A real-time non-invasive IEDF plasma sensor

Abstract

A controller for a plasma generating system includes a model evaluation module that receives sensed values ​​that vary according to a state of a plasma controlled by an RF power generator. The model evaluation module generates plasma parameters that vary according to the sensed values. A model integration module receives the plasma parameters, integrates the plasma parameters, and outputs integrated model parameters. An IEDF evaluation module receives the integrated model parameters and generates an ion energy distribution function (IEDF) according to the integrated model parameters. An IEDF controller module receives the IEDF and generates a signal to control an RF generator. An RF generator control module receives the signal and generates an RF generator control signal to control at least one of a power, a frequency, or a phase of the RF power generator.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Patent Application No. 17 / 715,672, filed April 7, 2022, the entire disclosure of which is incorporated herein by reference.

[0002] FIELD OF THE DISCLOSURE The present disclosure relates to RF generator systems and to the control of RF generators. [Background technology]

[0003] Plasma generation is frequently used in semiconductor fabrication. In plasma generation, ions are accelerated by an electric field to etch material from or deposit material onto the surface of a substrate. In one basic implementation, the electric field is generated based on an RF or DC power signal generated by a respective RF or DC generator in a power distribution system. The power signal generated by the generator must be precisely controlled to effectively perform plasma etching.

[0004] The Background Art discussion provided herein is intended to provide a general background to the present disclosure. The presently described inventors' work, as well as aspects of the specification that do not otherwise qualify as prior art at the time of filing, are not admitted, expressly or impliedly, as prior art to the present disclosure, to the extent that they are described in the Background Art. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 7,602,127 [Patent Document 2] U.S. Patent No. 8,110,991 [Patent Document 3] U.S. Patent No. 8,395,322 [Patent Document 4] U.S. Patent No. 10,821,542 [Patent Document 5] U.S. Patent No. 10,546,724 [Patent Document 6] U.S. Patent No. 10,049,857 [Patent Document 7] U.S. Patent No. 6,201,208 [Patent Document 8] U.S. Patent No. 1,158,488 Summary of the Invention [Means for solving the problem]

[0006] A system of one or more computers may be configured to perform particular operations or actions by having software, firmware, hardware, or a combination thereof installed on the system that, when in operation, causes the system to perform the actions. One or more computer programs may be configured to perform particular operations or actions by including instructions that, when executed by a data processing device, cause the device to perform the actions.

[0007] One general aspect includes a controller for a plasma generation system. The controller also includes a model evaluation module configured to receive sensed values ​​that vary according to a state of a plasma controlled by an RF power generator, the model evaluation module generating plasma parameters, the plasma parameters varying according to the sensed values. The controller is configured to receive the plasma parameters and to evaluate the plasma parameters. integral death, integral A model configured to output model parameters integral The controller also includes modules. integral Receives model parameters, integralThe method also includes an IEDF evaluation module configured to generate an IEDF according to the model parameters. The controller also includes an IEDF controller module configured to receive the IEDF and generate a signal to control the RF generator. The controller also includes an RF generator control module configured to receive the signal and generate an RF generator control signal to control at least one of the power, frequency, or phase of the RF power generator. Other embodiments of this aspect include corresponding computer systems, apparatuses, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the method.

[0008] Implementations may include one or more of the following features: integral Receives model parameters, integral The RF power generator may include an optimization module configured to compare the model parameters with predetermined parameters used to define the model and to modify the predetermined parameters according to the comparison. The RF power generator may be a bias RF generator, and the IEDF may vary according to at least one of a power, a frequency, or a phase of the bias RF generator. integral The model parameters vary according to the ion potential of the plasma. integralThe model parameter is an effective ion potential waveform, which characterizes the ion potential of the plasma. The RF generator control module is configured to receive the effective ion potential waveform to control at least one of the power, frequency, or phase of the RF power generator. The RF power generator may include multiple RF power generators, and the outputs of the RF power generators are combined and applied to the plasma. The sensed value can be detected at multiple locations in the plasma generating system. The RF power generator provides an output signal that can be one of a sinusoidal signal, a square wave signal, a rectangular wave signal, a triangular wave signal, a Gaussian signal, a piecewise linear signal, a narrow pulse voltage peak followed by a ramp-down signal, or any signal. The output signal is modulated by a pulse signal. The pulse signal has a shape that is trapezoidal, triangular, Gaussian, or any signal. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium.

[0009] One general aspect includes an RF power generation system. The RF power generation system also includes an RF power generator that generates an RF output signal that is applied to a load to generate a plasma. The system also includes a model evaluation module configured to receive sensed values ​​that vary according to a state of the plasma, the model evaluation module determining plasma parameters, the plasma parameters varying according to the sensed values. The system is configured to receive the plasma parameters and to evaluate the plasma parameters. integral death, integral A model configured to output model parameters integral The system also includes modules. integral Receives model parameters, integraland an RF generator control module configured to generate an RF generator control signal for controlling at least one of the power, frequency, or phase of the RF power generator according to the model parameters. 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 actions of the method.

[0010] Implementations may include one or more of the following features: In the RF power generation system, the RF power generator is a bias RF generator; integral The model parameters vary according to at least one of the frequency or phase of the bias RF generator. integral Receives model parameters, integral The RF generator control module may include an ion energy distribution function (IEDF) evaluation module configured to receive the IEDF and generate an IEDF according to the model parameters. integral The RF power generation system may include an IEDF controller module configured to receive the IEDF and generate a signal to control the RF generator. The RF generator control module receives the IEDF and generates a signal to control at least one of the power, frequency, or phase of the RF power generator according to the model parameters or the IEDF. integral The RF power generation system is configured to generate an RF generator control signal for controlling at least one of a power, a frequency, or a phase of an RF power generator according to the model parameters or IEDF. The RF power generator is a bias RF generator, and the IEDF varies according to at least one of a power, a frequency, or a phase of the bias RF generator. integral Receives model parameters, integralThe system may include an optimization module configured to compare the model parameters with predetermined parameters used to define the model and to modify the predetermined parameters according to the comparison. integral The model parameters vary according to the ion potential of the plasma. The RF power generator may include multiple RF power generators, and the outputs of the RF power generators are combined and applied to the plasma. The sensed value can be detected at multiple locations in the RF generation system. The RF output signal is one of a sinusoidal signal, a square wave signal, a rectangular wave signal, a triangular wave signal, a Gaussian signal, a piecewise linear signal, a narrow pulse voltage peak followed by a ramp-down signal, or any signal. The RF output signal is modulated by a pulse signal. The pulse signal is one of a trapezoidal, a triangular, a Gaussian, or any shape. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium.

[0011] One general aspect includes a non-transitory computer-readable medium storing instructions. The non-transitory computer-readable medium storing instructions also includes generating an RF power signal applied to a load to generate a plasma. The instructions also include receiving a sensed value that varies according to a state of the plasma and determining a plasma parameter, the plasma parameter varying according to the sensed value. The instructions include receiving the plasma parameter and determining the plasma parameter. integral death, integral The instructions also include generating model parameters. integral Receives model parameters, integral and generating an RF generator control signal for controlling at least one of the power, frequency, or phase of the RF power generator according to the model parameters. 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 actions of the method.

[0012] Implementations may include one or more of the following features: In a non-transitory computer-readable medium storing instructions, the RF power generator is a bias RF generator; integral The model parameters vary according to at least one of a frequency or a phase of the bias RF generator. integral Receives model parameters, integral generating an ion energy distribution function (IEDF) according to the model parameters. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium.

[0013] A non-transitory computer-readable medium storing instructions, the instructions including: receiving an IEDF; integral and generating an RF generator control signal for controlling at least one of a power, a frequency, or a phase of the RF power generator according to the model parameters or the IEDF. In a non-transitory computer-readable medium storing instructions, the instructions may include receiving the IEDF and generating a signal to control the RF generator. In a non-transitory computer-readable medium storing instructions, the instructions may include receiving the IEDF and generating a signal to control the RF generator. integral The method may include generating an RF generator control signal for controlling at least one of a power, a frequency, or a phase of an RF power generator according to the model parameters or the IEDF. The RF power generator is a bias RF generator, and the IEDF varies according to at least one of a power, a frequency, or a phase of the bias RF generator. In a non-transitory computer-readable medium storing instructions, the instructions include: integral Receives model parameters, integral This may include comparing the model parameters to predetermined parameters used to define the model and modifying the predetermined parameters in accordance with the comparison. integralThe model parameters vary according to the ion potential of the plasma. The RF power generator may include multiple RF power generators, and the outputs of the RF power generators are combined and applied to the plasma. The sensed value can be detected at multiple locations to obtain the sensed value. The RF output signal is one of a sinusoidal signal, a square wave signal, a rectangular wave signal, a triangular wave signal, a Gaussian signal, a piecewise linear signal, a narrow pulse voltage peak followed by a ramp-down signal, or any signal. The RF output signal is modulated by a pulse signal. The pulse signal is one of a trapezoidal, a triangular, a Gaussian, or any shape. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium.

[0014] Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims, and the 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.

[0015] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 illustrates a representation of an inductively coupled plasma system. [Figure 2] FIG. 1 illustrates a representation of a capacitively coupled plasma system. [Figure 3] FIG. 1 illustrates a generalized representation of a plasma system arranged in accordance with various embodiments of the present disclosure. [Figure 4] 1 is a schematic diagram of a power distribution system having multiple power feeds arranged in accordance with various embodiments of the present disclosure. [Figure 5] 1A and 1B are diagrams illustrating the waveform of an RF signal and pulses that modulate the RF signal. [Figure 6] FIG. 10 shows a histogram of the probability of ions having a particular ion energy crossing the plasma sheath. [Figure 7] FIG. 1 illustrates a circuit providing an electrical representation of a component of a model according to the present disclosure. [Figure 8A] FIG. 10 is a diagram showing waveforms relative to sheath potential. [Figure 8B] FIG. 10 is a diagram showing waveforms for component elements of sheath current. [Figure 9] FIG. 1 illustrates a plasma chamber and a driving RF generator for describing the plasma generation model of the present disclosure. [Figure 10] FIG. 1 illustrates a circuit providing an electrical representation of components of a model of a plasma chamber according to the present disclosure. [Figure 11] 10A-10C illustrate a circuit that provides an electrical representation of components of a model of a plasma chamber and includes a pair of RF generators that apply power to a match network in accordance with the present disclosure. [Figure 12] FIG. 1 is a block diagram of a plasma generation model arranged in accordance with the present disclosure. [Figure 13A] FIG. 10 illustrates waveforms representing various parameters of a model according to the present disclosure. [Figure 13B] FIG. 10 illustrates waveforms representing various parameters of a model according to the present disclosure. [Figure 13C] FIG. 10 illustrates waveforms representing various parameters of a model according to the present disclosure. [Figure 13D] FIG. 10 illustrates waveforms representing various parameters of a model according to the present disclosure. [Figure 14] FIG. 10 illustrates an example histogram that may be output using a non-invasive sensor and model according to the present disclosure. [Figure 15] FIG. 2 is a functional block diagram of an exemplary control module arranged in accordance with various embodiments. [Figure 16] 1 is a flowchart of the operation of a control system arranged in accordance with the principles of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0017] In the drawings, reference numbers may be reused to identify similar and / or identical elements.

[0018] The power system may include a DC or RF power generator or generator, a matching network, and a load (such as a process chamber, a plasma chamber, or a 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 matches the input impedance of the matching network to the characteristic impedance of a transmission line between the power generator and the matching network. Impedance matching helps maximize the amount of power sent to the matching network ("forward power") and minimize the amount of power reflected from the matching network 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, forward power may be maximized and reverse power may be minimized. In various configurations, a transmission line is not required between the power source and the impedance matching unit, and any reference characteristic impedance may be established to better suit other aspects of the system. In one non-limiting example, the characteristic impedance may be the output impedance of a power amplifier.

[0019] In the power supply or power source field, 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 or sinusoidal RF power signal that is continuously output by the power supply to the load. In the continuous mode approach, the power signal assumes a constant DC or sinusoidal output, and the amplitude and / or frequency (of an RF power signal) of the power signal may be varied to vary the output power applied to the load.

[0020] A second approach to applying a power signal to a load involves pulsing the RF signal rather than applying a continuous RF signal to the load. In a 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 may 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.

[0021] In a typical power source configuration, the output power applied to a load is determined by using sensors that measure the forward and reflected power or the voltage or potential and current of the RF signal applied to the load. Any set of these signals is analyzed in a control loop. The analysis typically determines a power value that is used to adjust the output of the power source to vary the power applied to the load. In a power distribution system where the load is a process chamber or other nonlinear or time-varying load, the applied power is, in part, a function of the impedance of the load, so varying impedance of the load causes corresponding variations in the power applied to the load.

[0022] In systems where the fabrication of various devices relies on the introduction of 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 may be achieved by wave coupling at microwave frequencies. Such techniques 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 those of conventional ICP and CCP systems. The power delivery system may 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, while the bias power modulates ions in the sheath formulation. The bias and source may share the same electrode or use separate electrodes, depending on various design considerations.

[0023] When a power distribution 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 a density of ions with 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 with bias power. For systems in which multiple RF power signals are applied to a load, one method of controlling the IEDF occurs by varying the multiple RF signals, which are related by amplitude, frequency, and phase. The relative amplitude, frequency, and phase of the multiple RF power signals may be related by Fourier series and related coefficients. The frequencies between the multiple RF power signals may be locked, and the relative phases between the multiple RF 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 which are assigned to the assignee of the present application and incorporated herein by reference.

[0024] Time-varying or nonlinear loads may exist in various applications. In some applications, a plasma processing system may also include components for plasma generation and control. One such component is a nonlinear load implemented 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, such as for thin film manufacturing, may use 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 the above-referenced patents require a closed-loop control system to adapt power source operation to control ion density and the corresponding ion energy distribution function (IEDF).

[0025] There are several approaches to controlling a process chamber, e.g., that can be used to generate a plasma. For example, in an RF power distribution system, the phase and frequency of multiple driving RF signals operating at the same or nearly the same frequency can be used to control plasma generation. For RF-driven plasma sources, the periodic waveforms that affect 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 distribution 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.

[0026] Another approach uses a broadband RF power source to drive the plasma chamber. Broadband approaches present several challenges. One challenge is coupling the power to the electrodes. A second challenge is that the transfer function of the generated waveform to the actual sheath potential for the desired IEDF must be formulated to support a wide process space for material-surface interaction. In one reactive approach in an inductively coupled plasma system, controlling the power applied to the source electrode controls the plasma density, and controlling the power applied to the bias electrode modulates ions to control the IEDF, providing etch rate control. Using source and bias electrode control, the etch rate is controlled by ion density and energy.

[0027] As integrated circuit and device fabrication continues to evolve, so too do the power requirements for controlling fabrication processes. For example, in memory device fabrication, the requirements for bias power continue to increase. Increasing power generates more energetic ions for faster surface interactions, thereby increasing the ion etch rate and directionality. In RF systems, increasing bias power can require a lower bias frequency along with an increase in the number of bias power supplies coupled to the plasma sheath created in the plasma chamber. Increasing power at lower bias frequencies and an increase in the number of bias power supplies results in intermodulation distortion (IMD) emissions from sheath modulation. IMD emissions can significantly reduce the power delivered by the source where plasma generation occurs. U.S. Patent No. 10,821,542, issued November 3, 2020, and entitled "Pulse Synchronization by Monitoring Power in Another Frequency Band," which is assigned to the assignee of the present application and incorporated herein by reference, describes a method for pulse synchronization by monitoring power in another frequency band. In the referenced U.S. patent application, the pulsing of the second RF generator is controlled according to detection at the second RF generator of the pulsing of the first RF generator, thereby synchronizing the pulsing between the two RF generators.

[0028] Non-invasive, i.e., real-time monitoring of plasma parameters and ion energy distribution (IED or IEDF) has been desired for many years. Real-time monitored plasma parameters and IED enable semiconductor tool manufacturers and process engineers to improve the etch or deposition performance of their systems. Precise ion energy control facilitates process control for depositing films or etching anisotropic features. Emerging fields such as atomic layer etch (ALE) also require precise control of ion energy to avoid subsurface damage according to the ideal ALE process. In the case of deposition, various film properties such as stress, refractive index, and density can also be controlled, at least in part, by varying ion energy.

[0029] Existing approaches for monitoring plasma parameters and IEDs propose ion energy modeling methods, and selected approaches attempt to derive plasma parameters. For example, one approach incorporates a sheath model and derivation of plasma parameters through the use of invasive sensors that contact the plasma. However, invasive sensors inherently disturb the plasma and introduce unwanted complexity into the measurement process. Such sensors do not work with electrically isolated or non-insulated electrodes. Other approaches implement methods to extract selected plasma parameters at several points in the RF cycle. However, such approaches are typically based on ion current extraction and not on known plasma parameters. Some approaches also require non-insulated electrodes. None of the approaches attempt to implement sensors capable of obtaining non-invasive, real-time measurements and deriving unknown plasma parameters for controlling various subsystems of an etch or deposition tool.

[0030] This disclosure describes a non-invasive technique for real-time estimation of IEDs and additional plasma properties, such as bulk plasma density and electron temperature, which are critical parameters that, when used correctly, can improve the accuracy of etch and deposition processes.

[0031] In various configurations, an RF V / I measurement sensor is positioned at the input of the chamber or post-match. The sensor may be encapsulated within the match or other system component if they represent the same electrical node. The captured data is then processed within a processing processor or module. While other approaches exist for determining plasma properties, this disclosure contemplates non-invasive sensors, which offer advantages over traditional invasive measurement techniques. Other non-invasive approaches rely on optical measurements that are not available or feasible for inclusion within a production chamber and have limited data rates. Such non-invasive methods are typically experimental and, at best, useful for calibration but not for production processing.

[0032] The signals generated by the disclosed system represent one or more of the following at the sheath-plasma interface: plasma density, ion energy, electron temperature, ion energy distribution, or ion velocity. Each of these signals can be used to control various aspects of the plasma generation system, such as the source and bias generators. For example, plasma density parameters are used to control the source power, and the ion energy peak from the IEDF is used to control the bias power. These parameters provide additional insight into the process dynamics and evolution.

[0033] FIG. 1 shows a representation of an inductively coupled plasma (ICP) system 110. The ICP system 110 includes a nonlinear load, such as a reactor, plasma reactor, or plasma chamber 112, referred to interchangeably herein, for generating a plasma 114. Power in the form of voltage and current is applied to the plasma chamber 112 through a pair of coils, which in various embodiments includes a coil assembly including an inner coil 116 and an outer coil 118. Power is applied to the inner coil 116 through an RF power generator or power supply 120, and power is applied to the outer coil 118 through an RF power generator or power supply 122. The coils 116 and 118 are attached to a dielectric window 124 that assists in coupling power to the plasma chamber 112. A substrate serves as an electrode 126 within the plasma chamber 112 and typically forms the workpiece that is the subject of the plasma action. An RF power generator, power feed, or power supply 128 (these terms may be used interchangeably herein) applies power to the plasma chamber 112 through the electrode 126. In various configurations, the power supplies 120, 122 provide a source voltage or current to ignite or generate the plasma 114 or to control the plasma density. Also in various configurations, the power supply 128 provides a bias voltage or current to modulate ions to control the ion energy or ion density of the plasma 114. In various embodiments, the power supplies 120, 122 are locked to operate at the same frequency, voltage, and current, with a fixed or variable relative phase. In various other embodiments, the power supplies 120, 122 can operate at different frequencies, voltages, and currents, and relative phases.

[0034] FIG. 2 shows a representation of a capacitively coupled plasma (CCP) system 210. The CCP system 210 includes a plasma chamber 212 for generating a plasma 214. A pair of electrodes 216, 218 disposed within the plasma chamber 212 connects to respective DC (ω=0) or RF power generators or sources 220, 222. In various embodiments, the source 220 provides a source voltage or current to ignite or generate the plasma 214 or to control the plasma density. In various embodiments, the source 222 provides a bias voltage or current to modulate ions in the plasma to control the ion energy and / or ion density of the plasma 214. In various RF embodiments, the source 220, 222 operate in relative phase when the sources are harmonically related. In various other embodiments, the source 220, 222 operate at different frequencies, voltages, and currents with fixed or variable relative phase. Again, in various embodiments, the power sources 220, 222 can be connected to the same electrode, but the counter electrode is also connected to ground or to a third DC (ω=0) or RF power generator (not shown).

[0035] 3 shows a cross-sectional view of a generalized representation of a dual power input plasma system 310. The plasma generation system 310 includes a plasma chamber that functions as a first electrode 312 connected to ground 314 and a second electrode 316 spaced apart from the first electrode 312. A first DC (ω=0) or first power supply 318 generates a first RF power at a first frequency f=ω1 that is applied to the second electrode 316. A second power supply 320 generates a second DC (ω=0) or RF power that is applied to the second electrode 316. In various embodiments, the second power supply 320 operates at a second frequency f=ω2, where ω2=nω, which is the nth harmonic of the frequency of the first power supply 318. In various other embodiments, the second power supply 320 operates at a frequency that is not a multiple of the frequency of the first power supply 318.

[0036] The coordinated operation of the respective power supplies 318, 320 generates and controls a plasma 322. As shown in the schematic diagram of FIG. 3, the plasma 322 is formed within an asymmetric sheath 330 of a plasma chamber 324. The sheath 330 includes a grounded or grounded sheath 332 and a powered sheath 334. The sheath is generally described as a charge-depleted region surrounding the plasma 322. As can be seen in the schematic diagram of FIG. 3, the grounded sheath 332 has a relatively large surface area 326. The powered sheath 334 has a relatively small surface area 328. Because each sheath 332, 334 acts as a dielectric between the conductive plasma 322 and the respective electrode 312, 316, each sheath 332, 334 forms a capacitance between the plasma 322 and the respective electrode 312, 316.

[0037] 4 illustrates an RF generator or feed system 410. The feed system 410 includes a pair of radio frequency (RF) generators or feeds 412a, 412b, matching networks 418a, 418b, and a load 432, such as a nonlinear load, which may be a plasma chamber, a process chamber, or the like. In various embodiments, the RF generator 412a is referred to as a source RF generator or feed, and the matching network 418a is referred to as a source matching network. Also in various embodiments, the RF generator 412b is referred to as a bias RF generator or feed, and the matching network 418b is referred to as a bias matching network. It will be understood that components may be referred to individually or collectively using reference numerals without letter subscripts or primes.

[0038] In various embodiments, the source RF generator 412a receives a control signal 430 from the matching network 418b, the generator 412b, or a control signal 430' from the bias RF generator 412b. As described in more detail below, the control signal 430 or 430' represents an input signal to the source RF generator 412a that indicates one or more operating characteristics or parameters of the bias RF generator 412b. In various embodiments, a synchronization bias detector 434 detects the RF signal output from the matching network 418b to the load 432 and outputs a synchronization or trigger signal 430 to the source RF generator 412a. In various embodiments, a synchronization or trigger signal 430', rather than the trigger signal 430, may be output from the bias RF generator 412b to the source RF generator 412a. The difference between the trigger or synchronization signals 430, 430' may result from the influence of the matching network 418b, which can adjust the phase between the input signal to and the output signal from the matching network. Signals 430, 430′, in various embodiments, contain information about the operation of bias RF generator 412b that enables predictive responsiveness to address periodic fluctuations in the impedance of load 432 caused by bias RF generator 412b. In the absence of control signals 430 or 430′, RF generators 412a, 412b operate autonomously.

[0039] The RF generators 412a, 412b include respective RF power sources or amplifiers 414a, 414b, RF sensors 416a, 416b, and processors, controllers, or control modules 420a, 420b. The RF power sources 414a, 414b generate respective RF power signals 422a, 422b that are output to the respective sensors 416a, 416b. The sensors 416a, 416b receive the outputs of the RF power sources 414a, 414b and generate respective RF power signals f1 and f2. The sensors 416a, 416b also output signals that vary according to various parameters sensed from the load 432. Although the sensors 416a, 416b are shown within the respective RF generators 412a, 412b, the RF sensors 416a, 416b may be located external to the RF power generators 412a, 412b. Such external sensing may occur at the output of the RF generator, between the RF generator and the load, or at the input of an impedance matching device located between the output of the impedance matching device and the load (including within the impedance matching device).

[0040] The sensors 416a, 416b detect various operating parameters and output signals X and Y. The sensors 416a, 416b may include voltage, current, and / or directional coupler sensors. The sensors 416a, 416b detect (i) the voltage V and current I and / or (ii) the forward power P output from the respective power amplifiers 414a, 414b and / or RF generators 412a, 412b. FWD and the reverse or reflected power P received from the respective matching network 418a, 418b or load 432 connected to the respective sensor 416a, 416b. 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 each power source 414a, 414b. The sensors 416a, 416b may be analog or digital sensors or a combination thereof. In a digital implementation, the sensors 416a, 416b may include an analog-to-digital (A / D) converter and a signal sampling component with a corresponding sampling rate. The signals X and Y represent the voltage V and current I or forward (or source) power P FWD Reverse (or reflected) power P REV It can represent either of the above.

[0041] The sensors 416a, 416b generate sensor signals X, Y, which are received by respective controller or power control modules 420a, 420b. The power control modules 420a, 420b process the respective X, Y signals 424a, 426a and 424b, 426b and generate one or more feedforward or feedback control signals 428a, 428b to the respective power supplies 414a, 414b. The power supplies 414a, 414b adjust the RF power signals 422a, 422b based on the received one or more feedback or feedforward control signals. In various embodiments, the power control modules 420a, 420b can control the matching networks 418a, 418b, respectively, via respective control signals 421a, 421b. The power control modules 420a, 420b may include at least a proportional-integral-derivative (PID) controller or a subset thereof and / or a direct digital synthesis (DDS) component and / or any of the various components described below in connection with the modules.

[0042] In various embodiments, the power control modules 420a, 420b are PID controllers or a subset thereof and may include functions, processes, processors, or sub-modules. The control signals 428a, 428b may be drive signals and may include DC offset or rail voltage, voltage or current magnitude, frequency, and phase components. In various embodiments, the feedback control signals 428a, 428b may be used as inputs to one or more control loops. In various embodiments, the multiple control loops may include proportional-integral-derivative (PID) control loops for the RF drive and for the rail voltage. In various embodiments, the control signals 428a, 428b may be used in a multiple-input, multiple-output (MIMO) control scheme. An example of a MIMO control scheme can be found in U.S. Patent No. 10,546,724, issued January 28, 2020, entitled "Pulsed Bidirectional Radio Frequency Source / Load," which is assigned to the assignee of the present application and incorporated herein by reference. In other embodiments, signals 428a, 428b may provide feed-forward control as described in US Pat. No. 10,049,857, which is assigned to the assignee of the present application and is incorporated herein by reference.

[0043] In various embodiments, the power supply system 410 may include a controller 420′. The controller 420′ may be disposed external to either or both of the RF generators 412a, 412b and may be referred to as an external or common controller 420′. In various embodiments, the controller 420′ may implement one or more functions, processes, or algorithms described herein with respect to one or both of the controllers 420a, 420b. Thus, the controller 420′ communicates with each of the RF generators 412a, 412b via a pair of respective links 436, 438 that enable the exchange of data and control signals as needed between the controller 420′ and the RF generators 412a, 412b. For various embodiments, the controllers 420a, 420b, 420′ may provide distributed and coordinated analysis and control in conjunction with the RF generators 412a, 412b. In various other embodiments, the controller 420' can provide control of the RF generators 412a, 412b, eliminating the need for respective local controllers 420a, 420b.

[0044] In various embodiments, the RF power supply 414a, the sensor 416a, the controller 420a, and the matching network 418a may be referred to as a source RF power supply 414a, a source sensor 416a, a source controller 420a, and a source matching network 418a. Similarly, in various embodiments, the RF power supply 414b, the sensor 416b, the controller 420b, and the matching network 418b may be referred to as a bias RF power supply 414b, a bias sensor 416b, a bias controller 420b, and a bias matching network 418b. In various embodiments, and as described above, the term source refers to an RF generator that generates a plasma, and the term bias refers to an RF generator that tunes the plasma ion energy distribution function (IEDF). In various embodiments, the source and bias RF feeds operate at different frequencies. In various embodiments, the source RF feed operates at a higher frequency than the bias RF feed. In various other embodiments, the source and bias RF feeds operate at the same frequency or substantially the same frequency.

[0045] According to various embodiments, the source RF generator 412a and the bias RF generator 412b include multiple ports for communicating with the outside world. The source RF generator 412a includes a pulse synchronization output port 440, a digital communication port 442, and an RF output port 444. The bias RF generator 412b includes an RF input port 448, a digital communication port 450, and a pulse synchronization input port 452. The pulse synchronization output port 440 outputs a pulse synchronization signal 456 to the pulse synchronization input port 452 of the bias RF generator 412b. The digital communication port 442 of the source RF generator 412a and the digital communication port 450 of the bias RF generator 412b communicate via a digital communication link 457. The RF output port 444 generates an RF control signal 458 that is input to the RF input port 448. In various embodiments, the RF control signal 458 is substantially the same as the RF control signal that controls the source RF generator 412a. In various other embodiments, RF control signal 458 is the same as the RF control signal controlling source RF generator 412a, but is phase shifted within source RF generator 412a according to the desired phase shift produced by bias RF generator 412b. Thus, in various embodiments, source RF generator 412a and bias RF generator 412b are driven by substantially identical RF control signals or by substantially identical RF control signals that are phase shifted by a predetermined amount.

[0046] FIG. 5 shows a plot of voltage versus time to describe a pulsed mode of operation for delivering power to a load, such as load 432 in FIG. 4. More specifically, FIG. 2 shows two multi-state pulses P1, P2 of a pulsed signal 512 having a plurality of states S1-S4 and S1-S3, respectively. In FIG. 5, an RF signal 510 is modulated by pulses P1 and P2. When the pulses are ON, as shown in states S1-S3 of P1 and S1-S2 of P2, the RF generator 412 outputs an RF signal 510 having an amplitude defined by the pulse magnitude in each state. Conversely, during states S4 of P1 and S3 of P2, the pulses are OFF, and the RF generator 412 does not output an RF signal 510. The pulses P1, P2 can repeat with a constant or variable duty cycle, and the states S1-S4 of each pulse P1, P2 can have the same or varying amplitude and width. Furthermore, the pulse signal 512 need not be embodied as a square wave as shown in FIG. 5. By way of non-limiting example, the pulse signal 512 may be square, rectangular, trapezoidal, triangular, or Gaussian in shape. Furthermore, the pulses P1, P2 may have multiple states S1, ..., Sn of varying amplitude, duration, and shape. The states S1, ..., Sn may repeat within a fixed or variable period. Also as shown in FIG. 5, the RF signal 510 operates at a frequency that varies between multiple states or within a state.

[0047] Various advanced plasma processing systems for semiconductor fabrication address atomic-scale control during film etch and deposition. To provide the necessary control precision, it is desirable to have representative feedback of key plasma parameters. Improved feedback allows process designers to more precisely control actuators to provide atomic-scale control during etch and deposition. In etch applications, for example, improved precision can be achieved by controlling the energy of ions impacting the substrate to within a few electron volts (eV). Current etch tools typically provide bias voltage measurements that desirably indicate ion energy, but current systems do not provide a sufficiently strong correlation between bias voltage and ion energy.

[0048] 6 shows a histogram plot 610 of ion energy (eV) versus ion energy distribution (IED). Histogram 612 has a low-energy peak 614, a high-energy peak 616, and a trough region 618. A typical bias voltage 620 shows ions of a particular energy impacting the wafer. However, the distribution of ion energies shows that most ions impact the substrate with higher and lower energies, as shown by low-energy peak 614 and high-energy peak 616. The present disclosure is directed to controlling the location of low-energy peak 614 and high-energy peak 616, or providing one single-energy peak, in various configurations.

[0049] In various configurations, a mathematical model of the plasma chamber can be used to determine the histogram of Figure 6 and the electrical parameters that determine the histogram of Figure 6. The sheath potential can be expressed as a derivative, and the integral of the derivative is the sheath potential voltage V s The time-dependent derivative of the sheath voltage or sheath potential is described below in equation (1).

[0050]

number

[0051] In the above equation, I p is the instantaneous sheath current, ε0 is the permittivity of free space, as defined above, A is the electrode discharge surface area, also defined above; e is the electron charge, also defined above, k b is the Boltzmann constant, n0 is the plasma density, T e is the electron temperature, m i is the ion mass, m e is the electron mass, V i is the instantaneous ionic potential, V s is the instantaneous sheath potential. moreover,

[0052]

number

[0053] is the partial derivative of the sheath electric field, and is written in equation (2).

[0054]

number

[0055] The sheath electric field E is described by equation (3).

[0056]

number

[0057] moreover,

[0058]

number

[0059] is the sheath electric field partial derivative, which is written in equation (4).

[0060]

number

[0061] ionic potential

[0062]

number

[0063] The time derivative of is written in equation (5).

[0064]

number

[0065] Resistance R due to ohmic and stochastic heating p is written in equation (6).

[0066]

number

[0067] In the above equation, X en is the electron neutral ion cross section, L is the length (height) of the active plasma. electronic inertia L p is written in equation (7).

[0068]

number

[0069] 7 shows an electrical circuit 710 that represents components of an electrical model of an electric sheath in a plasma chamber. The electrical circuit 710 includes a first node 712 that is connected to an electrode of the plasma chamber, such as electrodes 126, 218, and 316 of FIGS. 1-3. The voltage at the electrode is V Electrode The electrical circuit 710 is represented by the plasma voltage V Plasma , and a second node 714 representing the plasma current I p represents the current flowing through the plasma sheath, as described herein. The plasma sheath 716 is further represented by three components including a diode 718, a current source 720, and a capacitor 722. The sheath potential V Sheath denotes the voltage or potential across the plasma sheath 716. Electron current I e flows through the diode 718. Similarly, the ionic current I i flows through the current source 720. Furthermore, the displacement I d Current flows through capacitor 722. Resistor 724 represents the ohmic and stoichiometric heating effects on the plasma, R P The inductor 726 represents the electronic inertia, and L p It is modeled as:

[0070] From equations (1)-(7) above, the electrical characteristics for the various components of Figure 7 can be determined. For example, the plasma current I p is written in equation (8).

[0071]

number

[0072] The ion current I passing through the current source 720 i is written in equation (9).

[0073]

number

[0074] Electron flow I through diode 718 e is written in equation (10).

[0075]

number

[0076] Sheath displacement current I d is written in equation (11).

[0077]

number

[0078] 8A and 8B show waveforms for selected values ​​for the electrical representation of FIG. 7. Waveform 812 in FIG. 7 shows the sheath potential or sheath voltage of the electrical representation of FIG. 7. Waveform 812 represents the integral of equation (1), which must be solved iteratively since a closed-form solution for equation (1) does not exist. FIG. 8B shows the component currents in sheath 716 of FIG. 7. Waveform 814 shows the ion current I i and waveform 816 represents the electron flow I e and waveform 818 shows the displacement current I d Shows.

[0079] FIG. 9 illustrates a plasma generation system 910, which will be used to further describe the noninvasive sensor of the present disclosure. FIG. 9 includes a plasma chamber 912 in which a bulk plasma 914 is generated. By applying a source power at a predetermined power and frequency, the bulk plasma is ignited. Furthermore, by applying a bias power at a predetermined power and frequency, the ion energy for ions crossing a sheath 946 can be controlled to direct the ions onto a wafer 948 for fabricating semiconductor devices on the wafer 948. One parameter that can be controlled by the bias power is the energy of the ions impacting the substrate. This ion energy is generally represented by a distribution called the IED.

[0080] The bulk plasma 914 is generated by the application of power output by an RF generator 916. The RF power is applied to a matching network 920 via a transmission line 918. The matching network 920 provides an impedance match between the RF generator 916 and the plasma chamber 912, which acts as a load to the RF generator 916. The output of the matching network 920 is applied to an antenna 922, and excitation of the antenna 922 applies power to the interior of the plasma chamber 912 through a dielectric window 924. The RF generator 916 may be referred to as a source RF feed because the power provided by the RF source generator ignites the bulk plasma 914. Power from the RF generator 916 is coupled to the plasma chamber 912 via the antenna 922. Thus, the antenna 922 provides an inductive coupling between the RF generator 916 and the plasma chamber 912; this connection is referred to as an inductively coupled plasma (ICP).

[0081] A second RF generator 930 provides RF power to the plasma chamber 912 via a transmission line 932 and a matching network 934. The transmission line 932 and the matching network 934 operate similarly to the respective transmission line 918 and matching network 920. The output from the matching network 934 is applied to an electrode 936 that supports a workpiece or wafer (not shown). The RF generator 930 provides bias RF power to power delivery electrodes, such as 220, 222, and 316 in FIGS. 2 and 3, respectively, to control the ion voltage or potential and associated IEDs, thereby directing ions onto the wafer 948. Because the RF power output by the RF generator 930 is applied to the plasma chamber 912 via the electrode 936, this arrangement is referred to as a capacitively coupled plasma (CCP).

[0082] The bulk plasma 914 is surrounded by a sheath 940 that includes multiple segments. The sheath 940 includes an antenna sheath 942 that is shown above the bulk plasma 914 between the bulk plasma 914 and the dielectric window 924. Wall sheaths 944a, 944b interface with the sides and bottom of the plasma 914 between the bulk plasma 914 and the outer wall of the plasma chamber 912. A power delivery sheath or electrode sheath 946 is located between the bulk plasma 914 and the wafer 948. Referring to FIG. 7, an individual component, such as one of components 942, 944a, 944b, and 946, may be electrically represented as shown in FIG.

[0083] FIG. 10 shows a circuit 1010 providing an electrical representation of a portion of the plasma generation system 910 of FIG. 9. Similar components from FIG. 9 are shown in FIG. 10, but the reference numerals are preceded by a "10" instead of a "9." The circuit 1010 includes an RF generator 1030 that provides an RF power signal to a transmission line 1032 and a matching network 1034. As shown in FIG. 10, the RF generator 1030 provides a bias signal to an electrode or electrostatic chuck 1036. The electrostatic chuck 1036 connects to a power supply sheath or electrode sheath 946. The electrode sheath 946 is configured similarly to the electrical circuit 710 of FIG. 7, although it should be understood that component values ​​may differ for each representation of the elements of the model. The electrode sheath 946 connects to the bulk plasma 1014. In FIG. 10, the wall sheath 944 of FIG. 9 is configured similarly to the electrical circuit 710 of FIG. 7. The wall 1012 connects to ground and also to the wall sheath 944. The wall sheath 944 connects to the bulk plasma 1014 .

[0084] FIG. 11 shows another representation of a portion of an RF plasma generation system 1111. The RF plasma generation system 1111 includes a pair of RF power generators 1130a, 1130b implemented as a bias RF power generator pair. The RF power generator 1130a implements a high-frequency RF power generator that provides high-frequency bias power, and the RF power generator 1130b implements a low-frequency RF power generator that provides low-frequency bias power. Each RF power generator 1130a, 1130b can be operated to provide a desired ion potential and corresponding IED according to various design considerations. Each RF power generator 1130a, 1130b outputs RF power to a respective transmission line 1132a, 1132b. The output from each transmission line 1132a, 1132b is input to a matching network 1134. The matching network 1134 combines the respective RF powers and outputs a signal to the V / I sensor 1150, which may be implemented as any of the sensors described above, including a directional coupler. Furthermore, in various configurations, the sensor 1150 may be disposed over varying locations in FIG. 11 so that the sensor 1150 detects preselected parameters from which a model of the plasma can be constructed. The sensor 1150 outputs a sensed value that varies according to the state of the plasma. The output from the V / I sensor 1150 is coupled to a series capacitor ESC s and parallel capacitor ESC p The series capacitors ESC are applied to the electrostatic chuck 1136, which is represented as a pair of capacitors including s connects to a power supply or electrode sheath represented as 1146. The potential at the node connecting the electrostatic chuck 1136 and the power supply or electrode sheath 1146 is V E A power supply or electrode sheath 1146 connects to the wall sheath 1144, and the node between the power supply or electrode sheath 1146 and the wall sheath 1144 is at a potential V P The wall sheath 1144 also has a wall potential V W, and connects to ground through capacitor 1152. The current flowing through power supply or electrode sheath 1146, wall sheath 1144, and capacitor 1152 is I P It is shown as follows.

[0085] 11 shows pairs of sheath voltages or sheath potentials, it will be understood that the model can be constructed with one or more sheath potentials. A greater number of sheath potentials in the model may improve the accuracy of the model, but will require additional computational overhead when calculating the model.

[0086] FIG. 12 illustrates a plasma control system or control system 1210 for an RF power generation system, such as one or more of the RF power generation systems described above. In various configurations, the control system 1210 may be configured to control the RF power generators 1130a, 1130b of FIG. 11. In various other configurations, the control system 1210 of FIG. 12 may be configured to control a single, pair, or multiple RF power generators that generate one or more RF power signals for process control of the plasma chamber. The controller RF generator may be a bias RF generator in various other configurations, and the control system 1210 may be configured to control an RF power generator connected to a plasma system in an ICP or CCP configuration.

[0087] The control system 1210 includes an RF generator control module or RF generator frequency and power control module 1212 that outputs control signals to control one or more of the power, frequency, or phase of one or more RF generators to be controlled. The RF power signals output by the controlled RF power generators are detected via sensors, such as V / I sensors or directional couplers, as described above. The sensors 1150 output sensed values ​​that vary according to the plasma state. The sensor outputs are input to a data frame module 1214, which samples the sensor outputs at a predetermined sampling frequency. Thus, the data frame module 1214 provides a data processing scheme for measuring voltage and current.

[0088] The data frame module 1214 outputs the sampled data to an interpolation module 1216. The interpolation module 1216 receives the sampled data and generates intermediate data points between the sampled points to provide sufficient resolution for plasma modeling operations. In various configurations, voltage and current measurements may be interpolated to adjust for model nonlinearities. Additionally, in various configurations, block processing of data, for example, for several RF cycles, may be used for frequency domain interpolation and sheath modeling to settle the system. integral In some configurations, the interpolation may distort the endpoints, but it is possible to adjust for the endpoint distortion by discarding RF cycles from one or both ends of each block. The interpolated data is output to the model evaluation module 1222.

[0089] The model evaluation module 1222 receives the sampled data and calculates n0 and T eThe model evaluation module 1222 also receives initial estimates of one or more preselected values, such as θ, ... e Implement methods to extract fundamental plasma properties such as θ and θ. Nonlinear regression or system identification methods, non-limiting examples of which include Newton-Raphson or secant regression techniques, can be implemented to find the roots of three nonlinear equations at a given time in the RF cycle. These equations are derived from the sheath model and involve the unknown quantities to be found, namely, n and T. e is a function that depends on . Other non-linear fitting schemes may be implemented.

[0090] The model evaluation module 1222 evaluates various model parameters integral The model evaluation module 1222 also receives input from an optimization module 1228. The optimization module 1228 evaluates the model integral Receives feedback from module 1226 and compares the values ​​of various parameters to determine n0 and T e Determine whether the preselected parameters, such as n0 and T, are properly selected after initialization with the initial guesses 1224 or should be adjusted to improve the optimization of the model. e The adjusted preselected parameters, such as, are fed back to the model evaluation module 1222. The values ​​measured by the sensors and the sheath model integral Other parameters derived from are used to evaluate a set of equations that create the model. A process for searching for these data points over the RF cycle is performed, for example, by finding zero crossings or minimum / maximum values ​​within some characteristic time period of the sheath potential and current waveforms.

[0091] Model integralModule 1226 adjusts selected parameters of the module to improve its accuracy. integral Model integral Module 1226 is integral the specified parameter or integral The calculated model values ​​are output to the IEDF evaluation module 1230. An iterative process is performed to successively calculate the sheath model. integral and the unknown plasma parameters (n0, T e ), and provide the newly calculated plasma parameters to the sheath model 1220 for the block of data, which may include multiple or more RF cycles. This process is repeated for the same block of data until the unknown plasma parameters converge to within a preselected tolerance. integral contains the waveform to be used for IEDF calculation and general parameter extraction. This iteration may be performed for every data block or selected data blocks. In various configurations, selected combinations of values ​​may cause the mathematical model to give undesired results, including infinity, division by zero, or complex values. Therefore, processes may be established to address these situations.

[0092] Model integral Module 1226 outputs, among other values, an effective ion potential or effective ion voltage that represents the sheath potential presented in the decaying sinusoidal waveform. IEDF evaluation module 1230 receives the modeled data and generates an output value or signal according to the modeled data. In one configuration, IEDF evaluation module 1230 outputs a histogram showing the IEDF for the modeled plasma, such as those shown in FIGS. 6 and 14. In this instance, the IEDF output by IEDF evaluation module 1230 is a histogram showing the IEDF for the modeled plasma, such as those shown in FIGS. 6 and 14. integralThe IEDF may be based on the effective ion potential signal output by module 1226. The IEDF evaluation module 1230 outputs the IEDF to an IEDF controller module 1232. The IEDF controller module 1232 generates signals to control the RF power generator or one or more of the power, frequency, or phase of the RF power generator to be controlled to vary the IEDF.

[0093] 12, the output from the IEDF controller module 1232 is fed back to the RF frequency and power control module 1212. The signals output by the IEDF controller module 1232 to control one or more of the power, frequency, or phase of the RF power generator may be command signals for which the RF generator frequency and power control module 1212 generates actuator signals, or in various configurations may possibly be direct-actuator signals.

[0094] In various configurations, the control methodology may be configured to control a particular system or subsystem of the etch / deposition tool, such as n0, T eThe IEDF may rely on derived parameters such as ρ, ρ, and IEDF, or other parameters. For example, plasma density, i.e., n, is strongly determined by source power in ICP systems. Therefore, ICP RF source power may be controlled to maintain a given n during processing and as the system ages through process cycles. In CCP systems, plasma density is primarily affected by the high-frequency generator power in dual-frequency generator configurations, so n can be used to control this power. The IEDF peak can be used to maintain a given ion energy by controlling the bias RF power of a continuous wave or pulsed RF generator or a pulsed DC generator. The characteristic shape of the IEDF can also be adjusted by controlling the power, frequency, and / or phase and pulsing of one or more RF generators, or by shaping the pulsed DC waveform. Output from the IEDF controller module 1232 provides real-time feedback to facilitate this control scheme.

[0095] While the above description of FIG. 12 describes generation of control signals by the IEDF controller module 1232, in various configurations, the RF generator frequency and power control module 1212 may also be configured to generate control signals based on the model integral The model may be configured to generate one or more of power, frequency, or phase control according to one or both of the outputs from the IEDF evaluation module 1226 or the IEDF evaluation module 1230. integralThe effective ion potential signal output by module 1226 can be fed back to RF generator frequency and power control module 1212. Similarly, the IEDF output by IEDF evaluation module 1230 can be fed back to RF generator frequency and power control module 1212. Thus, control system 1210 of FIG. 12 provides multiple options for controlling the RF power generator by feeding back one or more signals output according to the operation of the model to RF generator frequency and power control module 1212.

[0096] The modules of FIG. 12 described above are shown as performing separate portions of the plasma control process. However, it should be understood that the modules of the control system 1210 described above may be implemented individually as shown, or may be combined collectively or distributedly through one or more control modules, functions, and processors of the control system 1210 and the underlying plasma control system as shown in FIG. 4. Similarly, the subsystems of the plasma control system may be implemented collectively or distributedly. Thus, the control system 1210 described in FIG. 12 may be implemented to non-invasively sense ion energy with respect to ion potential and model the IEDF for control of the RF power generator. For example, the bias RF generator described herein, as at least shown in FIG. 4, may control the non-invasive sensors and models to generate ion energy or ion potential and IEDF.

[0097] In various configurations, the control system 1210 of FIG. 12 can include an RF frequency and power control module 1212 that generates control signals for actuators or actuator signals to vary the output of one or more RF generators, such as the bias RF generators described above with respect to FIG. 4 or the RF generators 1130a, 1130b of FIG. 11. The output from the one or more RF generators can include output signals such as sinusoidal, square, rectangular, triangular, Gaussian, or piecewise linear signals, in various non-limiting examples. In various other configurations, the output signal from the one or more RF generators can have a complex shape including a narrow pulse voltage peak followed by a voltage ramp down, examples of which can be found in U.S. Patent No. 6,201,208, issued March 13, 2001, entitled "Method and Apparatus for Plasma Processing with Control of Ion Energy Distribution at the Substrates," which is incorporated herein by reference. In various other configurations, the output from the one or more RF generators can have any shape that is cycle-variable. In various other configurations, the output signal may be periodic or aperiodic. Thus, the RF generator described above with respect to Figure 4 may, in various non-limiting examples, be implemented with a direct digital synthesizer (DDS) configured to generate any of the waveforms described above.

[0098] In various configurations, the RF generator frequency and power control module 1212 may be configured to control one or more bias RF generators, such as one or a pair of RF generators 1130a, 1130b of FIG. 11 . In one non-limiting example, where the control module 1212 controls a pair of bias RF generators, the pair of RF generators may have one or both of a harmonic or phase relationship. In various other configurations, the RF generator frequency and power control module 1212 may generate actuator control signals or signals for modulating the output signals described above using pulses as described above with respect to FIG. 5 . In various embodiments, the pulse signals may be embodied as square or rectangular waves, as shown in FIG. 5 . As non-limiting examples, the pulse signals may be trapezoidal, triangular, or Gaussian in shape. Still further, as described above, the modulating signal may have pulses P1, P2 that include multiple states S1, ..., Sn of varying amplitude, duration, and shape. The states S1, ..., Sn may repeat within a fixed or variable period. Also as described above with respect to FIG. 5, the output signal may have a variable frequency, amplitude, or shape that varies between states or within a state.

[0099] In various configurations, the plasma control system or control system 1210 can generate signals describing plasma or electrical parameters useful for controlling other generators in the plasma generation system, such as the RF generator 412a, which may be referred to as a source RF generator. In various configurations, the RF generator 412a can be operated in a blanking or amplitude modulation mode, in which various source voltages are applied during selected regions of the bias voltage cycle. In one non-limiting example, during predetermined regions, such as the negative cycle of the bias voltage, the RF generator 412a is activated to output a predetermined voltage. During periods other than the predetermined regions of the bias voltage cycle, the voltage output by the RF generator 412a can be reduced or turned off (blanked), reducing the source power applied during the corresponding regions of the bias cycle. Examples of such application can be found in U.S. Patent No. 11,158,488, entitled "High Speed ​​Synchronization of Plasma Source / Bias Power Delivery," issued October 26, 2021, which is assigned to the assignee of the present application and incorporated herein by reference.

[0100] 13A, 13B, 13C, and 13D show waveforms for an exemplary plasma control system, such as control system 1210. FIG. 13A includes a plot of multiple waveforms 1310. Waveforms 1310 show voltage measurements versus time. The waveforms represent an RF voltage V as might be output by an RF power generator. RF 1312. In various configurations, the RF power generator may be one or more bias RF generators. The one or more bias RF generators output the RF voltage 1312. In various configurations, the RF voltage 1312 may result from a single RF generator or may represent the composite output of multiple RF generators measured by a sensor such as a V / I sensor or directional coupler. Waveform 1314 represents the electrode voltage V E and the electrostatic chuck voltage V ESC In the specific example, the electrode voltage VE and electrostatic chuck voltage V ESC are substantially the same, so only one waveform 1314 is shown. Waveform 1316 shows the ion energy, or ion voltage or potential, and the effective ion potential V EL The waveform 1318 may be referred to as the plasma voltage V P Shows.

[0101] In Figures 13B and 13C, waveform 1320 shows the current value versus time corresponding to waveform 1310 of Figure 13A. Figure 13C shows an expanded view of a single cycle of the waveform of Figure 13B. The waveform represents the RF current waveform I output by the RF power generator. RF 1322. As mentioned above, in various configurations, the RF power generator may be one or more bias RF generators. The one or more bias RF generators output RF current waveform 1322. In various configurations, RF current waveform 1322 may result from a single RF generator or may represent the composite output of multiple RF generators as measured by a sensor, such as a V / I sensor or directional coupler. Waveform 1324 represents the plasma current I P Waveform 1326 is the electronic chuck current I e The waveform 1328 is the ion current I i The waveform 1330 is the displacement current I d Waveform 1324, i.e., plasma current I P represents the individual waveforms 1326, i.e., the electron currents I e , 1328, i.e., the ion current I i , and 1330, i.e., the displacement current I d It is a mixture of.

[0102] In Figure 13D, waveform 1340 shows the derivative of a selected parameter. In particular, waveform 1342 shows the derivative of the powered electrode or electrostatic chuck potential.

[0103]

number

[0104] Similarly, waveform 1344 shows the differential of the plasma sheath potential.

[0105]

number

[0106] n0 and T e It should be noted that when the model parameters such as are correctly determined or fitted by the model, the waveform will have substantially the same characteristics.

[0107] FIG. 14 shows a histogram 1410 that plots ion energy versus the probability of a particular ion energy occurring, thereby defining the IEDF. The histogram 1410 of FIG. 14 includes a low-energy peak 1412 and a high-energy peak 1414. The histogram 1410 of FIG. 14 can be generated using the sheath potential waveform 1316 of FIG. 13A. Therefore, by utilizing a model that generates the effective ion potential, it is possible to define the ion potential or ion energy of the plasma, i.e., to develop a histogram such as that of FIG. 14. Furthermore, by modeling the effective ion potential, it is possible to determine the existing energy peaks in the histogram. Furthermore, by adjusting various control parameters, such as the power, frequency, or phase of an RF power generator, such as a bias RF power generator, the location of the IEDF peak can be determined or a single energy peak can be generated.

[0108] Figure 15 incorporates various components of Figures 1-14. Control module 1510 includes a power generation module 1512 and a sensor / model module 1530. Power generation module 1512 includes an amplitude control module 1514, which further includes an amplitude adjustment module 1520 and an amplitude update module 1522. Power generation module 1512 includes a frequency control module 1516, which further includes a frequency adjustment module 1524 and a frequency update module 1526. Control module 1510 also includes a sensor / model module 1530. Sensor / model module 1530 includes a sensor module 1532, a model / test module 1534, and a parameter generation module 1536. In various embodiments, the control module 1510 includes one or more processors that execute code associated with module sections or modules 1510, 1512, 1514, 1516, 1520, 1522, 1524, 1526, 1530, 1532, 1534, and 1536. The operation of module sections or modules 1510, 1512, 1514, 1516, 1520, 1522, 1524, 1526, 1530, 1532, 1534, and 1536 is described below with respect to the method of FIG.

[0109] For a more defined structure of the modules or controllers described herein, see the flowchart of FIG. 16 provided below and the definition of the term "module" provided below. The systems disclosed herein may be operated using numerous methods, examples, and various control system methods, although shown herein. The following operations are primarily described with respect to the implementation described herein, but the operations may be readily modified to apply to other implementations of the present disclosure. The operations may be performed iteratively. Although the following operations are shown and primarily described as being performed sequentially, one or more of the following operations may be performed while one or more of the other operations are being performed.

[0110] FIG. 16 shows a flowchart of a control system 1610 for implementing plasma control for, for example, the power distribution system described above. Control begins at block 1612, where variables for driving the process are initialized. Control proceeds to block 1614, where electrical parameters are measured as described above. In block 1616, one or more parameters may be interpolated based on the measured electrical parameters, although such interpolation is design-dependent and may not be necessary. Thus, in various configurations, block 1616 may be omitted. Control proceeds to block 1618, where a model is applied to one or more measured and interpolated parameters. As a non-limiting example, block 1618 may determine, among other parameters, an effective ion potential, or an ion potential of ions crossing the plasma sheath, which indicates ion energy. From the effective ion potential over a period of time, an IEDF can be determined, as in block 1620. From the plasma parameters generated in block 1620, RF power generator control commands can be determined and used to control the RF power generator. Control proceeds to block 1624, which determines whether the control cycle is complete. If the control cycle is not complete, control returns to block 1614. If the control cycle is complete, the process ends at block 1626.

[0111] At block 1630, the model values ​​are compared to the measured values ​​to determine the accuracy of the model. Based on the comparison, a decision is made at block 1634 whether to adjust the model. If the model does not require adjustment, control returns to block 1630. If at block 1634 it is determined that the model should be adjusted, control proceeds to block 1636, where the model is optimized by adjusting various model parameters using the techniques described above. At block 1638, the updated electrical or plasma parameters are inserted into the model. Following block 1638, control returns to block 1630.

[0112] In one application, the various parameters output from the model described above are the electron density n e 3 to generate a plasma 322 having a first and second power, respectively. In such applications where multiple RF frequencies are harmonically related, it can be shown that the sheath thickness, and therefore the ion energy or potential, can be controlled. The sheath thickness as a function of time is shown in equation (12): s(t)=Σ n s n (1-sin(ω n t+φ n-1 )) (12) In the above equation, ω n = 2πf is a harmonic of the fundamental frequency f1 of the multi-frequency system, φ n is the relative phase between the frequencies, where φ=0 by definition. The amplitude of each sheath oscillation component is defined in equation (13).

[0113]

number

[0114] In the above equation, I n is ω n is the drive current associated with n e is the electron density, A is the electrode discharge area, e is the electron charge.

[0115] Equations (1) and (2) are related to φ in the case of equation (12) and I in the case of equation (13). n We demonstrate that the thickness of the sheath varies according to the relative phase between the applied power, φ, and the applied power, φ, which is sometimes referred to as the relative amplitude variable or width, and the relative phase, φ, is sometimes referred to as the relative phase variable or skew, for an IEDF.

[0116] A useful property characterizing the sheath can be seen for the time-dependent sheath voltage or sheath potential, which is explained below with reference to equation (14).

[0117]

number

[0118] In the above equation, ε0 is the permittivity of free space, e, n e , and s 2 (t) is as described above.

[0119] As can be seen from equations (12)-(14) above, the sheath thickness varies with the frequency of the bias power feed. Because the surface area 328 of the power delivery sheath 334 causes a change in capacitance between the plasma 322 and the electrode 316, a change in sheath thickness according to equation (12) causes a change in sheath capacitance. The change in sheath capacitance causes a corresponding impedance fluctuation. The corresponding impedance fluctuation interrupts the continuous delivery of traveling wave power from a source power feed, such as the second power supply 320 of FIG. 3.

[0120] The systems and methods described herein can provide targeted feedback for controlling systems and subsystems that affect specific measured parameters, while conventional systems compensate for changes due to faulty actuators. The systems and methods described herein provide insight into process dynamics and evolution in real time. The present invention further provides ion energy feedback that can be used to control actuators in RF and DC power generators to tailor ion energy impacting the substrate. Plasma density and electron temperature feedback can be used to collectively control source and bias generators to achieve desired process results. The systems and methods described herein further enable the implementation of real-time plasma sheath models valid for typical semiconductor RF frequencies. Furthermore, the systems and methods described herein implement mathematical descriptions of relevant electrical elements, including the plasma sheath, to derive nodal voltage and current relationships at various nodes.

[0121] The systems and methods described herein control IEDF geometry in various configurations. The systems and methods described herein respond to process parameters such as pulsing rate, DC current, pressure, power, and gas flow in various configurations to determine the impact of process parameters in real time. The systems and methods described herein can fingerprint a system in various configurations. The systems and methods described herein can track system aging and tuning in various configurations. The systems and methods described herein control specific actuators in direct relation to parameters provided by the present invention in various configurations. The systems and methods described herein can provide metrics for feedback or feedforward control in various configurations. Metrics may include, for example, effective ionic potential.

[0122] The above description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the present disclosure can be implemented in a variety of forms. Thus, while the present disclosure includes specific examples, the true scope of the disclosure should not be so limited, as other modifications will become apparent from a study of the drawings, this specification, and the appended claims. In the written description and claims, one or more steps within a method may be performed in a different order (or simultaneously) without altering the principles of the present disclosure. Similarly, one or more instructions stored on a non-transitory computer-readable medium may be performed in a different order (or simultaneously) without altering the principles of the present disclosure. Unless otherwise expressly stated, numbering or other labeling of instructions or method steps is for convenient reference and not to indicate a fixed order.

[0123] Furthermore, while each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the present disclosure may be implemented in and / or combined with features of any of the other embodiments, even if the combination with the features of any of the other embodiments is not explicitly described. In other words, the described embodiments are not mutually exclusive, and the interchangeability of one or more embodiments with each other is within the scope of the present disclosure.

[0124] 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," "over," "above," "below," and "disposed." Unless expressly described as "direct," when a relationship between first and second elements is described in the above disclosure, the relationship may be a direct relationship in which no other intervening elements exist between the first and second elements, or an indirect relationship in which one or more intervening elements (either spatially or functionally) exist between the first and second elements.

[0125] The phrase "at least one of A, B, and C" should be intended to mean the logical (A OR B OR C) using a non-exclusive logical OR, 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, in some circumstances, a "set" may have zero elements. 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 some circumstances, a "subset" may have zero elements.

[0126] In the drawings, the direction of the arrows, indicated by the arrowheads, generally demonstrates the flow of information (such as data or instructions) that is the subject of the illustration. For example, element A and element B exchange various information, but when information sent from element A to element B pertains to the illustration, the arrow may point from element A to element B. This unidirectional arrow does not imply that other information is not sent from element B to element A. Furthermore, for information sent from element A to element B, element B may send a request for the information or an acknowledgment of its receipt to element A.

[0127] For the purposes of this application, the term "module" may be interchanged with the term "controller" or the term "circuitry," including the definitions below. For the purposes of this application, the term "controller" may be interchanged with the term "module." The term "module" may refer to, be a part of, or include an application specific integrated circuit (ASIC), a digital, analog, or mixed analog / digital discrete circuit, a digital, analog, or mixed analog / digital integrated circuit, a combinational logic circuit, a field programmable gate array (FPGA), processor hardware (shared, dedicated, or group) that executes code, memory hardware (shared, dedicated, or group) that stores code 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.

[0128] The module may include one or more interface circuits. In some examples, the interface circuit 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 are 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 are IEEE Standard 802.15.4 (including the ZIGBEE standard from the ZigBee Alliance) and the Bluetooth Special Interest Group (SIG), including the BLUETOOTH wireless networking standard (Core Specification versions 3.0, 4.0, 4.1, 4.2, 5.0, and 5.1 from the Bluetooth SIG).

[0129] Modules may communicate with other modules using interface circuits. Although modules may be depicted in this disclosure as logically communicating directly with other modules, in various implementations, modules may actually communicate through a communication system. A communication system includes physical and / or virtual network connectivity devices such as hubs, switches, routers, and gateways. In some implementations, a communication system connects to or traverses a wide area network (WAN) such as the Internet. For example, a communication system may include multiple LANs connected to each other via the Internet or point-to-point leased lines using technologies including multiprotocol label switching (MPLS) and virtual private networks (VPNs).

[0130] In various implementations, the functionality of a module may be distributed among multiple modules connected via a communication system. For example, multiple modules may implement the same functionality distributed by a load balancing system. In yet another example, the functionality of a module may be split between a server (also known as remote, or cloud) module and a client (or user) module. For example, the client module may include a native or web application running on a client device and in network communication with the server module.

[0131] Some or all of the hardware features of a module may be defined 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"). The hardware description language may be used to fabricate and / or program hardware circuits. In some implementations, some or all of the features of a module may be defined by a language, such as IEEE 1666-2005 (commonly referred to as "SystemC"), which encompasses both code and hardware descriptions, as described below.

[0132] 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 encompass multiple microprocessors on separate dies, multiple microprocessors on a single die, multiple cores of a single microprocessor, multiple threads of a single microprocessor, or combinations of the above.

[0133] Memory hardware may also store data, either together with or separately from the code. Shared memory hardware encompasses a single memory device that stores some or all code from multiple modules. An example of shared 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, in combination with other memory devices, stores some or all code from one or more modules. 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 that, combined, stores code for a particular module.

[0134] 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 through a medium (such as on a carrier wave), and the term computer-readable medium is therefore considered tangible and non-transitory. Non-limiting examples of non-transitory computer-readable media include non-volatile memory devices (such as flash memory devices, erasable programmable read-only memory devices, or masked read-only memory devices), volatile memory devices (such as static random access memory devices or dynamic random access memory devices), magnetic storage media (such as analog or digital magnetic tape or hard disk drives), and optical storage media (such as CDs, DVDs, or Blu-ray discs).

[0135] The apparatus and methods described in this application may be implemented partially or fully by a special-purpose computer created by configuring a general-purpose computer to perform one or more specific functions embodied in a computer program. Such apparatus and methods may be described as computerized apparatus and computerized method. The functional blocks and flowchart elements described above serve as software specifications, which may be translated into a computer program by the routine work of a skilled engineer or programmer.

[0136] A computer program includes processor-executable instructions stored on at least one non-transitory computer-readable medium. A computer program may also include or rely on stored data. A computer program may encompass a basic input / output system (BIOS) that interacts with the hardware of a special-purpose computer, device drivers that interact with specific devices of a special-purpose computer, one or more operating systems, user applications, background services, background applications, etc.

[0137] A computer program may include (i) written text to be parsed, such as HTML (Hypertext Markup Language), XML (Extensible Markup Language), or JSON (JavaScript Object Notation), (ii) assembly code, (iii) object code generated from source code by a compiler, (iv) source code for execution by an interpreter, (v) source code for compilation and execution by a just-in-time compiler, etc. By way of example only, source code can 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®, HTML5 (Hypertext Markup Language Fifth Revision), Ada, ASP (Active Server Pages), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, Visual Basic®, Lua, MATLAB, SIMULINK, and Python®. [Explanation of symbols]

[0138] 110 Inductively Coupled Plasma (ICP) System 112 Plasma Chamber 114 Plasma 116 inner coil, coil 118 outer coil, coil 120 Power supply 122 Power supply 124 Dielectric window 126 electrode 210 Capacitively Coupled Plasma (CCP) System 212 Plasma Chamber 214 Plasma 216 Electrode 218 Electrode 220 Power supply 222 Power supply 310 Dual Power Input Plasma System, Plasma Generation System 312 first electrode, electrode 316 Second electrode, electrode 318 First power supply, power supply 320 second power supply, power supply 322 Plasma, Conductive Plasma 324 Plasma Chamber 330 Asymmetric sheath, sheath 332 Sheath 334 Power Supply Sheath, Sheath 410 Power Supply System 412 Radio Frequency (RF) Generators, Power Sources, RF Power Generators 412a Source RF Generator 412b Bias RF Generator 414 RF power supplies, amplifiers, power amplifiers, power supplies 414a Source RF Power Supply 414b Bias RF Power Supply 416 RF Sensor, Sensor 416a Source Sensor 416b Bias Sensor 418 Matching Network 418a Source Matching Network 418b Bias Matching Network 420 Processor, Controller, Control Module, Power Control Module, Local Controller 420a Source Controller 420b Bias Controller 420' External or Common Controller, Controller 432 Load, Plasma Chamber 434 Synchronous Bias Detector 440 pulse synchronous output port 442 Digital Communication Port 444 RF output port 448 RF input port 450 digital communication port 452 Pulse Sync Input Port 710 Electrical Circuits 712 First Node 714 Second Node 716 Plasma sheath, sheath 718 Diode 720 current source 722 Capacitor 724 resistor 726 Inductor 910 Plasma Generation System 912 Plasma Chamber 914 Bulk Plasma, Plasma 916 RF Generator 918 Transmission Line 920 Matching Network 922 Antenna 924 Dielectric Window 930 second RF generator, RF generator 932 Transmission Line 934 Matching Network 936 Electrode 942 Antenna sheath, component 944 Wall sheath, component 946 Sheaths, components, electrode sheaths 948 wafers 1010 Circuit 1014 Bulk Plasma 1030 RF Generator 1032 Transmission Line 1034 Matching Network 1036 Electrostatic Chuck 1111 RF Plasma Generation System 1130a RF power generator, RF generator 1130b RF power generator, RF generator 1132a transmission line 1132b transmission line 1134 Matching Network 1136 Electrostatic Chuck 1144 Wall sheath 1146 Electrode sheath 1150 V / I sensor, sensor 1152 capacitor 1210 Control System 1212 RF Generator Frequency and Power Control Module, RF Frequency and Power Control Module, Control Module 1214 Data Frame Module 1216 Interpolation Module 1222 Model Evaluation Module 1226 model integral Module 1228 Optimization Module 1230 IEDF Evaluation Module 1232 IEDF Controller Module 1510 Control Module, Module Section, Module 1512 Power generation module, module section, module 1514 Amplitude Control Module, Module Section, Module 1516 Frequency Control Module, Module Section, Module 1520 Amplitude Adjustment Module, Module Section, Module 1522 Amplitude Update Module, Module Section, Module 1524 Frequency Regulation Module, Module Section, Module 1526 Frequency Update Module, Module Section, Module 1530 Sensor / Model Module, Module Section, Module 1532 Sensor Module, Module Section, Module 1534 Model / Test Module, Module Section, Module 1536 Parameter Generation Module, Module Section, Module

Claims

1. 1. A controller for a plasma generation system, comprising: a model evaluation module configured to receive sensed values ​​that vary according to a state of the plasma controlled by the RF power generator, the model evaluation module generating plasma parameters, the plasma parameters varying according to the sensed values; a model integration module configured to receive the plasma parameters, integrate the plasma parameters, and output integrated model parameters based on the integrated plasma parameters, the integrated model parameters representing properties of the plasma; and an ion energy distribution function (IEDF) evaluation module configured to receive the integral model parameters and generate an IEDF according to the integral model parameters; an IEDF controller module configured to receive the IEDF and generate a signal to control an RF generator; an RF generator control module configured to receive the signal and generate an RF generator control signal to control at least one of a power, a frequency, or a phase of the RF power generator.

2. 2. The controller of claim 1, comprising an optimization module configured to receive the integral model parameters, compare the integral model parameters to predetermined parameters used to define a model, and modify the predetermined parameters according to the comparison.

3. 2. The controller of claim 1, wherein the RF power generator is a bias RF generator, and the IEDF varies according to the at least one of the power, frequency, or phase of the bias RF generator.

4. The controller of claim 1 , wherein the integral model parameters vary according to an ion potential of the plasma.

5. The controller of claim 1 , wherein the integral model parameter is an effective ion potential waveform, the effective ion potential waveform characterizing an ion potential of ions accelerated by a plasma sheath.

6. The controller of claim 5 , wherein the RF generator control module is configured to receive the effective ionic potential waveform for controlling at least one of a power, a frequency, or a phase of the RF power generator.

7. The controller of claim 1 , wherein the RF power generator comprises a plurality of RF power generators, the outputs of the RF power generators being combined and applied to the plasma.

8. The controller of claim 1 , wherein the sensed value is detectable at a plurality of locations within the plasma generating system.

9. 10. The controller of claim 1, wherein the RF power generator provides an output signal that may be one of a sine wave signal, a square wave signal, a rectangular wave signal, a triangular wave signal, a Gaussian signal, a piecewise linear signal, a narrow pulse voltage peak followed by a ramp down signal, or any signal.

10. The controller of claim 9 , wherein the output signal is modulated by a pulse signal.

11. The controller of claim 10 , wherein the pulse signal is one of trapezoidal, triangular, Gaussian, or arbitrary in shape.

12. an RF power generator that generates an RF output signal that is applied to a load to generate a plasma; a model evaluation module configured to receive sensed values ​​that vary according to a state of the plasma, the model evaluation module determining plasma parameters, the plasma parameters varying according to the sensed values; a model integration module configured to receive the plasma parameters, integrate the plasma parameters, and output integrated model parameters based on the integrated plasma parameters, the integrated model parameters representing properties of the plasma; and an RF generator control module configured to receive the integral model parameters and generate an RF generator control signal to control at least one of a power, a frequency, or a phase of the RF power generator according to the integral model parameters.

13. 13. The RF power generation system of claim 12, wherein the RF power generator is a bias RF generator, and the integral model parameters vary according to at least one of a frequency or a phase of the bias RF generator.

14. 13. The RF power generation system of claim 12, comprising an ion energy distribution function (IEDF) evaluation module configured to receive the integral model parameters and generate an IEDF according to the integral model parameters.

15. 15. The RF power generation system of claim 14, wherein the RF generator control module is configured to receive the IEDF and generate the RF generator control signal for controlling at least one of a power, a frequency, or a phase of the RF power generator according to the integral model parameters or the IEDF.

16. 15. The RF power generation system of claim 14, further comprising an IEDF controller module configured to receive the IEDF and generate a signal to control an RF generator.

17. 17. The RF power generation system of claim 16, wherein the RF generator control module is configured to receive the IEDF and generate the RF generator control signal for controlling at least one of a power, a frequency, or a phase of the RF power generator according to the integral model parameters or the IEDF.

18. 15. The RF power generation system of claim 14, wherein the RF power generator is a bias RF generator, and the IEDF varies according to the at least one of the power, frequency, or phase of the bias RF generator.

19. 13. The RF power generation system of claim 12, further comprising an optimization module configured to receive the integral model parameters, compare the integral model parameters to predetermined parameters used to define a model, and modify the predetermined parameters according to the comparison.

20. 13. The RF power generation system of claim 12, wherein the integral model parameters vary according to an ion potential of ions accelerated by a plasma sheath.

21. 13. The RF power generation system of claim 12, wherein the RF power generator comprises a plurality of RF power generators, the outputs of the RF power generators being combined and applied to the plasma.

22. 13. The RF power generating system of claim 12, wherein the sensed value is detectable at a plurality of locations within the RF power generating system.

23. 13. The RF power generation system of claim 12, wherein the RF output signal is one of a sine wave signal, a square wave signal, a rectangular wave signal, a triangular wave signal, a Gaussian signal, a piecewise linear signal, a narrow pulse voltage peak followed by a ramp down signal, or any arbitrary signal.

24. 24. The RF power generating system of claim 23, wherein the RF output signal is modulated by a pulsed signal.

25. 25. The RF power generation system of claim 24, wherein the pulse signal is one of trapezoidal, triangular, Gaussian, or arbitrary in shape.

26. A non-transitory computer-readable medium storing instructions, the instructions comprising: generating an RF power signal that is applied to a load to generate a plasma; receiving a sensed value that varies according to a state of the plasma and determining a plasma parameter, the plasma parameter varying according to the sensed value; receiving the plasma parameters, integrating the plasma parameters, and generating integral model parameters based on the integrated plasma parameters, the integral model parameters representing characteristics of the plasma; receiving the integral model parameters; and generating an RF generator control signal to control at least one of a power, a frequency, or a phase of an RF power generator according to the integral model parameters.

27. 27. The non-transitory computer-readable medium storing instructions of claim 26, wherein the RF power generator is a bias RF generator, and the integral model parameters vary according to at least one of a frequency or a phase of the bias RF generator.

28. 27. The non-transitory computer-readable medium storing instructions of claim 26, wherein the instructions further comprise receiving the integral model parameters and generating an ion energy distribution function (IEDF) according to the integral model parameters.

29. 30. The non-transitory computer-readable medium storing instructions of claim 28, wherein the instructions further comprise receiving the IEDF and generating the RF generator control signal to control at least one of a power, a frequency, or a phase of the RF power generator according to the integral model parameters or the IEDF.

30. 30. The non-transitory computer-readable medium storing instructions of claim 28, wherein the instructions further comprise receiving the IEDF and generating a signal to control an RF generator.

31. 31. The non-transitory computer-readable medium storing instructions of claim 30, wherein the instructions further comprise receiving the IEDF and generating the RF generator control signal to control at least one of a power, a frequency, or a phase of the RF power generator according to the integral model parameters or the IEDF.

32. 30. The non-transitory computer-readable medium storing instructions of claim 28, wherein the RF power generator is a bias RF generator, and the IEDF varies according to the at least one of the power, frequency, or phase of the bias RF generator.

33. 27. The non-transitory computer-readable medium storing instructions of claim 26, wherein the instructions further comprise receiving the integral model parameters, comparing the integral model parameters to predetermined parameters used to define a model, and modifying the predetermined parameters according to the comparison.

34. 27. The non-transitory computer-readable medium storing instructions of claim 26, wherein the integral model parameters vary according to an ion potential of ions accelerated by a plasma sheath.

35. 27. The non-transitory computer-readable medium storing instructions of claim 26, wherein the RF power generator comprises a plurality of RF power generators, the outputs of the RF power generators being combined and applied to the plasma.

36. 27. The non-transitory computer-readable medium storing instructions of claim 26, wherein the sensed value can be sensed at a plurality of locations to obtain the sensed value.

37. 27. The non-transitory computer-readable medium storing instructions of claim 26, wherein the RF output signal is one of a sine wave signal, a square wave signal, a rectangular wave signal, a triangular wave signal, a Gaussian signal, a piecewise linear signal, a narrow pulse voltage peak followed by a ramp down signal, or any signal.

38. 38. The non-transitory computer-readable medium storing instructions of claim 37, wherein the RF output signal is modulated by a pulsed signal.

39. 40. The non-transitory computer-readable medium storing instructions of claim 38, wherein the pulse signal is one of trapezoidal, triangular, Gaussian, or arbitrary in shape.

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