Patent Publication Number: US-2018047543-A1

Title: Systems and methods for rf power ratio switching for iterative transitioning between etch and deposition processes

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/373,024, filed on Aug. 10, 2016. The entire disclosure of the application referenced above is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to etching and deposition systems, and more particularly, to transformer coupled capacitive tuning systems. 
     BACKGROUND 
     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. 
     During manufacturing of semiconductor devices, etch processes and deposition processes may be performed within a processing chamber. Ionized gas, or plasma, can be introduced into the plasma chamber to etch (or remove) material from a substrate such as a semiconductor wafer, and to sputter or deposit material onto the substrate. Creating plasma for use in manufacturing or fabrication processes typically begins by introducing process gases into the processing chamber. The substrate is disposed in the processing chamber on a substrate support such as an electrostatic chuck or a pedestal. 
     The processing chamber may include transformer coupled plasma (TCP) reactor coils. A radio frequency (RF) signal, generated by a power source, is supplied to the TCP reactor coils. A dielectric window, constructed of a material such as ceramic, is incorporated into an upper surface of the processing chamber. The dielectric window allows the RF signal to be transmitted from the TCP reactor coils into the interior of the processing chamber. The RF signal excites gas molecules within the processing chamber to generate plasma. 
     The TCP reactor coils are driven by a transformer coupled capacitive tuning (TCCT) match network. The TCCT match network receives the RF signal supplied by the power source and enables tuning of power provided to the TCP reactor coils. The TCCT match network may include variable capacitors. Each of the variable capacitors includes a stationary electrode and a movable electrode. Position of the movable electrode relative to the stationary electrode is directly related to a capacitance of the corresponding capacitor. The movable electrodes can be connected to a leadscrew, which can be driven by a rotary motor. 
     Power supplied to each of the TCP reactor coils is based on positions of the movable electrodes of the capacitors. A ratio of power delivered to the TCP coils is also based on the positions of the movable electrodes of the capacitors. One or more power ratios provided during etching can be different than one or more power ratios provided during deposition. 
     SUMMARY 
     A system is provided and includes a first linear motor, a first separator support assembly, and a controller. The first linear motor includes a shaft that is linearly driven based on a current supplied to the first linear motor. The first separator support assembly is configured to connect to the shaft of the first linear motor and to a rod of a first capacitor of a match network. The first linear motor is configured to actuate the rod to move a first electrode of the first capacitor relative to a second electrode of the first capacitor to change a capacitance of the first capacitor. The controller is connected to the first linear motor and is configured to adjust power supplied to a first radio frequency reactor coil of a plasma processing chamber by adjusting the current supplied to the first linear motor. 
     In other features, a system is provided and includes a first cam follower, a first cam, a first rotary motor, a first separator support assembly, and a controller. The first cam includes a slot. The slot has a predetermined path. The first cam follower is disposed at least partially within the slot and follows the predetermined path. The first rotary motor is connected to the first cam and configured to be driven based on a current supplied to the first rotary motor. The first rotary motor is configured to rotate the first cam causing the first cam follower to move along the predetermined path. The first separator support assembly is configured to connect to the first cam follower and a rod of a first capacitor of a match network. Rotation of the cam and movement of the cam follower actuates the rod and moves a first electrode relative to a second electrode of the first capacitor to change a capacitance of the first capacitor. The controller is connected to the first rotary motor and configured to adjust power supplied to a first radio frequency reactor coil of a plasma processing chamber by adjusting the current supplied to the first rotary motor. 
     In other features, a system is provided and includes a leadscrew, a first rotary motor, a first separator support assembly, a counterbalance assembly and a controller. The leadscrew is connected to a first electrode of a first capacitor of a match network. The first rotary motor is connected to and configured to rotate the leadscrew based on a current supplied to the first rotary motor. The first separator support assembly is configured to connect to the leadscrew and to a shaft of the first rotary motor. The first rotary motor is configured to rotate the leadscrew to move the first electrode relative to a second electrode of the first capacitor to change a capacitance of the first capacitor. The counterbalance assembly is connected to the shaft of the first rotary motor and is configured to counterbalance forces on the leadscrew by the first capacitor. The controller is connected to the first rotary motor and configured to adjust power supplied to a first radio frequency reactor coil of a plasma processing chamber by adjusting the current supplied to the first rotary motor. 
     In yet other features, a system is provided and includes a match network, a first one or more switches, a second one or more switches, and a controller. The match network includes a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor. The first one or more switches is configured to supply power from a power input circuit to the first capacitor and the second capacitor. The second one or more switches is configured to supply power from the power input circuit to the third capacitor and the fourth capacitor. The controller is configured to: (i) control states of the first one or more switches and the second one or more switches to switch between providing a first ratio of power and a second ratio of power; (ii) provide the first ratio of power to a first radio frequency reactor coil and a second radio frequency reactor coil of a plasma processing chamber by activating the first one or more switches; and (iii) provide the second ratio of power to the first radio frequency reactor coil and the second radio frequency reactor coil by activating the second one or more switches. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a functional block diagram of an example of a plasma processing system incorporating an RF power ratio switching system in accordance with the present disclosure; 
         FIG. 2  is a schematic view of an example of a TCCT match network and a corresponding capacitance adjustment system in accordance with the present disclosure; 
         FIG. 3  is a functional block diagram of an example of a TCCT match network including variable capacitors and inner coil circuits and outer coil circuits in accordance with the present disclosure; 
         FIG. 4  is a schematic diagram of the TCCT match network of  FIG. 3 ; 
         FIG. 5  is a side perspective view of an example of a dual capacitor system including a single linear motor in accordance with the present disclosure; 
         FIG. 6  is a side cross-sectional view of the dual capacitor system of  FIG. 5 ; 
         FIG. 7  is a side perspective view of an example of a single capacitor system including a single linear motor and a counterbalance assembly in accordance with the present disclosure; 
         FIG. 8  is a side cross-sectional view of the single capacitor system of  FIG. 7 ; 
         FIG. 9  is a perspective view of an example of a single capacitor including a single rotary motor and a cam in accordance with the present disclosure; 
         FIG. 10  is another perspective view of the single capacitor system of  FIG. 9 ; 
         FIG. 11  is a side cross-sectional view of the single capacitor system of  FIGS. 9-10 ; 
         FIGS. 12A-12C  are side perspective views of a portion of the single capacitor system of  FIGS. 9-11  illustrating cam movement; 
         FIG. 13  is a side perspective view of a single capacitor system including a single rotary motor and a counterbalance assembly in accordance with the present disclosure; 
         FIG. 14  is a side cross-sectional view of the single capacitor system of  FIG. 13 . 
         FIG. 15  is a cross-sectional view of a vacuum variable capacitor that may be used in the embodiments of  FIGS. 1-14 ; 
         FIG. 16  is a schematic diagram of another example of a TCCT match network including a shared switch for each set of etch and deposition capacitors in accordance with an embodiment of the present disclosure; and 
         FIG. 17  is a schematic diagram of another example of a TCCT match network including a switch for each etch capacitor and deposition capacitor in accordance with an embodiment of the present disclosure. 
     
    
    
     In the drawings, reference numbers may be reused to identify similar and/or identical elements. 
     DETAILED DESCRIPTION 
     A traditional TCCT match network may include two variable capacitors; one capacitor for each TCP reactor coil of a processing chamber. Each of the capacitors includes stationary electrodes and movable electrodes. The TCP reactor coils may include an inner coil and an outer coil. The inner coil is disposed within an outer coil. A ratio of power supplied to the inner coil relative to power supplied to the outer coil is adjusted by moving the moveable electrodes of the capacitors. The moveable electrodes may be moved via respective leadscrews and rotary motors. This technique for moving the moveable electrodes is too slow for a rapid alternating process (RAP), which includes rapidly switching between etch and deposition processes. The duration of each etch process and each deposition process may be 1 second or less. 
     An example speed requirement of a RAP is to provide RF power ratio switching of 10-90% in less than 100 milli-seconds (ms). RF power ratio switching of 10-90% includes switching from providing 10% power via a first capacitor and 90% power via a second capacitor to providing 90% power via the first capacitor to 10% power via the second capacitor. The traditional method of moving moveable electrodes via respective leadscrews and rotary motors is not capable of satisfying the stated speed requirement. 
     Examples are described below that allow for quick movement of movable electrodes of capacitors of a TCCT match network. This allows for fast RF power ratio switching to satisfy RAP speed requirements of, for example, a deep silicon etch (DSiE) process and thus fast transitioning between etch and deposition processes. The disclosed examples provide RF power ratio switching of 10-90% in less than 100 milli-seconds (ms). The quick transitioning allows for chemistries within a processing chamber to be quickly changed for etch and deposition processing, which allows for controlling and providing different uniformity patterns on a wafer. Etch processes are typically “edge fast” meaning etching occurs at a quicker rate near an edge of a substrate than near a center of a substrate. Deposition processes are typically “center fast” meaning material is deposited on a substrate at a quicker rate near a center of the substrate than near an edge of the substrate. The fast RF power ratio switching allows the uniformity patterns of the etch and deposition processes to be better controlled. 
       FIG. 1  shows a plasma processing system  10  that includes a RF power ratio switching system  11 , a plasma processing chamber  12 , a controller  13  and TCP reactor coils  14 . The RF power ratio switching system  10  switches RF power ratios of the TCP reactor coils  14 . The TCP reactor coils  14  are disposed outside and above the plasma processing chamber  12 . The first power source  16  provides a first RF source signal. A TCCT (or first) match network  17  is included between the first power source  16  and the TCP reactor coils  14 . The TCCT match network  17  enables tuning of power provided to the TCP reactor coils  14 . The TCCT match network  17  includes variable capacitors  18 , which are adjusted via the RF power ratio switching system  11 . The RF power ratio switching system  11  includes a capacitance adjustment system  19  and the controller  13 . Examples of the capacitance adjustment system  19  are shown in  FIGS. 5-14 . The capacitance adjustment system  19  may include motors (examples of which are shown in  FIGS. 5-14 ), which are controlled by the controller  13 . The controller  13  adjusts the capacitances of the capacitors  18  to adjust a RF power ratio of power supplied to the TCP reactor coils  14 . 
     The plasma processing chamber  12  includes a ceramic window  20 , which is located adjacent the TCP reactor coils  14  and allows efficient transmission of the first RF source signal into the plasma processing chamber  12  for plasma generation purposes. A substrate support  21  such as an electrostatic chuck, a pedestal or other suitable substrate support is disposed at the bottom of the plasma processing chamber  12 . The substrate support  21  supports a substrate  22 . If the substrate support  21  is an electrostatic chuck, the substrate support  21  includes electrically conductive portions  24  and  26 , which are electrically isolated from each other. The substrate support  21  is surrounded by an insulator  28  and is capacitively coupled to the substrate  22 . By applying a DC voltage across the conductive portions  24 ,  26 , an electrostatic coupling is created between the conductive portions  24 ,  26  and the substrate  22 . This electrostatic coupling attracts the substrate  22  against the substrate support  21 . 
     The plasma processing system  10  further includes a bias RF power source  30 , which is connected to a bias (or second) match network  32 . The second match network  32  is connected between the bias RF power source  30  and the substrate support  21 . The second match network  32  matches an impedance (e.g., 500) of the bias RF power source  30  to an impedance of the substrate support  21  and plasma  34  in the plasma processing chamber  12  as seen by the second matching network  32 . 
     The plasma processing system  10  further includes a voltage control interface (VCI)  40 . The VCI  40  may include a pickup device  42 , a voltage sensor  44 , a controller  13  and circuits between the voltage sensor  44  and the controller  13 . The pickup device  42  extends into the substrate support  21 . This pickup device  42  is connected via a conductor  48  to the voltage sensor  44  and is used to generate a RF voltage signal. 
     Operation of the voltage sensor  44  may be monitored, manually controlled, and/or controlled via the controller  13 . The controller  13  may display output voltages of the channels of the voltage sensor  44  on a display  50 . Although shown separate from the controller  13 , the display  50  may be included in the controller  13 . A system operator may provide input signals indicating (i) whether to switch between the channels, (ii) which one or more of the channels to activate, and/or (ii) which one or more of the channels to deactivate. 
     In operation, a gas capable of ionization flows into the plasma processing chamber  12  through the gas inlet  56  and exits the plasma processing chamber  12  through the gas outlet  58 . The first RF signal is generated by the RF power source  16  and is delivered to the TCP reactor coil  14 . The first RF signal radiates from the TCP reactor coil  14  through the window  20  and into the plasma processing chamber  12 . This causes the gas within the plasma processing chamber  12  to ionize and form the plasma  34 . The plasma  34  produces a sheath  60  along walls of the plasma processing chamber  12 . The plasma  34  includes electrons and positively charged ions. The electrons, being much lighter than the positively charged ions, tend to migrate more readily, generating DC bias voltages and DC sheath potentials at inner surfaces of the plasma processing chamber  12 . An average DC bias voltage and a DC sheath potential at the substrate  22  affects the energy with which the positively charged ions strike the substrate  22 . This energy affects processing characteristics such as rates at which etching or deposition occurs. 
     The controller  13  may adjust the bias RF signal generated by the RF power source  30  to change the amount of DC bias and/or a DC sheath potential at the substrate  22 . The controller  13  may compare outputs of the channels of the voltage sensor  44  and/or a representative value derived based on the outputs of the channels to one or more set point values. The set point values may be predetermined and stored in a memory  62  of the controller  13 . The bias RF signal may be adjusted based on differences between (i) the outputs of the voltage sensor  44  and/or the representative value and (ii) the one more set point values. The bias RF signal passes through the second match network  32 . An output provided by the second match network  32  (referred to as a matched signal) is then passed to the substrate support  21 . The bias RF signal is passed to the substrate  22  through the insulator  28 . 
       FIG. 2  shows an example of the TCCT match network  17  connected to examples TCP reactor coils  100 ,  102 ,  104 ,  106 . The TCP reactor coils  100 ,  102  are collectively referred to as an outer coil. The TCP reactor coils  104 ,  106  are collectively referred to as an inner coil. The outer coil and inner coil may be spiral-shaped as shown or may have a different shape and/or configuration. The TCCT match network  17  includes TCCT coil input circuits  110  and TCCT coil output circuits  112 . The TCCT coil input circuits  110  are connected to the inner coil at coil ends D and E and to the outer coil at coil ends B and G. The TCCT coil output circuits  112  are connected to the inner coil at coil ends C and F and to the outer coil at coil ends A and H. The TCCT coil input circuits  110  receive power from the power source  16 , which is connected to a reference terminal (or ground reference)  120 . The TCCT coil output circuits  112  are connected to the reference terminal  120 . 
     The TCCT coil input circuits  110  include the variable capacitors  18 , which when adjusted adjust power supplied from the TCCT coil input circuits  110  to the inner coil and the outer coil, respectively. This adjusts a RF power ratio between the inner coil and the outer coil. The capacitance adjustment system  19  is connected to the variable capacitors  18 . 
       FIG. 3  shows a TCCT match network  150  that may replace the TCCT match network  17  of  FIGS. 1-2 . The TCCT match network  150  receives power from the power source  16 . The TCCT match network  150  includes a power input circuit  152 , an inner coil input circuit  154 , an outer coil input circuit  156 , an inner coil output circuit  158 , and an outer coil output circuit  160 . The coil input circuits  154 ,  156  include a first variable capacitor  162  and a second variable capacitor  164  and provide power to an inner coil IC  166  and an outer coil OC  168 . Power out of the coils  166 ,  168  is provided to the coil output circuits  158 ,  160 , which are connected to the reference terminal  120 . The variable capacitors  162 ,  164  are adjusted by the capacitance adjustment system  19 . 
       FIG. 4  shows an example of the TCCT match network  150  of  FIG. 3 . The TCCT match network  150  receives power from the power source  16 . The TCCT match network  150  includes the power input circuit  152 , the inner coil input circuit  154 , the outer coil input circuit  156 , the inner coil output circuit  158 , and the outer coil output circuit  160 . The power input circuit  152  may include a first capacitor C 1 , a second capacitor C 2 , a third capacitor C 3  and an inductor L 1 . The capacitors C 1  and C 3  may be variable capacitors. The capacitors C 1 , C 3  and inductor L 1  are connected in series between the power source  16  and the coil input circuits  154 ,  156 . The capacitor C 2  is connected (i) at a first end to an output of the capacitor C 1  and an input of the capacitor C 3 , and (ii) at a second end to the reference terminal  120 . 
     The inner coil input circuit  154  may include a second inductor L 2  and a fourth capacitor C 4 . The inductor L 2  and capacitor C 4  are connected in series between the inductor L 1  and the inner coil  166 . The outer coil input circuit  156  may include a fifth capacitor C 5 . The capacitor C 5  is connected at a first end to the inductor L 1  and at a second end to the outer coil  168 . The capacitors C 4  and C 5  are variable capacitors, which are adjusted by the capacitance adjustment system  19 . 
     The inner coil output circuit  158  may include the reference terminal  120 , which is connected to an output of the inner coil  166 . The outer coil output circuit  160  may include a sixth capacitor C 6 , which is connected at a first end to the outer coil  168  and at a second end to the reference terminal  120 . 
     Examples of devices and components that may be included in the capacitance adjustment system  19  and examples of the variable capacitors C 4  and C 5  are shown in  FIGS. 5-14 . The capacitors C 4 , C 5  may be included in a dual capacitor assembly (e.g., dual capacitor assembly of  FIGS. 5-6 ) or in separate single capacitor assemblies (e.g., the single capacitor assemblies of  FIGS. 7-14 . The capacitance adjustment system  19  may include one of the dual capacitor assemblies, two of the single capacitor assemblies and the corresponding devices, components, motors, shafts, counterbalance assemblies, cams, cam followers, etc. The capacitance adjustment system  19  may include linear and/or rotary motors that are controlled by the controller  46  of  FIG. 1 . The motors are used to adjust capacitance of the capacitors C 4 , C 5 . Examples of the capacitors is shown in  FIGS. 5-15 . 
     The capacitive adjustment system  19  may include sensors  170  (e.g., potentiometers, encoders, etc.) for detecting positions of one or more shafts and/or rods of motors and capacitors (e.g., capacitors C 4 , C 5 ). The sensors  170  may be included in the motors, on the motors, and/or connected directly and/or indirectly to the shafts and/or rods. The controller  46  of  FIG. 1  may adjust voltage, current and/or power supplied to the motors to adjust position of the shafts and/or rods based on signals received from the sensors  170 . 
       FIGS. 5-6  show a dual capacitor system  200  including a single linear motor  202 , separator support assemblies  204 ,  206 , and capacitor  208 ,  210 . The linear motor  202  may be a voice coil derivative type motor or other suitable linear motor. The linear motor  202  includes a shaft  212  that extends through a housing  214  of the linear motor  202  and is connected to rods  216 ,  218  of the capacitors  208 ,  210  via the separator support assemblies  204 ,  206 . The linear motor  202 , based on a control signal received from the controller  46  of  FIG. 1 , moves the rods  216 ,  218  to change capacitances of the capacitors  208 ,  210 . 
     The separator support assemblies  204 ,  206 , as shown, include stand-off members  220 ,  222 , which are cylindrically-shaped. The stand-off members  220 ,  222  may include pairs of end rings  224 ,  226  that are connected to each other via connecting members  230 ,  232  providing holes through which flexible couplings  236 ,  238  can be seen. The stand-off members  220 ,  222  may be formed of insulative material and provide separation between the linear motor  202  and the capacitors  208 ,  210 . This prevents high-voltages and/or current received by the capacitors  208 ,  210  from being received by and/or interfering with operation of the linear motor  202 . 
     The flexible couplings  236 ,  238  allow for axial and/or radial misalignment of the shaft  212  relative to the rods  216 ,  218 . The flexible couplings  236 ,  238  may be formed of an insulative material. Although flexible couplings  236 ,  238  are described, fixed couplings, which do not allow for axial and/or radial misalignment of the shaft  212  and the rods  216 ,  218  may be used. The flexible couplings  236 ,  238  include respective inner couplings  240 ,  242 , outer couplings  244 ,  246 , coupling fasteners  248 ,  250  (e.g., screws), and center fasteners  252 ,  254  (e.g., screws). The inner couplings  240 ,  242  are connected to the shaft  212  of the linear motor  202  via corresponding ones of the coupling fasteners  248 ,  250  (or inner coupling fasteners). The outer couplings  244 ,  246  are connected to the rods  216 ,  218  of the capacitors  208 ,  210  via other ones of the coupling fasteners  248 ,  250  (or outer coupling fasteners). In one embodiment, at least a portion of the inner couplings  240 ,  242  are screwed into at least a portion of the outer couplings  244 ,  246 . In an embodiment, the center fasteners  252 ,  254  connect the outer couplings  244 ,  246  to the inner couplings  240 ,  242  and prevent the outer couplings  244 ,  246  from moving relative to the inner couplings  244 ,  242 . 
     The outer couplings  244 ,  246  (e.g., the outer coupling  246  as shown) may include an intermediary member  260  and an outer member  262 . The outer member  262  is connected to the rod  218 . The intermediary member  260  connects the inner coupling  242  to the outer member  262 . The fastener  250  connects the intermediary member  260  and the outer member  262  to the rod  218 . 
     The capacitors  208 ,  210  include terminals  211  (an input terminal and an output terminal). The input terminals receive RF power from, for example, inductors L 1 , L 2  of  FIG. 4 . One of the terminals  211  of each of the capacitors  208 ,  210  is connected to a corresponding one of RF brackets  213 . The RF power is provided from the output terminals to the coil output circuits  158 ,  160  of  FIG. 4 . The input terminals or the output terminals may receive the RF power, depending on the implementation. 
     In one embodiment, the capacitors  208 ,  210  are variable vacuum capacitors (e.g., a variable vacuum capacitor is shown in  FIG. 15 ). The capacitors  208 ,  210  include the rods  216 ,  218 , which are biased towards the capacitors  208 ,  210 . For example, the capacitors  208 ,  210  are configured such that there is a constant force applied on the rods  216 ,  218  in an inward direction away from the linear motor  202 . The constant force is provided by vacuum pressure within the capacitors  208 ,  210  and spring-based force provided by bellows within the capacitors  208 ,  210 . As an example, the force to pull one of the rods  216 ,  218  out of one of the capacitors  208 ,  210  may be 15 pounds (lbs.) per square inch (psi). Since the capacitors  208 ,  210  are connected on opposite sides of the shaft  212 , the forces applied on the rods  216 ,  218  counterbalance each other to allow easy movement of the shaft  212  and the rods  216 ,  218  via the linear motor  202 . 
     The embodiment of  FIGS. 5-6  allows for a single linear motor to actuate rods of multiple capacitors. Actuation of the rods causes first electrodes within the capacitors to move relative to other electrodes within the capacitors, thereby, changing capacitances of the capacitors. Example electrodes of a capacitor are shown in  FIG. 15 . The capacitors counterbalance each other without the need for other counterbalances. The forces of the capacitors on the rods and shaft of the linear motor effectively cancel each other to allow for the rods and shaft to be easily and quickly actuated. This reduces size and power requirements of the linear motor and/or allows for the linear motor to actuate the rods and shaft at high speeds for RAP and/or high-speed switching between RF power ratios of TCP reactor coils. 
     As shown, the linear motor  202  displaces the rods in opposite directions relative to the capacitors. For example, as one rod is being pulled out of one of the capacitors, the other rod is being pushed into the other capacitor. This is different than the embodiments of  FIGS. 7-14 , which allow for independent actuation of the rods of capacitors. 
       FIGS. 7-8  show a single capacitor system  300  including a single linear motor  302 , a separator support assembly  304 , a capacitor  306  and a counterbalance assembly  308 . The counterbalance assembly  308  is shown in  FIG. 7  and not in  FIG. 8 . This arrangement may be provided for each variable capacitor of a plasma processing system, where actuation of a rod of the capacitor is utilized. As a result, a linear motor is provided for each capacitor. Unlike the embodiment of  FIGS. 5-6 , the embodiment of  FIGS. 7-8  allows for independent actuation of the rods of the capacitors by providing a linear motor for each capacitor. Also, the forces on the rod of each of the capacitors are counterbalanced by a counterbalance assembly (e.g., the counterbalance assembly  308 ), which is connected on an opposite end of a shaft of the linear motor than the capacitor and separator support assembly. The separator support assembly  304  is configured similarly to the separator support assemblies  204 ,  206  of  FIGS. 5-6 . 
     In the embodiment shown, the counterbalance assembly  308  may include a spring  310  and spring retainers  312 ,  314 . The spring  310  is a compression spring and is held between the spring retainers  312 ,  314 . A fastener  316  (e.g., a screw) connects the counterbalance assembly  308  to the linear motor  302 . In the example shown, the fastener  316  is a screw that is inserted through the end most one of the spring retainers (e.g., spring retainer  314 ) and is screwed into an end of a shaft  320  of the linear motor  302  to hold the spring  310  and spring retainers  312 ,  314  to the linear motor  302 . 
     The counterbalance assembly  308  counterbalances a predetermined amount of the forces of the capacitor  306  on a rod  330  of the capacitor  306 . In one embodiment, the counterbalance assembly  308  counterbalances 90% of the forces of the capacitor  306  on the rod  330 . In this manner, the rod  330  is biased to be pulled into the capacitor  306 . This maintains some tension on the rod  330  and prevents the rod  330  from floating, which maintains accuracy in setting position of the rod  330  and thus capacitance of the capacitor  306 . 
       FIGS. 9-12C  show a single capacitor system  350  including a single rotary motor  352 , a support bracket  354 , a cam  356 , a cam follower  358 , a separator support assembly  360  and a capacitor  362 . The support bracket  354 , as shown, is ‘L’-shaped and holds the separator support assembly  360  in a fixed location relative to the rotary motor  352 . The rotary motor  352  may include a gearbox  361 . The separator support assembly  360  includes a stand-off member  364  and an inner coupling  366 . The inner coupling  366  is connected to the capacitor  362  and a cam follower support bracket  365  via fasteners  368  (e.g., screws). The stand-off member  364  and the inner coupling  366  may be formed of an insulative material. 
     The cam follower  358  is connected to the cam follower support bracket  365  via one of the fasteners  368 . The cam follower  358  may include a bearing (not shown), a roller  372 , and/or a rod  374 . The bearing may be located within the roller and allow the roller to roll freely on the rod  374 . The rod  374  may have a threaded end for attaching to the cam follower support bracket  365 . The rod  374  is connected to the cam follower support bracket  365 . During operation the rotary motor  352  rotates the cam  356 , which causes the roller  372  to move within a slot  376  of the cam  356 . This causes the cam follower  358  to move relative to the cam  356  and cause the inner coupling  366  to move in a linear direction, which actuates a rod  380  of the capacitor  362 . 
     The support bracket  354  includes one or more stops (a single stop  382  is shown), which limit movement of the cam  356  and thus the cam follower  358 , the inner coupling  366  and the rod  380 . As an example, the one or more stops may be pins, as shown by the stop  382 . The stops may be of various types. The cam  356  is shaped and includes a tab  384 . The cam  356  may be rotated to a point where the cam  356  and the tab  384  come in contact with the stops.  FIGS. 12A-12C  illustrate movement of the cam  356  and contacting of a portion (e.g., a surface  390 ) of the cam  356  and the tab  384  with the stops.  FIG. 12A  shows the tab  384  in contact with the stop  382  and the cam follower  358  at a first end of the slot  376 .  FIG. 12B  shows the cam  356  transitioning between a first position and a second position. The cam follower  358  is shown at a position between ends of the slot  376 .  FIG. 12C  shows the surface  390  in contact with the stop  382  and the cam follower  358  at a second end of the slot  376 . 
     The stop  382  may be positioned at various positions on the support bracket  354  depending on when the cam is to be prevented from rotating. The stop  382  may be located to prevent the cam follower  358  from coming in contact with an end of the slot  376 . Although a single tab  384  is shown, multiple tabs may be included as part of the cam  356 . 
     The slot  376  may have any predetermined pattern, which provides a predetermined path for the cam follower  358  to follow. The pattern of the slot  376  is set to maintain or vary a rate of change of capacitance of the capacitor  362 . The slot  376  may have a continuous curvature or may have one or more linear sections. Also, the angular rate of curvature along the slot  376  may vary. 
     In one embodiment, motion of the cam  356  is controlled to prevent the cam  356  and the tab  384  from contacting the stops. The stops may correspond to movement limits of the rod  380  or may assure that the rod  380  moves within a portion of an overall possible range of movement of the rod  380  relative to the capacitor  362  (or housing of the capacitor  362 ). For example, the stops may be positioned to limit the rod  380  to movement within a predetermined amount (e.g., 50%) of the overall possible range of movement of the rod  380 . This prevents the rod  380  from bottoming out, which minimizes degradation to the capacitor  362 . 
     As an example, the cam  356  may be connected to a shaft  392  of the rotary motor  352  and/or a shaft of the gearbox  361  via a clamp  394  and/or a key  396  (the key  396  is shown in  FIGS. 10-11 , but not  FIG. 12 ). The clamp  394  is connected to the cam  356  and slides over the key  396 . The shaft  392  or the shaft of the gearbox  361  is inserted in the key  396 . A set screw may be inserted in a side of the key  396  and prevent the key  396  from sliding off of the shaft  392  or the shaft of the gearbox  361 . The cam  356  may be connected to the shaft  392  or the shaft of the gearbox  361  using other suitable fasteners and/or techniques. As another example, the cam  356  may be held onto the shaft  392  or the shaft of the gearbox  361  by a screw screwed into an end of the shaft  392  or the shaft of the gearbox  361 . 
     The capacitor system  350  may further include a counterbalance assembly  398 , as shown in  FIG. 11 . The counterbalance assembly  398  may include a spring and/or other components to provide rotational force on the shaft  392  to counterbalance forces on the rod  380  of the capacitor  362 . As an example, the spring may be a flat wound coil with an inner end of the coil connected to the shaft  392 , such that as the shaft  392  rotates forces in the spring act on the shaft to counterbalance with forces on the rod  380 . The counterbalance assembly  398  may provide uniform counterbalance force or non-uniform counterbalance force (increasing or decreasing force) as the shaft is rotated in a single direction. The counterbalance assembly  398  may be configured to counterbalance a predetermined amount (e.g., 90%) of forces exerted on the rod  380  by the capacitor  362 . 
       FIGS. 13-14  show a single capacitor system  400  including a single rotary motor  402 , a separator support assembly  404 , a capacitor  406  and a counterbalance assembly  408 . The rotary motor  402  may include a gearbox  410 . The rotary motor  402  may operate similarly to the rotary motor  352  of  FIGS. 9-12C . The separator support assembly  404  may be configured similarly to the separator support assembly  304  of  FIGS. 7-8  or may include an intermediary shaft  412  that is connected to (i) a shaft  414  of the rotary motor  402  via a first flexible coupling  416 , and (ii) a leadscrew  418  of the capacitor  406  via a second flexible coupling  420 . The counterbalance assembly  404  may be configured similarly to the counterbalance assembly  398  of  FIG. 11 . 
     During operation the rotary motor  402  rotates the shaft  414 , which rotates the intermediary shaft  412  and the flexible couplings  416 ,  420 . This causes the leadscrew  418  to rotate, which moves a first electrode within the capacitor  406  relative to a second electrode within the capacitor  406 . Example electrodes of a capacitor are shown in  FIG. 15 . The leadscrew may have a high-pitch. As an example, the pitch of the threads of the leadscrew  418  may be, such that the leadscrew  418  has 6 revolutions per inch of travel. As another example, the pitch may be, such that the leadscrew  418  has 4 revolutions per inch of travel. As yet another example, the pitch may be, such that the leadscrew  418  has 3 revolutions per inch of travel. The pitch is higher than a pitch of a traditional vacuum variable capacitor of a plasma processing system, which may have a pitch providing 12 revolutions per inch of travel. 
     Typically, additional force is needed to rotate the leadscrew  418  due to the increased pitch. However, the counterbalance assembly  408  provides at least some of the increased force needed to rotate the leadscrew  418 . The counterbalance assembly  408  provides the increased amount of force and may be configured to counterbalance a predetermined amount (e.g., 90%) of forces exerted on the leadscrew  418  by the capacitor  406 . This allows the leadscrew  418  to be rotated with minimal effort while biasing the leadscrew  418 . The biased force on the leadscrew  418  causes the leadscrew  418  to rotate without applied force by the rotary motor  402 , such that the first electrode moves towards the second electrode. 
     In another embodiment, the counterbalance assembly  408  is replaced with a second separator support assembly and a second capacitor. The second separator support assembly is connected to the shaft on the opposite side of the rotary motor  402  as the first separator support assembly  404 . The second capacitor counterbalances the first capacitor  406 . The second separator support assembly may be configured similarly to the first separator support assembly  404 . This configuration is similarly to the configuration of  FIGS. 5-6 , however a rotary motor is used instead of a linear motor and the capacitors include leadscrews and corresponding couplings rather than rods. 
       FIG. 15  shows an example of a vacuum variable capacitor  500  that includes electrodes  502 ,  503  having opposing capacitor plate structures including a mounting plate  502   b  or  503   b , respectively. The vacuum variable capacitor  500  is shown as an example; other vacuum variable capacitors may be utilized in the above-described embodiments. The mounting plates have thereon multiple concentric cylindrically-shaped capacitor plates  502   a  or  503   a , respectively. In the following description, the reference numerals  502   a  and  503   a  can refer to one or multiple capacitor plates. The electrodes  502  and  503  are positioned with respect to each other to cause capacitor plates  502   a  of the electrode  502  to fit between adjacent capacitor plates  503   a  of the electrode  503  (and vice versa), such that a gap exists between adjacent capacitor plates  502   a  and  503   a . The electrodes  502  and  503  provide a capacitance that can be adjusted by moving the electrode  502  relative to the electrode  503 . 
     The electrodes  502  and  503  are positioned in a housing  501 . The electrode  503  is attached to the housing  501 , such that a position of the electrode  503  remains fixed with respect to the housing  501 . The electrode  502  is attached to the housing  501 , such that the position of the electrode  502  can move with respect to the housing  501 . 
     An end of a hollow shaft  504  is attached to the, electrode  502 . A first member  509  is attached to an end of the shaft  504  opposite the end attached to the electrode  502 . A second member (or rod)  505  is attached to (and as shown is screwed) into the first member  509 . The second member  505  is attached to a head  508  which is, in turn, attached to the housing  501 , such that the head  508  and second member  505  are held in place with respect to the housing  501  along a longitudinal axis  510  of the vacuum variable capacitor  500 . 
     As shown, the electrode  502  may be moved relative to the electrode  503  by rotating the head  508  and/or the second member  505  relative to the first member  509  causing the first member  509  to translate along the longitudinal axis  510 . This moves a shaft  504  connected at a first end to the first member  509 , which moves the electrode  502  relative to the electrode  503 . The shaft  504  is connected at a second end to the first member  509 . This threaded configuration may be used in the embodiment of  FIGS. 13-14 . If the second member  505  is attached to the first member  509  and is not threaded, the second member  505  may be translated without rotation to move the electrode  502  relative to the electrode  503 . This non-threaded configuration may be used in the embodiments of  FIGS. 5-12 . 
     A bellows  506  surrounds a shaft  504 . A bearing  507  enables the shaft  504  to rotate relative to the bellows  506  and the housing  501 . The housing  501 , bearing  507 , bellows  506  and mounting plate  502   b  form a sealed enclosure, held at a vacuum pressure, within which the capacitor plates  502   a  and  503   a  are positioned. The bellows  506  expands and contracts as necessary to allow movement of the threaded member  509 , bearing  507 , shaft  504  and electrode  502  along the longitudinal axis  510 . 
       FIG. 16  shows a TCCT match network  600  that receives power from the power source  16 . The TCCT match network  600  includes the power input circuit  152 , which includes a first capacitor C 1 , a second capacitor C 2 , a third capacitor C 3  and an inductor L 1 . The capacitors C 1  and C 3  may be variable capacitors. The capacitors C 1 , C 3  and inductor L 1  are connected in series between the power source  16  and switches  602 ,  604 . The capacitor C 2  is connected (i) at a first end to an output of the capacitor C 1  and an input of the capacitor C 3 , and (ii) at a second end to the reference terminal  120 . The switches  602 ,  604  are high-power capable solid-state RF switches. In one embodiment, the switches  602 ,  604  are silicone carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFETs). The first switch  602  is connected between (i) the inductor L 1  and (ii) inner coil input circuit  606  and outer coil input circuit  608 . The second switch  604  is connected between (i) the inductor L 1  and (ii) inner coil input circuit  610  and outer coil input circuit  612 . 
     The inner coil input circuits  606 ,  610  are connected between the first switch  602  and an inner coil (or inductor) L 2 . The outer coil input circuits  608 ,  612  are connected between second switch  604  and an outer coil (or inductor) L 3 . The inner coil L 2  is connected between the inner coil input circuits  606 ,  610  and an inner coil output circuit  614 . The inner coil L 3  is connected between the outer coil input circuits  608 ,  612  and an outer coil output circuit  616 . 
     In operation, the switches  602 ,  604  receive control signals from a controller  618  or the controller  46  of  FIG. 1  if the TCCT match network  600  is implemented in the plasma processing system  10  of  FIG. 1 . The controller  46  may perform the tasks described herein with respect to the controller  618 . The control signals control states of the switches  602 ,  604  to control whether power is provided to (i) the coil input circuits  606 ,  608 , or (ii) the coil input circuits  610 ,  612 . In one embodiment, the controller  618  rapidly switches between etch and deposition processes, where (i) the switch  602  is ON and power is provided to the coil input circuits  606 ,  608  during the etch processes, and (ii) the switch  604  is ON and power is provided to the coil input circuits  610 ,  612  during the deposition processes. During the etch processes, the switch  604  is OFF while the switch  602  is ON. During the deposition processes, the switch  604  is ON while the switch  602  is OFF. 
     The coil input circuits  606 ,  608 ,  610 ,  612  may respectively include variable capacitors C 4 , C 5 , C 6 , C 7 , which have respective capacitances. The capacitances of the capacitors C 4 , C 5 , C 6 , C 7  may be adjusted between processes and/or during a changeover between recipes. The capacitances of the capacitors C 4 , C 5 , C 6 , C 7  may be held at constant values during the processes and/or implementation of the recipes. As an example, the capacitances of capacitors C 6 , C 7  are different than the capacitances of the capacitors C 4 , C 5  to provide different power ratios. The capacitances of the capacitors C 4 , C 5 , C 6 , C 7  may be adjusted by the capacitance adjustment system  19  or the controller  46  of  FIG. 1  or the controller  618 . The capacitors C 4 , C 5 , C 6 , C 7  may each be configured for slow or rapid change in capacitance as any of the variable capacitors described and/or disclosed herein. 
     The inner coil output circuit  614  includes an inductor L 4  that is connected in series between the inner coil L 2  and ground  120 . The outer coil output circuit  616  includes a capacitor C 8  that is connected in series between the outer coil L 3  and the ground  120 . 
       FIG. 17  shows a TCCT match network  700  that receives power from the power source  16 . The TCCT match network  700  includes the power input circuit  152 , which includes a first capacitor C 1 , a second capacitor C 2 , a third capacitor C 3  and an inductor L 1 . The capacitors C 1  and C 3  may be variable capacitors. The capacitors C 1 , C 3  and inductor L 1  are connected in series between the power source  16  and switches  702 ,  703 ,  704 ,  705 . The capacitor C 2  is connected (i) at a first end to an output of the capacitor C 1  and an input of the capacitor C 3 , and (ii) at a second end to the reference terminal  120 . The switches  702 ,  703 ,  704 ,  705  are high-power capable solid-state RF switches. In one embodiment, the switches  602 ,  604  are SiC MOSFETs. The first switch  702  is connected between the inductor L 1  and inner coil input circuit  706 . The second switch  703  is connected between the inductor L 1  and outer coil input circuit  708 . The third switch  704  is connected between the inductor L 1  and inner coil input circuit  710 . The fourth switch  705  is connected between the inductor L 1  and outer coil input circuit  712 . 
     The inner coil input circuit  706  is connected between the first switch  702  and an inner coil (or inductor) L 2 . The outer coil input circuits  708  is connected between second switch  704  and an outer coil (or inductor) L 3 . The inner coil input circuit  710  is connected between the third switch  710  and the inner coil L 2 . The outer coil input circuits  712  is connected between the fourth switch  712  and the outer coil L 3 . The inner coil L 2  is connected between the inner coil input circuits  706 ,  710  and an inner coil output circuit  714 . The inner coil L 3  is connected between the outer coil input circuits  708 ,  712  and an outer coil output circuit  716 . 
     In operation, the switches  702 ,  703 ,  704 ,  705  receive control signals from a controller  718  or the controller  46  of  FIG. 1  if the TCCT match network  700  is implemented in the plasma processing system  10  of  FIG. 1 . The controller  46  may perform the tasks described herein with respect to the controller  718 . The control signals control states of the switches  702 ,  703 ,  704 ,  705  to control whether power is provided to (i) the coil input circuits  706 ,  708 , or (ii) the coil input circuits  710 ,  712 . In one embodiment, the controller  718  rapidly switches between etch and deposition processes, where (i) the switches  702 ,  703  are ON and power is provided to the coil input circuits  706 ,  708  during the etch processes, and (ii) the switches  704 ,  705  are ON and power is provided to the coil input circuits  710 ,  712  during the deposition processes. During the etch processes, the switches  704 ,  705  are OFF while the switches  702 ,  703  are ON. During the deposition processes, the switches  704 ,  705  are ON while the switches  702 ,  703  are OFF. 
     The coil input circuits  706 ,  708 ,  710 ,  712  may respectively include variable capacitors C 4 , C 5 , C 6 , C 7 , which have respective capacitances. The capacitances of the capacitors C 4 , C 5 , C 6 , C 7  may be adjusted between processes and/or during a changeover between recipes. The capacitances of the capacitors C 4 , C 5 , C 6 , C 7  may be held at constant values during the processes and/or implementation of the recipes. As an example, the capacitances of capacitors C 6 , C 7  are different than the capacitances of the capacitors C 4 , C 5  to provide different power ratios. The capacitances of the capacitors C 4 , C 5 , C 6 , C 7  may be adjusted by the capacitance adjustment system  19  or the controller  46  of  FIG. 1  or the controller  718 . The capacitors C 4 , C 5 , C 6 , C 7  may each be configured for slow or rapid change in capacitance as any of the variable capacitors described and/or disclosed herein. 
     The inner coil output circuit  714  includes an inductor L 4  that is connected in series between the inner coil L 2  and ground  120 . The outer coil output circuit  716  includes a capacitor C 8  that is connected in series between the outer coil L 3  and the ground  120 . 
     The embodiments of  FIGS. 16 and 17  allow for rapid switching between different sets of capacitors (e.g., the set including C 4 , C 5  and the set including C 6 , C 7 ) for etch and deposition processes without a need for changing a capacitance of one or more capacitors. This allows for rapid switching between power ratios for etch and deposition processes during a RAP without incurring high-cycling between capacitance values of one or more capacitors. The embodiment of  FIG. 17  reduces unwanted coupling between antenna circuits (e.g., the inner coil L 2  and the outer coil L 3 ) over the embodiment of  FIG. 16  by disconnecting unused splitter capacitors (e.g., one of the sets of the capacitors C 4 , C 5  and C 6 , C 7 ). 
     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 the 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. 
     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.” 
     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. 
     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. 
     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 in 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. 
     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. 
     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.