Station voltage regulation during plasma operation

Abstract

Various embodiments herein relate to systems, devices, and methods of station voltage regulation during plasma operation. In some embodiments, a system comprises: a processing chamber; at least one variable reactance element operably coupled to the unenergized electrode of the processing chamber; and a controller. In some embodiments, a controller is configured to determine one or more target voltages associated with one or more components. The controller may be configured to determine a value of the at least one variable reactance element based on the one or more target voltages. The controller may be configured to cause the at least one variable reactance element to have a determined value, wherein causing the at least one variable reactance element to have the determined value causes one or more voltages associated with one or more components of the processing chamber to move toward one or more target voltages.

Description

Incorporated by Reference

[0001] The PCT application form is filed concurrently with this specification as a part of this application. Each application identified in the concurrently filed PCT application form to which this application claims the benefit or priority is incorporated herein by reference in its entirety and for all purposes. Background Art

[0002] Plasma-based operations such as plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), atomic layer etching (ALE), or similar techniques are often performed in a plasma reactor including two electrodes configured to maintain a plasma in a region between the electrodes. When an RF signal is provided to a powered electrode of the two electrodes, the plasma can be ignited and / or maintained.

[0003] The background description provided here is for the purpose of generally presenting the context of the present disclosure. The work of the presently designated inventors is neither explicitly nor implicitly admitted to be prior art against the present disclosure to the extent that it is described in this background section and in aspects of the specification that were not determined to be prior art at the time the application was filed. Summary of the invention

[0004] Disclosed herein are systems, devices, and methods for station voltage regulation during plasma operation.

[0005] In some embodiments, a system is provided. The system may include: a processing chamber configured to perform a semiconductor manufacturing process including a plasma-based operation; at least one variable reactance element operably coupled to an unpowered electrode of the processing chamber; and a controller. The controller may be configured to determine one or more target voltages associated with one or more components of the processing chamber during or prior to the performance of the plasma-based operation. The controller may be configured to determine a value of the at least one variable reactance element based at least in part on the one or more target voltages. The controller may be configured to cause the at least one variable reactance element to have the determined value, wherein causing the at least one variable reactance element to have the determined value causes: one or more voltages associated with the one or more components of the processing chamber to move toward the one or more target voltages.

[0006] In some examples, the unpowered electrode of the process chamber comprises a showerhead of the process chamber, and wherein the at least one variable reactive element is electrically connected to or disposed in the showerhead.

[0007] In some examples, the unpowered electrode of the process chamber is a base of the process chamber, wherein the at least one variable reactive element is electrically connected to or disposed in the base of the process chamber.

[0008] In some examples, causing the one or more voltages associated with the one or more components of the processing chamber to move toward the one or more target voltages reduces the likelihood of a parasitic plasma within the processing chamber.

[0009] In some examples, at least one of the one or more target voltages is a voltage associated with an unpowered showerhead of the processing chamber.

[0010] In some examples, the system further includes a pedestal configured to support a wafer undergoing the semiconductor manufacturing process, and wherein at least one of the one or more target voltages is a voltage at a location proximate to a stationary position of the wafer. In some examples, causing the at least one variable reactive element to have the determined value causes: the voltage at the location proximate to the stationary position of the wafer to be significantly lower than the voltage at the location before causing the at least one reactive element to have the determined value. In some examples, the system further includes a radio frequency (RF) generator operably coupled to the pedestal.

[0011] In some examples, the at least one variable reactive element comprises a variable capacitor. In some examples, the system further comprises a stepper motor operably coupled to the variable capacitor, and wherein the controller is configured to cause the variable capacitor to have the determined value by actuating the stepper motor. In some examples, the value of the variable capacitor is determined based on an inductance associated with the unpowered electrode.

[0012] In some examples, the at least one variable reactive element includes a variable inductor.

[0013] In some examples, the at least one variable reactive element comprises a network configured to provide different reactances for different frequencies. In some examples, the different frequencies comprise: DC, multiple RF drive frequencies, multiple harmonics of one or more RF drive frequencies, or any combination thereof.

[0014] In some examples, the at least one variable reactive element comprises a replaceable hardware element.

[0015] In some examples, the plasma operation is a plasma-based etching operation or a plasma-based deposition operation.

[0016] In some embodiments, a method is provided. The method may include: determining one or more target voltages associated with one or more components of a processing chamber during or prior to performance of a plasma-based operation in the processing chamber, the processing chamber comprising an unpowered electrode. The method may include: determining a value of at least one variable reactive element operably coupled to the unpowered electrode. The method may include: causing the at least one variable reactive element to have the determined value, wherein causing the at least one variable reactive element to have the determined value causes: one or more voltages associated with the one or more components of the processing chamber to move toward the one or more target voltages.

[0017] In some examples, determining the value of the at least one variable reactance element includes using the one or more target voltages as a key value of a lookup table to identify the value of the at least one variable reactance element that causes the one or more voltages associated with the one or more components to fall within a predetermined range of the one or more target voltages.

[0018] In some examples, determining the value of the at least one variable reactive element is based on a circuit model of at least a portion of the process chamber, wherein the circuit model includes the at least one variable reactive element. In some examples, the circuit model includes one or more circuit elements associated with a plasma formed in the process chamber. In some examples, the one or more circuit elements associated with the plasma include a resistor representing a plasma resistance and a capacitor representing a capacitance associated with a plasma sheath. In some examples, the at least one variable reactive element includes a variable capacitor, and wherein the circuit model includes the variable capacitor coupled in series to an inductor, the inductor representing the inductance of the unpowered electrode. In some examples, the value of the variable capacitor is determined to be a value that causes an impedance associated with the variable capacitor to substantially cancel an impedance associated with the inductor representing the inductance of the unpowered electrode.

[0019] In some examples, the unpowered electrode comprises a base of the processing chamber.

[0020] In some examples, the at least one variable reactive element includes a variable inductor.

[0021] In some examples, the value of the at least one variable reactive element is determined based at least in part on a plasma characteristic determined from optical data captured by an optical sensor.

[0022] In some examples, the value of the at least one variable reactive element is determined based at least in part on plasma characteristics determined based on electrical power, voltage, current, and / or phase measurements of RF signals measured in: one or more regions of the processing chamber; or an RF power delivery system.

[0023] In some examples, the value of the at least one variable reactive element is determined based at least in part on a plasma characteristic determined from a DC bias signal measured at one or more of the powered electrode or the unpowered electrode.

[0024] In some examples, the value of the at least one variable reactive element is determined based at least in part on a plasma characteristic determined from an electrical plasma diagnostic in the processing chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic diagram of an exemplary apparatus according to some embodiments.

[0026] Figure 2 is a schematic diagram representing components of an apparatus configured for plasma operations as equivalent circuit elements, according to some embodiments.

[0027] Figure 3 is a schematic diagram illustrating the use of a variable reactive element for regulating the voltage of a station according to some embodiments.

[0028] Figure 4A and 4B is a graph showing the effect of an exemplary variable capacitor on voltage according to some embodiments.

[0029] Figure 5 is a flow chart of an exemplary process for regulating voltage using a variable reactive element according to some embodiments.

[0030] Figure 6 An exemplary computer system is presented that can be used to implement certain embodiments described herein. DETAILED DESCRIPTION Technical terms

[0031] The following terms are used throughout this manual:

[0032] The terms "semiconductor wafer", "wafer", "substrate", "wafer substrate" and "partially fabricated integrated circuit" may be used interchangeably. One of ordinary skill in the art understands that the term "partially fabricated integrated circuit" may refer to a semiconductor wafer during any of the many stages of integrated circuit fabrication thereon. Wafers or substrates used in the semiconductor device industry typically have a diameter of 200 mm, or 300 mm, or 450 mm. In addition to semiconductor wafers, other workpieces that may utilize the disclosed embodiments include various objects, such as printed circuit boards, magnetic recording media, magnetic recording sensors, mirrors, optical elements, display devices or components, such as backplanes for pixelated display devices, flat panel displays, micromechanical devices, and the like. The workpieces may have a variety of shapes, sizes, and materials.

[0033] As used herein, "semiconductor device manufacturing operations" are operations performed during the manufacture of semiconductor devices. Typically, the entire manufacturing process includes multiple semiconductor device manufacturing operations, each of which is performed in its own semiconductor manufacturing tool, such as a plasma reactor, an electroplating tank, a chemical mechanical planarization tool, a wet etching tool, etc. Categories of semiconductor device manufacturing operations include subtractive processes, such as etching processes and planarization processes; and additive processes, such as deposition processes (e.g., physical vapor deposition, chemical vapor deposition, atomic layer deposition, electrochemical deposition, electroless deposition). In the context of an etching process, a substrate etching process includes a process for etching a mask layer, or more generally, includes a process for etching any material layer previously deposited on and / or otherwise residing on the surface of a substrate. This etching process can etch stacked layers in a substrate.

[0034] "Fabrication equipment" refers to equipment in which a manufacturing process occurs. Fabrication equipment typically has a processing chamber in which a workpiece resides during processing. Typically, when in use, the fabrication equipment performs one or more semiconductor device fabrication operations. Examples of fabrication equipment used for semiconductor device fabrication include deposition reactors, such as electroplating units, physical vapor deposition reactors, chemical vapor deposition reactors, and atomic layer deposition reactors, as well as subtractive process reactors, such as dry etch reactors (e.g., chemical and / or physical etch reactors), wet etch reactors, and ashers. Station voltage regulation during plasma operation

[0035] Plasma-based operations such as plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), atomic layer etching (ALE), or similar processes are often performed in a plasma reactor including two electrodes, which are configured to maintain a plasma in a region between the electrodes. When an RF signal is provided to a powered electrode of the two electrodes, a plasma can be ignited and / or maintained. The unpowered electrode of the two electrodes fixed to the wall of the plasma reactor can be effectively DC grounded at relatively low RF frequencies. However, at higher RF frequencies, the unpowered electrode may generate a voltage relative to the wall of the plasma reactor. This voltage may have an adverse effect on the plasma within the reactor, such as causing parasitic plasma in regions of the reactor other than the region between the two electrodes. The adverse effect on the plasma may produce unpredictable and / or adverse conditions for, for example, semiconductor manufacturing operations, such as non-uniformities in the deposited layer, non-uniformities in the etched layer, and the like.

[0036] Disclosed herein are techniques for adjusting voltages at various regions of a station of a processing chamber during and / or prior to the execution of a plasma operation. In certain embodiments, one or more target voltages are determined, each associated with a component of the station. Exemplary station components for which target voltages may be determined include a showerhead of the station (e.g., where the target voltage is the voltage across the showerhead), a pedestal of the station (e.g., where the target voltage is in a region near the top or upper surface of the pedestal where the wafer resides during processing), or the like. In some implementations, one or more variable reactive elements may be tuned to values ​​that drive the station voltage toward one or more target voltages. The target voltages may be specified in a recipe (e.g., a recipe for a particular step or portion). For example, a target voltage for a region near the upper surface of the pedestal may be a value that minimizes parasitic plasma under the pedestal.

[0037] It should be noted that one or more variable reactive elements may be operably coupled to an unpowered electrode of the station. For example, in the case where an RF signal is provided to a pedestal that serves as a powered electrode, one or more variable reactive elements may be operably coupled to a showerhead that serves as an unpowered electrode. As another example, in the case where the showerhead is a powered electrode, one or more variable reactive elements may be operably coupled to the pedestal.

[0038] In some embodiments, a lookup table may be used to determine the value of one or more variable reactive elements that will drive the voltage toward one or more target voltages. For example, one or more target voltages may be provided as keys to a lookup table, where the value of the variable reactive element is identified from the value of the lookup table that may drive the voltage close to or substantially match the one or more target voltages. In some implementations, the value of the one or more variable reactive elements may be determined based at least in part on near real-time or prevalent plasma characteristics of the plasma in the station. In some implementations, the plasma characteristics may be based on optical data, such as from an optical sensor positioned to capture an image of the plasma within the station. In some implementations, the plasma characteristics may be determined based on electrical power, voltage, current, and / or phase measurements of one or more RF signals associated with or measured at any region (or at any plurality of regions) within the process chamber apparatus. In some implementations, the plasma characteristics may be determined based on a DC bias signal measured at a powered electrode and / or an unpowered electrode. In some implementations, the plasma characteristics may be determined based on an electrical plasma diagnostic run in the process chamber. Note that in some implementations, plasma characteristics may be determined based on a combination of one or more of the techniques described above.

[0039] It should be understood that a recipe for performing a plasma operation may include a variety of process conditions, such as the RF signal, process gas, flow rate, pressure, temperature, etc. used to generate or maintain the plasma. These process conditions may in turn affect the voltage at various regions of the station. For example, as will be described below in conjunction with Figure 2 and Figure 3 In more detail, the voltage across the showerhead and / or near the pedestal can be affected by plasma characteristics, where the plasma characteristics are driven by process conditions. Accordingly, the techniques described herein can be used to adjust the voltage after other process conditions have been set for a particular recipe step. In other words, using a variable reactive element associated with an unpowered electrode of the station to adjust the voltage may introduce additional variables that can be adjusted after the process conditions have been set.

[0040] Figure 1 A manufacturing tool is shown, which is represented as a substrate processing apparatus 100. Apparatus 100 may be configured for depositing films on or over a semiconductor substrate using any number of processes. For example, apparatus 100 may be particularly suitable for performing PECVD, ALD, or ALE.

[0041] Figure 1The processing apparatus 100 may utilize a single processing station 102 of a processing chamber having a single substrate holder 108 (e.g., a pedestal) within an interior volume that may be maintained under vacuum by a vacuum pump 118. A showerhead 106 and a gas delivery system 101 (which is fluidly coupled to the processing chamber) may allow for delivery of, for example, film precursors, as well as carrier and / or sweep and / or process gases, secondary reactants, and the like.

[0042] exist Figure 1 In the embodiment of the present invention, the gas delivery system 101 includes a mixing vessel 104 for mixing and / or conditioning process gases for delivery to a showerhead 106. One or more mixing vessel inlet valves 120 can control the introduction of process gases into the mixing vessel 104. Certain reactants can be stored in liquid form before being vaporized and subsequently delivered to a process station 102 in a process chamber. Figure 1 Implementations include a vaporization point 103 for vaporizing liquid reactants to be supplied to a mixing vessel 104. In some implementations, the vaporization point 103 may include a heated liquid injection module. In some other implementations, the vaporization point 103 may include a heated vaporizer. In still other implementations, the vaporization point 103 may be eliminated from the processing station. In some implementations, a liquid flow controller upstream of the vaporization point 103 may provide for controlling the mass flow of liquid for vaporization and delivery to the processing station 102.

[0043] The showerhead 106 is operable to distribute process gases and / or reactants (e.g., film precursors) toward the substrate 112 at the processing station, with the flow rate being controlled by one or more valves (e.g., valves 120, 120A, 105) upstream of the showerhead. Figure 1 In the illustrated implementation, the substrate 112 is depicted as being located below the showerhead 106 and is shown as being placed on the pedestal 108. The showerhead 106 can include any suitable shape and can include any suitable number and arrangement of ports to distribute process gases to the substrate 112. In some implementations involving two or more stations, the gas delivery system 101 includes a valve or other flow control structure upstream of the showerhead that can independently control the flow of process gases and / or reactants to each station so that gas flows to one station and simultaneously prohibits gas flow to a second station. In addition, the gas delivery system 101 can be configured to independently control the process gases and / or reactants delivered to each station in a multi-station apparatus so that the gas composition provided to different stations is different; for example, at the same time, the partial pressure of the gas components will vary between multiple stations.

[0044] exist Figure 1In some implementations, the gas volume 107 is depicted as being located below the showerhead 106. In some implementations, the pedestal 108 can be raised or lowered to expose the substrate 112 to the gas volume 107 and / or to change the size of the gas volume 107. The spacing between the pedestal 108 and the showerhead 106 is sometimes referred to as a "gap". Optionally, the pedestal 108 can be lowered and / or raised during portions of the deposition process to adjust the process pressure, reactant concentration, etc. within the gas volume 107. The showerhead 106 and the pedestal 108 are depicted as being electrically coupled to an RF signal generator 114 and a matching network 116 to couple power to the plasma generator. Thus, the showerhead 106 can be used as an electrode for coupling RF power into the processing station 102. The RF signal generator 114 and the matching network 116 can operate at any suitable RF power level that can operate to form a plasma having a desired composition of radical species, ions, and electrons. Additionally, the RF signal generator 114 can provide RF power having more than one frequency component, such as a low frequency component (e.g., less than about 2 MHz) and a high frequency component (e.g., greater than about 2 MHz). In some implementations, plasma ignition and maintenance conditions are controlled using appropriate hardware and / or appropriate machine-readable instructions in a system controller, which can provide control instructions via an input / output control instruction sequence.

[0045] As above combined Figure 1 As described above, the processing station may include a showerhead and a pedestal, each of which may be considered an electrode. As described above, an RF signal may be applied to one of the electrodes, such as the pedestal. In such an example, the showerhead may be considered an unpowered electrode. The showerhead may be considered to have a plurality of electrodes, generally referred to herein as L shd The inductance of the nozzle can be generally in the range of 10nH to 50nH. Due to the nozzle inductance, the impedance associated with the nozzle (generally referred to herein as Z shd ) is Z shd =jwL shd At relatively low RF frequencies, the effect of the showerhead inductance on the impedance associated with the showerhead may be a negligible effect. Accordingly, the voltage across the showerhead may also be negligible. In other words, at relatively low RF frequencies, the showerhead may be effectively DC grounded and thus have the same potential as the chamber. However, at higher RF frequencies (e.g., above 20 MHz, above 30 MHz, above 40 MHz, etc.), the impedance associated with the showerhead may increase, thereby causing a voltage across the showerhead (generally referred to herein as V) relative to the chamber. shd) corresponding increase. It should be understood that in the case where an RF signal is applied to the showerhead, the pedestal may be considered an unpowered electrode. Similar to what was described above regarding the voltage generated across the showerhead at a higher RF frequency in the case where the showerhead is an unpowered electrode, a voltage may be generated across the pedestal in the case where the pedestal is an unpowered electrode.

[0046] The components of the reactor including the pedestal, the showerhead, and the plasma maintained between the pedestal and the showerhead can be represented as an equivalent circuit of resistors, inductors, and / or capacitors. In particular, the equivalent circuit can be a series RLC circuit. In the case where the pedestal is a powered electrode, the RLC circuit can include an RF signal generator electrically coupled to an inductor representing the pedestal feed hardware, a series capacitor and resistor representing the plasma maintained between the pedestal and the showerhead, and an inductor representing the showerhead. As discussed above, the voltage across the showerhead (V Shd ) can be affected by the characteristics of the RF signal applied to the pedestal. The voltage at the top of the pedestal (generally referred to herein as V ped ) can also be affected by the characteristics of the RF signal. The top of the pedestal corresponds to the surface of the pedestal on which the substrate being processed is positioned. In addition, because the circuit elements are coupled in series, the voltage across the showerhead (V Shd ) also affects the voltage at the top of the base (V ped ). Therefore, an undesirable voltage across the showerhead (e.g., due to the inductance of the showerhead) may cause an undesirable voltage change at the surface of the pedestal, which may in turn cause an undesirable change in plasma conditions within the reactor. For example, such undesirable voltage changes across various components in the reactor may cause parasitic plasma. As a more specific example, such parasitic plasma may include plasma between the showerhead and the wall, plasma under a portion of the pedestal, and the like. In addition, such undesirable voltage changes may produce undesirable manufacturing effects on the wafer being processed in the reactor, such as uneven deposition, uneven etching, and the like. It should be understood that in the case where the powered electrode is the showerhead and the unpowered electrode is the pedestal, the RF signal generator can be electrically coupled to the inductor representing the showerhead.

[0047] Figure 2 A schematic diagram depicting components of a reactor using a susceptor as a powered electrode according to some embodiments is shown, with these components represented by equivalent circuit elements. As depicted, RF generator 202 is represented by current source 204. As shown above in conjunction with Figure 1 As described above, the RF signal generator 202 can be configured to provide an RF signal at one or more frequencies, including low frequencies (e.g., about 2 MHz) and / or high frequencies (e.g., above 2 MHz). The RF signal generator 202 is electrically coupled to the base 206. The RF signal generator 202 is electrically coupled to the base 206 via an inductor 208 (referred to as L ped) represents the rod of the base. Figure 2 As shown in FIG. 1 , the voltage at the top of the pedestal 206 is generally referred to herein as V ped The plasma 210, when present, is maintained between the pedestal 206 and the showerhead 216. The plasma 210 may be maintained between the pedestal 206 and the showerhead 216 by a capacitor 212 (generally referred to herein as C plasma ) and resistor 214 (generally referred to herein as R plasma ) represents the plasma 210. Generally speaking, R plasma represents the resistance of the plasma slab, and C plasma represents the plasma sheath capacitance. The showerhead 216 when fixed to the wall of the reactor (as in a conventional setup) is connected through an inductor 220 (referred to herein as L Shd ) indicates that the inductor 220 is further coupled to the ground (i.e., the station wall). This configuration is sometimes referred to as a "grounded sprinkler configuration." Figure 2 As shown in the figure, the voltage V across the nozzle Shd corresponds to the voltage at the ungrounded node of inductor 220 .

[0048] In some implementations, a variable reactive element may be used to adjust one or more voltages associated with the station. Examples of variable reactive elements include variable capacitors, variable inductors, and networks that can allow different behaviors at different frequencies (e.g., at DC, harmonics at the RF drive frequency, and / or multiple RF drive frequencies) by providing different reactances for different frequencies via different reactive elements. In some embodiments, the variable reactive element may be operably coupled to an unpowered electrode of the station. For example, in the case where the pedestal is a powered electrode of the station, the variable reactive element may be operably coupled to the showerhead. As another example, in the case where the showerhead is a powered electrode, the variable reactive element may be operably coupled to the pedestal.

[0049] Since the circuit elements representing various station components or areas (e.g., as in Figure 2 As shown in and above combination Figure 2 The contents described above are usually coupled in series, so varying the variable reactance element can adjust the voltage throughout the station. For example, varying the reactance of the variable reactance element will cause the voltage associated with the base (e.g., V ped , as in Figure 2 As shown in and above combination Figure 2 The contents of the above) and / or the voltage across the nozzle (e.g., V shd , as in Figure 2 As shown in and above combination Figure 2 changes in the content described).

[0050] According to some embodiments, Figure 3 Shows the depiction Figure 2The reactor is a component of the present invention and includes a nozzle operably coupled to the nozzle (i.e., Figure 2 Schematic diagram of a variable reactance element of a reactor (not powered electrode of a reactor). As depicted, variable capacitor 302 is operably coupled to showerhead 216. By tuning variable capacitor 302, the voltage (V shd ) and the voltage associated with the base (V ped ).

[0051] As described above, adjustment of the variable reactive element may cause a voltage change in one or more voltages associated with the station. The one or more voltages may include a voltage across the showerhead, a voltage at an upper portion or top of the pedestal (e.g., where the wafer resides during processing), etc. Note that the voltage change occurs regardless of whether the variable reactive element is operably coupled to the showerhead (e.g., in the case where the pedestal is a powered electrode) or the variable reactive element is operably coupled to the pedestal (e.g., in the case where the showerhead is a powered electrode).

[0052] It should be noted that the change in one or more voltages may depend on the characteristics of the plasma present in the station. Figure 2 and Figure 3 Described in and above combined Figure 2 and Figure 3 The contents can be connected by a series resistor (R plasma ) and capacitor (C plasma ) represents the plasma. Continuing with this example, the characteristics of the plasma may affect the value of the resistance and / or capacitance representing the plasma. The value of the resistance and / or capacitance representing the plasma may in turn affect the change of one or more voltages. In some implementations, C plasma The value of can be in the range of about 200 pF to about 1200 pF and can correspond to a plasma sheath thickness of about 0.25 mm to about 1.5 mm. In some implementations, the value of can be at least partially dependent on the resistance (R plasma ). For example, in some embodiments, larger voltage changes may be possible at relatively low plasma resistances (e.g., about 0.5 ohms, about 1 ohm, about 1.5 ohms, about 2 ohms, etc.) relative to higher plasma resistances (e.g., above about 9 ohms, above about 10 ohms, above about 15 ohms, etc.).

[0053] Figure 4A shows the voltage at the base (V ped ) Contour plot of reactance change with varying capacitors operably coupled to a station's showerhead. As depicted, the pedestal voltage may be able to vary between a range of approximately 20 to 100 (using arbitrary voltage units). Figure 4AThe contour plots are generated for various plasma characteristics (shown on the y-axis) assuming a fixed plasma resistance of 1 ohm. The x-axis shows the changing value of the variable showerhead capacitance. Note that for a given plasma capacitance (e.g., 1200 pF), the pedestal voltage can be varied between a dynamic voltage range by tuning the showerhead capacitor from 100 pF to 500 pF.

[0054] Figure 4B The voltage at the nozzle (V shd ) is a contour plot of the change in reactance with a variable capacitor operably coupled to the showerhead. In other words, Figure 4A and 4B Both are variations in the reactance of the variable sprinkler capacitor, but show variations at different areas of the station (i.e. Figure 4A Middle base, and Figure 4B The change of the voltage of the nozzle. Similar to the above combination Figure 4A The content described, Figure 4A The contour plots of are generated for various plasma characteristics (shown on the y-axis) assuming a fixed plasma resistance of 1 ohm. The x-axis shows the changing value of the variable showerhead capacitance. Note that for a given plasma capacitance (e.g., 1200 pF), the showerhead voltage can be varied between a dynamic voltage range by tuning the showerhead capacitor from 100 pF to 500 pF.

[0055] In some implementations, during and / or before the execution of a plasma operation, one or more target voltages associated with a component of a station in which a plasma operation is being performed or is to be performed are determined. The one or more target voltages may be associated with a pedestal of the station (e.g., the top of the pedestal on which the wafer is located during processing), a showerhead of the station, and the like. The plasma operation may be a plasma-based etching operation or a plasma-based deposition operation. In some embodiments, the one or more target voltages may be determined based on a target voltage indicated in a recipe to be implemented at the station. In some embodiments, for example, in a case where the goal is to minimize the voltage across the showerhead, a target voltage in the one or more target voltages may be 0 volts, or other minimum voltage. In some cases, target voltages may be specified for a particular component at multiple frequencies, such as multiple RF drive frequencies, harmonics of multiple RF drive frequencies, DC, and the like. In some implementations, the target voltages for a particular component may be determined based on an estimate of near real-time or universal plasma characteristics (e.g., during the execution of a plasma operation). In some embodiments, an optical sensor (eg, one or more camera devices) having a viewport pointed into the station may be used to estimate or determine near real-time or universal plasma properties.

[0056] In some embodiments, the value of at least one variable reactive element associated with a component of the station may be determined based at least in part on one or more target voltages. In some embodiments, the variable reactive element may be a variable inductor and / or a variable capacitor. In some implementations, the variable reactive element may be a network of reactive elements (e.g., a plurality of reactive elements) such that different reactances may be selected by, for example, selecting different nodes of the network at different frequencies. In some implementations, the variable reactive element may be a fixed hardware element that may be easily replaced in the field. Such fixed hardware elements may include capacitors, inductors, or other similar objects that are relatively low cost and / or easily replaced.

[0057] In some embodiments, at least one variable reactive element may be associated with a specific component of the station. The component may correspond to an unpowered electrode of the station. For example, as described above in conjunction with Figure 3 As described above, in the case where the base is a powered electrode, at least one variable reactive element can be operably coupled to the showerhead. As another example, in the case where the showerhead is a powered electrode, at least one variable reactive element can be operably coupled to the base.

[0058] In some embodiments, a lookup table may be used to determine the value of at least one variable reactive element. For example, one or more target voltages may be used as a key to a lookup table to determine the value of at least one variable reactive element that will produce a voltage that is closer to one or more target voltages relative to the current voltage value. It should be noted that in some cases, it is possible to drive the voltage associated with a particular component to substantially match the target voltage associated with the component. For example, the voltage may fall within a predetermined range of the target voltage associated with the component (e.g., within a range of + / -1%, + / -5%, + / -10%, or the like). In other cases, it is only possible to drive the voltage associated with a particular component closer to the target voltage relative to the current voltage associated with the component. In addition, it should be noted that in cases where multiple target voltages are used (e.g., a target voltage for a showerhead and a target voltage for a base), it may not be possible to match the multiple target voltages by tuning at least one variable reactive element. In such cases, the value of at least one reactive element may be selected to optimize the values ​​of the multiple voltages. In addition or alternatively, the value of at least one reactive element may also be selected to prioritize a subset of one or more target voltages. For example, in a case where the target voltage includes a pedestal voltage and a nozzle voltage, one or the other may be prioritized when determining the value of at least one variable reactance element to drive the voltage of the prioritized component voltage toward the corresponding target voltage with less consideration of the other component voltage.

[0059] After determining the value of the at least one variable reactive element, the at least one variable reactive element may be tuned or actuated to have the determined value. For example, a stepper motor may be utilized to cause the at least one variable reactive element to have the determined value. As a more specific example, a stepper motor may rotate the plates of a variable capacitor to achieve the determined reactance value. As another example, in the case where the at least one variable reactive element comprises a variable inductor, a solid core within a solenoid may be moved or positioned (e.g., using a stepper motor) to achieve a target inductance.

[0060] Figure 5 is a flow chart of an exemplary process 500 for tuning a variable reactive element to adjust a voltage associated with a station in which a plasma operation is being performed or is to be performed. In some implementations, blocks of process 500 may be performed by a controller or a processor associated with the station or a processor associated with a processing chamber associated with the station. In some embodiments, a process other than Figure 5 The blocks of process 500 may be performed in an order other than the order shown. In some implementations, two or more blocks of process 500 may be performed substantially in parallel. In some implementations, one or more blocks of process 500 may be omitted.

[0061] Process 500 may begin at 502, where one or more target voltages associated with a component of a station in which a plasma operation is being performed or is to be performed are determined during or prior to the execution of a plasma operation. The plasma operation may be a plasma-based etching operation or a plasma-based deposition operation. The one or more voltages may be associated with a showerhead of the station, a pedestal of the station (e.g., the top of the pedestal, where the wafer resides during processing), or the like. The one or more target voltages may be determined based on a recipe being implemented or to be implemented in the station. For example, the recipe may specify one or more target voltages. In some embodiments, the one or more target voltages may be based on a determination of a general plasma characteristic of the plasma within the station (e.g., during the execution of the plasma operation). The general plasma characteristic may indicate plasma uniformity or a plasma center of mass position within the station or within a region of the station. In some embodiments, the plasma characteristic may be determined based on optical data obtained from one or more optical sensors (e.g., a camera sensor) of the station. In some implementations, the one or more target voltages may be determined to modify the plasma characteristic toward a desired or optimal plasma characteristic. In some embodiments, at least one target voltage may be 0, or other minimum voltage value. For example, a target voltage associated with an unpowered electrode of a station may be determined to be 0 at a particular frequency so that the unpowered electrode may be considered to be DC grounded when the target voltage is reached.

[0062] At 504, the process 500 may determine a value of at least one variable reactive element associated with a component of the station based at least in part on one or more target voltages. For example, as described above, the process 500 may use the one or more target voltages as a key to a lookup table to identify the value of at least one variable reactive element that drives the component voltage of the station toward the one or more target voltages. In some implementations, the value of the at least one reactive element may be determined by considering multiple target voltages associated with multiple components. In addition or alternatively, in some implementations, the value of the at least one reactive element may also be determined by prioritizing a target voltage associated with a single component of the station. As described above, the at least one variable reactive element may include a variable capacitor, a variable inductor, and / or a variable reactive network that can be selectively tuned for different frequencies. The at least one variable reactive element may be associated with an unpowered electrode of the station.

[0063] At 506, process 500 can cause at least one variable reactive element to have a determined value, thereby causing one or more voltages associated with a component of the station to move toward one or more target voltages. For example, process 500 can cause a stepper motor to actuate a plate of a variable capacitor to achieve a target reactance of the variable capacitor. As another example, process 500 can actuate a core within a solenoid to achieve a target reactance of a variable inductor.

[0064] It should be noted that in some implementations, blocks of process 500 may be cycled multiple times. For example, process 500 may be performed during or before each step of a recipe. As another example, process 500 may be performed after certain process conditions have been achieved (e.g., as specified in a recipe) to perform further adjustments to the process, i.e., by adjusting voltages of various components after other process conditions have been locked or fixed. Background of the Disclosed Computing Implementations

[0065]

[0013] Some embodiments disclosed herein relate to computing systems for regulating voltage during plasma operation.

[0066] Many types of computer systems with any of a variety of computer architectures may be employed as disclosed systems for implementing the algorithms as described herein. For example, the system may include software components executed on one or more general purpose processors or specially designed processors, or specially designed processors such as application specific integrated circuits (ASICs) or programmable logic devices (e.g., field programmable gate arrays (FPGAs)). In addition, the system may be implemented on a single device or distributed across multiple devices. The functions of the computing elements may be combined with each other or further split into multiple submodules.

[0067] In some embodiments, the code executed during the generation or execution of the techniques described herein on an appropriately programmed system may be embodied in the form of software elements that can be stored in a non-volatile storage medium (e.g., a CD, a flash memory device, a removable hard drive, etc.), which includes some instructions for making a computer device (e.g., a personal computer, a server, a network device, etc.).

[0068] In one level, software elements are implemented as a set of commands prepared by a programmer / developer. However, modular software that can be executed by computer hardware uses "machine code" selected from a specific machine language instruction set, or "native instructions" designed into the hardware processor to submit executable code to the memory. The machine language instruction set, or native instruction set, is known and basically built into the hardware processor. This is the "language" used by system and application software to communicate with the hardware processor. Each native instruction is a discrete code recognized by the processing architecture, and the discrete code can specify a specific buffer for arithmetic, addressing, or control functions; a specific memory location or offset; and a specific addressing mode for interpreting operands. More complex operations are established by combining these simple native instructions, which are executed in sequence or in other ways guided by control flow instructions.

[0069] The relationship between executable software instructions and hardware processors is structural. In other words, the instructions themselves are a series of symbols or values. They do not inherently convey any information. The processor is pre-configured by design to interpret the symbols / values, thereby giving meaning to the instructions.

[0070] The methods and techniques used herein can be configured to be executed on a single machine at a single location, or on multiple machines at a single location, or on multiple machines at multiple locations. When multiple machines are employed, each machine can be customized for a specific task. For example, operations requiring large coding blocks and / or significant processing power can be implemented on large and / or fixed machines.

[0071] In addition, some embodiments relate to tangible and / or non-temporary computer-readable media or computer program products and include program instructions and / or data (including data structures) for performing various computer-implemented operations. Examples of computer-readable media include, but are not limited to, semiconductor memory devices, phase change devices, magnetic media such as disk drives, tapes, optical media such as CDs, magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as read-only memory devices (ROM) and random access memories (RAM). Computer-readable media can be directly controlled by end users or can be indirectly controlled by end users. Examples of directly controlled media include media located at user facilities and / or media not shared with other entities. Examples of indirectly controlled media include media that can be indirectly accessed by users via external networks and / or via servers that provide shared resources such as "clouds". Examples of program instructions include both machine codes produced by compilers and archives containing high-order coding that can be executed by computers using interpreters.

[0072] In various embodiments, data or information used in the disclosed methods and apparatus are provided in electronic format. Such data or information may include various coefficients and the like to be used in calculations. As used herein, data or other information provided in electronic format may be stored on a machine and may be transmitted between machines. Conventionally, electronic format data is provided digitally and may be stored as bits and / or bytes in various data structures, lists, databases, etc. Data may be embodied electronically, optically, etc.

[0073] System software is typically interfaced with computer hardware and associated memory. In some embodiments, system software includes operating system software and / or firmware, as well as any middleware and drivers installed in the system. System software provides the basic non-task-specific functions of the computer. In contrast, modules and other application software are used to implement specific tasks. Each native instruction for a module is stored in a memory device and represented using a numerical value.

[0074] Figure 6 6 is a block diagram of an example of a computing device 600 suitable for implementing some embodiments of the present disclosure. For example, the device 600 may be suitable for implementing some or all of the functionality of the image analysis logic disclosed herein.

[0075] The computing device 600 may include a bus 602 that directly or indirectly couples the following devices: a memory 604, one or more central processing units (CPUs) 606, one or more graphics processing units (GPUs) 608, a communication interface 1010, an input / output (I / O) port 612, an input / output component 614, a power supply 616, and one or more presentation components 618 (e.g., a display). In addition to the CPU 606 and the GPU 608, the computing device 600 may also include Figure 6 Additional logic devices not shown include, but are not limited to, an image signal processor (ISP), a digital signal processor (DSP), an ASIC, an FPGA, etc.

[0076] although Figure 6 The various blocks of are shown as being connected by wires via bus 602, but this is not intended to be limiting and is for clarity only. For example, in some embodiments, presentation components 618 such as a display device may be considered I / O components 614 (e.g., if the display is a touch screen). As another example, CPU 606 and / or GPU 608 may include memory (e.g., memory 604 may represent a storage device in addition to the memory of GPU 608, CPU 606, and / or other components). In other words, Figure 6 The computing devices described in the present disclosure are illustrative only. No distinction is made between categories such as "workstations," "servers," "laptops," "desktops," "tablets," "client devices," "mobile devices," "handheld devices," "electronic control units (ECUs)," "virtual reality systems," and / or other device or system types, as all of these are contemplated under Figure 6 within the range of computing devices.

[0077] The bus 602 may represent one or more buses, such as an address bus, a data bus, a control bus, or a combination thereof. The bus 1002 may include one or more bus types, such as an Industry Standard Architecture (ISA) bus, an Extended Industry Standard Architecture (EISA) bus, a Video Electronics Standards Association (VESA) bus, a Peripheral Component Interconnect (PCI) bus, a Peripheral Component Interconnect Express (PCIe) bus, and / or other types of buses.

[0078] Memory 604 may include any of a variety of computer-readable media. Computer-readable media may be any available media that can be accessed by computing device 600. Computer-readable media may include volatile and non-volatile media, and removable and non-removable media. By way of example and not limitation, computer-readable media may include computer storage media and / or communication media.

[0079] Computer storage media may include volatile and nonvolatile media and / or removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules, and / or other data types. For example, memory 1004 may store computer readable instructions (e.g., representing programs and / or program elements, such as an operating system). Computer storage media may include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by computing device 1000. As used herein, computer storage media itself does not include signals.

[0080] Communication media may embody computer-readable instructions, data structures, program modules, and / or other data types in a modulated data signal such as a carrier wave or other transport mechanism, and include any information delivery media. The term "modulated data signal" may refer to a signal having one or more of its characteristics that are set or changed in such a way as to encode information in the signal. By way of example and not limitation, communication media may include wired media such as a wired network or a direct wire connection, and wireless media such as acoustic, RF, infrared, and other wireless media. Combinations of any of the above items should also be included within the scope of computer-readable media.

[0081] The CPU 606 may be configured to execute computer-readable instructions to control one or more components of the computing device 600 to perform one or more of the methods and / or processes described herein. The CPUs 606 may each include one or more cores (e.g., one, two, four, eight, twenty-eight, seventy-two, etc.) capable of processing multiple software threads simultaneously. The CPU 606 may include any type of processor and may include different types of processors, depending on the type of computing device 600 implemented (e.g., a processor with fewer cores for a mobile device and a processor with more cores for a server). For example, depending on the type of computing device 600, the processor may be an ARM processor implemented using reduced instruction set computing (RISC) or an x86 processor implemented using complex instruction set computing (CISC). In addition to one or more microprocessors or auxiliary coprocessors (e.g., math coprocessors), the computing device 600 may also include one or more CPUs 606.

[0082] GPU 608 can be used by computing device 600 to render graphics (e.g., 3D graphics). GPU 608 may include many (e.g., tens, hundreds, or thousands) cores capable of processing many software threads simultaneously. GPU 608 may generate pixel data of an output image in response to a rendering command (e.g., a rendering command from CPU 606 received via a host interface). GPU 608 may include a graphics memory, such as a display memory, for storing pixel data. Display memory may be included as part of memory 604. GPU 608 may include two or more GPUs operating in parallel (e.g., via a link). When combined, each GPU 608 may generate pixel data of different parts of an output image or different output images (e.g., a first GPU for a first image, a second GPU for a second image). Each GPU may contain its own memory or may share memory with other GPUs.

[0083] In examples where computing device 600 does not include GPU 608 , CPU 606 may be used to render graphics.

[0084] The communication interface 610 may include one or more receivers, transmitters, and / or transceivers that enable the computing device 600 to communicate with other computing devices via an electronic communication network (including wired and / or wireless communications). The communication interface 610 may include components and functionality that enable communication over any of a variety of different networks, such as wireless networks (e.g., Wi-Fi, Z-Wave, Bluetooth, Bluetooth LE, ZigBee, etc.), wired networks (e.g., communicating over Ethernet), low-power wide area networks (e.g., LoRaWAN, SigFox, etc.), and / or the Internet.

[0085] I / O ports 612 can enable computing device 600 to be logically coupled to other devices, including coupling to I / O components 614, presentation components 618, and / or other components, some of which can be built into (e.g., integrated into) computing device 600. Illustrative I / O components 614 include microphones, mice, keyboards, joysticks, tracking pads, satellite antennas, scanners, printers, wireless devices, etc. I / O components 614 can provide a natural user interface (NUI) that processes air gestures, voice, or other physiological inputs generated by users. In some cases, the input can be transmitted to appropriate network elements for further processing. NUI can implement any combination of speech recognition, stylus recognition, facial recognition, biometric recognition, gesture recognition on and near the screen, air gestures, head and eye tracking, and touch recognition (as described in more detail below) related to the display of computing device 600. Computing device 600 may include a depth camera, such as a stereo camera system, an infrared camera system, an RGB camera system, a touch screen technology, and a combination of these, to perform gesture detection and recognition. Additionally, computing device 600 may include an accelerometer or gyroscope that enables detection of motion (e.g., as part of an inertial measurement unit (IMU)). In some examples, computing device 600 may use the output of the accelerometer or gyroscope to render an immersive augmented reality or virtual reality.

[0086] The power supply 616 may include a hardwired power supply, a battery power supply, or a combination thereof. The power supply 616 may provide power to the computing device 600 to enable the components of the computing device 600 to operate.

[0087] The presentation component 618 may include a display (e.g., a monitor, a touch screen, a television screen, a head-up display (HUD), other display types, or combinations thereof), speakers, and / or other presentation components. The presentation component 618 may receive data from other components (e.g., GPU 608, CPU 606, etc.) and output the data (e.g., as images, video, sound, etc.).

[0088] The present disclosure may be described in the general context of computer code or machine-usable instructions, including computer-executable instructions (e.g., program modules) executed by a computer or other machine (e.g., a personal data assistant or other handheld device). In general, program modules, including routines, programs, objects, components, data structures, etc., refer to code that performs specific tasks or implements specific abstract data types. The present disclosure may be practiced in a variety of system configurations, including in handheld devices, consumer electronics, general-purpose computers, more specialized computing devices, etc. The present disclosure may also be practiced in distributed computing environments, where tasks are performed by remote processing devices that are linked through a communications network. in conclusion

[0089] In the description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments presented. The disclosed embodiments may be implemented without some or all of these specific details. In other respects, well-known process operations are not described in detail in order not to unnecessarily obscure the disclosed embodiments. Although the disclosed embodiments are described in conjunction with specific embodiments, it will be understood that the specific embodiments are not intended to limit the disclosed embodiments.

[0090] Unless otherwise indicated, the method operations and apparatus features disclosed herein involve techniques and devices commonly used in metrology, semiconductor device manufacturing technology, software design and programming, and statistics, all of which are within the scope of the art.

[0091] Unless otherwise defined herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Various scientific dictionaries including the terms contained herein are well known and available to those skilled in the art. Certain methods and materials are described, but any methods and materials similar or equivalent to those described herein are useful in the practice or testing of the embodiments disclosed herein.

[0092] Numerical ranges include the numbers that define the ranges. It is intended that each maximum numerical limit given throughout this specification include each lower numerical limit, just as such lower numerical limits are explicitly written herein. Each minimum numerical limit given throughout this specification will include each higher numerical limit, just as such higher numerical limits are explicitly written herein. Each numerical range given throughout this specification will include each narrower numerical range that falls within such a wider numerical range, just as such narrower numerical ranges are explicitly written herein.

[0093] The headings provided herein are not intended to limit the disclosure.

[0094] As used herein, the singular terms "a," "an," and "the" include plural referents unless the context clearly indicates otherwise. As used herein, the term "or" refers to a non-exclusive or unless otherwise indicated.

[0095] Various computing components (including processors, memory, instructions, routines, modules, or other components) may be described or claimed as being "configured to" perform a task or tasks. In such contexts, the phrase "configured to" is used to represent structure by indicating that the component includes structure (e.g., stored instructions, circuits, etc.) that performs the task or tasks during operation. Thus, even when the particular component is not necessarily currently operational (e.g., not in a turned-on state), it can be said that the unit / circuit / component is configured to perform a task.

[0096] The components used with the "configured to" language may refer to hardware, such as circuits, memory that stores executable program instructions to implement operations, etc. In addition, "configured to" may refer to a general structure (e.g., a general circuit) manipulated by software and / or firmware (e.g., an FPGA or a general processor that executes software) to operate in a manner that can perform the task. In addition, "configured to" may refer to one or more memories or a memory element that stores computer executable instructions for performing the task (one or more). Such a memory element may include a memory on a computer chip with processing logic. In some cases, "configured to" may also include using a manufacturing process (e.g., a semiconductor manufacturing facility) to manufacture a device (e.g., an integrated circuit) that is adopted to implement or perform one or more tasks.

Claims

1. A system comprising: a processing chamber configured for performing a semiconductor manufacturing process involving plasma-based operations; at least one variable reactive element operably coupled to an unpowered electrode of the process chamber; as well as A controller configured to: determining, during or prior to performance of the plasma-based operation, one or more target voltages associated with one or more components of the processing chamber; determining a value of the at least one variable reactive element based at least in part on the one or more target voltages; as well as The at least one variable reactive element is caused to have the determined value, wherein causing the at least one variable reactive element to have the determined value causes one or more voltages associated with the one or more components of the processing chamber to move toward the one or more target voltages.

2. The system of claim 1, wherein the unpowered electrode of the process chamber comprises a showerhead of the process chamber, and wherein at least one variable reactive element is electrically connected to or disposed in the showerhead.

3. The system of claim 1 , wherein the unpowered electrode of the processing chamber is a base of the processing chamber, wherein the at least one variable reactance element is electrically connected to or disposed in the base of the processing chamber.

4. The system of any one of claims 1 to 3, wherein causing the one or more voltages associated with the one or more components of the processing chamber to move toward the one or more target voltages reduces the likelihood of a parasitic plasma within the processing chamber.

5. The system of any one of claims 1 to 3, wherein at least one of the one or more target voltages is a voltage associated with an unpowered showerhead of the processing chamber.

6. The system of any one of claims 1 to 3, further comprising a susceptor configured to support a wafer undergoing the semiconductor manufacturing process, and wherein at least one of the one or more target voltages is a voltage located at a position proximate to a stationary position of the wafer.

7. A system according to claim 6, wherein causing the at least one variable reactance element to have the determined value causes: the voltage at the position located near the stationary position of the chip is significantly lower than the voltage at the position before causing the at least one variable reactance element to have the determined value.

8. The system of claim 6, further comprising a radio frequency (RF) generator operably coupled to the base.

9. The system of any one of claims 1 to 3, wherein the at least one variable reactive element comprises a variable capacitor.

10. The system of claim 9, further comprising a stepper motor operably coupled to the variable capacitor, and wherein the controller is configured to cause the variable capacitor to have the determined value by actuating the stepper motor.

11. The system of claim 9, wherein the value of the variable capacitor is determined based on an inductance associated with the unpowered electrode.

12. The system of any one of claims 1 to 3, wherein the at least one variable reactive element comprises a variable inductor.

13. The system of any one of claims 1 to 3, wherein the at least one variable reactive element comprises a network configured to provide different reactances for different frequencies.

14. The system of claim 13, wherein the different frequencies comprise: DC, multiple RF drive frequencies, multiple harmonics of one or more RF drive frequencies, or any combination thereof.

15. The system of any one of claims 1 to 3, wherein the at least one variable reactive element comprises a replaceable hardware element.

16. The system of any one of claims 1 to 3, wherein the plasma operation is a plasma-based etching operation or a plasma-based deposition operation.

17. A method for regulating a voltage in a processing chamber, the method comprising: determining, during or prior to performance of a plasma-based operation within a processing chamber, one or more target voltages associated with one or more components of the processing chamber, the processing chamber comprising an unpowered electrode; determining a value of at least one variable reactive element operatively coupled to the unpowered electrode; The at least one variable reactive element is caused to have the determined value, wherein causing the at least one variable reactive element to have the determined value causes one or more voltages associated with the one or more components of the processing chamber to move toward the one or more target voltages.

18. A method according to claim 17, wherein determining the value of the at least one variable reactance element includes: using the one or more target voltages as key values ​​of a lookup table to identify the value of the at least one variable reactance element that causes the one or more voltages associated with the one or more components to fall within a predetermined range of the one or more target voltages.

19. A method according to any one of claims 17 or 18, wherein determining the value of the at least one variable reactive element is based on a circuit model of at least a portion of the processing chamber, wherein the circuit model includes the at least one variable reactive element.

20. The method of claim 19, wherein the circuit model includes one or more circuit elements associated with a plasma formed in the processing chamber.

21. The method of claim 20, wherein the one or more circuit elements associated with the plasma include a resistor representing a resistance of a plasma and a capacitor representing a capacitance associated with a plasma sheath.

22. The method of claim 19, wherein the at least one variable reactive element comprises a variable capacitor, and wherein the circuit model comprises the variable capacitor coupled in series to an inductor, the inductor representing the inductance of the unpowered electrode.

23. The method of claim 22, wherein the value of the variable capacitor is determined to be a value that causes an impedance associated with the variable capacitor to substantially cancel an impedance associated with the inductor representing the inductance of the unpowered electrode.

24. The method of any one of claims 17 or 18, wherein the unpowered electrode comprises a pedestal of the processing chamber.

25. The method of any one of claims 17 or 18, wherein the at least one variable reactive element comprises a variable inductor.

26. The method of any one of claims 17 or 18, wherein the value of the at least one variable reactive element is determined based at least in part on plasma characteristics determined from optical data captured by an optical sensor.

27. The method of any one of claims 17 or 18, wherein the value of the at least one variable reactive element is determined based at least in part on plasma characteristics determined based on electrical power, voltage, current, and / or phase measurements of RF signals measured in: one or more regions of the processing chamber; an RF power delivery system; or any combination thereof.

28. The method of any one of claims 17 or 18, wherein the value of the at least one variable reactive element is determined based at least in part on a plasma characteristic determined from a DC bias signal measured at one or more of a powered electrode or the unpowered electrode.

29. The method of any one of claims 17 or 18, wherein the value of the at least one variable reactive element is determined based at least in part on a plasma characteristic determined from an electrical plasma diagnostic in the processing chamber.

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