Plasma processing system including segmented upper electrode connected to variable impedances

Abstract

A plasma processing system for processing substrates includes a variable impedance circuit for providing S impedances at a first RF frequency for each of S segments of a first electrode, respectively, where S is an integer greater than one. For each of the S segments, the variable impedance circuit includes a switched resistor circuit including a first plurality of resistors and a first plurality of switches configured to vary an impedance of the switched resistor circuit in a first impedance range at the first RF frequency and a switched capacitor circuit including a second plurality of resistors, a plurality of capacitors and a second plurality of switches configured to vary an impedance of the switched capacitor circuit in a second impedance range at the first RF frequency. A switch configuration controller is configured to select one of the switched resistor circuit and the switched capacitor circuit.

Description

Attorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POAPLASMA PROCESSING SYSTEM INCLUDING SEGMENTED UPPERELECTRODE CONNECTED TO VARIABLE IMPEDANCESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 717,033 filed on November 6, 2024. The entire disclosure of the above application is incorporated herein by reference.FIELD

[0002] The present disclosure relates to plasma processing systems for substrates, and more particularly to plasma processing systems including a segmented electrode connected to variable impedances.BACKGROUND

[0003] The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

[0004] Substrate processing systems may be used to treat substrates such as semiconductor wafers. The substrate treatments may include deposition, etching, cleaning, and / or other treatments. During processing, a substrate is arranged on a substrate support in a processing chamber of the substrate processing system. Gas mixtures are introduced into the processing chamber using a gas delivery device. In some processes, radio frequency (RF) plasma may be used to initiate chemical reactions.

[0005] When generating plasma, the substrate processing system may include an RF plasma generator including an RF source and a matching network that supply RF voltage / power to a first electrode in the substrate support. The substrate is arranged on the substrate support between the first electrode and a second electrode. The second electrode includes a plate that is grounded. When using a grounded electrode, plasma density varies as a radial distance of the substrate varies. The plasma density variations cause processing non-uniformities.Attorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POASUMMARY

[0006] A plasma processing system for processing substrates includes a variable impedance circuit for providing S impedances at a first RF frequency for each of S segments of a first electrode, respectively, where S is an integer greater than one. For each of the S segments, the variable impedance circuit includes a switched resistor circuit including a first plurality of resistors and a first plurality of switches configured to vary an impedance of the switched resistor circuit in a first impedance range at the first RF frequency and a switched capacitor circuit including a second plurality of resistors, a plurality of capacitors and a second plurality of switches configured to vary an impedance of the switched capacitor circuit in a second impedance range at the first RF frequency. A switch configuration controller is configured to select one of the switched resistor circuit and the switched capacitor circuit.

[0007] In other features, the second impedance range is greater than the first impedance range. The switch configuration controller is configured to select the switched resistor circuit when one of the S impedances for a corresponding one of the S segments is in the first impedance range. The switch configuration controller is configured to select the switched capacitor circuit when the one of the S impedances for the corresponding one of the S segments is in the second impedance range.

[0008] In other features, the first electrode is arranged above a substrate support. The S segments of the first electrode are arranged concentrically and include gaps located therebetween.

[0009] In other features, the substrate support including a second electrode. A plasma generator is configured to supply RF voltage at a first RF frequency to the second electrode to generate and maintain plasma. The first plurality of resistors of the switched resistor circuit are connected in series and the first plurality of switches are connected in parallel across the first plurality of resistors. The variable impedance circuit is configured to select states of the first plurality of switches to set at least one of the S impedances in the first impedance range.

[0010] In other features, a first capacitor is connected between at least one of the first plurality of switches and ground. Pairs of the plurality of capacitors and the second plurality of switches are connected in series across one of the second plurality of resistors. The variable impedance circuit is configured to select states of the second plurality of switches to set at least one of the S impedances in the second impedanceAttorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA range. A first capacitor and a second capacitor are connected between first and second terminals of at least one of the second plurality of switches and ground. A filter is arranged between the variable impedance circuit and each of the S segments. The filter passes the first RF frequency and blocks a second RF frequency greater than the first RF frequency. The first RF frequency is in a range from 100 kHz to 500 kHz and the second RF frequency is greater than 5 MHz.

[0011] In other features, the variable impedance circuit includes an impedance measuring circuit configured to measure an impedance between the corresponding ones of the S segments and ground. Prior to the impedance measuring circuit measuring capacitive coupling between the corresponding ones of the S segments and ground, the switch configuration controller is configured to connect the impedance measuring circuit to the corresponding ones of the S segments.

[0012] In other features, the variable impedance circuit includes one of a model and a lookup table configured to determine at least one of the S impedances for the corresponding one of the S segments. The one of the model and the lookup table is indexed by the impedance that is measured between the corresponding ones of the S segments and ground. The switch configuration controller and the impedance measuring circuit are configured to measure an impedance of the switched resistor circuit. The switch configuration controller and the impedance measuring circuit are configured to measure an impedance of the switched capacitor circuit.

[0013] In other features, sides of the S segments are configured to prevent line of sight from plasma through the gaps. Sides of the S segments are one of stair-stepped or sloped. The S segments include a plurality of gas through holes. An insulating gel is arranged between the S segments and a grounded surface.

[0014] A plasma processing system for processing substrates includes a variable impedance circuit for providing S impedances at a first RF frequency for each of S segments of a first electrode, respectively, where S is an integer greater than one. For each of the S segments, the variable impedance circuit includes a series resonance circuit including a first inductor and a variable capacitor configured to vary an impedance of the series resonance circuit in a first impedance range at the first RF frequency. A switched capacitor circuit includes a first plurality of resistors, a plurality of capacitors, and a first plurality of switches configured to vary an impedance of the switched capacitor circuit in a second impedance range at the first RF frequency. A switch configurationAttorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA controller is configured to select one of the series resonance circuit and the switched capacitor circuit.

[0015] In other features, the second impedance range is greater than the first impedance range. The switch configuration controller is configured to select the series resonance circuit when one of the S impedances for a corresponding one of the S segments is in the first impedance range. The switch configuration controller is configured to select the switched capacitor circuit when the one of the S impedances for the corresponding one of the S segments is in the second impedance range.

[0016] In other features, the first electrode is arranged above a substrate support. The S segments of the first electrode are arranged concentrically and include gaps located therebetween.

[0017] In other features, the substrate support including a second electrode. A plasma generator is configured to supply RF voltage at a first RF frequency to the second electrode to generate and maintain plasma. The first inductor and the variable capacitor are connected in series between an input of the series resonance circuit and ground. The series resonance circuit further includes a capacitor connected in parallel to the input of the series resonance circuit. A switch is connected in series with a first resistor between ground and the input of the series resonance circuit.

[0018] In other features, the series resonance circuit further includes a voltage sensor configured to sense DC and AC voltage at the input of the series resonance circuit. Pairs of the plurality of capacitors and the first plurality of switches are connected in series across one of the first plurality of resistors.

[0019] In other features, the variable impedance circuit is configured to select states of the first plurality of switches to set at least one of the S impedances in the second impedance range. A first capacitor and a second capacitor are connected to first and second terminals of at least one of the first plurality of switches and ground. A filter is arranged between the variable impedance circuit and each of the S segments. The filter passes the first RF frequency and blocks a second RF frequency greater than the first RF frequency. The first RF frequency is in a range from 100 kHz to 500 kHz and the second RF frequency is greater than 5 MHz.

[0020] In other features, the variable impedance circuit includes an impedance measuring circuit configured to measure capacitive coupling between the correspondingAttorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA ones of the S segments and ground. Prior to the impedance measuring circuit measuring capacitive coupling between the corresponding ones of the S segments and ground, the switch configuration controller is configured to connect the impedance measuring circuit to the corresponding ones of the S segments.

[0021] In other features, the variable impedance circuit includes one of a model and a lookup table configured to determine at least one of the S impedances for the corresponding one of the S segments. The one of the model and the lookup table is indexed by inductance that is measured between the corresponding ones of the S segments and ground.

[0022] In other features, the variable impedance circuit and the switch configuration controller are configured to measure impedance of the series resonance circuit. The variable impedance circuit and the switch configuration controller are configured to measure impedance of the switched capacitor circuit.

[0023] Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims, and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0025] FIG. 1 A is a functional block diagram of an example of a processing chamber including an RF plasma generator, a grounded non-segmented upper electrode, and a lower electrode that receives an RF voltage to generate plasma in the processing chamber;

[0026] FIG. 1 B is a functional block diagram of an example of a processing chamber including an RF plasma generator, a segmented upper electrode with one or more floating segments, and a lower electrode that receives an RF voltage to generate plasma in the processing chamber according to the present disclosure;

[0027] FIGS. 2A to 2E show examples of variations in ion tilt and plasma density as a function of substrate radius when using electrodes with various combinations of floating and / or grounded segment(s) according to the present disclosure;Attorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA

[0028] FIG. 3 is a functional block diagram of an example of a segmented electrode with segments connected to variable impedances according to the present disclosure;

[0029] FIG. 4 is a side cross sectional view of an example of a temperature-controlled, segmented electrode and a variable impedance circuit according to the present disclosure;

[0030] FIG. 5 is a side view showing an example of a segmented electrode according to the present disclosure;

[0031] FIG. 6 is a functional block diagram of an example of a variable impedance circuit including a switched resistor circuit, a switched capacitor circuit, and a switch configuration controller according to the present disclosure;

[0032] FIG. 7 is an electrical schematic of examples of the switched resistor circuit and the switched capacitor circuit according to the present disclosure;

[0033] FIG. 8 is an electrical schematic and functional block diagram of another example of a variable impedance circuit including the switched resistor circuit, the switched capacitor circuit, and the switch configuration controller according to the present disclosure;

[0034] FIG. 9 is a flowchart of an example of a method for operating the variable impedance circuit according to the present disclosure; and

[0035] FIG. 10 is an electrical schematic of examples of a series resonance circuit and the switched capacitor circuit according to the present disclosure.

[0036] In the drawings, reference numbers may be reused to identify similar and / or identical elements.DETAILED DESCRIPTION

[0037] The present disclosure relates to electrodes for plasma processing systems that include multiple segments where one or more of the segments are connected to a variable impedance. Rather than using a grounded, non-segmented electrode, the present disclosure uses an electrode that is segmented radially and includes segments that are arranged concentrically and spaced from one another by a gap.

[0038] Impedance is the opposition to alternating current presented by the combined effect of resistance and reactance in a circuit. Examples of sources of impedances include resistors, inductors, capacitors, and / or combinations thereof. For example, theAttorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA impedances can include different values of resistors, inductors, capacitors, resistors and inductors, resistors and capacitors, capacitors and inductors, and / or resistors, capacitors, and inductors. The resistors affect direct current (DC) and alternating current (AC) coupling and reactive components such as inductors and capacitors vary alternating current (AC) coupling between the segments and ground.

[0039] Varying the impedances connected to each of the segmented electrodes allows plasma density to be tuned or adjusted in a radial direction to achieve a desired plasma density pattern during substrate processing. For example, the impedances connected to the radially segmented electrodes can be used to make the plasma density more uniform from a center of a substrate to a radially outer edge of the substrate (as compared to non-segmented electrodes that are grounded). However, in other examples, the variable impedances can also be tuned for other non-uniform plasma profiles.

[0040] In some examples, the substrate support is biased by RF signals at a first RF frequency and a second RF frequency. In some examples, the variable impedance circuit includes a filter such as a notch filter that passes the first RF frequency (e.g., 100 kHz to 500 kHz (e.g., 400kHz)) and blocks the second RF frequency which is greater than the first RF frequency (e.g., greater than 1 MHz (e.g., 60 MHz)). The variable impedance circuit is configured to supply ground or a desired effective impedance to the segments while operating at the first RF frequency.

[0041] The variable impedances can be implemented using series-connected switched resistors with parallel-connected switches (to short or not short each of the resistors). However, parasitic capacitance may limit the highest effective impedance value that can be achieved using this topology. For example, when operating in the range from 300 kHz to 400 kHz, the parasitic capacitance of the resistors and / or switches limits the range of effective impedance to less than about 650 ohms even though the series-connected switched resistors provide greater than 1200 ohms. Adding additional resistors to the series-connected switched resistors to further increase the effective impedance at the first RF frequency is ineffective since the response is dominated by the parasitic capacitance at this frequency range.

[0042] The variable impedance circuit according to the present disclosure for each of the segments of the electrode includes a switched resistor circuit and a switched capacitor circuit. When the desired effective impedance value for one of the segments is less than a predetermined effective impedance value (e.g., about 650 ohms), the variableAttorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA impedance circuit selects the switched resistor circuit to provide the effective impedance value (and deselects the switched capacitor circuit). The variable impedance circuit configures the switches of the switched resistor circuit to provide the predetermined effective impedance value in a first impedance range (e.g., 0 to 650 ohms) at the first RF frequency.

[0043] When the desired effective impedance value for one of the segments is greater than the predetermined effective impedance (e.g., about 650 ohms), the variable impedance circuit selects the switched capacitor circuit to provide the desired effective impedance value (and deselects the switched resistor circuit). The variable impedance circuit sets the switches of the switched capacitor circuit to provide the effective impedance value in a second impedance range (e.g., 650 to 4200 ohms or higher values) at the first RF frequency. The variable impedance circuit provides a wider range of impedance values to provide additional control over the plasma generated by the corresponding segment.

[0044] During operation of the plasma processing system, components of the plasma processing system may change over time due to exposure to RF plasma and / or process chemistry. For example, an insulating gel may be used between the segments of the electrode and an adjacent grounded surface. As the insulating gel is exposed to RF plasma and / or process chemistry during plasma processing, the properties of the insulating gel change and capacitive coupling between the segment and the adjacent grounded surface changes or shifts. This, in turn, changes the plasma near the corresponding segment.

[0045] In some examples, the impedances of the segments are measured after an event or a predetermined period (such as a predetermined number of RF hours) occurs. The variable impedance circuit reconfigures the switches to connect an impedance measuring circuit to the segments. The impedance measuring circuit measures capacitive coupling of the segment to ground. The impedance measuring circuit uses a lookup table or model (indexed by the measured capacitive coupling of the segment) and adjusts the effective impedance value connected to the corresponding segment in response to the capacitance shift. As a result, the variable impedance circuit can maintain uniformity of the RF plasma and improve process uniformity.

[0046] Referring now to FIG. 1 A, a substrate processing system 100 includes a processing chamber 102 including a gas distribution device 104 and a substrate supportAttorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA106. In some examples, the substrate support 106 includes an electrostatic chuck (ESC). During operation, a substrate 108 is arranged on the substrate support 106. If an ESC is used, the substrate support 106 includes a baseplate 1 10. In some examples, the baseplate 110 is made of a conducting material such as aluminum. The baseplate 110 supports a top plate 1 12, which may be made of ceramic or material resistant to plasma. A bond layer 1 14 may be disposed between the top plate 1 12 and the baseplate 110 to bond the top plate 1 12 and the baseplate 110. The baseplate 1 10 may include one or more coolant channels 1 16 for flowing coolant through the baseplate 1 10. In some examples, an edge ring 1 18 is arranged around the substrate support 106 to shape the plasma.

[0047] A gas delivery system 130 includes one or more gas sources 132. The gas sources 132 supply one or more process gas mixtures. For an etching process, the process gas mixture may include carrier gas, inert gases, etching gas, etc. For a deposition process, the process gas mixture may include including carrier gas, inert gases, deposition precursor gases, etc. The gas sources 132 are connected by flow metering devices 134 (e.g., mass flow controllers and valves) to a manifold 140. An output of the manifold 140 is fed to the gas distribution device 104. In some examples, a vapor delivery system 170 includes one or more vapor delivery sources that supply vapor to the manifold 140 or connect to the gas distribution device 104 downstream from the manifold 140. In some examples, the vapor delivery system 170 includes one or more ampoules 174, vaporizers 176, and flow metering devices 178 to controllably supply the vapor to the processing chamber.

[0048] In some examples, a temperature controller 142 is connected to heating elements 144 (e.g., thermal control elements (TCEs) or resistive heaters) arranged in the top plate 1 12. The temperature controller 142 may be used to supply power to the heating elements 144 to control a temperature of the substrate support 106 and the substrate 108 during processing. The temperature controller 142 also operates a coolant assembly 146 that controls coolant flow through the coolant channels 116. For example, the coolant assembly 146 may include a coolant pump and coolant reservoir (not shown). The temperature controller 142 operates the coolant assembly 146 to selectively flow the coolant through the coolant channels 1 16 to cool the substrate support 106 and the substrate 108.Attorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA

[0049] A valve 150 and a pump 152 are connected to a gas line 148 (e.g., an exhaust gas line) and are used to control pressure within the processing chamber 102 and / or to evacuate reactants from the processing chamber 102. A plasma generator 154 includes a radio frequency (RF) source 156 to output RF voltage / power to a matching network 158. The matching network 158 matches the impedance of the RF source 156 to the impedance of the load including the processing chamber and plasma. Plasma generator 154 may include multiple RF generators and match networks combined to drive electrode baseplate 1 10. A controller 160 may be used to monitor system parameters and to control components of the substrate processing system 100 based on a recipe. One or more robots 161 may be used to deliver substrates onto, and remove substrates from, the substrate support 106.

[0050] The gas distribution device 104 includes a gas plenum 182 that distributes gas from the gas delivery system 130 and / or vapor from the vapor delivery system 170 to gas through holes 184 passing through a non-segmented electrode 186 that is grounded. In this example, the non-segmented electrode 186 comprises a circular plate made of a conducting material that is shorted to ground. The uniformity of the plasma that is generated between the non-segmented electrode 186 and the substrate 108 may vary from one radial location of the substrate 108 to another. For example, plasma density may be higher in a central region of the substrate 108 and lower in radially outer regions of the substrate 108. In some applications, the variation in plasma density causes processing non-uniformities.

[0051] Referring now to FIG. 1 B, a substrate processing system 200 according to the present disclosure includes an electrode 220 that is radially segmented and includes S segments 222-1 , 222-2, ..., and 222-S, where S is an integer greater than one. In some examples, the electrode 220 comprises an upper electrode. One or more of the S segments 222-1 , 222-2, ..., and 222-S include gas through holes 223 as described above. Positions of the powered electrode and floating / grounded electrode can be swapped. In some examples, S is greater than or equal to 2 and less than or equal to 6. An RF plasma generator 240 includes one or more RF sources 242 and one or more matching networks 244 that supply RF voltage to the baseplate 110 to strike and maintain plasma.

[0052] A first one of the S segments 222-1 is arranged at a center location above the substrate support 106. The first one of the S segments 222-1 has a circular cross section.Attorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POARemaining ones of the S segments 222-2, and 222-S have annular cross sections and are arranged concentrically around the first one of the S segments 222-1 .

[0053] As will be described further below, the S segments 222-1 , 222-2, ..., and 222-S are connected to impedances of a variable impedance segment control circuit 256, respectively. One or more of the S segments 222-1 , 222-2, ..., and 222-S is floating (rather than grounded) to allow adjustment of the plasma density in the processing chamber 102 (e.g., via a plasma density controller 248 and a sensing circuit 252). In some examples, all of the S segments 222-1 , 222-2, ..., and 222-S are floating (and connected to the same impedance or two or more different impedance values) to allow adjustment of the plasma density in the substrate processing chamber. In some examples, at least one of the S segments 222-1 , 222-2, ..., and 222-S is grounded and the remaining segments are floating (and connected to the same impedance or two or more different impedance values) to allow adjustment of the plasma density in the processing chamber 102. In some examples, the plasma density is tuned using the impedances of the variable impedance segment control circuit 256 to provide relatively uniform plasma density across the substrate in a radial direction. In other examples, other plasma density patterns are created using different combinations of grounded and / or floating segments.

[0054] The S impedances of the variable impedance segment control circuit 256 can be configured to connect the S segments to a ground connection and / or a variable impedance connected to ground. Each of the S impedances of the variable impedance segment control circuit 256 can include resistive, inductive, and / or capacitive impedances such as resistors, inductors, and / or capacitors that are connected in series and / or parallel combinations. In some examples, at least one of the S impedances of the variable impedance segment control circuit 256 is a variable impedance (rather than a direct connection to ground). In some examples, at least one of the S impedances of the variable impedance segment control circuit 256 is connected to ground (e.g., the center segment is connected to ground).

[0055] In some examples, the segments of the segmented electrode have increasing or decreasing radial widths and / or thicknesses from a center to an edge of the segmented electrode. In other examples, the segments of the segmented electrode do not have increasing or decreasing radial widths and / or thicknesses from a center to an edge of the segmented electrode. The radial thickness variation of the segments may be used toAttorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA change the radial length scale of the plasma density modulation through impedance control.

[0056] Referring now to FIGS. 2A to 2E, examples of variations in plasma density (and plasma density modulation with respect to a grounded electrode) as a function of substrate radius is shown for electrodes with various combinations of floating and / or grounded segment(s). In FIGS. 2A to 2B, a non-segmented electrode is grounded (represented by solid blocks) or floating (represented by open blocks), respectively. In FIGS. 20 to 2E, electrodes with both grounded and floating segments in various combinations have tunable plasma density profiles and plasma density modulation profiles with respect to grounded electrodes. In some examples, the segments of the electrode are symmetrical about a center of the substrate. In FIG. 20, the electrode includes an annular grounded segment arranged around a floating segment. In FIG. 2D, the electrode includes a first floating segment, an annular grounded segment arranged around the first floating segment, and a second floating segment arranged around the annular grounded segment. In FIG. 2E, the electrode includes an annular floating segment are arranged around a grounded segment.

[0057] Referring now to FIG. 3, a segmented electrode 310 is arranged above the substrate 108 on the substrate support 106. The segmented electrode 310 includes a plurality of segments 312-1 , 312-2, ..., and 312-S separated by gaps 313, where S is an integer greater than one. The shape and / or size of each of the gaps 313 may be same as, or different than, each other. One or more of the plurality of segments 312-1 , 312-2, ..., and 312-S is connected to corresponding electrical path or circuit with a variable impedance 340-1 , 340-2, ..., and 340-S (corresponding to effective impedance values Z1 , Z2, ..., and ZS at the first RF frequency). In some examples, one or more of the variable impedances 340-1 , 340-2, ..., and 340-S are connected directly to ground (e.g., a middle one of the segments). In other examples, all of the effective impedance values Z1 , Z2, ..., and ZS provide a variable impedance (and not ground). In some examples, the effective impedance values Z1 , Z2, ..., and ZS are different from one another. In other examples, one or more of the impedances Z1 , Z2, ..., and ZS are the same.

[0058] The segmented electrode allows impedance adjustment to be made in independent radial zones of the electrode to vary plasma density across the substrate. In some examples, the segmented electrode allows compensation of plasma nonuniformity from center to edge to provide a relatively flat electrode plasma density. TheAttorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA floating segmented electrode also enables a wider range of process conditions to be used in recipes (powers, pressure, etc.).

[0059] Referring now to FIG. 4, an example of a temperature-controlled upper electrode is shown. A cooling plate 414 including cooling channels 415 is arranged adjacent to a heating plate 418 including one or more resistive heaters 419. Thermal interface layers 416 are arranged between the cooling plate 414 and the heating plate 418 and between the heating plate 418 and a gas distribution plate 422.

[0060] The gas distribution plate 422 may include one or more gas plenums in fluid communication with gas through holes (not shown) extending through the gas distribution plate 422 to supply process gas to an upper surface of the electrode 440. A barrier layer 426 and a thermal gasket layer 430 are arranged between the gas distribution plate 422 and an electrode 440 including S segments 440-1 , 440-2, 440-3, ..., and 440-S. The thermal gasket layer 430 provides electrical insulation while allowing heat exchange to occur between the segments of the electrode that are exposed to plasma and the cooling plate 414 and / or the heating plate 418. In some examples, a variable impedance circuit 480 is connected to individual segments of the segmented electrode.

[0061] In some examples, the variable impedance circuit 480 includes a switched resistor circuit, a switched capacitor circuit, an impedance measuring circuit, and / or an impedance controller as will be described below. In some examples, the variable impedance circuit 480 is arranged above the cooling plate 414 or in another suitable location.

[0062] Referring now to FIG. 5, the S segments 440-1 , 440-2, 440-3, ..., and 440-S of the electrode 440 are spaced from one another and define gaps 439 to prevent shorting between adjacent segments. In some examples, side surfaces of the segments can have various different configurations to reduce arcing, plasma light up, and / or accumulation of any unwanted products or undesirable residues. In some examples, substrate facing surfaces of the segments can be sloped to change the radial length scale of the plasma density modulation through impedance control. In other words, varying the slope of the segments can be used to increase or decrease a radial width of a Gaussian response of the plasma for the segment.

[0063] In some examples, radially facing surfaces of the S segments 440-1 , 440-2, 440- 3, ..., and 440-S include one or more stair steps 450 to prevent line of sight paths and to reduce voltage breakdown. However, the S segments 440-1 , 440-2, 440-3, ..., and 440-Attorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POAS may have different radial widths and / or numbers of stair steps. Facing surfaces of the S segments 440-1 , 440-2, 440-3, ..., and 440-S can be sloped relative to a direction transverse to a plane including the substrate to prevent line of sight paths associated with arcing and light-up, or to reduce manufacturing costs. In some examples, O-rings are used between one or more pairs of adjacent segments. In some examples, the segments of the electrode are made of silicon (e.g., high resistance silicon, low resistance silicon), polysilicon, silicon carbide, quartz, ceramic, or other plasma resistant materials. Additional examples of segmented electrodes are shown and described in commonly- assigned PCT Application No. PCT / US24 / 42899, filed on August 19, 2024, which is incorporated herein by reference in its entirety. In some examples, insulating material can be arranged between adjacent segments.

[0064] Referring now to FIG. 6, a variable impedance circuit 510 includes a switched resistor circuit 520 and a switched capacitor circuit 530 for each of the segmented electrodes. A switch configuration controller 540 is configured to control states of switches used to select either the switched resistor circuit 520 or the switched capacitor circuit 530 and to select impedance values for the switched resistor circuit 520 or the switched capacitor circuit 530, respectively. A switch SWKI selects either the switched resistor circuit 520 or the switched capacitor circuit 530. Internal switches (FIG. 7) change the impedances of the switched resistor circuit 520 or the switched capacitor circuit 530 as will be described further below.

[0065] Referring now to FIG. 7, an example of the switched resistor circuit 520 and the switched capacitor circuit 530 are shown. The switched resistor circuit 520 includes series-connected resistors RRI , RR2, ..., and RRN. Switches SWRI , SWR2, ..., and SWRN are connected is parallel across the resistors RRI , RR2, ..., and RRN, respectively, where N is an integer greater than one. The switches SWRI , SWR2, ..., and SWRN selectively short zero, one or more of the resistors RRI , RR2, ..., and RRN in different combinations to vary the effective impedance.

[0066] Closing and opening different combinations of the switches SWRI , SWR2, ..., and SWRN can be used to select different combinations of the resistors RRI , RR2, ..., and RRN to vary the effective impedance for each of the segments. In some examples, the resistors RRI , RR2, ..., and RRN can be configured to provide 0 to 1270 ohms to provide an effective impedance range from 0 to 650 ohms (due to parasitic capacitance at the first RF frequency (e.g., 400 kHz)).Attorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA

[0067] The switched capacitor circuit 530 includes resistors RCA, RCB, and Rcc connected in series. Capacitors CCA and CCB include first terminals connected to first and second terminals of the resistor RCA, respectively. Second terminals of the capacitors CCA and CCB are connected to ground. Pairs of capacitors Cm, Cc2, ..., and CCF and switches SWm, SWc2, ..., and SWCF, respectively, are connected in series and then connected in parallel across the resistor Rcc, where F is an integer greater than one. Closing and opening different combinations of the switches SWm, SWc2, ..., and SWCF can be used to select different combinations of the capacitors Cm, Cc2, ..., and CCF to vary the corresponding impedance for each of the segments. In some examples, the capacitors Cm, Cc2, ..., and CCF can be configured to provide an effective impedance range from 650 to 4200 ohms or higher values at the first RF frequency (e.g., 400 kHz).

[0068] Referring now to FIG. 8, an example of a variable impedance circuit providing additional functionality is shown. The variable impedance circuit includes the switched resistor circuit 520, the switched capacitor circuit 530, and an impedance controller 610. The impedance controller 610 is configured to access a model or lookup table 612 to select a desired effective impedance value for each of the segmented electrodes to compensate for changes that may occur (e.g., changes in capacitive coupling between the segments and adjacent grounded surfaces).

[0069] An impedance measuring circuit 618 is configured to measure the capacitive coupling of the segmented electrode and / or the impedances provided by the switched resistor circuit 520 and / or the switched capacitor circuit 530. In some examples, the impedance measuring circuit 618 supplies current at a predetermined frequency (e.g., 10 kHz or other frequency) and estimates capacitance shift based on the measured voltage. A switch configuration controller 614 is configured to select states of switches to connect or disconnect appropriate components of the variable impedance circuit when operating in the RF plasma processing mode. The switch configuration controller 614 is also configured to select states of switches to connect or disconnect appropriate components of the variable impedance circuit during impedance measuring modes (when RF plasma operation is not occurring). During the impedance measuring modes, the impedances of the segments, the switched resistor circuit 520, and / or the switched capacitor circuit 530 can be measured.

[0070] In some examples, the substrate support includes a DC bias operating at a first frequency (e.g., 300kHz to 400kHz) and a second frequency (e.g., 60 MHz). In someAttorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA examples, a filter 630 (e.g., a notch filter) is arranged between an input of the variable impedance and the segment 632 to block the second RF frequency while passing the first RF frequency.

[0071] In some examples, the segment 632 is separated from a grounded plate 634 or other grounded surface by an insulating gel 636. Because the insulating gel 636 is exposed to plasma and process chemistry during RF plasma processing, characteristics of the insulating gel 636 change and capacitive coupling between the segment 632 and ground (e.g., the grounded plate 634) shifts. The capacitance coupling shift causes corresponding changes to the RF plasma near the corresponding segment.

[0072] After an event or a predetermined processing period (e.g., such as 5 radio frequency (RF) hours, 10 RF hours, or another period), the RF plasma process is stopped and the impedance controller 610 reconfigures the switches to allow the impedance between the segment 632 and the grounded plate 634 to be measured. The impedance controller 610 measures the impedance of the segment. The impedance controller 610 uses the model or lookup table 612 to adjust the impedance connected to the segment 632 to compensate for the measured shift in impedance between the segment 632 and the grounded plate 634 (e.g., due to changes in the insulating gel 636). The switches can also be configured to measure the impedance of the switched resistor circuit 520 and / or the switched capacitor circuit 530.

[0073] In other examples, the switch configuration controller 614 configures the switches SWKI , SWK2, and SWKS to measure the impedance from the switched resistor circuit 520 or the switched capacitor circuit 530 to ground.

[0074] Referring now to FIG. 9, a method for operating the impedance controller 610 for each of the segments is shown. At 710, one of the segments of the electrode is selected. At 720, the method determines whether the effective impedance for the segment at the first RF frequency is less than a predetermined impedance (ITH) (e.g., 650 ohms). If 720 is true, the switched resistor circuit 520 is selected and the switches of the switched resistor circuit 520 are configured to provide the desired impedance at 728. If 720 is false, the switched capacitor circuit 530 is selected and the switches of the switched capacitor circuit 530 are configured to provide the desired impedance at 724. At 738, the method determines whether all of the segments of the segmented electrode have been configured. If 732 is false, the next segment is selected and the method returns to 720 to configure the next segment at 736.Attorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA

[0075] If 732 is true, the processing chamber performs plasma processing of substrates. At 744, the method determines whether an event has occurred or a predetermined number of RF hours or another period has elapsed. If 744 is true, the method continues at 748, stops RF plasma processing, and reconfigures the switches to measure the impedance (or capacitive coupling) of one of the segments. At 752, the method determines whether the measured impedance (or capacitive coupling) of the segment has changed sufficiently to require adjustment of the corresponding variable impedance. If 752 is true, the method reconfigures the switches of the switched resistor circuit 520 or the switched capacitor circuit 530 at 754 to provide the desired effective impedance value. If 752 false, the method does not reconfigure the switches of the switched resistor circuit 520 or the switched capacitor circuit 530 at 758. At 762, the method determines whether all of the segments have been measured and reconfigured (if needed). If 762 is false, the next segment is selected at 766 and the method returns to 752. If 762 is true, the method returns to 740.

[0076] Referring now to FIG. 10, a series resonance circuit 710 can be used in conjunction with the switched capacitor circuit 530 (instead of the switched resistor circuit 520). The series resonance circuit 710 includes an inductor Li that is connected in series with a variable capacitor Ci between the input of the series resonance circuit 710 and ground. In some examples, the series resonance circuit 710 includes a capacitor C2 connected in parallel to the input of the series resonance circuit 710. In some examples, the capacitor C2 has a capacitance value in a range from 100 pF to 400 pF, although other capacitance values can be used. In some examples, the inductor Li has an inductance value in a range from 200 pH to 300 pH, although other inductance values can be used.

[0077] In some examples, a switch SW and a resistor R2 are connected in series between ground and a node located between a first terminal of the inductor Li and the input of the series resonance circuit 710. In some examples, the resistor R2 has a low resistance value (e.g., greater than 0 and less than 10 Q (e.g., 1 Q)). The resistor R2 prevents current surge when the switch SW is closed by the relay 716.

[0078] In some examples, the variable capacitor Ci includes overlapping cylinders, spiral plates, or another suitable metal shapes that can be adjusted to provide a variable overlap. A motor 712 is configured to vary the amount of overlap in increments to improve control of the impedance value provided by the variable capacitor Ci. In some examples,Attorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA the variable capacitor Ci has a capacitance value in a range from 150 pF to 1500 pF, although other capacitance values can be used. In some examples, the motor 712 includes a stepper motor providing tens, hundreds, or thousands of steps between the lowest and highest capacitance values depending upon the precision desired.

[0079] The relay 716 is configured to selectively close the switch SW to short the inductor Li and the variable capacitor Ci (to minimize impedance) or to open the switch SW to allow the impedance value to be set by the inductor Li and the variable capacitor Ci. While the switched resistor circuit 520 is capable of switching the impedance in discrete steps, the series resonance circuit 710 is configured to provide finer control of the impedance value that is provided.

[0080] In some examples, the components of the series resonance circuit 710 are located in a metal enclosure 724 to provide isolation and / or reduce cross talk. In some examples, the motor 712, the relay 716, and the voltage sensor 718 are further separated by another metal wall 726 to provide isolation and / or reduce cross talk. In some examples, the filter 630 (e.g., an inductor) can be arranged in the metal enclosure 724 at the input of the series resonance circuit 710 or spaced from the metal enclosure 724 and connected by a coaxial cable or other suitable connector to the input of the series resonance circuit 710.

[0081] The voltage sensor 718 includes a first input including a resistor Ri that is connected between the input and the first terminal of the inductor Li. In some examples, the resistor R1 has a resistance value in a range from 2MQ to 10 MQ. The first input of the voltage sensor 718 can be used to sense a DC voltage charge on the capacitors Ci and C2. A second input of the voltage sensor 718 can be used to sense AC voltage.

[0082] In other examples, the switch configuration controller 614 configures the switches SWKI, SWK2, and SWKS to measure the impedance of the series resonance circuit 710 or the switched capacitor circuit 530 to ground.

[0083] The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of theAttorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA present disclosure. Further, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the 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 one another remain within the scope of this disclosure.

[0084] Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connected,” “engaged,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “disposed.” Unless explicitly described as being “direct,” when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”

[0085] In some implementations, a controller is part of a system, which may be part of the above-described examples. Such systems can comprise semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform, or platforms for processing, and / or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as the “controller,” which may control various components or subparts of the system or systems. The controller, depending on the processing requirements and / or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and / or load locks connected to or interfaced with a specific system.Attorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA

[0086] Broadly speaking, the controller may be defined as electronics having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some embodiments, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0087] The controller, in some implementations, may be a part of or coupled to a computer that is integrated with the system, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e.g., a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and / or settings, which are then communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control. Thus, as described above, the controller may be distributed, such as by comprising one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber inAttorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.

[0088] Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and / or manufacturing of semiconductor wafers.

[0089] As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and / or load ports in a semiconductor manufacturing factory.

Claims

Attorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POACLAIMSWhat is claimed is:1 . A plasma processing system for processing substrates, comprising: a variable impedance circuit for providing S impedances at a first RF frequency for each of S segments of a first electrode, respectively, where S is an integer greater than one, for each of the S segments, the variable impedance circuit includes: a switched resistor circuit including a first plurality of resistors and a first plurality of switches configured to vary an impedance of the switched resistor circuit in a first impedance range at the first RF frequency; and a switched capacitor circuit including a second plurality of resistors, a plurality of capacitors and a second plurality of switches configured to vary an impedance of the switched capacitor circuit in a second impedance range at the first RF frequency; and a switch configuration controller configured to select one of the switched resistor circuit and the switched capacitor circuit.

2. The plasma processing system of claim 1 , wherein the second impedance range is greater than the first impedance range.

3. The plasma processing system of claim 1 , wherein: the switch configuration controller is configured to select the switched resistor circuit when one of the S impedances for a corresponding one of the S segments is in the first impedance range, and the switch configuration controller is configured to select the switched capacitor circuit when the one of the S impedances for the corresponding one of the S segments is in the second impedance range.

4. The plasma processing system of claim 1 , further comprising: the first electrode arranged above a substrate support; and the S segments of the first electrode, wherein the S segments are arranged concentrically and include gaps located therebetween.Attorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA5. The plasma processing system of claim 4, further comprising: the substrate support including a second electrode; and a plasma generator configured to supply RF voltage at a first RF frequency to the second electrode to generate and maintain plasma.

6. The plasma processing system of claim 1 , wherein the first plurality of resistors of the switched resistor circuit are connected in series and the first plurality of switches are connected in parallel across the first plurality of resistors.

7. The plasma processing system of claim 6, wherein the variable impedance circuit is configured to select states of the first plurality of switches to set at least one of the S impedances in the first impedance range.

8. The plasma processing system of claim 6, further comprising a first capacitor connected between at least one of the first plurality of switches and ground.

9. The plasma processing system of claim 1 , wherein pairs of the plurality of capacitors and the second plurality of switches are connected in series across one of the second plurality of resistors.

10. The plasma processing system of claim 9, wherein the variable impedance circuit is configured to select states of the second plurality of switches to set at least one of the S impedances in the second impedance range.1 1 . The plasma processing system of claim 9, further comprising a first capacitor and a second capacitor connected between first and second terminals of at least one of the second plurality of switches and ground.

12. The plasma processing system of claim 1 , further comprising a filter arranged between the variable impedance circuit and each of the S segments.

13. The plasma processing system of claim 12, wherein the filter passes the first RF frequency and blocks a second RF frequency greater than the first RF frequency.Attorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA14. The plasma processing system of claim 13, wherein the first RF frequency is in a range from 100 kHz to 500 kHz and the second RF frequency is greater than 5 MHz.

15. The plasma processing system of claim 1 , wherein the variable impedance circuit includes an impedance measuring circuit configured to measure an impedance between the corresponding ones of the S segments and ground.

16. The plasma processing system of claim 15, wherein prior to the impedance measuring circuit measuring capacitive coupling between the corresponding ones of the S segments and ground, the switch configuration controller is configured to connect the impedance measuring circuit to the corresponding ones of the S segments.

17. The plasma processing system of claim 16, wherein the variable impedance circuit includes one of a model and a lookup table configured to determine at least one of the S impedances for the corresponding one of the S segments.

18. The plasma processing system of claim 17, wherein the one of the model and the lookup table is indexed by the impedance that is measured between the corresponding ones of the S segments and ground.

19. The plasma processing system of claim 15, wherein the switch configuration controller and the impedance measuring circuit are configured to measure an impedance of the switched resistor circuit.

20. The plasma processing system of claim 15, wherein the switch configuration controller and the impedance measuring circuit are configured to measure an impedance of the switched capacitor circuit.21 . The plasma processing system of claim 4, wherein sides of the S segments are configured to prevent line of sight from plasma through the gaps.

22. The plasma processing system of claim 4, wherein sides of the S segments are one of stair-stepped or sloped.Attorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA23. The plasma processing system of claim 4, wherein the S segments include a plurality of gas through holes.

24. The plasma processing system of claim 4, further comprising an insulating gel arranged between the S segments and a grounded surface.

25. A plasma processing system for processing substrates, comprising: a variable impedance circuit for providing S impedances at a first RF frequency for each of S segments of a first electrode, respectively, where S is an integer greater than one, for each of the S segments, the variable impedance circuit includes: a series resonance circuit including a first inductor and a variable capacitor configured to vary an impedance of the series resonance circuit in a first impedance range at the first RF frequency; and a switched capacitor circuit including a first plurality of resistors, a plurality of capacitors, and a first plurality of switches configured to vary an impedance of the switched capacitor circuit in a second impedance range at the first RF frequency; and a switch configuration controller configured to select one of the series resonance circuit and the switched capacitor circuit.

26. The plasma processing system of claim 25, wherein the second impedance range is greater than the first impedance range.

27. The plasma processing system of claim 25, wherein: the switch configuration controller is configured to select the series resonance circuit when one of the S impedances for a corresponding one of the S segments is in the first impedance range, and the switch configuration controller is configured to select the switched capacitor circuit when the one of the S impedances for the corresponding one of the S segments is in the second impedance range.Attorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA28. The plasma processing system of claim 25, further comprising: the first electrode arranged above a substrate support; and the S segments of the first electrode, wherein the S segments are arranged concentrically and include gaps located therebetween.

29. The plasma processing system of claim 28, further comprising: the substrate support including a second electrode; and a plasma generator configured to supply RF voltage at a first RF frequency to the second electrode to generate and maintain plasma.

30. The plasma processing system of claim 25, wherein the first inductor and the variable capacitor are connected in series between an input of the series resonance circuit and ground.31 . The plasma processing system of claim 30, wherein the series resonance circuit further includes a capacitor connected in parallel to the input of the series resonance circuit.

32. The plasma processing system of claim 30, further comprising a switch, wherein the switch is connected in series with a first resistor between ground and the input of the series resonance circuit.

33. The plasma processing system of claim 30, wherein the series resonance circuit further includes a voltage sensor configured to sense DC and AC voltage at the input of the series resonance circuit.

34. The plasma processing system of claim 25, wherein pairs of the plurality of capacitors and the first plurality of switches are connected in series across one of the first plurality of resistors.

35. The plasma processing system of claim 25, wherein the variable impedance circuit is configured to select states of the first plurality of switches to set at least one of the S impedances in the second impedance range.Attorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA36. The plasma processing system of claim 35, further comprising a first capacitor and a second capacitor connected to first and second terminals of at least one of the first plurality of switches and ground.

37. The plasma processing system of claim 25, further comprising a filter arranged between the variable impedance circuit and each of the S segments.

38. The plasma processing system of claim 37, wherein the filter passes the first RF frequency and blocks a second RF frequency greater than the first RF frequency.

39. The plasma processing system of claim 38, wherein the first RF frequency is in a range from 100 kHz to 500 kHz and the second RF frequency is greater than 5 MHz.

40. The plasma processing system of claim 25, wherein the variable impedance circuit includes an impedance measuring circuit configured to measure capacitive coupling between the corresponding ones of the S segments and ground.

41. The plasma processing system of claim 40, wherein prior to the impedance measuring circuit measuring capacitive coupling between the corresponding ones of the S segments and ground, the switch configuration controller is configured to connect the impedance measuring circuit to the corresponding ones of the S segments.

42. The plasma processing system of claim 41 , wherein the variable impedance circuit includes one of a model and a lookup table configured to determine at least one of the S impedances for the corresponding one of the S segments.

43. The plasma processing system of claim 42, wherein the one of the model and the lookup table is indexed by inductance that is measured between the corresponding ones of the S segments and ground.

44. The plasma processing system of claim 25, wherein the variable impedance circuit and the switch configuration controller are configured to measure impedance of the series resonance circuit.Attorney Docket No. 12119-1 WOHDP Ref. No. 15545-001309-WO-POA45. The plasma processing system of claim 25, wherein the variable impedance circuit and the switch configuration controller are configured to measure impedance of the switched capacitor circuit.

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