Plasma process control of a multi-electrode system equipped with an ion energy sensor

Abstract

The RF generator includes a first RF power supply configured to output a first RF output signal to a first electrode of the load. The RF generator includes a first sensor for detecting a first parameter of the first RF output signal to determine a first characteristic of the plasma in the load. The second RF power supply outputs a second RF output signal to the second electrode. The second sensor detects a second parameter of the second RF output signal to determine a second characteristic of the plasma in the load. The RF power controller receives the first characteristic and the second characteristic and generates a first control signal and a second control signal. The first control signal adjusts the first RF output signal, and the second control signal adjusts the second RF output signal.

Description

[Technical Field]

[0001] Cross-references to related applications This application claims the benefits of U.S. Application No. 17 / 884,711, filed on 10 August 2022. The disclosures of the said application are incorporated herein by reference in their entirety.

[0002] This disclosure relates to an RF generator system and control of an RF generator. [Background technology]

[0003] Plasma processing is frequently used in semiconductor manufacturing. In plasma processing, ions are accelerated by an electric field to etch material from the surface of a substrate or to 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 produced by the respective radio frequency (RF) or direct current (DC) generators of the power supply system. The power signal generated by the generator must be precisely controlled in order to effectively perform plasma etching.

[0004] The background information provided herein is for the purpose of providing a general overview of the contents of this disclosure. The research of the inventors currently named, as described in this background section, and any aspects of the specification that may not qualify as prior art at the time of filing, are not expressly or implicitly recognized as prior art to this disclosure. [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. 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 Application No. 17 / 715,672 [Overview of the project] [Means for solving the problem]

[0006] One general embodiment includes an RF generator, which includes a first RF power supply configured to output a first RF output signal to a first electrode of a load. The generator also includes a first sensor for detecting a first parameter of the first RF output signal and determining a first characteristic of the plasma in the load. The generator also includes a second RF power supply configured to output a second RF output signal to a second electrode. The generator also includes a second sensor for detecting a second parameter of the second RF output signal and determining a second characteristic of the plasma in the load. The generator also includes an RF power controller configured to receive the first and second characteristics and generate a first control signal, and to generate a second control signal. The generator also includes the first control signal adjusting the first RF output signal and the second control signal adjusting the second RF output signal. Other embodiments of this embodiment include a corresponding computer system, apparatus, and computer program recorded on one or more computer storage devices, each configured to perform the actions of the method.

[0007] The implementation may include one or more of the following features: An RF generator in which the first sensor is a plasma sensor and the first characteristic is at least one of plasma density, electron temperature, ion potential, sheath thickness, sheath capacitance, or ion energy distribution function (IEDF) related to the first electrode, and the second sensor is a plasma sensor and the second characteristic is at least one of plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF) related to the second electrode. The first characteristic is the IEDF related to the first electrode. The second characteristic is the IEDF related to the second electrode. The first characteristic is the IEDF related to the first electrode, and the second characteristic is the IEDF related to the second electrode. The RF power controller may include a first power controller and a second power controller, the first power controller configured to receive a first characteristic and generate a first control signal to change a first RF output signal, and the second power controller configured to receive a second characteristic and generate a second control signal to change a second RF output signal. The RF generator may include a communication link between the first power controller and the second power controller, the first and second power controllers configured to communicate settings defining the respective first and second RF output signals. The first RF power supply is a main bias power supply, the first electrode is a main bias electrode, the second RF power supply is an auxiliary bias power supply, the second electrode is an auxiliary bias electrode, and the main bias electrode and the auxiliary bias electrode form a composite bias electrode. A first control signal controls at least one of the rail voltage, drive, frequency, phase, or pulsing of a first RF output signal, and a second control signal controls at least one of the rail voltage, drive, frequency, phase, or pulsing of a second RF output signal. The RF generator may include a third RF power supply configured to output a third RF output signal to a third electrode, and an RF power controller is further configured to generate a third control signal for varying the third RF output signal.The RF power controller is configured to generate a third control signal, which varies according to at least one of the first or second characteristics. The third RF power supply is a source power supply, and the third electrode is a source electrode. Implementations of the described technique may include hardware, methods or processes, or computer software on a computer-accessible medium.

[0008] One common embodiment includes an RF system including a main bias RF generator, which includes a main bias power supply configured to output a main bias RF output signal to the main bias electrode of a load, and a main bias plasma sensor configured to detect the main bias parameter of the main bias RF output signal and determine the main bias characteristics of the plasma in the load. The system also includes an auxiliary bias RF generator, which includes an auxiliary bias RF power supply configured to output an auxiliary bias RF output signal to an auxiliary bias electrode, and an auxiliary bias plasma sensor configured to detect the auxiliary bias parameter of the auxiliary bias RF output signal and determine the auxiliary bias characteristics of the plasma in the load. The system also includes an RF power controller configured to receive the main bias characteristics and the auxiliary bias characteristics and to generate a main bias control signal for changing the main bias RF output signal, and to generate an auxiliary bias control signal for changing the auxiliary bias RF output signal. Other embodiments of this embodiment include a corresponding computer system, apparatus, and computer program recorded on one or more computer storage devices, each configured to perform the actions of the method.

[0009] The implementation configuration may include one or more of the following features: An RF system in which the RF power controller is one of a proportional-integral controller, a proportional-integral-derivative controller, or a linear second-order response controller. An RF system in which the primary bias plasma sensor includes one of a VI probe or a directional coupler for detecting a primary bias parameter, and the auxiliary bias plasma sensor includes one of a VI probe or a directional coupler for detecting an auxiliary bias parameter. An RF system in which the primary bias characteristic is one of plasma density, electron temperature, ion potential, sheath thickness, sheath capacitance, or ion energy distribution function (IEDF) associated with the primary bias electrode, and the auxiliary bias characteristic is one of plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF) associated with the auxiliary bias electrode. The RF power controller may include a primary bias power controller and an auxiliary bias power controller, the primary bias power controller being configured to receive the primary bias characteristic and generate a primary bias control signal according to the primary bias characteristic, and the auxiliary bias power controller being configured to receive the auxiliary bias characteristic and generate an auxiliary bias control signal according to the primary bias characteristic. The primary bias electrode and the auxiliary bias electrode form a composite bias electrode. An RF system in which one of the main bias control signal controls at least one of the rail voltage, drive, frequency, phase, or pulsing of the main bias RF output signal, and the auxiliary bias control signal controls at least one of the rail voltage, drive, frequency, phase, or pulsing of the auxiliary bias RF output signal. One of the main bias characteristics and the auxiliary bias characteristics includes a plurality of plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF) associated with the respective main bias electrode and auxiliary bias electrode, and the other of the main bias characteristics includes a plurality of plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF) associated with the respective main bias electrode and the other auxiliary bias electrode.An RF system may include a source RF power supply configured to output a source RF output signal to a source electrode, and an RF power controller further configured to generate a source control signal for varying the source RF output signal. An RF system in which one of the primary bias characteristics and auxiliary bias characteristics includes a plurality of plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF) associated with the respective primary and auxiliary bias electrodes, and the other of the primary and auxiliary bias characteristics includes a plurality of plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF) associated with the respective primary and auxiliary bias electrodes. The RF power controller is configured to generate a source control signal, which varies according to at least one of the primary or auxiliary bias characteristics. The primary bias characteristic is an IEDF associated with the primary bias electrode. The auxiliary bias characteristic is an IEDF associated with the auxiliary bias electrode. Implementations of the described techniques may include hardware, methods or processes, or computer software on a computer-accessible medium.

[0010] One common embodiment includes a non-temporary computer-readable medium storing processor-executable instructions. The non-temporary computer-readable medium storing processor-executable instructions also includes generating a main bias RF output signal to the main bias electrode of a load. The instructions also include detecting the main bias parameter of the main bias RF output signal and determining the main bias characteristics of the plasma in the load. The instructions also include generating an auxiliary bias RF output signal to the auxiliary bias electrode of the load. The instructions also include detecting the auxiliary bias parameter of the auxiliary bias RF output signal and determining the auxiliary bias characteristics of the plasma in the load. The instructions also include receiving the main bias characteristics and the auxiliary bias characteristics, generating a main bias control signal to change the main bias RF output signal according to the main bias parameter, and generating an auxiliary bias control signal to change the auxiliary bias RF output signal according to the main bias characteristics. The instructions also include the main bias control signal adjusting the main bias RF output signal and the auxiliary bias control signal adjusting the auxiliary bias RF output signal. Other embodiments of this embodiment include a corresponding computer system, apparatus, and computer program recorded on one or more computer storage devices, each configured to perform the actions of the method.

[0011] The implementation may include one or more of the following features: a non-temporary computer-readable medium for storing processor-executable instructions, wherein the primary bias characteristic is at least one of plasma density, electron temperature, ion potential, sheath thickness, sheath capacitance, or ion energy distribution function (IEDF) associated with the primary bias electrode, and the auxiliary bias characteristic is at least one of plasma density, electron temperature, ion potential, sheath thickness, sheath capacitance, or ion energy distribution function (IEDF) associated with the auxiliary bias electrode; the primary and auxiliary bias electrodes form a composite bias electrode; the primary bias control signal controls at least one of rail voltage, drive, frequency, phase, or pulsing of the primary bias RF output signal; and the auxiliary bias control signal controls at least one of rail voltage, drive, frequency, phase, or pulsing of the auxiliary bias RF output signal. A non-temporary computer-readable medium storing processor-executable instructions, wherein the instructions may include generating one of a main bias characteristic and an auxiliary bias characteristic, each comprising at least two of the following: plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF) associated with a main bias electrode and an auxiliary bias electrode, and the other of the main bias characteristic and auxiliary bias characteristic each comprising at least one of the following: plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF) associated with the other of the main bias electrode and an auxiliary bias electrode. A non-temporary computer-readable medium storing processor-executable instructions, wherein the instructions may include generating a source RF output signal to a source electrode and generating a source control signal to change the source RF output signal.A non - transient computer - readable medium storing processor - executable instructions, where the instructions may include generating one of main - bias characteristics and auxiliary - bias characteristics, the command including a plurality of plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF) related to a main - bias electrode and an auxiliary - bias electrode respectively, and the other of the main - bias characteristics and the auxiliary - bias characteristics including a plurality of plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF) related to the other of the main - bias electrode and the auxiliary - bias electrode respectively. The instructions may include changing a source control signal according to at least one of the main - bias characteristics or the auxiliary - bias characteristics. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer - accessible medium.

[0012] Further applicable areas of the present disclosure will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are intended for illustrative purposes only and are not intended to limit the scope of the present disclosure.

[0013] The present disclosure will be more fully understood from the detailed description and the accompanying drawings.

Brief Description of the Drawings

[0014] [Figure 1] A diagram showing a depiction of a plasma processing system having a high plasma density at the center. [Figure 2] A diagram showing a depiction of a plasma processing system having a low plasma density at the center. [Figure 3] A schematic block diagram of a power supply system having a plurality of power supply devices arranged according to various configurations of the present disclosure. [Figure 4] A diagram showing waveforms of an RF signal and a pulse for modulating the RF signal to explain a pulse operation mode. [Figure 5]This figure shows a depiction of a plasma system arranged in accordance with the principles of this disclosure. [Figure 6] This is a schematic block diagram of a pair of controllers that transmit control signals to an RF generator. [Figure 7] This is a schematic block diagram of a pair of RF generators communicating to supply power to multiple electrodes of a load electrode set. [Figure 8] This is a schematic block diagram of a common controller configured to transmit control inputs to each of the pair of RF generators in order to transmit power to multiple electrodes of a set of electrodes in a load. [Figure 9] This is a schematic block diagram of a common controller configured to communicate with a third electrode that supplies power to a load, by transmitting control inputs to each of the pair of RF generators to supply energy to multiple electrodes of a set of electrodes in the load. [Figure 10] This is a functional block diagram of exemplary control modules arranged according to various configurations. [Figure 11] This is a flowchart of the operation of a control system arranged in accordance with the principles of this disclosure. [Modes for carrying out the invention]

[0015] In drawings, reference numbers may be reused to identify similar and / or identical elements.

[0016] A power system may include a DC or RF power generator, a matching network, and a load (such as a process chamber, plasma chamber, or reactor with fixed or variable impedance). The power generator produces a DC or RF power signal that is received by the matching network or an impedance-optimizing controller or circuit. The matching network or impedance-optimizing controller or circuit converts the load impedance to the characteristic impedance of the transmission line between the power generator and the matching network. Impedance matching helps to maximize the amount of power transferred to the load ("forward power") and minimize the power reflected from the load to the power generator ("reverse power" or "reflected power"). When the input impedance of the matching network matches the characteristic impedance of the transmission line and the generator, forward power can be maximized and reverse power can be minimized.

[0017] In the field of power supplies or power supply devices, there are typically two methods for applying a power signal to a load. The first, more traditional method is to apply a continuous power signal to the load. In continuous mode or continuous wave mode, a continuous power signal is typically a constant DC power signal or sinusoidal RF power signal that is continuously output to the load by the power supply. In the continuous mode method, the power signal is assumed to have a constant DC output or sinusoidal output, and the amplitude and / or frequency (of the RF power signal) of the power signal can be varied to change the output power applied to the load.

[0018] A second method for applying a power signal to a load involves pulsing the RF signal rather than applying a continuous RF signal to the load. In pulsed operation mode or pulsed operation mode, the RF signal is modulated by a modulation signal to define the envelope of the modulated power signal. The RF signal can be, for example, a sinusoidal RF signal or another time-varying signal. The power supplied to the load is typically changed by changing the modulation signal.

[0019] In a typical power supply configuration, the output power applied to the load is determined using sensors that measure the forward and reflected power or voltage and current of the RF signal applied to the load. Any set of these signals is analyzed in a control loop. The analysis typically determines the power values ​​used to adjust the power supply output to vary the power applied to the load. In power supply systems where the load is a process chamber or other nonlinear or time-varying load, the applied power is partially a function of the load's impedance; therefore, the changing impedance of the load causes a corresponding change in the power applied to the load.

[0020] In systems where the manufacture of various devices relies on supplying power to a load to control the manufacturing process, the power is typically supplied in one of two configurations. In the first configuration, the power is capacitively coupled to the load. Such systems are called capacitively coupled plasma (CCP) systems. In the second configuration, the power is inductively coupled to the load. Such systems are typically called inductively coupled plasma (ICP) systems. Power coupling to the plasma can also be achieved 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 conventional ICP and CCP systems. The power supply 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 sheath formation. Depending on various design considerations, the bias and source may share the same electrode or use separate electrodes.

[0021] When a power supply 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 results in ion densities with varying ion energies. One characteristic measure of ion energy is the ion energy distribution function (IEDF). The IEDF can be controlled by bias power. One way to control the IEDF of a system in which multiple RF power signals are applied to a load is by varying multiple RF signals that are associated by at least one of amplitude, frequency, and phase. At least one of the amplitude, frequency, and phase of the multiple RF power signals can also be associated by a Fourier series and associated coefficients. The frequencies between the multiple RF power signals can be locked, and the relative phases between the multiple RF signals can also be locked. Examples of such systems can be seen by referring to U.S. Patents 7,602,127, 8,110,991, and 8,395,322, all of which have been assigned to the assignee of this application and are incorporated by reference herein.

[0022] Time-varying or nonlinear loads can exist in a variety of applications. In one application, 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. For example, a typical plasma chamber or reactor used in a plasma processing system for thin-film manufacturing can utilize a dual power system. One power generator (source) controls the plasma generation, and the other power generator (bias) controls the ion energy. Examples of dual power systems include those described in U.S. Patents 7,602,127, 8,110,991, and 8,395,322, referenced above. The dual power systems described in the patents referenced above use a closed-loop control system to adapt the operation of the power supply in order to control the ion density and the corresponding ion energy distribution function (IEDF).

[0023] Several techniques exist for controlling a process chamber, which can be used to generate plasma. For example, in an RF power supply system, the phases and frequencies of multiple drive RF signals operating at the same or nearly the same frequencies can be used to control plasma generation. For RF-driven plasma sources, the periodic waveform and corresponding ion energy that affect plasma sheath dynamics are generally known and controlled by the frequency of the periodic waveform and the associated phase interaction. Another technique in RF power supply systems involves dual-frequency control, where two RF frequency sources operating at different frequencies are used to power the plasma chamber in order to provide substantially independent control of ion density and electron density.

[0024] Another approach utilizes a broadband RF power supply to drive the plasma chamber. The broadband approach presents specific 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 voltage for the desired IEDF must be formulated for a wide process space to support material surface interactions. In one responsive approach in an inductively coupled plasma system, controlling the power applied to the source electrode controls the plasma density, while controlling the power applied to the bias electrode modulates ions to control the IEDF, providing control over etching rate and etching characteristic profile. By using source electrode control and bias electrode control, etching rate and various other etching characteristics are controlled via ion density and ion energy.

[0025] As the manufacturing of integrated circuits and devices continues to evolve, the power requirements that control the manufacturing process are also evolving. For example, in the manufacturing of memory devices, the requirements for bias power are constantly increasing. The increased power generates higher, more energetic ions for increased directional or anisotropic etching feature profiles and faster surface interactions, thereby increasing the etching rate and allowing features with higher aspect ratios to be etched. In RF systems, increased ion energy may be accompanied by lower bias frequency requirements, along with increased power and number of bias power supplies coupled to the plasma sheath created within the plasma chamber. The increased power at lower bias frequencies and the increased number of bias power supplies result in intermodulation distortion (IMD) from sheath modulation. The emission of IMD can significantly reduce the power supplied from the source from which the plasma generation originates. U.S. Patent No. 10,821,542, issued 3 November 2020, titled Pulse Synchronization by Monitoring Power in Another Frequency Band, which is assigned to the assignee of this application and incorporated herein by reference, describes a method of pulse synchronization by monitoring power in another frequency band. In the referenced U.S. Patent Application, the pulsing of a second RF generator is controlled in accordance with the detection of the pulsing of a first RF generator in the second RF generator, thereby synchronizing the pulsing between the two RF generators.

[0026] Figure 1 shows a depiction 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, which are interchangeably referred to herein, for generating plasma 114. Power, in the form of voltage or current, is applied to the plasma chamber 112 via coils, which include a coil assembly containing one or more coils arranged in various configurations. In one non-limiting configuration shown in Figure 1, the plasma chamber 112 includes one or both of a first coil 116 and a second coil 118. In various configurations, multiple coils may be arranged concentrically, entangled, or in a helical configuration. Power is applied to the first coil 116 via an RF power generator or power supply 120, and power is applied to the second coil 118 via an RF power generator or power supply 122. Coils 116 and 118 are arranged to supply power to the plasma chamber 112. The dielectric window 124 allows power to be coupled to the plasma while providing a vacuum seal. A substrate or wafer (not shown) is placed inside the plasma chamber 112 and typically forms the workpiece to be subjected to plasma operation. An RF power generator, power supply, or power supply 128 (these terms may be used interchangeably herein) applies power to the plasma chamber 112 via electrodes 126 supporting the substrate.

[0027] In various configurations, power supplies 120 and 122 provide a source voltage or current to ignite or generate the plasma 114 or to control the plasma density. Also in various configurations, power supply 128 provides a bias voltage or current to modulate ions to control the ion potential or ion energy of the plasma 114. In various configurations, power supplies 120 and 122 are locked to operate at the same frequency, voltage, and current, with a fixed or varying relative phase. In various other configurations, power supplies 120 and 122 may operate at different frequencies, voltages, and currents, as well as relative phases.

[0028] Figure 2 shows a depiction of a capacitively coupled plasma (CCP) system 210. The CCP system 210 includes a plasma chamber 212 for generating plasma 214. A pair of electrodes 216, 226, positioned within the plasma chamber 212, are connected to their respective DC (ω=0) or RF power generators or power supplies 220, 222. Electrode 226 supports a substrate or wafer (not shown) as described above with reference to Figure 1. In various configurations, power supply 220 provides a source voltage or current to ignite or generate plasma 214 or to control plasma density, although a bias power supply may also be used to ignite the plasma. In various configurations, power supply 222 provides a bias voltage or current to modulate ions in the plasma to control the ionic potential or ionic energy of plasma 214. In various CCP configurations, bias power and source power may be applied in various combinations to an upper electrode such as electrode 216 and a lower electrode such as electrode 226. In other non-limiting examples, bias power and source power may be applied to the lower electrode, such as electrode 226, while the upper electrode, such as electrode 216, is grounded or floating. In various RF configurations, power supplies 220 and 222 operate in relative phase when the sources are harmonically related. In various other configurations, power supplies 220 and 222 operate at different frequencies, voltages, and currents with fixed or variable relative phases. Also in various configurations, power supplies 220 and 222 can be connected to the same electrode, while the counter electrode is connected to ground or further to a third DC (ω=0) or RF power generator (not shown).

[0029] Figures 1 and 2 show, respectively, conventional single-bias electrode systems in which each bias electrode 216, 226 is configured as a single electrode, compared to multiple powers. In conventional single-bias electrode systems, the plasmas 114, 214 can form as either a bulk plasma with a high-density center or a bulk plasma with a low-density center. Figure 1 shows plasma 114 formed as a bulk plasma with a high-density center, and Figure 2 shows plasma 214 formed as a bulk plasma with a low-density center. Each bulk plasma results in plasma sheaths 130, 230 having one of the following shapes: convex, concave, or other non-planar shapes, none of which are parallel to the generally planar workpiece mounted on the surface of each bias electrode 126, 226. With respect to Figure 1, the plasma sheath 130 is displaced away from electrode 126 near the edge of electrode 126 and towards electrode 126 near the center of electrode 126. This results in a non-uniform feeding sheath thickness on the feeding bias electrode. With respect to Figure 2, the plasma sheath 230 is displaced toward the electrode 226 near the edge of the electrode 226 and away from the electrode 226 near the center of the electrode 226. It should be recognized that, in various configurations, the ICP system in Figure 1 can generate either a bulk plasma with a high density at the center or a bulk plasma with a low density at the center. Similarly, it should be recognized that, in various configurations, the CCP system in Figure 2 can generate either a bulk plasma with a high density at the center or a bulk plasma with a low density at the center.

[0030] As a non-limiting example, as can be seen in Figures 1 and 2, a bulk plasma 114 with a high density center results in a plasma sheath 130 with the shape shown in Figure 1, and a bulk plasma 214 with a low density center results in a plasma sheath 230 with the shape shown in Figure 2. Thus, Figures 1 and 2 illustrate an example of how a single electrode can result in a non-planar plasma sheath profile across the entire substrate. In various other configurations, the sheath profile can be a complex shape on the substrate and electrode. The shapes of the plasma sheaths 130 and 230 depend on waveform parameters such as voltage, power, frequency, and phase, as well as the geometry of the electrode, the geometry of the reactor, and the materials used during plasma processing. Controlling these parameters for a single electrode may not allow for the generation of a plasma that generally produces a flat plasma sheath, resulting in the plasma sheaths 130 and 230 shown in Figures 1 and 2, respectively. In various configurations, a generally flat sheath profile can be achieved by adjusting the electrode geometry, reactor geometry, the materials used during plasma processing, or by adding other components within the reactor.

[0031] The non-planar plasma sheath results in a heterogeneous bulk plasma, which in turn produces ion orbitals that are not orthogonal to the single bias electrode and the workpiece attached to it. As shown in Figure 1, ion orbital 132 is directed towards the edge of electrode 126. Conversely, ion orbital 232 is directed away from the edge of bias electrode 226. When ions are directed to orbitals that are not orthogonal to electrodes 126, 226 (and the workpiece attached thereto), the resulting etching near the edge of the workpiece becomes non-uniform. Non-uniformity can also occur away from the edge of the workpiece, as in multi-coil ICP sources, which can produce a "W"-shaped sheath profile resulting in off-axis ions in locations other than near the edge. Single-bias electrode plasma etching systems have been the dominant industry choice for many years, but as device dimensions continue to shrink, there is less room for the imperfections that can occur when ion orbitals are not orthogonal to the bias electrode. Furthermore, wafer uniformity and device yield partially define the success of high-volume manufacturing (HVM) processes.

[0032] To improve the etching process and enhance non-orthogonal ion orbitals, etching systems with one or both of multiple feed bias electrodes and source electrodes are implemented to provide uniformity and profile control almost to the wafer edge. This control is achieved by tuning the drive RF or pulsed DC (pDC) waveform to achieve a uniform sheath thickness across the wafer. A uniform sheath thickness across the wafer causes ions to collide onto the substrate almost perpendicular to the substrate surface, i.e., vertically. Waveform parameters such as voltage, power, frequency, and phase must be determined empirically based on a specific recipe implemented in the plasma chamber. In addition to presenting significant challenges, this plan lacks feedback and real-time control.

[0033] Non-uniformity in a plasma sheath arises from many aspects of the plasma generation system, including the geometric design of the components, the interaction between the plasma radical source and the loss surface, the coatings and materials used, the control methods, and other factors. Given the challenge of adequately modeling and simulating the plasma reactor, a sensor is needed that can provide real-time feedback of relevant parameters characterizing the plasma, such as ion energy and sheath thickness. Such a sensor measures the combined system response to specific controlled stimuli.

[0034] According to various aspects of this disclosure, IEDF sensors are placed within the RF / DC path of each electrode. The IEDF sensors provide real-time feedback of plasma-characterizing variables such as ion energy, IEDF, sheath thickness, sheath capacitance, and node voltage. In various configurations, one or more of these variables from each IEDF sensor are used to control power, frequency, phase, etc., to maintain a complex and uniform sheath thickness across the electrodes, as described in more detail below.

[0035] Figure 3 shows an RF generator or power supply system 310. The power supply system 310 includes a pair of radio frequency (RF) generators or power supplies 312a, 312b, matching networks 318a, 318b, and a load 332, such as a nonlinear load, which may be a plasma chamber, plasma reactor, process chamber, etc. In various configurations, RF generator 312a is referred to as the source RF generator or power supply, and matching network 318a is referred to as the source matching network. Also, in various configurations, RF generator 312b is referred to as the bias RF generator or power supply, and matching network 318b is referred to as the bias matching network. It will be understood that the components can be referred to individually or collectively using reference numbers, with or without letters, subscripts, or prime symbols.

[0036] In various configurations, the source RF generator 312a receives a control signal 330 from the matching network 318b, a control signal 330 from the generator 312b, or a control signal 330' from the bias RF generator 312b. The control signal 330 or 330' represents an input signal to the source RF generator 312a that indicates one or more operating characteristics or parameters of the bias RF generator 312b. In various configurations, a synchronous bias detector 334 senses the RF signal output from the matching network 318b to the load 332 and outputs a synchronous or trigger signal 330 to the source RF generator 312a. In various configurations, the synchronous or trigger signal 330', rather than the trigger signal 330, may be output from the bias RF generator 312b to the source RF generator 312a. One difference between the trigger or synchronous signals 330, 330' may result from the effect of the matching network 318b, which may change the phase between the input signal to the matching network and the output signal from the matching network. Signals 330 and 330' contain information regarding the operation of the bias RF generator 312b, which enables predictive responsiveness to address periodic fluctuations in the impedance of the load 332 caused by the bias RF generator 312b in various configurations. In the absence of control signals 330 or 330', the RF generators 312a and 312b operate autonomously.

[0037] Each RF generator 312a, 312b includes an RF power supply or amplifier 314a, 314b, sensors 316a, 316b, and a processor, controller, or control module 320a, 320b, respectively. The RF power supplies 314a, 314b generate their respective RF power signals 322a, 322b, which are output to their respective sensors 316a, 316b. The sensors 316a, 316b receive the output of the RF power supplies 314a, 314b and generate their respective RF power signals f1 and f2. The sensors 316a, 316b also output signals that vary according to various parameters sensed from the load 332. Although the sensors 316a, 316b are shown within their respective RF generators 312a, 312b, they can be located outside of the RF power generators 312a, 312b. Such external sensing can occur at the output of an RF generator, at the input of an impedance matching device placed between the RF generator and the load, or between the output of an impedance matching device (including within the impedance matching device) and the load.

[0038] Sensors 316a and 316b detect various operating parameters and output signals X and Y. Sensors 316a and 316b may include voltage sensors, current sensors, and / or directional coupler sensors. Sensors 316a and 316b receive (i) voltage V and current I, and / or (ii) forward power P output from their respective power amplifiers 314a, 314b and / or RF generators 312a and 312b. FWD , and the reverse or reflected power P received from the respective matched networks 318a, 318b or load 332 connected to the respective sensors 316a, 316b. REV It can detect voltage V, current I, and forward power P. FWD , and reverse power P REVThis may be a scaled, filtered, or scaled and filtered version of the actual voltage, current, forward power, and reverse power associated with each power supply 314a, 314b. Sensors 316a, 316b may be analog sensors, digital sensors, or a combination thereof. In a digital implementation, sensors 316a, 316b may include an analog-to-digital (A / D) converter and a signal sampling component having a corresponding sampling rate. Signals X and Y are voltage V and current I, or forward (or source) power P. FWD and the reverse (or reflected) power P REV It can represent either of the following:

[0039] Sensors 316a and 316b generate sensor signals X and Y, respectively, which are received by their respective power controllers or control modules 320a and 320b. Control modules 320a and 320b process their respective X and Y signals, 324a, 326a, and 324b, and generate one or more feedforward or feedback control signals 328a and 328b to their respective power supplies 314a and 314b. Power supplies 314a and 314b adjust their RF power signals 322a and 322b based on the received feedback or feedforward control signals. In various configurations, control modules 320a and 320b can control their respective matched networks 318a and 318b via their respective control signals 328a and 328b. The control modules 320a and 320b may include at least a proportional-integral (PI) controller, a proportional-integral-derivative (PID) controller, a linear secondary regulator (LQR), or a subset thereof, and / or a direct digital synthesis (DDS) component, and / or any of the various components described below in relation to the module.

[0040] In various configurations, control modules 320a, 320b may include functions, processes, processors, or submodules. Control signals 328a, 328b may be control signals or drive signals capable of transmitting DC offset or rail voltage, voltage or current magnitude, frequency, and phase components. In various configurations, feedback control signals 328a, 328b may be used as inputs to one or more control loops. In various configurations, multiple control loops may include control loops for RF drive and rail voltage. In various configurations, control signals 328a, 328b may be used in single-input single-output (SISO) or multiple-input multiple-output (MIMO) control schemes. An example of a MIMO control scheme can be seen with U.S. Patent No. 10,546,724, published on 28 January 2020, titled Pulsed Bidirectional Radio Frequency Source / Load, assigned to the assignee of this application and incorporated herein by reference. In other configurations, signals 328a and 328b can provide feedforward control as described in U.S. Patent No. 10,049,857, which is assigned to the assignee of this application and incorporated herein by reference.

[0041] In various configurations, the power supply system 310 may include a controller 320'. The controller 320' may be located outside of either or both of the RF generators 312a, 312b, and may be referred to as the external controller 320' or the common controller 320'. In various configurations, the controller 320' may implement one or more of the functions, processes, or algorithms described herein with respect to one or both of the controllers 320a, 320b. Thus, the controller 320' communicates with the respective RF generators 312a, 312b via pairs of links 336, 338, respectively, which enable the exchange of data and control signals between the controller 320' and the RF generators 312a, 312b as needed. In various configurations, the controllers 320a, 320b, and 320' can provide distributed and coordinated analysis and control of the RF generators 312a, 312b. In various other configurations, controller 320' can provide control of RF generators 312a and 312b, eliminating the need for separate local controllers 320a and 320b.

[0042] In various configurations, the RF power supply 314a, sensor 316a, controller 320a, and matching network 318a may also be referred to as the source RF power supply 314a, source sensor 316a, source controller 320a, and source matching network 318a. Similarly, in various configurations, the RF power supply 314b, sensor 316b, controller 320b, and matching network 318b may also be referred to as the bias RF power supply 314b, bias sensor 316b, bias controller 320b, and bias matching network 318b. In various configurations, as described above, the source term refers to the RF generator that produces the plasma, and the bias term refers to the RF generator that adjusts the plasma's ion potential or IEDF. In various configurations, the source RF power supply and the bias RF power supply operate at different frequencies. In various configurations, the source RF power supply operates at a higher frequency than the bias RF power supply. In various other configurations, the source RF power supply and the bias RF power supply operate at the same frequency or substantially the same frequency.

[0043] Depending on the configuration, the source RF generator 312a and the bias RF generator 312b include multiple ports for external communication. The source RF generator 312a includes a pulse-synchronized output port 340, a digital communication port 342, and an RF output port 344. The bias RF generator 312b includes an RF input port 348, a digital communication port 350, and a pulse-synchronized input port 352. The pulse-synchronized output port 340 outputs a pulse-synchronized signal 356 to the pulse-synchronized input port 352 of the bias RF generator 312b. The digital communication port 342 of the source RF generator 312a and the digital communication port 350 of the bias RF generator 312b communicate via a digital communication link 357. The RF output port 344 generates an RF control signal 358 which is input to the RF input port 348. In various configurations, the RF control signal 358 is substantially the same as the RF control signal that controls the source RF generator 312a. In various other configurations, the RF control signal 358 is the same RF control signal that controls the source RF generator 312a, but is phase-shifted within the source RF generator 312a according to the requested phase shift generated by the bias RF generator 312b. Thus, in various configurations, the source RF generator 312a and the bias RF generator 312b are driven by substantially identical RF control signals, or by substantially identical RF control signal phases shifted by a predetermined amount.

[0044] In various configurations, the power supply system 310 may include a plurality of RF source generators 312a and a plurality of RF bias generators 312b. A non-limiting example is a plurality of source RF generators 312a, 312a', 312a'', ..., 312a n It can be arranged to provide multiple output power signals to one or more source electrodes of the load 332. Similarly, multiple bias RF generators 312b, 312b', 312b'', ..., 312b nThis may provide multiple output power signals to multiple bias electrodes of the load 332. If the source RF generator 312a and bias RF generator 312b are configured to include multiple respective source RF generators or bias RF generators, each RF generator outputs a separate signal in a one-to-one correspondence to the corresponding multiple matching networks 318a, 318b configured to operate as described above. In various other configurations, there may not be a one-to-one correspondence between each RF generator and the matching network. In various configurations, multiple source electrodes may refer to multiple electrodes working together to define a composite source electrode. Similarly, multiple bias electrodes may refer to multiple connections to multiple electrodes working together to define a composite bias electrode.

[0045] Figure 4 shows a voltage-to-time plot illustrating a pulse operation mode or pulsed operation mode for supplying power to a load such as the load 332 in Figure 3. More specifically, Figure 4 shows two multi-state pulses P1 and P2 of a pulse signal 412, each having multiple states S1-S4 and S1-S3, respectively. In Figure 4, the RF signal 410 is modulated by pulses P1 and P2. When the pulse is ON, as shown in state S1 of P1 and state S1 of P2, the RF generator 312 outputs an RF signal 410 having an amplitude defined by the magnitude of the pulse in each state. Conversely, between state S4 of P1 and state S3 of P2, the pulse is OFF, and the RF generator 312 does not output an RF signal 410. Pulses P1 and P2 can repeat a constant duty cycle or a variable duty cycle, and each pulse P1 and P2 in states S1-S4, S1-S3 may have the same amplitude and width or a varying amplitude and width. Furthermore, the pulse signal 412 does not necessarily have to be a square wave, as shown in Figure 2. As a non-limiting example, the pulse signal 412 may be trapezoidal, triangular, Gaussian, or other shapes. In addition, pulses P1, P2 may have multiple states S1, ..., Sn in which amplitude, duration, and shape vary. States S1, ..., Sn may repeat within a fixed or variable period. Also, as shown in Figure 4, the RF signal 410 operates at frequencies that vary between or within states.

[0046] Figure 5 shows a plasma generation system 510. The plasma generation system 510 includes a plasma chamber 512. Plasma 514 is generated in the plasma chamber 512 by applying source power to a conductor 516. The conductor 516 can be implemented in either an inductively coupled plasma (ICP) configuration or a capacitively coupled plasma (CCP) configuration, as described above with respect to Figures 1 and 2. Plasma 514 can be a bulk plasma with a high density at the center or a bulk plasma with a low density at the center. The configuration in Figure 5 provides a control method for providing a generally uniform plasma sheath 530 by controlling an RF generator that supplies power to at least a pair of electrodes cooperating to provide bias electrodes.

[0047] As shown in Figure 5, the bias electrode 526 includes a main bias electrode 526b and an auxiliary bias electrode 526b'. The main bias electrode 526b and the auxiliary bias electrode 526b' cooperate to define the bias electrode 526. The main bias electrode 526b defines the central portion of the bias electrode 526, and the auxiliary bias electrode 526b' defines the peripheral portion of the bias electrode 526. In various configurations, the auxiliary bias electrode 526b' surrounds the outer periphery of the bias electrode 526. In various other configurations, the bias electrode 526 can be subdivided into various shapes, including multiple rectangular, square, or other shaped sections, or generally circular sections arranged concentrically around a central axis.

[0048] The main bias electrode 526b receives an RF power signal from the main bias RF generator 540b. The main bias RF generator 540b includes a main bias RF power supply 542b and a main bias IEDF sensor 544b. The main bias RF power supply 542b generates an RF output signal applied to the main bias electrode 526b according to one or more input signals received from the main bias IEDF sensor 544b. Similarly, the auxiliary bias RF generator 540' includes an auxiliary bias RF power supply 542b' and an auxiliary bias IEDF sensor 544b'. The auxiliary bias RF power supply 542b' generates an RF output signal applied to the auxiliary bias electrode 526b' according to one or more input signals received from the auxiliary bias IEDF sensor 544b'. By controlling the main bias electrode 526b and auxiliary bias electrode 526b' using power from the respective main bias RF generator 540b and auxiliary bias RF generator 540b', the ion orbital 532 can be changed to an angle that is generally orthogonal to the workpiece placed on the bias electrode 526, compared to Figures 1 and 2.

[0049] The elements in Figure 5 can be replaced with those in Figure 3, with the bias RF generators 540b and 540b' replaced by the respective bias RF generators 312b and 312b' in Figure 3. Such a replacement would replace the sensors 316b and 316b' (not shown) in Figure 3 with the respective IEDF sensors 544b and 544b' in Figure 5. The bias RF generators 540b and 540b' may be controlled by one or more controllers 320b and 320b', or the respective RF generators 312b and 312b', as shown in Figure 3. Throughout this specification, the main and auxiliary components may also be referred to as the first and second components. Similarly, the various control signals and sensor signals may be referred to as the main and auxiliary control signals and the main and auxiliary sensor signals, or the first and second control signals and the first and second sensor signals.

[0050] Figure 6 shows a block diagram of an RF power generation system 610, including a pair of RF generator controllers 620b, 620b', which may be referred to as the main RF generator controller 620b and the auxiliary RF generator controller 620b', respectively, arranged according to this disclosure. In various embodiments, the main RF generator controller 620b represents a controller for an RF generator that supplies power to the main bias electrode of a load, such as the main bias electrode 526b in Figure 5. Similarly, in various embodiments, the auxiliary RF generator controller 620b' represents a controller for an RF generator that supplies power to the auxiliary bias electrode of a load, such as the auxiliary bias electrode 526b' in Figure 5.

[0051] The main RF generator controller 620b includes an adder 650b that receives at least one pair of inputs, including the main bias electrode ion potential or energy, as measured by the main bias IEDF sensor 544b in Figure 5, and the main target ion potential. The main target ion potential may be provided by a monitoring controller for the system and may be specified by the user. Similarly, the auxiliary RF generator controller 620b' includes an adder 650b' that receives at least one pair of inputs, including the auxiliary ion potential, as measured by the auxiliary bias IEDF sensor 544b' in Figure 5, and the auxiliary target ion potential. The auxiliary target ion potential may be provided by a monitoring controller for the system and may be specified by the user. In various configurations, the main target ion potential and the auxiliary target ion potential may be the same value, as indicated by the dotted line in Figure 6. Thus, only a single target ion energy may be provided to the RF power generation system 610 and to the respective adders 650b, 650b'.

[0052] This specification describes the main RF generator controller 620b of the RF power generation system 610. It should be understood that the auxiliary RF generator controller 620b' of the RF power generation system 610 operates similarly and is not described in detail. Adder 650b outputs IEDF errors to the respective proportional and integral sections of the proportional-integral (PI) controller. The proportional section of the PI controller includes combiner 652b, which also receives the proportionality coefficient P 645b. Combiner 652b outputs the proportional term to adder 662b. The integral section of the PI controller includes combiner 656b, which also receives the integral coefficient I 658b. Combiner 656b outputs the combined value to adder 660b. Adder 660b also receives the integral feedback term from integrator 666b. The output from adder 660b is input to clamp 668b, which clamps the output from adder 660b. The range of clamp 668b is defined by the integrator minimum term 670b and the integrator maximum term 672b. The output from clamp 668b is fed back to integrator 666b and also to adder 662b. As previously mentioned, the output from integrator 666b is fed back to adder 662b. Adder 662b transmits a control signal to the main power control section of the RF generator. In various configurations, the control section may include one or more drive actuators or controllers. As previously mentioned, the auxiliary RF generator controller 620b' is configured similarly but receives the auxiliary ion energy signal input to adder 650b' and transmits a control signal to the auxiliary power control section of the RF generator.

[0053] Although described herein as PI controllers, the main RF generator controller 620b and the auxiliary RF generator controller 620b' may be individually configured as one or more of the following: proportional-integral (PI) controllers, proportional-integral-derivative (PID) controllers, or linear secondary regulator (LQR) controllers. Furthermore, the main RF generator controller 620b and the auxiliary RF generator controller 620b' are shown in Figure 5 as single-input single-output (SISO) controllers. However, it should be recognized that one or both of the main RF generator controller 620b and the auxiliary RF generator controller 620b' may be configured as multiple-input multiple-output (MIMO) controllers, as described herein.

[0054] Figure 7 is a schematic block diagram of an RF power generation system 710 including a pair of RF generators 712b, 712b' configured in the same manner as described above. The RF generators 712b, 712b' communicate to coordinate the power supply to a load such as a plasma chamber 732. In non-limiting examples, in various configurations, RF generator 712b may be referred to as the main RF generator 712b, and RF generator 712b' may be referred to as the auxiliary RF generator 712b'. In various configurations, the RF generators 712b, 712b' may be configured to power multiple electrodes of a plasma chamber that cooperate to define the bias electrode. The main RF generator 712b includes a main RF amplifier or RF power supply 714b that receives one or more control signals from the main controller 720b. The RF power supply 714b transmits an output signal to the main IEDF sensor 716b. The main IEDF sensor 716b transmits an output signal to the main bias electrode 726b. The main IEDF sensor 716b also outputs one or more signals to the main bias controller 720b indicating the IEDF associated with the main bias electrode 726b. Similarly, the auxiliary RF generator 712b' includes an auxiliary RF amplifier or auxiliary RF power supply 714b' that receives control signals from the auxiliary controller 720b'. The auxiliary RF power supply 714b' transmits an output signal to the auxiliary bias IEDF sensor 716b'. The auxiliary bias IEDF sensor 716b' transmits an output signal to the auxiliary bias electrode 726b'. The auxiliary bias IEDF sensor 716b' outputs one or more signals to the auxiliary bias controller 720b' indicating the IEDF associated with the auxiliary bias electrode.

[0055] The main controller 720b and auxiliary controller 720b' generate various control signals to the main RF amplifier or RF power supply 714b and auxiliary RF amplifier or RF power supply 714b', respectively. The main RF amplifier or RF power supply 714b and auxiliary RF amplifier or RF power supply 714b' may each be configured to generate a continuous wave signal or a pulsed RF signal. The control inputs or control parameters to the main RF power supply 714b and auxiliary RF power supply 714b' include one or more of the following: DC voltage or rail voltage, low-level drive signal, frequency, phase, and one or more pulsing parameters. Thus, the main controller 720b and auxiliary controller 720b' transmit one or more control signals to the main RF power supply 714b and auxiliary RF power supply 714b', respectively, according to the complexity of the RF power signals supplied to the main bias electrode 726b and auxiliary bias electrode 726b'.

[0056] In various configurations, the main controller 720b and auxiliary controller 720b' communicate via a communication link 730. Communication between the main controller 720b and auxiliary controller 720b' via the communication link 730 allows for adjustment of the power supply to the main bias power 726b and auxiliary bias electrode 726b', respectively, to better control the ion potential and feed sheath of the plasma 736, as described above. In various configurations, the communication link 730 allows for the synchronization of one or more control parameters. As a non-limiting example, frequency, phase, and pulsing can be locked or synchronized between the main RF generator 712b and auxiliary RF generator 712b', while DC voltage or rail voltage can be controlled independently by each of the main controller 720b and auxiliary controller 720b', or by a subset of all parameters. In other configurations, parameters may not be locked or synchronized between RF generators 712b and 712b', or all parameters or a subset of all parameters may be locked or synchronized.

[0057] The main IEDF sensor 716b and the auxiliary IEDF sensor 716b’ can generally be characterized as plasma sensors. A plasma sensor can be configured to detect one or more parameters, such as voltage and current, or forward power and reverse power, and generate one or more parameters that characterize the plasma. Parameters that characterize the plasma can include plasma density (n o ), electron temperature (T e ), ion potential (V i ), sheath thickness (s), sheath capacitance (c s ), and IEDF. An example of a plasma sensor can be found by reference to U.S. Patent Application No. 17 / 715,672, filed Apr. 7, 2022, titled Real-Time, Non-Invasive IEDF Plasma Sensor, assigned to the assignee of the present application, and incorporated herein by reference.

[0058] FIG. 8 shows a plasma generation system 810 for controlling the main bias electrode and the auxiliary bias electrode of a plasma chamber. The plasma generation system 810 includes a common controller 820 that transmits control signals to respective RF generators including a main RF generator 812b and an auxiliary RF generator 812b’. In various configurations, the controller 820 outputs commands or signals for power set points and phase set points to respective RF generators 812b, 812b’. The main RF generator 812b receives a power set point input and a phase set point input and generates an RF output signal as described above. As also described above, the output from the main RF generator 812b is input to a main matching network 818b that operates as described above. The output from the main matching network 818b is input to a main VI probe 816b-1. The VI probe 816b-1 applies RF voltage (V RF ) and RF current (I RFThe plasma sensor 816b-2 operates as described above, and one or more signals are fed back to the controller 820. The controller 820 generates the respective power setpoint and phase setpoint according to the signals fed back to the controller 820.

[0059] As shown in Figure 8, the VI probe 816b-1 and the plasma sensor 816b-2 cooperate to perform the sensor functions described above, as with respect to sensor 316b in Figure 3. The VI probe 816b-1 also transmits an RF signal to the main bias electrode 826b. The VI probe 816b-1 may also be implemented as a directional coupler or to detect other parameters that the plasma sensor 816b-2 can use to determine the parameters characterizing the plasma. The auxiliary bias electrode 826b' is similarly driven, and it should be understood that similar components of the auxiliary drive section in Figure 8 operate as also described above in relation to the main power supply section described herein.

[0060] In Figure 8, VI probes 816b-1 and 816b-1' are connected to the RF voltage (V RF ) and RF current (I RF The VI probes 816b-1 and 816b-1' act as probes to detect one or more of the plasma density (n). The VI probes 816b-1 and 816b-1' output the detected parameters to their respective plasma sensors 816b-2 and 816b-2'. Thus, the VI probes 816b-1 and 816b-1' and their respective plasma sensors 816-2 and 816-2' cooperate to bring the sensors of the parameters characterizing the plasma, as described above. One or more of the parameters can be input to the controller 820, which can be the plasma density (n). o ) and electron temperature (T e ) and the ionic potential (V i ) and sheath thickness (s) and sheath capacitance (c sThe IEDF includes the voltage (V) and current (I). Controller 820 transmits the respective voltage setpoint and phase setpoint to the respective main RF generator 812b and auxiliary RF generator 812b'. Other control signals or commands output by controller 820 to the respective RF generators 812b, 812b' include the pulse rate, duty cycle and number of pulse states.

[0061] In various configurations, selected plasma parameters input to the controller 820 can be used according to a specific control scheme. As a non-limiting example, IEDF information from each plasma sensor 816b-2, 816b-2' can be input to the controller 820. Feedback of main IEDF information and auxiliary IEDF information corresponding to the IEDF associated with each main bias electrode 826b and auxiliary bias electrode 826b' can be used in IEDF histogram-dependent applications or machine learning applications. In other configurations, ion potential (V) from each plasma sensor 816b-2, 816b-2' can be input. i The ion potential (V) associated with each main bias electrode 826b and auxiliary bias electrode 826b' can be transmitted to the controller 820. i ) corresponds to the principal ion potential (V i ) and auxiliary ion potential (V i The feedback of ) can be used in applications that rely on time-domain control or pulse shaping. The configuration in Figure 8 provides an example of an RF power generation system having a controller that implements the SISO control method.

[0062] Figure 9 shows an RF power generation system 910 in various configurations of the present disclosure. The RF power generation system 910 is configured similarly to Figure 8 and further includes an RF source generator 912a. The RF source generator 912a receives power setpoint commands from the controller 920. The controller 920 transmits power setpoint commands to the RF source generator 912a, partly based on feedback signals received from plasma sensors 916b-2, 916b-2'. The RF source generator 912a outputs an RF signal to a matching network 918a. The matching network 918a provides the matching function described above to provide impedance matching between the RF source generator 912a and the antenna / source electrode 924 of the plasma chamber. In the configuration of Figure 9, the controller 920 provides power commands that vary according to parameters characterizing the plasma at the bias electrodes 926b, 926b'. In this way, both the plasma density and the ion voltage can be controlled according to parameters sensed by the plasma sensors 916b-2, 916b-2'. Varying the output of the RF source generator 912a controls the plasma density, and varying the output of the RF bias generators 912b and 912b' controls the ion potential. The RF power generation system 910 provides improved control over the plasma. In various configurations, the main plasma sensors 816b-2 control the ion potential (V i ) and IEDF are output to the controller 920. Similarly, in various configurations, the auxiliary plasma sensor 916b-2' outputs the ion potential (V i The IEDF is output to the controller 920. In various other configurations, other parameters characterizing the plasma can be transmitted to the controller 920. Thus, Figure 9 provides an example of an RF power generation system having a controller that implements a MIMO control method.

[0063] Figure 10 incorporates various components from Figures 1 to 9. The control module 1010 includes a main power generation module section 1012b and an auxiliary power generation module section 1012b'. The main power generation module section 1012b includes a power amplifier module 1014b, a sensor module 1016b, and a control module 1020b. The auxiliary power generation module section 1012b' includes a power amplifier module 1014b', a sensor module 1016b', and a control module 1020b'. The control modules 1020b and 1020b' can communicate via a communication link 1070 and may be integrated into a single processor or distributed across multiple processors. In various configurations, the control module 1010 includes one or more processors that execute code associated with the module section or modules 1010, 1012b, 1012b', 1014b, 1014b', 1016b, 1016b', 1020b, and 1020b'. The operation of the module section or modules 1010, 1012b, 1012b', 1014b, 1014b', 1016b, 1016b', 1020b, and 1020b' will be described below in relation to the method shown in Figure 11.

[0064] For a more defined structure of the controller described above, please refer to the flowchart in Figure 11 provided below and the definition of the term “module” provided below. The systems disclosed herein may operate using numerous methods, examples, and various control system methods shown in Figures 3 to 9. The following operations are described primarily with respect to the implementations in Figures 3 to 9, but the operations can be readily modified for application to other implementations of the disclosure. The operations may be performed repeatedly. The following operations are shown and described primarily as being performed sequentially, but one or more of the following operations may be performed while one or more of the other operations are being performed.

[0065] Figure 11 shows a flowchart of a control system 1110 for controlling RF power generation, for example, the power supply systems in Figures 3 to 9. The control system 1110 includes a control section 1112b for a main RF power generator, such as for supplying power to the main bias electrode of a plasma system, and a control section 1112b' for auxiliary bias electrodes of a plasma system, such as for supplying power to the auxiliary bias electrodes of a plasma system. In control section 1112b, control begins in block 1114b and continues sensing parameters in block 1116b. From the sensed parameters, plasma characteristics are determined in block 1118b. The plasma characteristics are then used to determine the control of plasma parameters in block 1120b. The control then proceeds to block 1122b, where it controls a power supply or power device to adjust the power applied to the main bias electrode. The control ends in block 1124b. The control system 1110 includes a control section 1112b' for an auxiliary RF power generator, such as for supplying power to the auxiliary bias electrode of a plasma system. Control section 1112b' operates in the same manner as control section 1112b.

[0066] The systems and methods described herein offer one or more of the following advantages in various configurations: The systems and methods described herein can improve etching uniformity control. The systems and methods described herein can improve die yield. The systems and methods described herein can also eliminate the need for recipe-by-recipe empirical mapping. The systems and methods described herein also provide ion energy control, real-time correction of system dynamics, and sheath thickness feedback and correction, which can facilitate the implementation of control schemes that are usually complex.

[0067] The foregoing description is merely illustrative and is not intended to limit the Disclosure, its application, or its uses. The broad teachings of this Disclosure can be implemented in various forms. Therefore, although this Disclosure includes certain examples, the true scope of this Disclosure should not be limited in this way, as other modifications will become apparent when considering the drawings, specification, and the claims below. In the specification and claims, one or more steps within a method may be performed in a different order (or simultaneously) without altering the principles of this Disclosure. Similarly, one or more instructions stored in a non-temporary computer-readable medium may be performed in a different order (or simultaneously) without altering the principles of this Disclosure. Unless otherwise indicated, the numbering or other labeling of instructions or method steps is for convenience only and not to indicate a fixed order.

[0068] Furthermore, while each embodiment is described above as having specific features, any one or more of these features described in relation to any embodiment of the Disclosure may be implemented and / or combined with any feature of any other embodiment, even if such combination is not expressly described. In other words, the embodiments described are not mutually exclusive, and the substitution of one or more embodiments with one another remains within the scope of the Disclosure.

[0069] The spatial and functional relationships between elements (e.g., between modules, between circuit elements, between semiconductor layers, etc.) are described using a variety of terms, including “connected,” “engaged,” “joined,” “adjacent,” “adjacent to,” “above,” “above,” “below,” and “positioned.” Unless explicitly described as “direct,” if a relationship between a first element and a second element is described in the above disclosure, that relationship may be a direct relationship in which there are no other intervening elements between the first and second elements, or an indirect relationship in which one or more intervening elements (spatially or functionally) exist between the first and second elements.

[0070] The phrase "at least one of A, B, and C" should be interpreted as meaning a logic (A OR B OR C) using non-exclusive logic OR, and not as meaning "at least one A, at least one B, and at least one C." The term "set" does not necessarily exclude empty sets; in other words, in some situations, a "set" can have zero elements. The term "non-empty set" may be used to indicate the exclusion of empty sets; in other words, a non-empty set always has one or more elements. The term "subset" does not necessarily require a suitable subset; in other words, a "subset" of a first set may have the same extent (or be equal to) the first set. Furthermore, the term "subset" does not necessarily exclude empty sets; in some situations, a "subset" can have zero elements.

[0071] In the diagram, the direction of the arrowhead indicates the flow of information (such as data or instructions) that is important to the illustration. For example, if elements A and B exchange various types of information, and the information sent from element A to element B is relevant to the diagram, the arrow may point from element A to element B. This one-way arrow does not mean that no other information is sent from element B to element A. Furthermore, with respect to the information sent from element A to element B, element B may send a request or acknowledgment of receipt of that information to element A.

[0072] In this application, which includes the following definitions, the term “module” may be replaced by the term “controller” or “circuit.” In this application, the term “controller” may be replaced by the term “module.” The term “module” may refer to, be part of, or include some or all of the above, such as 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 system-on-a-chip.

[0073] A module may include one or more interface circuits. In some examples, the interface circuits may implement a wired or wireless interface that connects to a local area network (LAN) or a wireless personal area network (WPAN). Examples of LANs include IEEE standard 802.11-2020 (also known as the Wi-Fi wireless networking standard) and IEEE standard 802.3-2018 (also known as the Ethernet wired networking standard). Examples of WPANs include IEEE standard 802.15.4 (including the ZIGBEE® standard from the ZigBee® Alliance) and the BLUETOOTH® wireless networking standard from the Bluetooth® SIG (including core specification versions 3.0, 4.0, 4.1, 4.2, 5.0, and 5.1 from the Bluetooth® SIG).

[0074] Modules can communicate with other modules using interface circuits. While modules may be shown in this disclosure as communicating logically directly with other modules, in various implementations modules may actually communicate via a communication system. A communication system includes physical and / or virtual networking 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 dedicated lines using technologies including Multiprotocol Label Switching (MPLS) and Virtual Private Networks (VPNs).

[0075] In various implementations, the functionality of a module can 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 a further example, the functionality of a module can be divided between a server (also known as a remote or cloud) module and a client (or user) module. For example, a client module may include a native or web application that runs on a client device and communicates over a network with the server module.

[0076] Some or all of the module's hardware functions may be defined using a hardware description language, such as IEEE standard 1364-2005 (commonly known as "Verilog") and IEEE standard 1076-2008 (commonly known as "VHDL"). Hardware description languages ​​can be used to manufacture and / or program hardware circuits. In some implementations, some or all of the module's functions may be defined by a language such as IEEE 1666-2005 (commonly known as "SystemC"), which encompasses both the code described below and the hardware description.

[0077] The term "code" as used above may include software, firmware, and / or microcode, and may refer to programs, routines, functions, classes, data structures, and / or objects. Shared processor hardware encompasses a single microprocessor that runs some or all of the code from multiple modules. Group processor hardware encompasses a microprocessor that, in combination with additional microprocessors, runs some or all of the code from one or more modules. References to multiple microprocessors include multiple microprocessors on separate dies, multiple microprocessors on a single die, multiple cores in a single microprocessor, multiple threads in a single microprocessor, or a combination of the above.

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

[0079] The term "memory hardware" is a subset of the term "computer-readable media." As used herein, the term "computer-readable media" does not include transient electrical or electromagnetic signals that propagate through a medium (such as on a carrier wave), and therefore, the term "computer-readable media" is considered tangible and non-transient. Non-exclusive examples of non-transient computer-readable media include non-volatile memory devices (such as flash memory devices, erasable programmable read-only memory devices, or mask read-only memory devices), volatile memory devices (such as static random-access memory devices or dynamic random-access memory devices), magnetic storage media (such as analog or digital magnetic tapes or hard disk drives), and optical storage media (such as CDs, DVDs, or Blu-ray® discs).

[0080] The apparatus and methods described in this application may be partially or fully implemented by a dedicated 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 methods. The functional blocks and flowchart elements described above serve as software specifications that can be translated into computer programs through the routine work of a skilled technician or programmer.

[0081] A computer program includes processor-executable instructions stored on at least one non-temporary computer-readable medium. A computer program may also include, or depend on, stored data. A computer program may encompass a basic input / output system (BIOS) that interacts with the dedicated computer's hardware, device drivers that interact with specific devices on the dedicated computer, one or more operating systems, user applications, background services, background applications, and the like.

[0082] A computer program may include (i) descriptive text to be parsed, such as HTML (Hypertext Markup Language), XML (Extended 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; and (v) source code for compilation and execution by a just-in-time compiler. For example only, source code may be written using syntax from languages ​​including C, C++, C#, Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl, Pascal, Curl, OCaml, JavaScript®, HTML5 (Hypertext Markup Language 5th 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]

[0083] 110 Inductively coupled plasma (ICP) systems, ICP systems 112 Plasma Chamber 114 Plasma, a bulk plasma with a high density at its center 116 First coil, coil 118 The second coil, coil 120 RF power generator or power supply, power supply 122 RF power generator or power supply, power supply 124 Dielectric window 126 electrode 128 RF power generator, power supply, or power supply 130 Plasma Sheath 132 Ion Orbitals 210 Capacitively Coupled Plasma (CCP) Systems, CCP Systems 212 Plasma Chamber 214 Plasma, a bulk plasma with a low density at its center. 216 electrodes, bias electrodes 220 DC (ω=0) or RF power generator or power supply, power supply 222 DC (ω=0) or RF power generator or power supply, power supply 226 electrodes, bias electrodes 230 Plasma Sheath 232 Ion Orbitals 310 RF generator or power supply system, power supply system 312 RF Generator 312a Radio frequency (RF) generator or power supply, RF generator, RF power generator, source RF generator, RF source generator 312a' Source RF Generator 312a'' Source RF Generator 312a n Source RF generator 312b Radio frequency (RF) generator or power supply, bias RF generator, RF generator, RF power generator, RF bias generator 312b' Bias RF Generator 312b'' Bias RF Generator 312b n Bias RF generator 314a RF power supply or amplifier, RF power supply, power amplifier, power supply, source RF power supply, source RF generator 314b RF power supply or amplifier, RF power supply, power amplifier, power supply, bias RF power supply, bias RF generator 316a Sensor, Source Sensor 316b Sensor, Bias Sensor 318a Matched network, source matched network 318b Matched networks, biased matched networks 320a Processor, controller, or control module, power controller or control module, control module, controller, local controller, source controller 320b Processor, controller, or control module, power controller or control module, control module, controller, local controller, bias controller 320b' Controller 320' Controller 322a RF power signal 322b RF power signal 324a X signal 324b X signal 326a Y signal 326b Y signal 328a Feedforward control signal or feedback control signal, control signal, feedback control signal, signal 328b Feedforward control signal or feedback control signal, control signal, feedback control signal, signal 330 Control signal, synchronous or trigger signal, trigger signal, trigger or synchronous signal, signal 330' Control signal, synchronous or trigger signal, trigger or synchronous signal, signal 332 load 334 Synchronized Bias Detector 336 links 338 links 340 pulse-synchronous output ports 342 Digital communication ports 344 RF output ports 348 RF input ports 350 digital communication ports 352 pulse synchronous input ports 356 pulse synchronization signal 357 Digital Communication Link 358RF control signal 410 RF signal 412 pulse signal 510 Plasma Generation System 512 Plasma Chamber 514 Plasma 516 Conductor 526 Bias electrode 526b Main bias electrode 526b' Auxiliary bias electrode 530 Plasma Sheath 532 Ion Orbitals 540b Main bias RF generator 540b' Auxiliary bias RF generator 542b Main bias RF power supply 542b' Auxiliary bias RF power supply 544b Main bias IEDF sensor, IEDF sensor 544b' Auxiliary bias IEDF sensor, IEDF sensor 610 RF Power Generation System 620b RF generator controller, main RF generator controller 620b' RF generator controller, auxiliary RF generator controller 645b Proportional coefficient P 650b Adder 650b' Adder 652b Receiving combiner, combiner 656b Receiving combiner, combiner 658b Integral coefficient I 666b Integrator 668b Clamp 670b Integrator minimum term 672b Integrator maximum term 710 RF Power Generation System 712b RF generator, main RF generator 712b' RF generator, auxiliary RF generator 714b Main RF amplifier or RF power supply, RF power supply, main RF power supply 714b' Auxiliary RF amplifier or RF power supply, auxiliary RF power supply 716b Main IEDF Sensor 716b' Auxiliary bias IEDF sensor 720b Main Controller, Main Bias Controller 720b' Auxiliary controller, auxiliary bias controller 726b Main bias electrode 726b' Auxiliary bias electrode 730 Communication Link 732 Plasma Chamber 810 Plasma Generation System 812b Main RF Generator 812b' Auxiliary RF Generator 816b-1 Main VI probe, VI probe 816b-1' VI probe 816b-2 Plasma sensor, main plasma sensor 816b-2' Plasma Sensor 818b Main Aligned Network 820 Common Controller, Controller 826b Main bias electrode 826b' Auxiliary bias electrode 910 Power Generator System, Power Generation System 912a RF Source Generator 912b RF bias generator 912b' RF bias generator 916b-2 Plasma Sensor 916b-2' Plasma sensor, auxiliary plasma sensor 918a harmonized network 920 Controller 924 Antenna / Source Electrode 1010 Control Module 1012b Main power generation module section 1012b' Auxiliary power generation module section 1014b Power Amplifier Module 1014b' Power Amplifier Module 1016b Sensor Module 1016b' Sensor Module 1020b Control Module 1020b' Control Module 1070 Communication Link 1110 Control System

Claims

1. A first RF power supply configured to output a first RF output signal to a first electrode of a load, A first sensor for detecting a first parameter of the first RF output signal and determining a first characteristic of the plasma in the load, A second RF power supply configured to output a second RF output signal to the second electrode of the load, A second sensor for detecting a second parameter of the second RF output signal and determining a second characteristic of the plasma in the load, An RF power controller configured to receive the first characteristic and the second characteristic and generate a first control signal and a second control signal. Equipped with, An RF generator in which the first control signal adjusts the first RF output signal, and the second control signal adjusts the second RF output signal.

2. The first sensor is a plasma sensor, and the first characteristic is at least one of the following related to the first electrode: plasma density, electron temperature, ion potential, sheath thickness, sheath capacitance, or ion energy distribution function (IEDF). The RF generator according to claim 1, wherein the second sensor is a plasma sensor, and the second characteristic is at least one of plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF) related to the second electrode.

3. The RF generator according to claim 1, wherein the first characteristic is an IEDF related to the first electrode.

4. The RF generator according to claim 1, wherein the second characteristic is an IEDF related to the second electrode.

5. The RF generator according to claim 1, wherein the first characteristic is an IEDF related to the first electrode, and the second characteristic is an IEDF related to the second electrode.

6. The RF generator according to claim 1, wherein the RF power controller comprises a first power controller and a second power controller, the first power controller is configured to receive the first characteristics and generate a first control signal for changing the first RF output signal, and the second power controller is configured to receive the second characteristics and generate a second control signal for changing the second RF output signal.

7. The RF generator according to claim 6, further comprising a communication link between the first power controller and the second power controller, wherein the first power controller is configured to transmit settings defining the first RF output signal, and the second power controller is configured to transmit settings defining the second RF output signal.

8. The RF generator according to claim 1, wherein the first RF power supply is a main bias power supply, the first electrode is a main bias electrode, the second RF power supply is an auxiliary bias power supply, the second electrode is an auxiliary bias electrode, and the main bias electrode and the auxiliary bias electrode form a composite bias electrode.

9. The RF generator according to claim 1, wherein the first control signal controls at least one of the rail voltage, frequency, phase, or pulsing of the first RF output signal, and the second control signal controls at least one of the rail voltage, frequency, phase, or pulsing of the second RF output signal.

10. The RF generator according to claim 1, further comprising a third RF power supply configured to output a third RF output signal to a third electrode, wherein the RF power controller is further configured to generate a third control signal for changing the third RF output signal.

11. The RF generator according to claim 10, wherein the RF power controller is configured to generate the third control signal, and the third control signal changes according to at least one of the first or second characteristics.

12. The RF generator according to claim 11, wherein the third RF power supply is a source power supply and the third electrode is a source electrode.

13. A main bias RF generator, A main bias power supply configured to output a main bias RF output signal to the main bias electrode of the load, A main bias plasma sensor configured to detect the main bias parameter of the main bias RF output signal and determine the main bias characteristics of the plasma in the load, Includes a main bias RF generator, An auxiliary bias RF generator, An auxiliary bias RF power supply configured to output an auxiliary bias RF output signal to the auxiliary bias electrode of the load, An auxiliary bias plasma sensor configured to detect the auxiliary bias parameter of the auxiliary bias RF output signal and determine the auxiliary bias characteristics of the plasma in the load, This includes an auxiliary bias RF generator, An RF power controller configured to receive the main bias characteristics and the auxiliary bias characteristics, and to generate a main bias control signal for changing the main bias RF output signal and an auxiliary bias control signal for changing the auxiliary bias RF output signal. An RF system equipped with...

14. The RF system according to claim 13, wherein the RF power controller is one of a proportional-integral controller, a proportional-integral-derivative controller, or a linear secondary regulator controller.

15. The main bias plasma sensor includes one of a VI probe or a directional coupler for detecting the main bias parameter. The RF system according to claim 13, wherein the auxiliary bias plasma sensor includes one of a VI probe or a directional coupler for detecting the auxiliary bias parameter.

16. The main bias characteristic is one of the following related to the main bias electrode: plasma density, electron temperature, ion potential, sheath thickness, sheath capacitance, or ion energy distribution function (IEDF). The RF system according to claim 13, wherein the auxiliary bias characteristic is one of the plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF) related to the auxiliary bias electrode.

17. The RF system according to claim 13, wherein the RF power controller comprises a main bias power controller and an auxiliary bias power controller, the main bias power controller is configured to receive the main bias characteristics and generate the main bias control signal according to the main bias characteristics, and the auxiliary bias power controller is configured to receive the auxiliary bias characteristics and generate the auxiliary bias control signal according to the auxiliary bias characteristics.

18. The RF system according to claim 13, wherein the main bias electrode and the auxiliary bias electrode form a composite bias electrode.

19. The RF system according to claim 13, wherein the main bias control signal controls at least one of the rail voltage, frequency, phase, or pulsing of the main bias RF output signal, and the auxiliary bias control signal controls at least one of the rail voltage, frequency, phase, or pulsing of the auxiliary bias RF output signal.

20. The main bias characteristics include a plurality of the following related to the main bias electrode: plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF). The RF system according to claim 13, wherein the auxiliary bias characteristics include a plurality of plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF) related to the auxiliary bias electrode.

21. The RF system according to claim 13, further comprising a source RF power supply configured to output a source RF output signal to a source electrode, wherein the RF power controller is further configured to generate a source control signal for changing the source RF output signal.

22. The main bias characteristics include a plurality of the following related to the main bias electrode: plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF). The RF system according to claim 21, wherein the auxiliary bias characteristics include a plurality of plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF) related to the auxiliary bias electrode.

23. The RF system according to claim 21, wherein the RF power controller is configured to generate the source control signal, and the source control signal varies according to at least one of the main bias characteristics or the auxiliary bias characteristics.

24. The RF system according to claim 13, wherein the main bias characteristic is an IEDF related to the main bias electrode.

25. The RF system according to claim 13, wherein the auxiliary bias characteristic is an IEDF related to the auxiliary bias electrode.

26. The RF system according to claim 13, wherein the primary bias characteristic is an IEDF related to the primary bias electrode, and the auxiliary bias characteristic is an IEDF related to the auxiliary bias electrode.

27. A non-temporary computer-readable medium for storing processor-executable instructions, wherein the processor-executable instructions are To generate a main bias RF output signal to the main bias electrode of the load, The main bias parameter of the main bias RF output signal is detected, and the main bias characteristics of the plasma in the load are determined. To generate an auxiliary bias RF output signal to the auxiliary bias electrode of the load, The auxiliary bias parameter of the auxiliary bias RF output signal is detected, and the auxiliary bias characteristics of the plasma in the load are determined. The main bias characteristics and the auxiliary bias characteristics are received, a main bias control signal is generated to change the main bias RF output signal according to the main bias characteristics, and an auxiliary bias control signal is generated to change the auxiliary bias RF output signal according to the auxiliary bias characteristics. Includes, A non-temporary computer-readable medium for storing processor-executable instructions, wherein the main bias control signal adjusts the main bias RF output signal, and the auxiliary bias control signal adjusts the auxiliary bias RF output signal.

28. The main bias characteristic is at least one of the following related to the main bias electrode: plasma density, electron temperature, ion potential, sheath thickness, sheath capacitance, or ion energy distribution function (IEDF). A non-temporary computer-readable medium for storing processor-executable instructions according to claim 27, wherein the auxiliary bias characteristic is at least one of plasma density, electron temperature, ion potential, sheath thickness, sheath capacitance, or ion energy distribution function (IEDF) related to the auxiliary bias electrode.

29. A non-temporary computer-readable medium for storing processor-executable instructions according to claim 27, wherein the main bias electrode and the auxiliary bias electrode form a composite bias electrode.

30. A non-temporary computer-readable medium for storing processor-executable instructions according to claim 27, wherein the main bias control signal controls at least one of the rail voltage, frequency, phase, or pulsing of the main bias RF output signal, and the auxiliary bias control signal controls at least one of the rail voltage, frequency, phase, or pulsing of the auxiliary bias RF output signal.

31. The main bias characteristics include at least two of the following related to the main bias electrode: plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF). A non-temporary computer-readable medium for storing processor-executable instructions according to claim 27, wherein the auxiliary bias characteristics include at least two of the plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF) related to the auxiliary bias electrode.

32. A non-temporary computer-readable medium for storing processor-executable instructions according to claim 27, further comprising generating a source RF output signal to a source electrode and generating a source control signal to change the source RF output signal.

33. The main bias characteristics include a plurality of the following related to the main bias electrode: plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF). A non-temporary computer-readable medium for storing processor-executable instructions according to claim 32, wherein the auxiliary bias characteristics include a plurality of plasma density, electron temperature, ion potential, or ion energy distribution function (IEDF) related to the auxiliary bias electrode.

34. A non-temporary computer-readable medium for storing a processor-executable instruction according to claim 32, further comprising the instruction changing the source control signal according to at least one of the primary bias characteristics or the auxiliary bias characteristics.

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