Degaussing coil for improving current ratio linearity in plasma processing systems - Patents.com

Abstract

The RF generator has an RF power source configured to generate an output signal. The power divider is configured to receive the output signal and generate a plurality of split signals. The degaussing circuit is configured to receive the plurality of split signals. The degaussing circuit is configured to include a plurality of inductances corresponding to the plurality of split signals. The plurality of inductances are configured to reduce an effect of mutual impedance of the ICP chamber in series with the plurality of inductances such that a ratio between pairs of the plurality of split signals changes substantially linearly as one of the pairs of the plurality of split signals changes.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Patent Application No. 17 / 566,274, filed December 30, 2021. The entire disclosure of the above application is incorporated herein by reference.

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

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

[0004] The background discussion provided herein is for purposes of generally presenting the contents of the present disclosure. The work of the currently named inventors to the extent described in this background section, as well as aspects of the present specification that may not qualify as prior art at the time of filing, are not admitted expressly or impliedly as prior art to the present disclosure. [Prior art documents] [Patent documents]

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

[0006] In some aspects, techniques described herein relate to an RF generator including an RF power source configured to generate an output signal, a power divider configured to receive the output signal and generate a plurality of split signals, and a degaussing circuit configured to receive the plurality of split signals, the degaussing circuit configured to include a plurality of inductances corresponding to the plurality of split signals, the plurality of inductances configured to reduce an effect of mutual impedance of an ICP chamber in series with the plurality of inductances such that a ratio between pairs of the plurality of split signals changes substantially linearly as one of the pairs of the plurality of split signals changes.

[0007] In some embodiments, the techniques described herein relate to an RF generator in which the multiple inductances can be one of a coil having an inductance, or an inductance induced by conducting a current through an electrical conductor.

[0008] In some embodiments, the techniques described herein relate to an RF generator in which the degaussing circuit includes multiple outputs, the multiple outputs corresponding to respective ones of multiple antennas of the ICP chamber, and a combined mutual inductance of the multiple inductances corresponding to the multiple split signals is substantially equal to the combined mutual inductance of the multiple antennas of the ICP chamber.

[0009] In some aspects, techniques described herein relate to an RF generator further including a matching network configured to receive an output signal from an RF power source and provide the output signal to a power divider, where the matching network is configured to provide impedance matching with the RF power source.

[0010] In some aspects, the techniques described herein relate to an RF generator in which a degaussing circuit is disposed between a power splitter and a load.

[0011] In some aspects, the techniques described herein relate to an RF generator in which a load is disposed between the degaussing circuit and the power splitter.

[0012] In some embodiments, the techniques described herein relate to an RF generator in which the multiple inductances are two, the degaussing circuit has an inner inductance and an outer inductance, the inner inductance corresponding to the inner coil of the ICP chamber and the outer inductance corresponding to the outer coil of the ICP chamber.

[0013] In some embodiments, the techniques described herein relate to an RF generator where the plurality of inductances is three, and the degaussing circuit has an inner inductance, a middle inductance, and an outer inductance, where the inner inductance corresponds to the inner coil of the ICP chamber, the middle inductance corresponds to the middle coil of the ICP chamber, and the outer inductance corresponds to the outer coil of the ICP chamber.

[0014] In some embodiments, techniques described herein relate to an RF generator including an RF power source configured to generate an output signal, a power divider configured to receive the output signal and generate a plurality of split signals, and a degaussing circuit configured to receive the plurality of split signals, the degaussing circuit configured to include a plurality of coils corresponding to the plurality of split signals, the plurality of coils configured to reduce an effect of mutual impedance of an ICP chamber in series with a plurality of inductances such that a ratio between pairs of the plurality of split signals changes substantially linearly as one of the pairs of the plurality of split signals changes.

[0015] In some embodiments, the techniques described herein relate to an RF generator in which the degaussing circuit includes multiple outputs, the multiple outputs corresponding to respective ones of multiple antennas of the ICP chamber, and a combined mutual inductance of multiple coils corresponding to the multiple split signals is substantially equal to a combined mutual inductance of the multiple antennas of the ICP chamber.

[0016] In some aspects, techniques described herein relate to an RF generator further including a matching network configured to receive an output signal from an RF power source and provide the output signal to a power divider, where the matching network is configured to provide impedance matching with the RF power source.

[0017] In some aspects, the techniques described herein relate to an RF generator in which a degaussing circuit is disposed between a power splitter and a load.

[0018] In some aspects, the techniques described herein relate to an RF generator in which a load is disposed between the degaussing circuit and the power splitter.

[0019] In some embodiments, the techniques described herein relate to an RF generator in which the multiple coils are two, the degaussing circuit has an inner coil and an outer coil, the inner coil corresponding to the inner coil of the ICP chamber and the outer coil corresponding to the outer coil of the ICP chamber.

[0020] In some embodiments, the techniques described herein relate to an RF generator where the plurality of coils is three, and the degaussing circuit has an inner coil, an intermediate coil, and an outer coil, where the inner coil corresponds to the inner coil of the ICP chamber, the intermediate coil corresponds to the intermediate coil of the ICP chamber, and the outer coil corresponds to the outer coil of the ICP chamber.

[0021] In some embodiments, techniques described herein relate to a degaussing circuit for an ICP system including a first inductance, the first inductance configured to receive a first RF signal and the first inductance electrically connected to a first antenna of the ICP chamber, and a second inductance, the second inductance configured to receive a second RF signal and the second inductance electrically connected to a second antenna of the ICP chamber, wherein the first inductance and the second inductance are configured to reduce an effect of mutual impedance of the ICP chamber in series with the multiple inductances such that a ratio between the first RF signal and the second RF signal changes substantially linearly as one of the first RF signal or the second RF signal changes.

[0022] In some embodiments, the techniques described herein relate to a degaussing circuit for an ICP system, where the first inductance can be one of a first coil having an inductance, or a first inductive inductance by conducting a current through a first electrical conductor, and the second inductance can be one of a second coil having an inductance, or a second inductive inductance by conducting a current through a second electrical conductor.

[0023] In some embodiments, the techniques described herein relate to a degaussing circuit for an ICP system, in which a combined mutual inductance of a first inductance and a second inductance is substantially equal to a combined mutual inductance of a first antenna and a second antenna of the ICP system.

[0024] In some aspects, the techniques described herein relate to a degaussing circuit for an ICP system, where the degaussing circuit is disposed between a power splitter and a load.

[0025] In some embodiments, the techniques described herein relate to a degaussing circuit for an ICP system in which a load is disposed between the degaussing circuit and a power splitter.

[0026] Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims, and the drawings. The detailed description and specific examples are for purposes of illustration only and are not intended to limit the scope of the present disclosure.

[0027] The present disclosure will become more fully understood from the detailed description and the accompanying drawings. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 illustrates a representation of an inductively coupled plasma system. [Diagram 2] FIG. 1 is a schematic diagram of a power delivery system having multiple power sources arranged in accordance with the present disclosure. [Diagram 3] FIG. 1 illustrates a portion of an RF power delivery system using a degaussing coil in accordance with the present disclosure. [Figure 4] FIG. 1 is a circuit diagram of an RF power delivery system using a degaussing coil in accordance with the present disclosure. [Diagram 5] FIG. 13 illustrates waveforms of an RF power delivery system operating with and without a degaussing coil. [Figure 6] 1A-1C show diagrams of a degaussing circuit having a degaussing coil positioned at different positions relative to a load in accordance with the present disclosure. [Figure 7] FIG. 2 illustrates a degaussing circuit having three or more degaussing coils in accordance with the present disclosure. [Figure 8] FIG. 1 illustrates busbars arranged to provide a degaussing coil configuration according to the present disclosure. [Figure 9] FIG. 1 illustrates busbars arranged to provide a degaussing coil configuration according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] In the drawings, reference numbers may be reused to identify similar and / or identical elements.

[0030] A power system may include a DC or RF generator or generator, a matching network, and a load (such as a process chamber, plasma chamber, or reactor with fixed or variable impedance). The generator generates a DC or RF power signal, which is received by a matching network or impedance optimization controller or circuit. The matching network or impedance optimization controller or circuit matches the input impedance of the matching network to the characteristic impedance of the transmission line between the generator and the matching network. The impedance matching helps to maximize the amount of power transferred to the matching network ("forward power") and minimize the amount of power reflected from the matching network to the generator ("reverse power" or "reflected power"). If the input impedance of the matching network matches the characteristic impedance of the transmission line and the generator, the forward power can be maximized and the reverse power can be minimized.

[0031] In the field of power supplies or power delivery, there are typically two approaches to applying a power signal to a load. The first, more traditional approach is to apply a continuous power signal to the load. In continuous or continuous wave mode, the continuous power signal is typically a constant DC power signal or a sinusoidal RF power signal that is continuously output by the power supply to the load. In the continuous mode approach, the power signal assumes a constant DC or sinusoidal output, and the amplitude and / or frequency (of the RF power signal) of the power signal can be varied to vary the output power applied to the load.

[0032] A second approach to applying a power signal to a load involves pulsing the RF signal rather than applying a continuous RF signal to the load. In a pulsed mode of operation, the RF signal is modulated by a modulation signal to define an envelope for the modulated power signal. The RF signal can be, for example, a sinusoidal RF signal or other time-varying signal. The power delivered to the load is typically changed by varying the modulation signal.

[0033] In a typical power supply configuration, the output power applied to a load is determined by using sensors that measure the forward and reflected power, or the voltage and current of the RF signal applied to the load. Either set of these signals is analyzed in a control loop. The analysis typically determines a power value that is used to adjust the output of the power supply to vary the power applied to the load. In a power delivery system where the load is a process chamber or other nonlinear or time-varying load, the power applied is in part a function of the impedance of the load, so changing the impedance of the load causes a corresponding change in the power applied to the load.

[0034] In systems where the manufacture of various devices relies on the introduction of power to a load to control the manufacturing process, the power is typically delivered in one of two configurations. In the first configuration, the power is capacitively coupled to the load. Such systems are referred to as Capacitively Coupled Plasma (CCP) systems. In the second configuration, the power is inductively coupled to the load. Such systems are typically referred to as Inductively Coupled Plasma (ICP) systems. Power coupling to the plasma can also be achieved by wave coupling at microwave frequencies. Such approaches typically use Electron Cyclotron Resonance (ECR) or microwave sources. Helicon sources are another form of wave-coupled source, typically operating at RF frequencies similar to those of conventional ICP and CCP systems. The power delivery system may include at least one bias power and / or source power applied to one or more electrodes of the load. The source power typically generates the plasma and controls the plasma density, and the bias power modulates the ions in the formation of the sheath. The bias and source may share the same electrode or may use separate electrodes, depending on various design considerations.

[0035] When the power delivery system drives a time-varying or nonlinear load, such as a process or plasma chamber, the power absorbed by the bulk plasma or plasma sheath results in an ion density with a range of ion energies. One characteristic measure of ion energy is the ion energy distribution function (IEDF). The ion energy distribution function (IEDF) can be controlled using bias power. One method of controlling the IEDF for a system in which multiple RF power signals are applied to a load occurs by varying the multiple RF signals related by amplitude, frequency, and phase. The relative amplitude, frequency, and phase of the multiple RF power signals may also be related by a Fourier series and associated coefficients. The frequency between the multiple RF power signals may be locked, and the relative phase between the multiple RF signals may also be locked. Examples of such systems can be found with reference to U.S. Pat. Nos. 7,602,127, 8,110,991, and 8,395,322, all of which are assigned to the assignee of the present application and incorporated herein by reference.

[0036] Time-varying or nonlinear loads may be present in a variety of applications. In one application, a plasma processing system may also include components for generating and controlling the plasma. One such component is a nonlinear load implemented as a process chamber, such as a plasma chamber or reactor. As an example, a typical plasma chamber or reactor utilized in a plasma processing system, such as for thin film manufacturing, may utilize a dual power supply system. One generator (source) controls the generation of the plasma and one generator (bias) controls the ion energy. Examples of dual power supply systems include those described in the above-referenced U.S. Pat. Nos. 7,602,127, 8,110,991, and 8,395,322. The dual power supply systems described in the above-referenced patents require a closed-loop control system to adapt the power supply operation for the purpose of controlling the ion density and its corresponding ion energy distribution function (IEDF).

[0037] There are several approaches to control a process chamber such that it can be used to generate a plasma. For example, in an RF power delivery system, the phase and frequency of multiple driving RF signals operating at the same or nearly the same frequency can be used to control plasma generation. For RF-driven plasma sources, the periodic waveforms that affect the plasma sheath dynamics and the corresponding energy are generally known and controlled by the frequency and associated phase interactions of the periodic waveforms. Another approach in RF power delivery systems involves dual frequency control. That is, two RF frequency sources operating at different frequencies are used to power the plasma chamber to provide substantially independent control of ion and electron density.

[0038] Other approaches utilize broadband RF power sources to drive the plasma chamber. Broadband approaches present certain 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 interaction. 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 the ions to control the IEDF to provide etch rate control. By using control of the source and bias electrodes, the etch rate is controlled via the density and energy of the ions.

[0039] As the manufacturing of integrated circuits and devices continues to evolve, so do the power requirements for controlling the manufacturing process. For example, in the manufacturing of memory devices, the requirements for bias power continue to increase. Increased power produces more energetic ions for faster surface interaction, thereby increasing the etching rate and directionality of the ions. In RF systems, increased bias currents are sometimes accompanied by a requirement for lower bias frequencies, along with an increase in the number of bias power sources coupled to the plasma sheath created in the plasma chamber. The power increase at the lower bias frequency, and the increased number of bias power sources, results in intermodulation distortion (IMD) emissions from sheath modulation. The IMD emissions can significantly reduce the power delivered by the source where plasma generation occurs. U.S. Patent No. 10,821,542, issued November 3, 2020 and entitled Pulse Synchronization by Monitoring Power in Another Frequency Band, which is assigned to the assignee of the present application and incorporated herein by reference, describes a method of pulse synchronization by monitoring power in another frequency band. In the referenced U.S. patent application, the pulsing of the second RF generator is controlled in accordance with detecting the pulsing of the first RF generator at the second RF generator, thereby synchronizing the pulsing between the two RF generators.

[0040] In plasma processing systems, plasma uniformity control is one important consideration to meet certain production yield requirements. Conductor etcher (or poly etcher) is a type of ICP that uses selective dry etching on wafer patterns. Conventional ICP etchers use multiple antenna coils separated from the vacuum space by windows, which are dielectric materials that allow RF power penetration into the plasma chamber or reactor to ignite and sustain the plasma. The antenna coil is an electrode structure that directs external electrical energy into the plasma generation space. Antenna coils can take on various shapes and definitions depending on their structure, but typical ICP systems have evolved from single antenna to dual or multiple antenna coil shapes. Such shapes may be used, for example, in 300 mm (about 12 inch) wafer processing.

[0041] A typical electrical energy supply and delivery method for structures using two or more antenna coils is powered from one electrical energy supply or power source, such as an RF generator operating in the frequency range from kilohertz (kHz) to megahertz (MHz) in the semiconductor equipment industry, although other frequency ranges are also considered. The frequency signal is typically applied to a plasma chamber or reactor through a matching network to match the load impedance and a power splitter to distribute the power to the two or more antenna coils. The magnetic field generated by the current flowing through each antenna coil penetrates the plasma discharge space, and the induced electric field ionizes the space particles, resulting in the generation of plasma. The resulting plasma forms a localized discharge space depending on the strength of the magnetic field and the subsequent strength of the induced electric field, which is typically concentrated within a range of a few to tens of Debye lengths. The plasma-induced radicals and ionized particles can diffuse throughout the discharge space.

[0042] The power divider distributes the appropriate power to each antenna. The power divider is usually a combination of variable capacitors and inductors in a series-parallel configuration. These electric circuits are also called current divider circuits because they control the current by adjusting the impedance of each antenna by changing the additional variable capacitors and inductors inserted in the power divider circuit. Thus, by adjusting the current divider, the ratio of the currents flowing to each antenna is controlled, and the distribution of the plasma generated is controlled. In various configurations, it is possible to divide the voltage instead of the current.

[0043] In the conventional current splitter circuit, the plasma distribution cannot be linearly controlled by the ratio of the currents flowing to each antenna. Since the plasma is a dielectric for the bulk plasma and the conductive medium for the plasma sheath is in contact with the boundary, the antennas are not separated by independent loads, so each antenna is coupled to each other and through the generated plasma. In addition, the plasma coupling also directly affects the driving electric circuit, including the current splitter. Therefore, the current ratio is not expressed linearly. In other words, if additional current needs to be applied to any of the antennas, the current ratio is nonlinear. As a result, controlling the current ratio by changing the actuator in the region with a steep slope is less accurate, resulting in large plasma dispersion between chambers. Even if the current ratio is controlled and set through the current splitter, a small variation in the plasma will show differences between the etching equipment, which will lead to differences in the quality of the semiconductor devices manufactured, ultimately affecting the production yield.

[0044] Conventional approaches to matching networks for multi-coil ICP chambers do not address the nonlinear interactions between the RF currents. A first conventional approach uses a capacitor connected in series with the two branch antenna coils to control the current to each antenna, and a second conventional approach uses a capacitor configured in parallel with the two branch antenna coils to control the current to each antenna.

[0045] The first approach uses a variable capacitor in a branch circuit in series with the chamber impedance to adjust the current ratio in an ICP system. A pair of inductances reduces the magnitude of the current. However, RF coil coupling or coupling through the plasma is not considered. Furthermore, this first approach does not address the nonlinear current ratio of the RF currents. A second conventional approach to current ratio control uses one or more variable capacitors connected in parallel with the RF coil. This second approach does not address the nonlinear characteristics of the current ratio.

[0046] In the conventional ICP systems described above, due to the mutual inductance between the two RF coils and / or the underlying characteristics of the ICP chamber or reactor, the currents in the RF coils interact. The interaction between the currents results in a nonlinear current ratio. The nonlinear current ratio between the RF currents complicates the plasma density control implemented by the control loop of the current ratio controller.

[0047] Plasma processing systems that do not account for the nonlinear interactions of RF currents inhibit consistent and smooth current ratio control, increasing the response time in the current ratio control loop and increasing the overall impedance matching time of the system. It is desirable to reduce impedance matching time in plasma processing systems (e.g., to less than 500 microseconds using electronic variable capacitors). The improved response time of the current ratio control loop facilitates reducing the impedance matching time of ICP systems.

[0048] This disclosure describes the use of a degaussing coil to increase the linearity of the current ratio between RF coils, which helps to improve the controllability of the plasma density or plasma uniformity in a plasma processing system.

[0049] FIG. 1 shows a representation of an inductively coupled plasma (ICP) system 110. The ICP system 110 includes a nonlinear load, such as a reactor, plasma reactor, or plasma chamber 112, referred to interchangeably herein, to generate a plasma 114. Power in the form of voltage or current is applied to the plasma chamber 112 through a pair of coils, which in various embodiments include a coil assembly including an inner coil 116 and an outer coil 118. Power is applied to the inner coil 116 through an RF generator or power supply 120, and power is applied to the outer coil 118 through an RF generator or power supply 122. The coils 116 and 118 are attached to a dielectric window 124 that helps couple the power to the plasma chamber 112. A substrate 126 is disposed within the plasma chamber 112 and typically forms a workpiece that is the subject of the plasma operation. An RF generator, power supply, or power supply 128 (these terms may be used interchangeably herein) applies power to the plasma chamber 112 through the substrate 126. In various configurations, the power supplies 120, 122 provide a source voltage or current to ignite or generate the plasma 114 or to control the plasma density. Also, in various configurations, the power supply 128 provides a bias voltage or current to modulate the ions to control the ion energy or ion density of the plasma 114. In various embodiments, the power supplies 120, 122 are locked to operate at the same frequency, voltage, and current, with a fixed or varying relative phase. In various other embodiments, the power supplies 120, 122 may operate at different frequencies, voltages, and currents, and relative phases.

[0050] 2 illustrates an RF generator or power supply system 210. The power supply system 210 includes a pair of radio frequency (RF) generators or power supplies 212a, 212b, matching networks 218a, 218b, and a load 232, such as a nonlinear load, which may be a plasma chamber, a process chamber, or the like. In various embodiments, the RF generator 212a is referred to as a source RF generator or power supply, and the matching network 218a is referred to as a source matching network. Also, in various embodiments, the RF generator 212b is referred to as a bias RF generator or power supply, and the matching network 218b is referred to as a bias matching network. It will be understood that components may be referred to individually or collectively using reference numbers without subscripts or primes.

[0051] In various embodiments, the source RF generator 212a receives a control signal 230 from the matching network 218b, generator 212b, or receives a control signal 230' from the bias RF generator 212b. As described in more detail, the control signal 230 or 230' represents an input signal to the source RF generator 212a indicative of one or more operating characteristics or parameters of the bias RF generator 212b. In various embodiments, the synchronization bias detector 234 senses the RF signal output from the matching network 218b to the load 232 and outputs a synchronization or trigger signal 230 to the source RF generator 212a. In various embodiments, the synchronization or trigger signal 230', rather than the trigger signal 230, may be output from the bias RF generator 212b to the source RF generator 212a. The difference between the trigger or synchronization signals 230, 230' may result from the effect of the matching network 218b, which may adjust the phase between the input signal to the matching network and the output signal from the matching network. The signals 230, 230', in various embodiments, contain information regarding the operation of the bias RF generator 212b that enables predictive responsiveness to address periodic variations in the impedance of the plasma chamber or load 232 caused by the bias RF generator 212b. In the absence of the control signals 230 or 230', the RF generators 212a, 212b operate autonomously.

[0052] The RF generators 212a, 212b include respective RF power sources or amplifiers 214a, 214b, RF sensors 216a, 216b, and processors, controllers, or control modules 220a, 220b. The RF power sources 214a, 214b generate respective RF power signals 222a, 222b that are output to the respective sensors 216a, 216b. The sensors 216a, 216b receive the output of the RF power sources 214a, 214b and generate respective RF power signals f1, f2. The sensors 216a, 216b also output signals that vary according to various parameters sensed from the load 232. Although the sensors 216a, 216b are shown within the respective RF generators 212a, 212b, the RF sensors 216a, 216b can be located external to the RF generators 212a, 212b. Such external sensing may occur at the output of the RF generator, at the input of an impedance matching device disposed between the RF generator and the load, or between the output of the impedance matching device (including within the impedance matching device) and the load.

[0053] The sensors 216a, 216b detect various operating parameters and output signals X and Y. The sensors 216a, 216b may include voltage sensors, current sensors, and / or directional coupler sensors. The sensors 216a, 216b detect (i) the voltage V and current I, and / or (ii) the forward power P output from the respective power amplifiers 214a, 214b and / or RF generators 212a, 212b. FWD , and the reverse or reflected power P received from the load 232 connected to the respective matching network 218a, 218b or the respective sensor 216a, 216b. REV It can detect voltage V, current I, forward power P FWD , and reverse power P REVmay be scaled, filtered, or scaled and filtered versions of the actual voltage, current, forward power, and reverse power associated with each power source 214a, 214b. The sensors 216a, 216b may be analog sensors, digital sensors, or a combination thereof. In a digital implementation, the sensors 216a, 216b may include an analog-to-digital (A / D) converter and a signal sampling component with a corresponding sampling rate. The signals X and Y represent the voltage V and current I, or the forward (or source) power P FWD and the reverse (or reflected) power P REV It can represent either:

[0054] The sensors 216a, 216b generate sensor signals X, Y that are received by respective controllers or power control modules 220a, 220b. The power control modules 220a, 220b process the respective X, Y signals 224a, 226a and 224b, 226b and generate one or more feedforward or feedback control signals 228a, 228b to the respective power supplies 214a, 214b. The power supplies 214a, 214b adjust the RF power signals 222a, 222b based on the received one or more feedback or feedforward control signals. In various embodiments, the power control modules 220a, 220b may control the matching networks 218a, 218b via respective control signals 221a, 221b. The power control modules 220a, 220b may include at least a proportional-integral-derivative (PID) controller or a subset thereof, and / or a direct digital synthesis (DDS) component, and / or any of the various components described below in connection with the modules.

[0055] In various embodiments, the power control modules 220a, 220b may be a PID controller or a subset thereof and may include functions, processes, processors, or sub-modules. The control signals 228a, 228b may be drive signals and may include DC offset or rail voltages, voltage or current magnitude, frequency, and phase components. In various embodiments, the feedback control signals 228a, 228b may be used as inputs to one or more control loops. In various embodiments, the multiple control loops may include proportional-integral-derivative (PID) control loops for RF drive and rail voltages. In various embodiments, the control signals 228a, 228b may be used in a multiple-input multiple-output (MIMO) control scheme. An example of a MIMO control scheme may be found with reference to U.S. Pat. No. 10,546,724, issued Jan. 28, 2020, entitled Pulsed Bidirectional Radio Frequency Source / Load, assigned to the assignee of the present application, and incorporated herein by reference. In other embodiments, the signals 228a, 228b may provide feed-forward control as described in US Pat. No. 10,049,857, which is assigned to the assignee of the present application and is incorporated herein by reference.

[0056] In various embodiments, the power supply system 210 can include a controller 220'. The controller 220' may be located external to either or both of the RF generators 212a, 212b and may be referred to as an external or common controller 220'. In various embodiments, the controller 220' may implement one or more functions, processes, or algorithms described herein with respect to one or both of the controllers 220a, 220b. Thus, the controller 220' communicates with each of the RF generators 212a, 212b via a pair of respective links 236, 238 that enable the exchange of data and control signals as needed between the controller 220' and the RF generators 212a, 212b. For various embodiments, the controllers 220a, 220b, 220' can provide analysis and control in a distributed and cooperative manner with the RF generators 212a, 212b. In various other embodiments, the controller 220' can provide control of the RF generators 212a, 212b, eliminating the need for each local controller 220a, 220b.

[0057] In various embodiments, the RF power source 214a, the sensor 216a, the controller 220a, and the matching network 218a may be referred to as the source RF power source 214a, the source sensor 216a, the source controller 220a, and the source matching network 218a. Similarly, in various embodiments, the RF power source 214b, the sensor 216b, the controller 220b, and the matching network 218b may be referred to as the bias RF power source 214b, the bias sensor 216b, the bias controller 220b, and the bias matching network 218b. In various embodiments, as explained above, the source term refers to the RF generator that generates the plasma, and the bias term refers to the RF generator that adjusts the plasma ion energy distribution function (IEDF). In various embodiments, the source RF power source and the bias RF power source operate at different frequencies. In various embodiments, the source RF power source operates at a higher frequency than the bias RF power source. In various other embodiments, the source RF power source and the bias RF power source operate at the same frequency or substantially the same frequency.

[0058] According to various embodiments, the source RF generator 212a and the bias RF generator 212b include multiple ports for communicating with the outside world. The source RF generator 212a includes a pulse synchronization output port 240, a digital communication port 242, and an RF output port 244. The bias RF generator 212b includes an RF input port 248, a digital communication port 250, and a pulse synchronization input port 252. The pulse synchronization output port 240 outputs a pulse synchronization signal 256 to the pulse synchronization input port 252 of the bias RF generator 212b. The digital communication port 242 of the source RF generator 212a and the digital communication port 250 of the bias RF generator 212b communicate via a digital communication link 257. The RF output port 244 generates an RF control signal 258 that is input to the RF input port 248. In various embodiments, the RF control signal 258 is substantially the same as the RF control signal that controls the source RF generator 212a. In various other embodiments, the RF control signal 258 is the same as the RF control signal that controls the source RF generator 212a, but is phase shifted within the source RF generator 212a according to the requested phase shift produced by the bias RF generator 212b. Thus, in various embodiments, the source RF generator 212a and the bias RF generator 212b are driven by substantially identical RF control signals or by substantially identical RF control signals that are phase shifted by a predetermined amount.

[0059] In various configurations, one or both of the matching networks 218a, 218b may be configured as a combination matching network and current divider, as shown in the matching network / current divider 218a. The matching network / current divider 218a performs at least two functions. The first function is conventional impedance matching. The second function is to split the input RF power signal f1 into one or more outputs that are applied to the respective coils ICP coils, such as the coils 116, 118 of FIG. 1, of the load 232. Splitting the input RF output signal f1 into one or more outputs allows the power applied to the respective coils 116, 118 to be varied. In various configurations, the RF output power signal may be split between the coils 116, 118 of FIG. 1 using a ratio technique. The power is split to provide a desired ratio between the power applied to one of the coils 116, 118 and the power applied to the other of the coils 116, 118. In various configurations, and throughout this specification, the matching network and current divider of matching network / current divider 218a may be an integrated unit, may be separate units, or may be distributed across one or more components.

[0060] As shown in Figure 2, the pair of RF power signals output by the matching network / current divider 218a are input to a degaussing circuit 260. As described in more detail below, the degaussing circuit 260 includes an inductive component that receives the RF power signals output from the matching network / current divider 218a, which generates a mutual coupling. The mutual coupling is configured to substantially cancel the mutual coupling in the coils 116, 118, as shown in Figure 1. It will be appreciated that the configuration of the matching network / current divider 218a may be implemented in one or both of the matching networks 218a, 218b.

[0061] As will be described in detail in the following figures, the present disclosure discloses a degaussing coil in series with an ICP chamber to increase the linearity of the RF coil current ratio and the control of the plasma density or plasma uniformity in a plasma processing system. FIG. 3 shows a block diagram of a plasma system 310 including a degaussing circuit according to the present disclosure. An RF generator 312 generates an RF output that is applied to an impedance matching network / current divider 318. The impedance matching network / current divider 318 operates in a similar manner as described above with respect to FIG. 2. The impedance matching network / current divider 318 generates a pair of outputs or split signals to a degaussing circuit 360. The degaussing circuit 360 includes a degaussing coil for generating an induced magnetic field that opposes the magnetic fields induced in the inner and outer coils in an ICP configuration. The degaussing circuit 360 generates a pair of RF power signals, one of which is applied to one of a pair of terminals 362a, 362b of an inner coil 362 and the other of which is applied to one of a pair of terminals 364a, 364b of an outer coil 364. The impedance at the output of the RF generator 312 is an equivalent impedance Z eq and represents the impedance resulting from the equivalent impedances of the components including the impedance matching network / current divider 318, the degaussing circuit 360, and the plasma chamber or load 332.

[0062] The plasma chamber or load 332 is energized by an RF signal applied to each of the inner coil 362 and the outer coil 364. The electrode 334 may be grounded or powered via a second RF generator (not shown in FIG. 3 ) that applies power via an ICP or CCP configuration. The application of power to the plasma chamber or load 332 generates a plasma 336 inside the plasma chamber or load 332. The plasma 336 enables the application of a variety of manufacturing and fabrication processes.

[0063] 4 shows a circuit diagram of a portion 410 of a power delivery system arranged in accordance with the present disclosure. An RF power supply or source 412 has an equivalent impedance Z 1 that includes a matching network / current divider 418, a degaussing circuit 460, and a plasma chamber or load 432. eq The matching network portion of the matching network / current divider 418 is connected to a variable capacitor V C1 and an inductor L8 in series with the variable capacitor V C2 Inductor L8 and variable capacitor V C1 forms the shunt leg of the matching network, and is connected to inductor L5 and variable capacitor V C2 forms the series leg of the matching network. Current division is performed by the circuit formed by the inductor L7 in parallel with the capacitor C4 and the inductor L6. The variable capacitor V C3 provides a shunt to ground between capacitor C4 and inductor L6. V C3 Varying the capacitance of the coil changes the power ratio between the RF power applied to the inner coil and the RF power applied to the outer coil.

[0064] The matching network / current divider 418 is shown using an L-type matching circuit. The total impedance Z seen by the RF generator is eq Other matching circuits may also be used, including a T-type or π-type matching circuit or combinations thereof that controls the current ratio between the variable capacitor V and the RF coil L1 and the RF coil L2. C1 , V C2is varied to provide an impedance to reduce reflected power to the RF power source 412, thereby increasing the forward power applied to the plasma chamber or load 432. The power ratio between the inner coil L1 and the outer coil L2, which adjusts the plasma density in the inner and outer regions of the plasma chamber or load 432, is controlled by the total forward power delivered from the RF power source 412 and the current ratio between the inner coil L1 and the outer coil L2. In one non-limiting example, the target power of the inner coil L1 and the outer coil L2 are 1000W and 500W, respectively. In such a configuration, the system controller controls the total forward power from the RF power source 412 to the plasma chamber or load 432 to be 1500W, and the current ratio of the inner coil L1 and the outer coil L2 is controlled to be 2:1. As described above, the current division circuit of the matching network is controlled by a shunt variable capacitor V C3 However, the present invention is not limited to other configurations for controlling the current ratio of the RF coils.

[0065] The matching circuit / current divider 418 outputs a pair of RF power signals that are applied to respective inner coil or inductor L3 and outer coil or inductor L4 of the degaussing circuit 460. Thus, the degaussing circuit 460 outputs a plurality of signals. As described further herein, a plurality can be two, three, or four or more split signals. The inner coil L3 and outer coil L4 output RF power signals to respective inner antenna, inductor, or coil L1 and outer antenna, inductor, or coil L2 of the plasma chamber or load 432. The inner coil L1 and outer coil L2 output respective impedances Z that represent the impedance at the plasma chamber or load 432. in and Z out Connect to ground via

[0066] 4, the inner coil L3 and the outer coil L4 are represented as inductors formed by the coils. However, the inner coil L3 and the outer coil L4 may, in various configurations, have a mutual inductance M that substantially cancels or offsets the mutual inductance created by the inner coil or inductor L1 and the outer coil or inductor L2 in the ICP chamber or load 432. 34 Thus, L3 and L4 may also refer to inductances, where such inductances are induced rather than generated via an induction coil.

[0067] The equivalent circuit of the ICP chamber or load 432 is the self-inductances L1 and L2 of the RF coils and the mutual inductance M 12 and the two equivalent impedances of the chamber, Z In and Z Out The inner coil L1 and the outer coil L2 have respective impedances Z in and Z out Connect to ground via mutual inductance M 12 represents the coupling impedance or mutual inductance created by the two RF coils and / or the chamber plasma.

[0068] The degaussing circuit 460 includes degaussing coils L3 and L4 in series with a plasma chamber or load 432 connected to the ICP. The current ratio CR between the inner and outer RF coils is given by Equation (1):

number

number

[0069] From the above, it can be seen that the current ratio is linear under one of the following conditions:

number

[0070] In the circuit of FIG. 4, the degaussing circuit 460 uses the ratio of equation (1) to provide linearity in the current ratio between RF coils such as the inner coil L1 and the outer coil L2.

number

number

[0071] In the mutual inductance compensation approach, the self-inductances L3 and L4 of the degaussing circuit 460 can have the same or different self-inductance as the coils L1, L2. 34 is the mutual inductance M of coils L1 and L2 12 must be substantially equal in magnitude to the mutual inductance M, which represents the complex coupling between the RF coils and / or the plasma in the chamber. 12 and mutual inductance M 34 The mutual inductance M of the chamber through the coils L1 and L2 is 12 The interaction between the two inner and outer currents, represented by the mutual inductance M of the degaussing coils L3 and L4, 34 6 may be integrated with inductors L3 and L4 of degaussing circuit 460 to reduce the size, cost, or assembly of matching network / current divider 418.

[0072] In the mutual inductance suppression method, the mutual inductance M of the demagnetizing inner coil L3 and the outer coil L4 34 is zero (M34 =0) or non-zero (M 34 ≠ 0). The self-inductance of the inner degaussing coil L3 and the outer degaussing coil L4, or the total self-inductance of the inner path (L3 and L7) and the outer path (L4 and L6), is equal to the total mutual inductance (M 12 +M 34 ) in such a configuration. In such a configuration, nonlinear interactions between the RF current coils have less effect and the current ratio becomes more linear.

[0073] FIG. 5 shows a plot of the current ratio versus capacitance between two RF coils of an ICP chamber with and without a degaussing coil. The x-axis shows the capacitance of the variable capacitor V versus the power ratio of the RF power applied to the inner coil L1 and the outer coil L2. C3 5 represents values ​​of . Plot 510 shows the current ratios for a conventional system that does not use the degaussing circuit of the present disclosure. As can be seen, plot 510 exhibits a non-linear configuration.

[0074] Plot 512 shows the current ratio using the mutual inductance suppression technique. For plot 512, the mutual inductance M 34 is zero, while the mutual inductance M 12 is non-zero. The total self-inductance Z of the inner and outer circuits Si is the mutual inductance Z M , which is about five times larger than the current ratio, which represents the complex coupling of the ICP chamber. Plot 514 shows the current ratio using the mutual inductance compensation technique. In the mutual inductance compensation technique, the mutual inductance M of the inner degaussing coil L3 and the outer degaussing coil L4 is 34 is the mutual inductance M of the inner coil L1 and the outer coil L2 for supplying power to the plasma chamber or load 432 in the ICP configuration 12 514, but with opposite polarity. Both the mutual inductance compensation technique shown in plot 514 and the mutual inductance suppression technique shown in plot 512 can improve the linearity of the current ratio in the RF coil of the ICP chamber.

[0075] 6 shows a circuit diagram of a portion 610 of a power delivery system arranged in accordance with the present disclosure. The configuration of FIG. 6 is similar to that of FIG. 4, except that the degaussing circuit 660 is located on the opposite side of the impedance matching network / current divider 618 from the plasma chamber or load 632. The RF power source 612 is connected to the matching network / current divider 618 via the degaussing circuit 660 and the plasma chamber or load 632 via an equivalent impedance Z eq 6 outputs an RF signal to the inner coil 660. The components of Figure 6 operate similarly to those of Figure 4, with the degaussing circuit 660 and the plasma chamber or load 632 located at opposite positions in the circuit. The circuits of Figures 4 and 6 operate similarly in that they allow for a linear current ratio between the RF power applied to the inner coil and the RF power applied to the outer coil.

[0076] FIG. 7 shows a circuit diagram of a portion 610 of a power delivery system arranged in accordance with the present disclosure. The configuration of FIG. 7 is similar to that of FIG. 4 or FIG. 6, but three coils provide an ICP connection between an impedance match network / current divider 718 and a plasma chamber or load 732 that occurs using a three-coil ICP connection. The three ICP coils include an inner coil L3, a middle coil L2, and an outer coil L2'. A degaussing circuit 760 includes three coils including an inner coil L3, a middle coil L4, and an outer coil L4', which correspond to the inner coil L1, the middle coil L2, and the outer coil L2', respectively. The degaussing circuit 760 is connected to the mutual inductance M of the RF coils in the chamber, respectively. 12 , M 22 , and M. 12 3 mutual inductances M to compensate for ' 34 , M 44 , and M. 34 In such a configuration, equation (1) may be adjusted to account for the additional term introduced by the addition of the third coil.

[0077] As with Figure 6, in various configurations, the degaussing circuit 760 of Figure 7 can be located on the opposite side of the impedance matching network / current divider 718 from the plasma chamber or load 732. That is, the plasma chamber or load 732 is located between the matching network / current divider 718 and the degaussing circuit 760. In either configuration, with the degaussing circuit 760 located before the plasma chamber or load, or the plasma chamber or load 732 located before the degaussing circuit 730, the circuit of Figure 7 operates to provide a linear current ratio between the RF power applied to the three coils or inductances, the inner coil or inductance L1, the middle coil or inductance L2, and the outer coil or inductance L2'.

[0078] 8 and 9 show various degaussing circuit configurations arranged according to the present disclosure. In FIG. 8, the degaussing circuit 810 shows a bus bar including connectors arranged to correspond to the inner coil L3 and the outer coil L4, respectively. Power is provided to the inner degaussing coil L3 via a terminal or connector 812 and flows through a conductor or electrical conductor 814 to a terminal or connector 818. The terminal or connector 818 connects to an ICP outer coil L1 of a plasma chamber or load, such as the plasma chamber or load 432, 632, or 732. Similarly, power is provided to the degaussing outer coil L4 via a terminal or connector 820 and flows through an electrical conductor 822 to a terminal or connector 824. The terminal or connector 824 connects to an ICP outer coil L2 of a plasma chamber or load, such as the plasma chamber or load 432, 632, or 732.

[0079] A current or power flowing through the electrical conductor 814 generates a magnetic flux 830, and the same current flowing through the inner coil L1 generates a magnetic flux 832. The magnetic fluxes 830 and 832 are considered mutual magnetic fluxes and have opposite polarities to provide a demagnetizing effect. Similarly, a current or power flowing through the electrical conductor 822 generates a magnetic flux 834, and the same current flowing through the outer coil L2 generates a magnetic flux 836. The magnetic fluxes 834 and 836 are considered mutual magnetic fluxes and have opposite polarities to provide a demagnetizing effect. By appropriate selection of the length L of the electrical conductors 814, 822 and the gap G between the electrical conductors 814 and 822, the respective magnetic fluxes 830, 834 can be adjusted to substantially cancel the respective magnetic fluxes 832, 836. Thus, the demagnetizing circuit 810 can be provided by selectively configuring the dimensions of the busbars shown in FIG. 8.

[0080] In FIG. 9, the degaussing circuit 910 shows a bus bar formed to include an inner degaussing coil L3 and an outer degaussing coil L4, respectively. Power is provided to the inner degaussing coil L3 via a terminal or connector 912 and flows through a degaussing inner coil 914 (L3) to a terminal or connector 918. The terminal or connector 918 connects to an ICP outer coil L1 of a plasma chamber or load, such as a plasma chamber or load 432, 632, or 732. Similarly, power is provided to the degaussing outer coil L4 via a terminal or connector 920 and flows through a degaussing outer coil 922 (L4) to a terminal or connector 924. The terminal or connector 924 connects to an ICP outer coil L2 of a plasma chamber or load, such as a plasma chamber or load 432, 632, or 732.

[0081] A current or power flowing through the degaussing inner coil 914 generates a magnetic flux 930, and the same current flowing through the inner coil L1 generates a magnetic flux (not shown). The magnetic flux of the inner coil L1 and the magnetic flux 930 are considered mutual magnetic fluxes and have opposite polarities to provide the degaussing effect. Similarly, a current or power flowing through the degaussing outer coil 922 generates a magnetic flux 934, and the same current flowing through the outer coil L2 generates a magnetic flux (not shown). The magnetic flux of the outer coil L2 and the magnetic flux 934 are considered mutual magnetic fluxes and have opposite polarities to provide the degaussing effect.

[0082] The subject disclosure may, but is not required to, provide one or more of the following advantages: The degaussing coil compensates or suppresses the effects of mutual inductance between RF coils of a plasma processing system. By using the disclosed degaussing coil, the nonlinear current ratio between the inner and outer RF ICP coils becomes linear, which shortens the response time, improves the accuracy, and improves the smoothness of the current ratio control loop. In operation, the matching control loop is completed after the current ratio control loop. Thus, the improvement of the current ratio control loop shortens the impedance matching time of the matching network. The location of the degaussing coil and the impedance matching network is flexible. The present invention includes, but is not limited to, two RF coils or multiple ICP coils or antennas for a plasma chamber. The degaussing coil includes, but is not limited to, a common RF coil, a busbar, a microstrip, or a stripline. Various advantages include improved efficiency and quality of the etching process, as well as reduced maintenance and repair time.

[0083] Although plasma etch customers may benefit from using a degaussing coil that linearly improves the current ratio between the RF coils of an ICP chamber, the degaussing coil described herein is not required, but may provide other benefits. ICP chambers used for etching include multiple RF coils and require control of the current ratio between those RF coils to improve controllability of plasma uniformity. Such configurations include process requirements of sufficient impedance matching time and control loop accuracy. The nonlinear relationship between the RF coils and / or plasma of an ICP chamber limits the response time, accuracy, and matching speed of the system. Furthermore, current ratio control in a system with a nonlinear slope is less accurate, resulting in large plasma dispersion between the chambers. The proposed degaussing coil disclosed herein can improve the linearity of the current ratio between the RF coils, which helps improve the speed and accuracy of the control loop of the ICP chamber system.

[0084] The foregoing description is merely exemplary in nature and is not intended to limit the disclosure, its application, or uses in any way. The broad teachings of the disclosure can be implemented in various forms. Thus, while the disclosure includes specific examples, other variations will become apparent upon review of the drawings, the specification, and the following claims, and the true scope of the disclosure should not be so limited. In the specification and claims, one or more steps in a method may be executed in a different order (or simultaneously) without changing the principles of the disclosure. Similarly, one or more instructions stored in a non-transitory computer-readable medium may be executed in a different order (or simultaneously) without changing the principles of the disclosure. Unless otherwise indicated, numbering or other labeling of instructions or method steps is done for convenient reference and not to indicate a fixed order.

[0085] Furthermore, although each of the embodiments is described above as having certain features, any one or more of these features described with respect to any embodiment of the present disclosure can be implemented in and / or combined with features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with each other remain within the scope of the present disclosure.

[0086] Spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.) have been described using a variety of terms, including "connected," "engaged," "coupled," "adjacent," "on top of," "above," "below," and "disposed." Unless expressly described as "direct," when a relationship between a first element and a second element is described in the disclosure above, the relationship can be a direct relationship where there are no other intervening elements between the first element and the second element, but can also be an indirect relationship where there are one or more intervening elements (spatial or functional) between the first element and the second element.

[0087] The phrase "at least one of A, B, and C" should be interpreted to mean a logical (A OR B OR C) using a non-exclusive logical OR, and not to mean "at least one A, at least one B, and at least one C." The term "set" does not necessarily exclude an empty set, in other words, in some circumstances, a "set" may have zero elements. The term "non-empty" set may be used to indicate the exclusion of an empty set, in other words, a non-empty set always has one or more elements. The term "subset" does not necessarily require a proper subset. In other words, a "subset" of a first set may be coextensive (equal) with the first set. Furthermore, the term "subset" does not necessarily exclude an empty set, in some circumstances, a "subset" may have zero elements.

[0088] In the figures, the direction of the arrow, indicated by the arrowhead, generally indicates the flow of information (such as data or instructions) that is important to the example. For example, when element A and element B exchange various information, but information sent from element A to element B is relevant to the example, the arrow may point from element A to element B. This unidirectional arrow does not mean that other information is not sent from element B to element A. Additionally, for information sent from element A to element B, element B may send a request for or acknowledgement of receipt of that information to element A.

[0089] In this application, including the definitions below, the term "module" can be replaced with the term "controller" or the term "circuitry." In this application, the term "controller" can be replaced with the term "module." The term "module" can refer to, be part of, or include an application specific integrated circuit (ASIC), digital, analog, or mixed analog / digital discrete circuitry, digital, analog, or mixed analog / digital integrated circuitry, combinatorial logic circuitry, field programmable gate array (FPGA), processor hardware (shared, dedicated, or group) that executes code, memory hardware (shared, dedicated, or group) that stores code executed by the processor hardware, other suitable hardware components that provide the described functionality, or a combination of some or all of the above, such as in a system on a chip.

[0090] The module may include one or more interface circuits. In some examples, the interface circuit may implement a wired or wireless interface to connect to a local area network (LAN) or a wireless personal area network (WPAN). Examples of LANs are the Institute of Electrical and Electronics Engineers (IEEE) standard 802.11-2020 (also known as the WIFI wireless networking standard), and the IEEE standard 802.3-2018 (also known as the Ethernet wired networking standard). Examples of WPANs are the IEEE standard 802.15.4 (including the ZIGBEE standard from the ZigBee Alliance), and the Bluetooth Special Interest Group (SIG), including the BLUETOOTH wireless networking standard (including core specification versions 3.0, 4.0, 4.1, 4.2, 5.0, and 5.1 from the Bluetooth SIG).

[0091] Modules may communicate with other modules using interface circuits. Although modules may be shown in this disclosure as logically communicating directly with other modules, in various implementations, modules may actually communicate through a communication system. A communication system includes physical and / or virtual networking equipment such as hubs, switches, routers, and gateways. In some implementations, a communication system connects to or traverses a wide area network (WAN) such as the Internet. For example, a communication system may include multiple LANs connected to each other via the Internet or point-to-point leased lines using technologies including Multiprotocol Label Switching (MPLS) and Virtual Private Networks (VPNs).

[0092] In various implementations, the functionality of a module may be distributed among multiple modules connected via a communication system. For example, multiple modules may implement the same functionality distributed by a load balancing system. In a further example, the functionality of a module may be split between a server (also known as remote or cloud) module and a client (or user) module. For example, a client module may include a native application or a web application that runs on a client device and is in network communication with a server module.

[0093] Some or all of the hardware functions of the modules may be defined using a language for hardware description, such as IEEE Standard 1364-2005 (commonly referred to as "Verilog") and IEEE Standard 1076-2008 (commonly referred to as "VHDL"). The hardware description language may be used to manufacture and / or program the hardware circuit. In some implementations, some or all of the functions of the modules may be defined by a language such as IEEE 1666-2005 (commonly referred to as "SystemC"), which encompasses both code, as described below, and a hardware description.

[0094] The term code as used above may include software, firmware, and / or microcode and may refer to programs, routines, functions, classes, data structures, and / or objects. Shared processor hardware encompasses a single microprocessor that executes some or all code from multiple modules. Group processor hardware encompasses a microprocessor that executes some or all code from one or more modules in combination with additional microprocessors. References to multiple microprocessors encompass multiple microprocessors on separate dies, multiple microprocessors on a single die, multiple cores of a single microprocessor, multiple threads of a single microprocessor, or combinations of the above.

[0095] Memory hardware may also store data together with or separately from the code. Shared memory hardware encompasses a single memory device that stores some or all code from multiple modules. An example of shared memory hardware may be a level 1 cache on or near a microprocessor die that may store code from multiple modules. Another example of shared memory hardware may be persistent storage such as a solid-state drive (SSD) that may store code from multiple modules. Group memory hardware encompasses a memory device that stores some or all code from one or more modules in combination with other memory devices. An example of group memory hardware is a storage area network (SAN) that may store the code of a particular module across multiple physical devices. Another example of group memory hardware is the random access memory of each of a set of servers that in combination store the code of a particular module.

[0096] The term memory hardware is a subset of the term computer-readable medium. The term computer-readable medium as used herein does not encompass a transitory electrical or electromagnetic signal propagating through a medium (such as on a carrier wave), and therefore the term computer-readable medium is considered to be tangible and non-transient. Non-limiting examples of non-transient computer-readable media are non-volatile memory devices (such as flash memory devices, erasable programmable read-only memory devices, or masked read-only memory devices), volatile memory devices (such as static random access memory devices or dynamic random access memory devices), magnetic storage media (such as analog or digital magnetic tape or hard disk drives), and optical storage media (such as CDs, DVDs, or Blu-ray® disks).

[0097] The apparatus and methods described in this application may be implemented in part or in full by a special-purpose computer created by configuring a general-purpose computer to perform one or more specific functions embodied in a computer program. Such apparatus and methods may be described as computerized apparatus and computerized method. The functional blocks and flow chart elements described above function as software specifications that can be converted into a computer program by the routine work of a skilled technician or programmer.

[0098] A computer program includes processor-executable instructions stored on at least one non-transitory 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 hardware of a special-purpose computer, device drivers that interact with specific devices of a special-purpose computer, one or more operating systems, user applications, background services, background applications, and the like.

[0099] A computer program may include (i) written text to be parsed, such as HTML (Hypertext Markup Language), XML (Extensible Markup Language), or JSON (JavaScript Object Notation); (ii) assembly code; (iii) object code generated by a computer from source code; (iv) source code for execution by an interpreter; (v) source code for compilation and execution by a just-in-time compiler; etc. By way of example only, the 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]

[0100] 110 Inductively Coupled Plasma (ICP) System, ICP System 112 Plasma Chamber 114 Plasma 116 Inner coil, coil 118 Outer coil, coil 120 Power supply 122 Power supply 124 Dielectric Window 126 Board 128 Power supply 210 Power System 212a RF generator, source RF generator, RF generator 212b RF Generator, Bias RF Generator, RF Power Generator 214a RF power supply or amplifier, RF power supply, power supply, source RF power supply 214b RF power supply or amplifier, RF power supply, power supply, bias RF power supply 216a RF Sensor, Sensor, Source Sensor 216b RF Sensor, Sensor, Bias Sensor 218a Matching network, source matching network, matching circuit 218b Matching network, bias matching network, matching circuit 220' Controller, External or Common Controller 220a Processor, controller, or control module, controller or power control module, power control module, local controller, source controller 220b Processor, controller, or control module, controller or power control module, power control module, local controller, bias controller 222a RF power signal 222b RF power signal 224a X signal 224b X signal 226a Y signal 226b Y signal 228a Feedforward and / or feedback control signals, control signals, feedback control signals, signals 228b Feedforward and / or feedback control signals, control signals, feedback control signals, signals 230 control signal, synchronization or trigger signal, trigger signal, trigger or synchronization signal, signal 230' control signal, synchronization or trigger signal, trigger or synchronization signal, signal 232 Load 234 Synchronous Bias Detector 236 Links 238 Link 240 Pulse synchronous output port 242 Digital Communication Port 244 RF output ports 248 RF input ports 250 digital communication ports 252 Pulse sync input port 256 pulse sync signal 257 Digital Communication Link 258 RF Control Signals 260 Degaussing circuit 310 Plasma System 312 RF Generator 318 Impedance Matching Network / Current Divider 332 Plasma chamber or load 334 Electrode 336 Plasma 360 degaussing circuit 362 Inner Coil 362a Terminal 362b Terminal 364 Outer Coil 364a Terminal 364b terminal 410 Part of the power delivery system 412 RF power supply or power source, RF power source 418 Matching Network / Current Divider 432 Plasma chamber or load, ICP chamber or load 460 Degaussing circuit 510 Plot 512 Plot 514 Plot 610 Part of the power delivery system 612 RF power supply 618 Impedance Matching Network / Current Divider, Matching Network / Current Divider 632 Plasma chamber or load 660 Degaussing circuit 718 Impedance Matching Network / Current Divider, Matching Network / Current Divider 730 Degaussing circuit 732 Plasma chamber or load 760 Degaussing circuit 810 Degaussing circuit 812 Terminals or Connectors 814 Conductors or electric conductors, electric conductors 818 Terminal or Connector 820 Terminal or Connector 822 Electrical conductors 824 Terminals or Connectors 830 Magnetic Flux 832 Magnetic Flux 834 Magnetic Flux 836 Magnetic Flux 910 Degaussing circuit 912 Terminal or Connector 914 Degaussing inner coil 918 Terminal or Connector 920 Terminals or Connectors 922 Degaussing outer coil 924 Terminals or Connectors 930 Magnetic Flux 934 Magnetic Flux

Claims

1. an RF power source configured to generate an output signal; a power divider configured to receive the output signal and generate a plurality of divided signals; a degaussing circuit configured to receive the plurality of split signals, the degaussing circuit configured to include a plurality of inductances corresponding to the plurality of split signals; 1. An RF generator comprising: the plurality of inductances are configured to reduce an effect of a mutual impedance of an ICP chamber in series with the plurality of inductances such that a ratio between the pair of the plurality of split signals changes substantially linearly as one of the pair of the plurality of split signals changes; RF generator.

2. 13. The RF generator of claim 1, wherein the multiple inductances can be one of a coil having an inductance or an inductance induced by conducting a current through an electrical conductor.

3. 2. The RF generator of claim 1, wherein the degaussing circuit includes a plurality of outputs, the plurality of outputs corresponding to respective ones of a plurality of antennas of an ICP chamber, and a combined mutual inductance of the plurality of inductances corresponding to the plurality of split signals is substantially equal to a combined mutual inductance of the plurality of antennas of the ICP chamber.

4. 13. The RF generator of claim 1, further comprising a matching network configured to receive the output signal from the RF power source and provide the output signal to the power divider, the matching network configured to provide an impedance match with the RF power source.

5. 2. The RF generator of claim 1, wherein the degaussing circuit is disposed between the power divider and a load.

6. 10. The RF generator of claim 1, wherein a load is disposed between the degaussing circuit and the power divider.

7. 2. The RF generator of claim 1, wherein the plurality of inductances is two, the degaussing circuit has an inner inductance and an outer inductance, the inner inductance corresponding to an inner coil of an ICP chamber and the outer inductance corresponding to an outer coil of the ICP chamber.

8. 2. The RF generator of claim 1, wherein the plurality of inductances is three, and the degaussing circuit has an inner inductance, a middle inductance, and an outer inductance, the inner inductance corresponding to an inner coil of an ICP chamber, the middle inductance corresponding to the middle coil of the ICP chamber, and the outer inductance corresponding to the outer coil of the ICP chamber.

9. an RF power source configured to generate an output signal; a power divider configured to receive the output signal and generate a plurality of divided signals; a degaussing circuit configured to receive the plurality of split signals, the degaussing circuit configured to include a plurality of coils corresponding to the plurality of split signals; 1. An RF generator comprising: the plurality of coils are configured to reduce an effect of a mutual impedance of an ICP chamber in series with the plurality of inductances such that a ratio between the pair of the plurality of split signals varies substantially linearly as one of the pair of the plurality of split signals varies; RF generator.

10. 10. The RF generator of claim 9, wherein the degaussing circuit includes a plurality of outputs, the plurality of outputs corresponding to respective ones of a plurality of antennas of an ICP chamber, and a combined mutual inductance of the plurality of coils corresponding to the plurality of split signals is substantially equal to a combined mutual inductance of the plurality of antennas of the ICP chamber.

11. 10. The RF generator of claim 9, further comprising a matching network configured to receive the output signal from the RF power source and provide the output signal to the power divider, the matching network configured to provide an impedance match with the RF power source.

12. 10. The RF generator of claim 9, wherein the degaussing circuit is disposed between the power divider and a load.

13. 10. The RF generator of claim 9, wherein a load is disposed between the degaussing circuit and the power divider.

14. 10. The RF generator of claim 9, wherein the plurality of coils is two, and the degaussing circuit has an inner coil and an outer coil, the inner coil corresponding to an inner coil of an ICP chamber and the outer coil corresponding to an outer coil of the ICP chamber.

15. 10. The RF generator of claim 9, wherein the plurality of coils is three, and the degaussing circuit has an inner coil, a middle coil, and an outer coil, the inner coil corresponding to the inner coil of an ICP chamber, the middle coil corresponding to the middle coil of the ICP chamber, and the outer coil corresponding to the outer coil of the ICP chamber.

16. a first inductance, the first inductance configured to receive a first RF signal, the first inductance electrically connected to a first antenna of the ICP chamber; and a second inductance, the second inductance configured to receive a second RF signal, the second inductance electrically connected to a second antenna of the ICP chamber; 1. A degaussing circuit for an ICP system comprising: the first inductance and the second inductance are configured to reduce an effect of a mutual impedance of an ICP chamber in series with the plurality of inductances such that a ratio between the first RF signal and the second RF signal varies substantially linearly as one of the first RF signal or the second RF signal varies; Degaussing circuits for ICP systems.

17. 17. The degaussing circuit for an ICP system as described in claim 16, wherein the first inductance can be one of a first coil having an inductance or a first induced inductance by conducting a current through a first electrical conductor, and the second inductance can be one of a second coil having an inductance or a second induced inductance by conducting a current through a second electrical conductor.

18. 17. The degaussing circuit for an ICP system as described in claim 16, wherein a combined mutual inductance of the first inductance and the second inductance is substantially equal to a combined mutual inductance of a first antenna and a second antenna of the ICP system.

19. 17. The degaussing circuit for an ICP system as recited in claim 16, wherein the degaussing circuit is disposed between a power splitter and a load.

20. 20. The degaussing circuit for an ICP system as recited in claim 16, wherein a load is disposed between the degaussing circuit and a power divider.

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