, and the fixed power generation unit and the weighted power generation unit are connected in series. Fewer than all of the first plurality of power amplifiers of the fixed power generation unit generate an output voltage at a time, and the first plurality of power amplifiers switch between generating an output voltage and an off state. The fractional multiple of the first voltage is 1 times the first voltage divided by a power of 2. Embodiments of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium.

[0007] 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 generator. The RF power generator also includes a fixed power generation section including a first plurality of power amplifiers each configured to receive a supply voltage and output a first voltage. The generator also includes a weighted power generation section including a plurality of weighted power amplifier modules, each configured to receive a weighted supply voltage, the voltage at the output of each weighted power amplifier module being a fractional multiple of the first voltage. 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 RF power generator, at least one of the weighted power amplifiers of the weighted power amplifier modules receives a fractional multiple of the supply voltage, and the at least one of the weighted power amplifier modules is configured to output a fractional multiple of the first voltage. At least one of the weighted power amplifier modules receives the supply voltage, and the at least one of the weighted power amplifier modules is configured to output a fractional multiple of the first voltage. The weighted supply voltage is input to the weighted power amplifiers of the weighted power amplifier modules. The weighted supply voltage is one times the supply voltage divided by a power of two. The RF power generator may include a harmonic filter configured to convert the impedance of each power amplifier to an inductive impedance. The first plurality of power amplifiers of the fixed power generation section are connected in series. Each of the first plurality of power amplifiers of the fixed power generation unit is configured to output the first voltage to a respective transformer, the respective transformers being connected in series. The weighted power amplifier modules of the weighted power generation unit are connected in series. Each of the plurality of weighted power amplifier modules of the weighted power generation unit is configured to output the fractional multiple of the first voltage to a respective transformer, the respective associated transformers being connected in series. Each power amplifier of the fixed power generation unit is connected in series to a respective power amplifier module of the weighted power generation unit, and the fixed power generation unit is connected in series to the weighted power generation unit. Fewer than all of the first plurality of power amplifiers of the fixed power generation unit generate an output voltage at a time, and the first plurality of power amplifiers are switched between generating an output voltage and an off state. Embodiments of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium.

[0009] One general aspect includes a non-transitory computer-readable medium having instructions stored thereon, the non-transitory computer-readable medium having instructions stored thereon including receiving a commanded output voltage, the instructions including determining a number of power amplifiers among a plurality of power amplifiers that, when activated, produce the commanded output voltage, the instructions including generating a control word according to the number of power amplifiers, and controlling the determined number of power amplifiers according to the control word to produce the output voltage. 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 the non-transitory computer-readable medium, the instructions include comparing the output voltage to the command output voltage and adjusting the determined number of power amplifiers according to a difference between the output voltage and the command output voltage; The plurality of power amplifiers includes a first plurality of power amplifiers configured to receive a supply voltage and output a first voltage, and a second plurality of power-weighted power amplifiers configured to receive respective weighted supply voltages and output voltages that are fractional multiples of the first voltage. Embodiments of the described techniques may include hardware, a method or process, or 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 is a schematic block diagram of a power transfer system having multiple power supplies arranged according to various configurations of the present disclosure.

[0014] [Figure 2] FIG. 2 shows the waveform of an RF signal and the pulses that modulate the RF signal to illustrate the pulsed mode of operation.

[0015] [Figure 3A] FIG. 3A illustrates an RF generator having multiple power amplifiers arranged according to various configurations of the present disclosure.

[0016] [Figure 3B] FIG. 3B illustrates the weighted power generating portion of the RF generator of FIG. 3A arranged according to various configurations of the present disclosure.

[0017] [Figure 3C] FIG. 3C illustrates the weighted power generating portion of the RF generator of FIG. 3A arranged according to various configurations of the present disclosure.

[0018] [Figure 4] FIG. 4 shows a Smith chart illustrating the inductive operating region of an RF generator arranged according to various configurations of the present disclosure.

[0019] [Figure 5] FIG. 5 shows a plot of the power and voltage output by an RF generator in response to drive words controlling each power amplifier of the RF generator for a square root scaling control configuration.

[0020] [Figure 6] FIG. 6 shows a plot of the number of power amplifiers in the fixed power generation section that are driven in response to a drive word for a square root scaling control configuration.

[0021] [Figure 7]FIG. 7 shows a plot of the weighted voltages output by the power amplifiers of the weighted power generation section of the RF generator in response to drive words controlling the power amplifiers for a square root scaling control configuration.

[0022] [Figure 8] FIG. 8 shows a plot of the number of power amplifiers in the fixed power generation section that are driven in response to a drive word for a linear scaling control configuration.

[0023] [Figure 9] FIG. 9 shows a plot of the number of power amplifiers in the fixed power generation section that are driven in response to a drive word for a linear scaling control configuration.

[0024] [Figure 10] FIG. 10 shows a plot of the weighted voltages output by the power amplifiers of the weighted power generation section of the RF generator in response to drive words controlling the power amplifiers for a linear scaling control configuration.

[0025] [Figure 11] FIG. 11 shows an example of envelope modulation with a linear voltage ramp output by an RF generator configured in accordance with the present disclosure.

[0026] [Figure 12] FIG. 12 illustrates a functional block diagram of an example control module arranged according to various configurations of the present disclosure.

[0027] [Figure 13] FIG. 13 illustrates a flow chart of the operation of a control system arranged in accordance with the principles of the present disclosure.

[0028] In the drawings, reference numbers may be reused to identify similar and / or identical elements. DETAILED DESCRIPTION OF THE INVENTION

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] The fabrication of modern high-performance memory devices, such as non-volatile flash memory (3D NAND flash) and dynamic random access memory (DRAM), in which memory cells are stacked vertically in multiple layers, requires the precision etching of extremely high aspect ratio (HAR) features with height-to-width ratios on the order of greater than 50:1. An RF bias generator, operating in pulsed mode as described in more detail below, is a key component for meeting the challenging requirements of semiconductor processing systems used for HAR etching. Pulsing the bias RF generator enables switching between high-energy ion-assisted etching of memory structures and low-energy polymer formation to protect the HAR feature sidewalls.

[0040] Current RF bias generators provide multilevel pulsing in a power range from 200 W to approximately 50 kW with pulse widths approaching 100 microseconds. However, new device manufacturing processes require wider power ranges (on the order of 50 W to over 200 kW) and narrower pulse widths of less than approximately 25 microseconds. Existing RF bias generator designs typically control power using pulse-width modulation (PWM) or outphasing (Chireix) power amplifier drive schemes. These drive schemes limit the available dynamic range to approximately 20 dB and the minimum pulse width to approximately 20 RF cycles. Furthermore, conventional PWM and Chireix drive schemes are highly inefficient when RF generators are operated to meet HAR manufacturing requirements, which include generating pulse waveforms with low duty cycles, such as less than approximately 5% of the pulse period, and low power pulse waveforms with durations longer than approximately 95% of the pulse period. Furthermore, increased bias power requirements increase wafer fabrication facility space requirements, and floor space in a typical wafer fabrication facility is at a premium. Therefore, there is a demand for RF generators that have improved power density and output high power over an improved dynamic range. With regard to RF bias generators in particular, the ever-changing requirements of wafer manufacturing require RF bias generators that can meet these capabilities.

[0041] FIG. 1 illustrates an RF generator or power supply system 110. The power supply system 110 includes a pair of radio frequency (RF) generators or power supplies 112a, 112b, matching networks 118a, 118b, and a load 132, 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 112a is referred to as a source RF generator or power supply, and the matching network 118a is referred to as a source matching network. In various configurations, the RF generator 112b is referred to as a bias RF generator or power supply, and the matching network 118b 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 118a, 118b may be implemented as an RF blocking filter rather than impedance matching, as may be the case for a matching network receiving, for example, a pulsed DC or non-sinusoidal signal. In various other configurations, one or both of the matching networks 118a, 118b may be omitted.

[0042] In various configurations, the source RF generator 112a receives a control signal 130 from the matching network 118b, generator 112b, or a signal 130' from the bias RF generator 112b. The control signal 130 or 130' represents an input signal to the source RF generator 112a that represents one or more operating characteristics or parameters of the bias RF generator 112b. In various configurations, a synchronization bias detector 134 detects the RF signal output from the matching network 118b to the load 132 and outputs a synchronization or trigger signal 130 to the source RF generator 112a. In various configurations, a synchronization or trigger signal 130', rather than the trigger signal 130, may be output from the bias RF generator 112b to the source RF generator 112a. A difference between the trigger or synchronization signals 130, 130' may result from the effect of the matching network 118b, which allows for adjustment of the phase between the input signal to the matching network and the output signal from the matching network. The signals 130, 130', in various configurations, contain information about the operation of the bias RF generator 112b that allows a predictable response to periodic variations in the impedance of the plasma chamber or load 132 caused by the bias RF generator 112b. In the absence of the control signals 130 or 130', the RF generators 112a, 112b operate autonomously.

[0043] The RF generators 112a and 112b each include an RF power supply or amplifier 114a and 114b, a sensor 116a and 116b, and a processor, controller, or control module 120a and 120b, respectively. The RF power supplies 114a and 114b generate RF power signals 122a and 122b that are output to the sensors 116a and 116b, respectively. The RF power signals 122a and 122b pass through the sensors 116a and 116b and are provided to matching networks 118a and 118b as RF power signals f1 and f2, respectively. The sensors 116a and 116b output signals that vary in response to various parameters sensed from the load 132. While the sensors 116a and 116b are shown within the respective RF generators 112a and 112b, the sensors 116a and 116b may also be located external to the RF generators 112a and 112b. 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.

[0044] The sensors 116a, 116b detect various operating parameters and output signals X and Y. The sensors 116a, 116b may include voltage sensors, current sensors, and / or directional coupler sensors. The sensors 116a, 116b measure (i) the voltage V and current I and / or (ii) the forward power P output from the respective power amplifiers 114a, 114b and / or RF generators 112a, 112b. FWD and the reverse or reflected power P received from the respective matching networks 118a, 118b or loads 132 connected to the respective sensors 116a, 116b. 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 114a, 114b. The sensors 116a, 116b may be analog or digital sensors, or a combination thereof. In digital implementations, the sensors 116a, 116b 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

[0045] The sensors 116a, 116b generate sensor signals X, Y, which are received by respective controllers or control modules 120a, 120b. The control modules 120a, 120b process the respective X and Y signals 124a, 126a and 124b, 126b and generate one or more feedforward or feedback control signals 128a, 128b for the respective power supplies 114a, 114b. The power supplies 114a, 114b adjust the RF power signals 122a, 122b based on the received one or more feedforward or feedback control signals. In various configurations, the power control modules 120a, 120b may control the matching networks 118a, 118b, respectively, via control signals 129a, 129b, respectively, based on, for example, the X and Y signals 124a, 126a and 124b, 126b. Power control modules 120a, 120b 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.

[0046] In various configurations, the power control modules 120a, 120b may include multiple functions, multiple processes, multiple processors, or multiple sub-modules. The control signals 128a, 128b 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 128a, 128b 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 128a, 128b 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 128a, 128b 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.

[0047] In various configurations, the power supply system 110 can include a controller 120′. The controller 120′ can be located external to either or both of the RF generators 112a, 112b and may be referred to as an external or common controller 120′. In various configurations, the controller 120′ can implement one or more functions, processes, or algorithms described herein with respect to either or both of the controllers 120a, 120b. As such, the controller 120′ communicates with each of the RF generators 112a, 112b via a pair of links 136, 138 that enable the exchange of data and control signals, as appropriate, between the controller 120′ and the RF generators 112a, 112b. For various configurations, the controllers 120a, 120b, 120′ can perform distributed and collaborative analysis and control of the RF generators 112a, 112b. In various other configurations, the controller 120' can control the RF generators 112a, 112b, eliminating the need for respective local controllers 120a, 120b.

[0048] In various configurations, the RF power supply 114a, the sensor 116a, the controller 120a, and the matching network 118a can be referred to as the source RF power supply 114a, the source sensor 116a, the source controller 120a, and the source matching network 118a, respectively. Similarly, in various configurations, the RF power supply 114b, the sensor 116b, the controller 120b, and the matching network 118b can be referred to as the bias RF power supply 114b, the bias sensor 116b, the bias controller 120b, and the bias matching network 118b, 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.

[0049] According to various configurations, the source RF generator 112a and the bias RF generator 112b each include multiple ports for communicating with the outside world. The source RF generator 112a includes a pulse synchronization output port 140, a digital communication port 142, an RF output port 144, and a control signal port 160. The bias RF generator 112b includes an RF input port 148, a digital communication port 150, and a pulse synchronization input port 152. The pulse synchronization output port 140 outputs a pulse synchronization signal 156 to the pulse synchronization input port 152 of the bias RF generator 112b. The digital communication port 142 of the source RF generator 112a and the digital communication port 150 of the bias RF generator 112b communicate via a digital communication link 157. The control signal port 160 of the source RF generator 112a receives one or both of the control signals 130 and 130′. The RF output port 144 generates an RF control signal 158 that is input to the RF input port 148. In various configurations, RF control signal 158 is substantially identical to the RF control signal controlling source RF generator 112a. In various other configurations, RF control signal 158 is identical to the RF control signal controlling source RF generator 112a, but is phase shifted within source RF generator 112a by a desired phase shift produced by bias RF generator 112b. Thus, in various configurations, source RF generator 112a and bias RF generator 112b are driven by substantially identical RF control signals or by substantially identical RF control signals phase shifted by a predetermined amount.

[0050] In various configurations, the power supply system 110 may include multiple RF source generators 112a and multiple RF bias generators 112b. As a non-limiting example, the multiple source RF generators 112a, 112a', 112a'', ..., 112a may be configured to provide multiple output power signals to one or more source electrodes of the load 132. n Similarly, multiple bias RF generators 112b, 112b', 112b'', ..., 112b may be arranged to provide multiple output power signals to multiple bias electrodes of the load 132. nmay be arranged. When the source RF generator 112a and the bias RF generator 112b 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 118a, 118b, 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.

[0051] FIG. 2 is a plot of voltage versus time illustrating a pulse or pulsed mode of operation for delivering power to a load, such as load 132 in FIG. 1 . More specifically, FIG. 2 shows two multi-state pulses P1 and P2 of a pulse signal 212 having multiple states S1-S4 and S1-S3. In FIG. 2 , an RF signal 210 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 112 outputs an RF signal 210 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 112 does not output an RF signal 210. Pulses P1 and P2 can repeat with a constant or 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.

[0052] In various configurations, RF signal 210 need not be implemented as a sinusoidal waveform as shown in FIG. 2. As referenced above with respect to FIG. 2, in addition to a sinusoidal waveform, RF signal 210 may be a non-sinusoidal waveform in various configurations. By way of non-limiting example, RF signal 210 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, pulse signal 212 may be other than a square wave as shown in FIG. 2. Further, by way of non-limiting example, the envelope of pulse signal 212 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 other various configurations, the pulse signal may change shape between occurrences. In various other configurations, the pulse signal may occur or reoccur within a fixed or variable time period and may vary in shape between occurrences. Furthermore, pulses P1, P2 may have multiple states S1, ..., Sn that vary in amplitude, duration, and shape. States S1, ..., Sn may repeat within a fixed or variable time period and may include all or some of the various shapes described above. Also, as shown in FIG. 2, RF signal 210 may operate at a frequency that varies between states or within a state.

[0053] 3A illustrates an RF generator 310 arranged in accordance with the principles of the present disclosure. The RF generator 310 includes a plurality of fixed voltage power amplifiers 314 and a weighted voltage power amplifier 326 coupled in series to obtain a composite output voltage at the input of a harmonic filter 334. The fixed power generation section 312 includes a plurality of fixed power supplies or power amplifiers 314a, ..., 314(n-1), 314n, each of which is connected to a PA F1 ,…,PA F(n-1) ,PA Fn Also called a fixed power amplifier (PA). F1 ,…,PA F(n-1) ,PA FnEach of the weighted power generators 322 outputs a voltage signal or voltage V to a transformer 324, all of which are arranged in series. The weighted power generator 322 includes a plurality of weighted power supplies or power amplifiers 326a, 326b, ..., 326(m-1), 326m, which are connected to the PA W1 ,PA W2 ,…,PA W(m-1) ,PA Wm Also called a weighted power amplifier (PA). W1 ,PA W2 ,…,PA W(m-1) ,PA Wm where i is the subscript (1, 2, ..., m-1, m) of the power amplifier, and i to transformers 324, all of which are arranged in series. Although only one transformer 324 is labeled in Figure 3A, all of the transformers shown in Figure 3A are substantially identical, or may have different turns ratios, and are arranged in series. In various configurations, weighted power amplifiers 326 and associated transformers 324 may also be referred to as weighted power amplifier modules.

[0054] The voltage signals or voltages output from the fixed power generator 312 and the weighted power generator 322 are summed via a series connection of transformers 324. The voltage generated via the series connection of transformers 324 is sent to the input of a harmonic filter 334. The harmonic filter 334 is configured to remove selected harmonics from the voltage signal input to the harmonic filter 334. The output of the harmonic filter 334 is input to a matching network 318, which is configured similarly to the matching networks 118a and 118b of FIG. 1. The matching network 318 operates as described above to generate a matched voltage signal that is sent to a load 332, which may be configured similarly to the load 132 of FIG. 1. Sensors (not shown in FIG. 3A but configured similarly to sensors 116a, 116b of FIG. 1) generate one or more feedback signals that vary in response to one or more electrical parameters, such as voltage and current in one non-limiting example, that are sent to controller 320. Controller 320 is configured to operate generally similarly to controllers 120, 120′ described above with respect to FIG. 1 and as further described below.

[0055] The controller 320 receives one or more feedback signals and other command inputs and generates enable and drive signals for each of the power amplifiers in the fixed power generator 312 and the weighted power generator 322. The controller 320 outputs (n+m) enable signals, one of which is input to each power amplifier 314, 326 to activate it. In various configurations, the controller 320 outputs the (n+m) enable signals via a bus structure. The controller 320 also outputs one or more drive signals applied to each power amplifier, controlling the frequency and phase of the voltage signal output by each power amplifier via the phase and frequency of the drive signals. The one or more feedback signals input to the controller 320 are analyzed by the controller 320, which may vary the enable signals to change one or more electrical parameters detected to generate the one or more feedback signals. In various configurations, the enable signals are individual signals applied to each power amplifier. In various configurations, the drive signal is a common signal that is buffered separately to each power amplifier.

[0056] As shown in FIG. 3A, the supply voltage signal or supply voltage V d may be a regulated, non-isolated supply voltage generated internally by RF generator 310 or received from an external source. d provides a voltage that is directly input to the fixed power amplifiers 314 of the fixed power generating unit 312. Each power amplifier of the fixed power generating unit 312 outputs a voltage signal or voltage V when turned on, and 0V when turned off. d is input to one or more direct current / direct current (DC / DC) converters 328. In various configurations, the DC / DC converters 328 convert the input voltage V d V d A fractional multiple of the weighted power amplifier PA W1 ,PA W2 ,…,PA W(m-1) ,PA Wm This V dA fractional multiple of is sometimes called a weighted voltage signal or weighted voltage. W1 ,PA W2 ,…,PA W(m-1) ,PA Wm receives each partial voltage signal or voltage and outputs a corresponding fractional multiple of V. Each power amplifier in the weighted power generating unit 322 outputs 0V when turned off. W1 ,PA W2 ,…,PA W(m-1) ,PA Wm The weighted voltage output by provides step control for minimum steps of some fractional multiple of V.

[0057] In one of various configurations, the DC / DC converter 328 receives an input voltage V d V d where i denotes the subscript (1, 2, ..., m-1, m) of each weighted power amplifier, the binary weighted voltage signal or voltage V d / 2 i ) is used as a weighted power amplifier PA W1 ,PA W2 ,…,PA W(m-1) ,PA Wm Therefore, the power amplifier PA W1 ,PA W2 ,…,PA W(m-1) ,PA Wm is the binary weighted voltage signal or voltage V d / 2 i and generates a binary weighted voltage signal or voltage V / 2 (where i represents the subscript (1, 2, ..., m-1, m) of each weighted power amplifier). i Each power amplifier of the weighted power generating unit 322 outputs 0V when it is off. W1 ,PA W2 ,…,PA W(m-1) ,PA Wm The binary-weighted voltage output by mThe controller 320 determines which amplifier to activate based on the amplitude setting.

[0058] The fixed power generating section 312 and the weighted power generating section 322 are configured as follows: F1 ,…,PA F(n-1) ,PA Fn and P.A. W1 ,PA W2 ,…,PA W(m-1) ,PA Wm , and generates a composite series voltage that is input to the harmonic filter 334. The composite voltage of the fixed power generator 312 is applied to the power amplifier PA F1 ,…,PA F(n-1) ,PA Fn As a non-limiting example, the power amplifier PA F1 ,…,PA F(n-1) ,PA Fn When one of the power amplifiers PA is activated, the voltage output from the weighted power generator 322 is V. Similarly, as a non-limiting example, F1 ,…,PA F(n-1) ,PA Fn When two of the power amplifiers PA are activated, the voltage output from the weighted power generator 312 is 2V. F1 ,…,PA F(n-1) ,PA Fn When n of these are operating, the voltage output from the fixed power generating unit 312 is nV.

[0059] Similarly, when on, each power amplifier of the weighted power generating unit 322 outputs 1 times V divided by a power of 2, which is equal to V / 2i, where i represents the subscript (1, 2, ..., m-1, m) of each weighted power amplifier, and when off, outputs 0V. W1 ,PA W2 ,…,PA W(m-1) ,PA Wm The figure shows the voltage output from PA W1 V / 2 1=V / 2 PA W2 V / 2 2 =V / 4 · · PA W(m-1) V / 2 m-1 PA Wm V / 2 m The composite voltage of the weighted power generating unit 322 is W1 ,PA W2 ,…,PA W(m-1) ,PA Wm As a non-limiting example, the power amplifier PA W1 When only the weighted power generating unit 322 is operating, the voltage output from the weighted power generating unit 322 is V / 2 1 =V / 2. Similarly, as a non-limiting example, a power amplifier PA W1 and P.A. W2 When the weighted power generating unit 322 is in operation, the voltage output from the weighted power generating unit 322 is (V / 2 1 =V / 2)+(V / 2 2 =V / 4)=3V / 4. Further, as a non-limiting example, two power amplifiers PA W1 and P.A. Wm When (m=6) is activated, the voltage output from the weighted power generating unit 322 is (V / 2 1 =V / 2)+(V / 2 6 =V / 64)=33V / 64.

[0060] In one non-limiting example, the weighted power generation unit 322 includes six power supplies or power amplifiers PA W1 ,PA W2 ,PA W3 ,PA W4 ,PA W5 ,PA W6 (m=6) may be included. W1 ,PA W2 ,PA W3 ,PA W4 ,PA W5 ,PA W6are V / 2, V / 4, V / 8, V / 16, V / 32, V / 64 respectively (assuming i has subscripts (1, 2, …, m - 1, m), then V / 2 i ). By adding binary-weighted voltage power amplifiers, fine step control for a minimum step of V / 64 is provided for the weighted power generation unit 322 having six power amplifiers. The controller 320 determines which amplifier to activate based on the amplitude setting value. This power control scheme can generate output quantization steps from zero volts to ((n + 1) × 64 - 1) volts with a resolution of v / 64 volts per step (n is the maximum number of active power amplifiers). As a result, the AC / DC front-end power supply device that converts the DC input voltage (V d ) input to the RF generator into an AC voltage can be a fixed-voltage non-isolated step-down converter. With such a configuration, the size of the RF generator can be reduced and the power density can be increased.

[0061] FIG. 3B discloses one of various configurations of the weighted power generation unit 322. In FIG. 3B, the transformer 324 associated with each weighted power amplifier PA W1 , PA W2 , …, PA W(m-1) , PA Wm outputs the same voltage as the corresponding transformer across the weighted power amplifiers in FIG. 3A. However, in the weighted power generation unit 322 of FIG. 3B, the voltage applied to each transformer 324 varies according to the supply voltage input to each weighted power amplifier and the turns ratio of the transformer at the output of each weighted power amplifier. With such a configuration, the number of DC / DC converters required to implement the weighted power generation unit 322 can be reduced.

[0062] As a non-limiting example, the weighted power amplifiers PA W1 , PA W2 each receive the same supply voltage V d / 2. The weighted power amplifier PA W1The transformer at the output of the weighted power amplifier PA has a turns ratio of 1:1 (input:output). W2 The transformer at the output of the weighted power amplifier PA has a turns ratio of 2:1. W1 ,PA W2 The supply voltage input to V d / 2, the weighted power amplifier PA W1 ,PA W2 The output of each weighted power amplifier PA is V / 2. W1 ,PA W2 Due to the different turns ratios of the transformers associated with the weighted power amplifier PA W1 The voltage across the transformer at the output of the weighted power amplifier PA W2 The voltage across the transformer at the output of the weighted power amplifier PA is V / 4. W(m-1) ,PA Wm are the same supply voltage V d / 2 m-1 Weighted Power Amplifier PA W(m-1) The transformer at the output of the weighted power amplifier PA has a turns ratio of 1:1. Wm The output section of the weighted power amplifier PA has a turns ratio of 2:1. W(m-1) ,PA Wm The supply voltage input to V d / 2 m-1 Then, the weighted power amplifier PA W1 ,PA W2 The output is V / 2 m-1 Because of the different turns ratio, W(m-1) The voltage across the transformer at the output of m-1 and P.A. Wm The voltage across the transformer at the output of m is.

[0063] 3C discloses one of various configurations of the weighted power generating unit 322. In FIG. 3C, each weighted power amplifier PA W1 ,PA W2 ,…,PA W(m-1) ,PA Wm3C, the transformers 324 associated with each weighted power amplifier PA output the same voltage as the corresponding transformers across the weighted power amplifiers of FIG. W1 ,PA W2 ,…,PA W(m-1) ,PA Wm are the weighted power amplifiers PA W1 ,PA W2 ,…,PA W(m-1) ,PA Wm output voltage V d The output of each transformer 324 associated with each weighted power amplifier varies depending on the turns ratio of the respective transformer. Such a configuration can reduce the number of DC / DC converters required to implement the weighted power generation section 322.

[0064] As a non-limiting example, a weighted power amplifier PA W1 ,PA W2 ,…,PA W(m-1) ,PA Wm are the same supply voltage V d Weighted Power Amplifier PA W1 ,PA W2 ,…,PA W(m-1) ,PA Wm The transformer 324 at the output of i :1). Therefore, each weighted power amplifier PA W1 ,PA W2 ,…,PA W(m-1) ,PA Wm The turns ratio of each transformer associated with 1 :1),(2 2 :1),…,(2 m-1 :1),(2 m :1) Therefore, each weighted power amplifier PA W1 ,PA W2 ,…,PA W(m-1) ,PA Wm The supply voltage input to V d Then, the weighted power amplifier PAW1 ,PA W2 ,…,PA W(m-1) ,PA Wm The output is V / 2, V / 4, …, V / 2 m-1 ,V / 2 m This becomes:

[0065] In various configurations, the weighted power generation section 322 may include a hybrid of Figures 3A and 3B. In a hybrid configuration, the first group or first plurality of weighted power amplifiers PA W1 ,PA W2 ,…,PA W(m-1) ,PA Wm is the first supply voltage signal or voltage V d or V d Since each of the first group or first plurality of weighted power amplifiers receives the same supply voltage, the voltage across each of the transformers associated with each weighted power amplifier of the first plurality of weighted power amplifiers is determined according to the turns ratio of the respective transformer. Similarly, each of the second group or second plurality of weighted power amplifiers PA W1 ,PA W2 ,…,PA W(m-1) ,PA Wm is the second supply voltage signal or voltage V d or V d The second group or second plurality of weighted power amplifiers may receive a voltage that is a fractional multiple of the first supply voltage signal or voltage. The second supply voltage signal or voltage is different from the first supply voltage signal or voltage. Because each of the second group or second plurality of weighted power amplifiers receives the same supply voltage, the voltage across each of the transformers associated with each weighted power amplifier of the second plurality of weighted power amplifiers is determined according to the turns ratio of the respective transformer. In various configurations, a third group or third plurality of weighted power amplifiers PA W1 ,PA W2 ,…,PA W(m-1) ,PA Wmcan be similarly configured. In various configurations, the voltage across each transformer of weighted power generator 322 varies to provide the flat step described above. In other various configurations, the voltage across each transformer may be 1 / power of 2 times the unique output voltage V.

[0066] In wafer fabrication, plasma loads are highly nonlinear and prone to rapid load transients during plasma ignition, arcing, and pulsing. The plasma load is represented as a complex impedance Z = R ± jX. The impedance Z is transformed to the fixed power amplifier 314 and weighted power amplifier 326 of the RF generator 310 through a matching network, such as the matching network 118a, 118b, or 318 described above, and a harmonic filter 334. In various configurations, it is generally preferable for the load impedance of the RF generator 310 and its power amplifier to be inductive, which occurs when Z = R + jX. If the impedance is capacitive (which occurs when Z = R - jX), the power amplifier will experience high losses, reduced efficiency, and reduced reliability. The optimal load impedance for an RF power amplifier is inductive, i.e., Z = R ± jX, providing maximum performance and maximum efficiency. Therefore, the harmonic filter 334 in various configurations is designed to add a large inductance with a positive phase angle to shift the power amplifier load impedance toward a more inductive phase angle, which improves the efficiency of the RF generator 310 and favorably modifies the plasma impedance lobe.

[0067] FIG. 4 illustrates a Smith chart 410, which is used to further describe the operation of an RF power amplifier with an impedance transformation to the inductive portion of the Smith chart 410. An impedance circle 414 represents a typical impedance for a power amplifier driving a plasma load in the absence of an inductive load shift, such as that provided by the harmonic filter 334. The impedance circle 414 is sometimes referred to as the plasma impedance lobe. By using the harmonic filter 334, the RF power amplifier is shifted from the impedance circle 414 along an impedance transformation path 416 to an impedance circle 412. The impedance circle 412 represents the inductive region of operation of the RF generator 310. As shown in FIG. 4, the impedance circle 412 appears approximately cylindrical. Furthermore, the impedance transformation path 416 represents a seventh-order or seven-pole transformation. Thus, the harmonic filter 334 converts the operation of the fixed power amplifier 314 and weighted power amplifier 326 of the RF generator 310 to an inductive mode of operation by shifting the impedance of the power amplifiers from low impedance to the upper half of the Smith chart 410 (above the horizontal axis).

[0068] 5-7 show graphs for example control schemes in which the drive actuator of a feedback, feedforward, or MIMO controller is transformed so that output power is linear for linear changes in the drive actuator and the output voltage follows the square root of the output power. FIG. 5 shows a graph 510 including a plot of output power 512 versus drive actuator or drive word and a plot of output voltage 514 versus drive actuator or drive word. The drive word indicates which power amplifiers, such as those shown in FIGS. 3A-3C, are turned on and off. In FIG. 5, output power 512 is linear with the drive word, while output voltage 514 is shown as the square root of output power 512. In various configurations, to achieve a smooth, monotonic, and linear power characteristic, a controller such as controller 320 of FIGS. 3A-3C can be configured to use fixed power generator 312 as a fixed-voltage power amplifier and weighted power generator 322 as a binary-weighted power amplifier to provide the desired output power. FIG. 6 shows a graph 610 including a plot 612 representing the relationship between drive word and power amplifier number. The power amplifier count indicates the number of power amplifiers in the fixed power generator 312 that are driven to provide the coarse voltage step. FIG. 7 shows a graph 710 including a plot 712 of the weighted power amplifier output voltages output by the weighted power generator 322 versus the driving word. The voltages output by the weighted power generator 322 provide the fine voltage steps. In the non-limiting example of FIGS. 5-7, each power amplifier in the fixed power generator 312 is driven by a given supply voltage V d Similarly, in the non-limiting example of FIGS. 5-7, each power amplifier in weighted power generation section 322 is configured to output 98V for a given supply voltage V if there are six weighted power amplifiers. d The supply voltage V output from the DC / DC converter 328 d / 2 i5-6, coarse voltage steps are generated by enabling the correct number of fixed voltage power amplifiers, and fine voltage steps are provided by enabling the correct number of weighted power amplifiers, as shown in FIG.

[0069] FIGS. 8-10 show graphs for example control schemes in which the drive actuator of a feedback, feedforward, or MIMO controller is transformed so that the output power is linear with respect to the drive actuator and the output voltage follows the square of the output power. FIG. 8 shows a graph 810 including a plot of output voltage 812 versus drive actuator or drive word and a plot of output power 814 versus drive actuator or drive word. The drive word indicates which power amplifiers, such as those shown in FIGS. 3A-3C, are turned on and off. In FIG. 8, the output voltage 812 is linear with respect to the drive word, while the output power 814 is shown as the square of the output voltage 812. In various configurations, to achieve a smooth, monotonic, and linear power characteristic, a controller such as controller 320 of FIGS. 3A-3C may enable fixed power generator 312 to be a fixed-voltage power amplifier and weighted power generator 322 to be a binary-weighted power amplifier to provide the desired output power. FIG. 9 shows a graph 910 including a plot 912 representing the relationship between drive word and the number of power amplifiers. The power amplifier count indicates the number of power amplifiers in the fixed power generator 312 that are attenuated to provide a coarse voltage step. FIG. 10 shows a graph 1010 that includes a plot 1012 of the weighted power amplifier output voltages output by the weighted power generator 322 versus the drive word. The voltages output by the weighted power generator 322 provide the fine voltage steps. In the non-limiting example of FIGS. 8-10, each power amplifier in the fixed power generator 312 is attenuated for a given supply voltage V dSimilarly, in the non-limiting example of FIGS. 8-10, each power amplifier in weighted power generation section 322 is configured to output 98V for a given supply voltage V if there are six weighted power amplifiers. d The supply voltage V output from the DC / DC converter 328 d / 2 i 8-10, coarse voltage steps are generated by enabling the correct number of fixed voltage power amplifiers, as shown in FIG. 9, and fine voltage steps are provided by enabling the correct combination of weighted power amplifiers, as shown in FIG.

[0070] FIG. 11 shows a graph 1110 with a plot or waveform 1112 representing a linear ramp pulse envelope. The pulse envelope of FIG. 11 shows two pulses P1 and P2, each with a 10 kHz repetition rate. Feedforward control can be used to control the pulse shape during rapid impedance changes that occur when driving a plasma. In addition, MIMO control can be used to simultaneously control the drive actuator and frequency actuator to control the pulse shape and minimize reflected power. Modern semiconductor etch and deposition processes require bias generators capable of producing complex amplitude-modulated envelopes, also known as multi-state pulsing. The RF generator described in this disclosure offers superior performance compared to previous RF generators by enabling near-instantaneous changes in output voltage amplitude at the RF power zero crossing.

[0071] Figure 12 encompasses various components of Figures 1-11. Control module 1210 may include an amplitude control module portion 1214, a frequency control module portion 1216, and an impedance matching module 1218. Amplitude control module portion 1214 includes a DC voltage generator module 1220, an amplitude adjustment module 1222, and an amplitude update module 1224. Frequency control module portion 1216 includes a frequency adjustment module 1226 and a frequency update module 1228. In various configurations, control module 1210 includes one or more processors that execute code associated with the module portions or modules 1210, 1212, 1214, 1216, 1218, 1220, 1222, 1224, 1226, and 1228. The operation of modular sections or modules 1210, 1212, 1214, 1216, 1218, 1220, 1222, 1224, 1226, 1228 is described below with respect to the method of FIG.

[0072] For more detailed structure of controllers 120a, 120b, 120' of FIG. 1, see the flowchart in FIG. 13 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. 1. While the following operations are primarily described with respect to the embodiment of FIG. 1, 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.

[0073] FIG. 13 shows a flow chart of a control system 1310 for performing mode-based impedance control for the power transfer system of FIG. 1, in a non-limiting example. Control begins at start / initialization block 1312. Control proceeds to block 1314, where a commanded output voltage is received. Control proceeds to block 1316, where a determination is made as to how many power amplifiers in the fixed power generator 312 and which power amplifiers in the weighted power generator 322 are needed to generate the commanded output voltage. Control proceeds to block 1318, where a control word is generated based on the number of power amplifiers needed to generate the commanded output voltage. Control proceeds to block 1320, where an output voltage is generated according to the control word by generating drive and enable signals for each power amplifier. Control proceeds to block 1322, where a determination is made as to whether the commanded output voltage is being generated. If the commanded output voltage is not being generated, control proceeds to block 1316, where the process continues by updating the power amplifier control signals to progress toward the commanded output voltage. If the commanded output voltage is being achieved, control proceeds to block 1324, where the process ends, but monitoring of the output voltage continues.

[0074] Plasma loads are highly nonlinear and prone to rapid load transients during plasma ignition, arcing, and pulsing. The RF generator described in this disclosure can be configured to protect the circuit from mismatched loads by switching the power amplifiers of the fixed power generation section 312 between operation and non-operation to prevent overheating. This switching occurs at the zero crossings of the PA module output waveform and does not disrupt the overall output of the RF generator 310. In the RF generator described above, n fixed power amplifiers 314a, ..., 314(n-1), 314n (each of which is a PA F1 ,…,PA F(n-1) ,PA Fn Similarly, the weighted power generating unit 322 is illustrated as having m power amplifiers 326a, 326b, ..., 326(m-1), 326m (PA W1 ,PA W2 ,…,PA W(m-1) ,PA WmIn various configurations, where n=N and m=M, RF generator 310 may have a frequency range of 0 to ((N+1)×V−(V / 2 M )) It can output a voltage between 1000V and 1000V.

[0075] In various configurations, the total output voltage can be limited to a value less than the output voltage that the total number of power amplifiers can output. As a non-limiting example, if n=N+A, the fixed power generator 312 may include (N+A) power amplifiers, but may drive no more than N of the power amplifiers in the fixed power generator 312 at one time. In such a configuration, to prevent overheating, the (N+A) power amplifiers may be switched between operating so that all of the (N+A) power amplifiers have on and off periods. In such a configuration, switching occurs at the zero crossings of the power amplifier output module waveform so as not to disrupt the overall output of the RF generator 310.

[0076] In a conventional phase-shifted class-D power amplifier, such as that implemented in the power amplifier of FIGS. 3A-3C, a typical failure occurs when the main power amplifier device shorts to ground, resulting in a loss of control and power. If such an event occurs during a wafer fabrication process, it is conceivable that the wafer may need to be scrapped. In the RF plasma generator of the present disclosure, the granularity of redundancy can be improved by increasing the number of independent, identical amplifiers. As a non-limiting example, the (N+A) power amplifiers described above can create an additional inventory of A power amplifiers, allowing the power amplifier to be removed from the switch list in the event of a failure. Thus, even if one power amplifier fails, the failed amplifier does not affect the remaining amplifiers because the power amplifiers are coupled in series using the transformer 324. In various configurations, a fault sensor may be associated with each power amplifier to indicate the failure of that power amplifier. Furthermore, in various configurations, each power amplifier is individually fused to isolate that particular power amplifier from the bulk voltage supply in the event of a power amplifier short. This allows the voltage to remain uninterrupted for the other RF power amplifiers. Furthermore, at the next zero crossing, the failed power amplifier is identified and switched over to an alternative power amplifier to minimize output disturbances.

[0077] The RF power generators described herein may provide one or more of the following advantages: dThe RF power generators described herein provide higher power density because a non-isolated fixed voltage step-down regulator can be used to generate the RF power. Such voltage regulators are smaller than isolated agile rail voltage supplies. The RF power generators described herein can generate narrower pulses, increase peak-to-average power ratios, and enable more complex envelopes at faster drive rates, improving pulsing performance. The RF power generators described herein can increase power efficiency during multi-level pulsing because power amplifier modules are on or off and unnecessary power amplifiers are disabled, so power is not wasted during low power portions of the pulse envelope. The RF power generators described herein can achieve low harmonic distortion at even harmonic frequencies because the inherent symmetry of the output waveform reduces even harmonics and simplifies harmonic output filters by eliminating the need to filter even harmonics. The RF power generators described herein can provide a high dynamic range, on the order of more than 60 dB of dynamic range. The RF power generator described herein improves plasma stability in pulsed operation because the power amplifiers inherently drive amplitude changes that are matched to changing pulse conditions, allowing power changes to be matched to pulse conditions. The RF power generator described herein has a fast response time. This fast response time is due to a constant voltage power supply that powers all of the power amplifiers. This eliminates the power supply control loop and its associated response time, as well as the turn-on delays used in other designs. The serially coupled power amplifiers are synchronously switched on and off every RF clock cycle to generate output quantized step voltages from zero volts to ((n+1)×64-1) volts (n=maximum number of active fixed power amplifiers) with a resolution of v / 64 volts per step for six weighted power amplifiers.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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).

[0085] 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).

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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).

[0091] 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.

[0092] 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.

[0093] 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. a fixed power generation section including a first plurality of power amplifiers each configured to receive a supply voltage and output a first voltage; a weighted power generation section including a plurality of weighted power amplifier modules each including a weighted power amplifier and a transformer; wherein each weighted power amplifier of the plurality of weighted power amplifier modules receives a weighted supply voltage, and the voltage across the transformer of each weighted power amplifier module is a fractional multiple of the first voltage. RF power generator.

2. 2. The RF power generator of claim 1, wherein at least one of the weighted power amplifiers of the weighted power amplifier modules receives a voltage that is a fractional multiple of the supply voltage, and wherein the at least one of the weighted power amplifier modules is configured to output a voltage that is a fractional multiple of the first voltage.

3. 3. The RF power generator of claim 2, wherein the at least one of the plurality of weighted power amplifier modules is configured to output a voltage that is a fractional multiple of the first voltage that is different from the other ones of the plurality of weighted power amplifier modules.

4. 10. The RF power generator of claim 1, wherein two or more of the plurality of weighted power amplifier modules receive the same fractional multiple of the supply voltage.

5. 5. The RF power generator of claim 4, wherein a transformer associated with one of the two or more of the plurality of weighted power amplifier modules has a different turns ratio than others of the two or more of the plurality of weighted power amplifier modules.

6. 2. The RF power generator of claim 1, wherein at least one of the plurality of weighted power amplifier modules receives the supply voltage, and wherein the at least one of the plurality of weighted power amplifier modules is configured to output a voltage that is a fractional multiple of the first voltage.

7. 7. The RF power generator of claim 6, wherein a transformer associated with at least one of the plurality of weighted power amplifier modules has a different turns ratio such that the at least one of the plurality of weighted power amplifier modules outputs a voltage that is a fractional multiple of the first voltage.

8. 2. The RF power generator of claim 1, wherein two or more of the plurality of weighted power amplifier modules receive the supply voltage, and wherein the two or more of the plurality of weighted power amplifier modules are configured to output a voltage that is a fractional multiple of the first voltage.

9. 9. The RF power generator of claim 8, wherein transformers associated with two or more of the plurality of weighted power amplifier modules have a different turns ratio than others of the two or more of the plurality of weighted power amplifier modules.

10. 10. The RF power generator of claim 1, further comprising a DC / DC converter configured to receive the supply voltage and generate weighted supply voltages, the weighted supply voltages being input to weighted power amplifiers of the plurality of weighted power amplifier modules.

11. 2. The RF power generator of claim 1, further comprising a plurality of DC / DC converters each configured to receive the supply voltage and generate a respective weighted supply voltage, the respective weighted supply voltages being input to a respective weighted power amplifier of the plurality of weighted power amplifier modules.

12. 12. The RF power generator of claim 11, wherein the weighted supply voltage is one times the supply voltage divided by a power of two.

13. 10. The RF power generator of claim 1, further comprising a harmonic filter configured to transform the impedance of each power amplifier into an inductive impedance.

14. 14. The RF power generator of claim 13, wherein the inductive impedance is located above the horizontal axis of a Smith chart.

15. 2. The RF power generator of claim 1, wherein the first plurality of power amplifiers of the fixed power generation section are connected in series.

16. 2. The RF power generator of claim 1, wherein each of the first plurality of power amplifiers of the fixed power generation section is configured to output the first voltage to a respective transformer, the respective transformers being connected in series.

17. 2. The RF power generator of claim 1, wherein the weighted power amplifier modules of the weighted power generation section are connected in series.

18. 2. The RF power generator of claim 1, wherein each of the plurality of weighted power amplifier modules of the weighted power generation section is configured to output the fractional multiple of the first voltage to a respective associated transformer, the respective associated transformers being connected in series.

19. 2. The RF power generator of claim 1, wherein each power amplifier module of the fixed power generating unit and each power amplifier module of the weighted power generating unit are connected in series, and the fixed power generating unit and the weighted power generating unit are connected in series.

20. 2. The RF power generator of claim 1, wherein fewer than all of the first plurality of power amplifiers of the fixed power generation section generate an output voltage at one time, and the first plurality of power amplifiers switch between generating an output voltage and an off state.

21. 2. The RF power generator of claim 1, wherein the fractional multiple of the first voltage is one multiple of the first voltage over a power of two.

22. a fixed power generation section including a first plurality of power amplifiers each configured to receive a supply voltage and output a first voltage; a weighted power generation section including a plurality of weighted power amplifier modules; each weighted power amplifier module is configured to receive a weighted supply voltage, the voltage at the output of each weighted power amplifier module being a fractional multiple of the first voltage; RF power generator.

23. 23. The RF power generator of claim 22, wherein at least one of the weighted power amplifiers of the weighted power amplifier modules receives a voltage that is a fractional multiple of the supply voltage, and wherein the at least one of the weighted power amplifier modules is configured to output a voltage that is a fractional multiple of the first voltage.

24. 23. The RF power generator of claim 22, wherein at least one of the plurality of weighted power amplifier modules receives the supply voltage, and wherein the at least one of the plurality of weighted power amplifier modules is configured to output a voltage that is a fractional multiple of the first voltage.

25. 23. The RF power generator of claim 22, further comprising at least one DC / DC converter configured to receive the supply voltage and generate weighted supply voltages, the weighted supply voltages being input to weighted power amplifiers of the plurality of weighted power amplifier modules.

26. 23. The RF power generator of claim 22, wherein the weighted supply voltage is one times the supply voltage divided by a power of two.

27. 23. The RF power generator of claim 22, further comprising a harmonic filter configured to transform the impedance of each power amplifier into an inductive impedance.

28. 23. The RF power generator of claim 22, wherein the first plurality of power amplifiers of the fixed power generation section are connected in series.

29. 23. The RF power generator of claim 22, wherein each of the first plurality of power amplifiers of the fixed power generation section is configured to output the first voltage to a respective transformer, the respective transformers being connected in series.

30. 23. The RF power generator of claim 22, wherein the weighted power amplifier modules of the weighted power generation section are connected in series.

31. 23. The RF power generator of claim 22, wherein each of the weighted power amplifier modules of the weighted power generation section is configured to output the fractional multiple of the first voltage to a respective transformer, the associated transformers being connected in series.

32. 23. The RF power generator of claim 22, wherein each power amplifier module of the fixed power generation unit and each power amplifier module of the weighted power generation unit are connected in series, and the fixed power generation unit and the weighted power generation unit are connected in series.

33. 23. The RF power generator of claim 22, wherein fewer than all of the first plurality of power amplifiers of the fixed power generation section generate an output voltage at a time, and the first plurality of power amplifiers switch between generating an output voltage and an off state.

34. A non-transitory computer-readable medium having instructions stored thereon, the instructions comprising: Receives the command output voltage, determining a number of power amplifiers among a plurality of power amplifiers that, when driven, produce the commanded output voltage; generating a control word according to the number of power amplifiers; and controlling the determined number of power amplifiers according to the control word to generate an output voltage. a non-transitory computer-readable medium,

35. 35. The non-transitory computer-readable medium of claim 34, wherein the instructions include comparing the output voltage to a command output voltage and adjusting the determined number of power amplifiers according to a difference between the output voltage and the command output voltage.

36. 35. The non-transitory computer-readable medium of claim 34, wherein the plurality of power amplifiers comprises a first plurality of power amplifiers configured to receive a supply voltage and output a first voltage, and a second plurality of power-weighted power amplifiers configured to receive respective weighted supply voltages and output voltages that are fractional multiples of the first voltage.

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