Variable resistance network

Abstract

A variable resistance network includes a plurality of resistance modules electrically connected in series along an electrical conduction path between an input electrical node and an output electrical node. The variable resistance network includes a plurality of relay modules electrically connected to control activation and deactivation of respective ones of the plurality of resistance modules. The variable resistance network includes a controller electrically connected to each of the plurality of relay modules. The controller is configured to transmit electrical control signals to each of the plurality of relay modules to independently control operation of each of the plurality of relay modules and correspondingly control activation and deactivation of the plurality of resistance modules. The variable resistance network is implementable for controlling radiofrequency signal return pathways from one or more electrodes within a plasma processing chamber.

Description

Variable Resistance Network by inventorsChang Liu, Janies E. Caron, Aleksander Sharetsky Background of the Invention

[0001] Plasma processing systems are used to manufacture semiconductor devices, e.g., chips / die, on semiconductor wafers. In the plasma processing system, the semiconductor wafer is exposed to various types of plasma to cause prescribed changes to a condition of the semiconductor wafer, such as through material deposition and / or material removal and / or material implantation and / or material modification, etc. During plasma processing of the semiconductor wafer, radiofrequency (RF) signals are transmitted through a process gas within a chamber to impart RF power into the process gas and correspondingly transform the process gas into the plasma in exposure to the semiconductor wafer. Reactive constituents of the plasma, such as radicals and ions, interact with materials on the semiconductor wafer to achieve a prescribed effect on the semiconductor wafer. In some plasma processing systems, the RF signals are transmitted from an electrode structure within the chamber to the processing region in order to transform the process gas into the plasma in exposure to the semiconductor wafer. It is within this context that various embodiments described herein arise.Summary of the Invention

[0002] In an example embodiment, a variable resistance network is disclosed. The variable resistance network includes a plurality of resistance modules electrically connected in series along an electrical conduction path between an input electrical node and an output electrical node. The variable resistance network also includes a plurality of relay modules electrically connected to control activation and deactivation of respective ones of the plurality of resistance modules. The variable resistance network also includes a controller electrically connected to each of the plurality of relay modules, the controller is configured to transmit electrical control signals to each of the plurality of relay modules to independently control operation of each of the plurality of relay modules and correspondingly control activation and deactivation of the plurality of resistance modules.

[0003] In an example embodiment, a plasma processing system is disclosed. The plasma processing system includes a plasma processing chamber. The plasma processing system also includes an electrode disposed within the plasma processing chamber. The plasma processing system also includes a variable resistance network electrically connected between the electrode and a reference ground potential. The variable resistance network includes a plurality of resistance modules electrically connected in series. The variable resistance network also includesa plurality of relay modules electrically connected to control activation and deactivation of respective ones of the plurality of resistance modules. The variable resistance network also includes a controller that is electrically connected to each of the plurality of relay modules. The controller is configured to transmit electrical control signals to each of the plurality of relay modules to independently control operation of each of the plurality of relay modules and correspondingly control activation and deactivation of the plurality of resistance modules.

[0004] In an example embodiment, a method is disclosed for providing controlled variable electrical resistance. The method includes electrically connecting a plurality of resistance modules in series along an electrical conduction path between an input electrical node and an output electrical node. The method also includes electrically connecting a plurality of relay modules to control activation and deactivation of the plurality of resistance modules, such that a different one of the plurality of relay modules is electrically connected to control a correspondingly different one of the plurality of resistance modules. The method also includes setting a cumulative resistance along the electrical conduction path between the input electrical node and the output electrical node by controlling each of the plurality of relay modules in an independent manner to activate or deactivate the corresponding one of the plurality of resistance modules to which said each of the plurality of relay modules is electrically connected to control. Activation of a given one of the plurality of resistance modules causes an electrical resistance of the given one of the plurality of resistance modules to be imparted along the electrical conduction path between the input electrical node and an output electrical node. Deactivation of the given one of the plurality of resistance modules causes the electrical resistance of the given one of the plurality of resistance modules to not be imparted along the electrical conduction path between the input electrical node and an output electrical node.

[0005] In an example embodiment, a method is disclosed for controlling radiofrequency signal return paths of a plasma processing chamber. The method includes electrically connecting a plurality of resistance modules in series along an electrical conduction path between an electrode within the plasma processing chamber and a reference ground potential. The method also includes electrically connecting a plurality of relay modules to control activation and deactivation of the plurality of resistance modules, such that a different one of the plurality of relay modules is electrically connected to control a correspondingly different one of the plurality of resistance modules. The method also includes setting a cumulative resistance along the electrical conduction path between the electrode and the reference ground potential by controlling each of the plurality of relay modules in an independent manner to activate or deactivate the corresponding one of the plurality of resistance modules to which said each of theplurality of relay modules is electrically connected to control. Activation of a given one of the plurality of resistance modules causes an electrical resistance of the given one of the plurality of resistance modules to be imparted along the electrical conduction path between the electrode and the reference ground potential. Deactivation of the given one of the plurality of resistance modules causes the electrical resistance of the given one of the plurality of resistance modules to not be imparted along the electrical conduction path between the electrode and the reference ground potential. The method also includes transmitting radiofrequency signals into the plasma processing chamber, such that at least a portion of the radiofrequency signals return through the electrode and through the cumulative resistance that is set by one or more of plurality of resistance modules along the electrical conduction path between the electrode and the reference ground potential. In some embodiments, the method also includes filtering radiofrequency signals between the electrode and the plurality of resistance modules to block at least one specified frequency range of the radiofrequency signals.

[0006] In an example embodiment, a method is disclosed for controlling radiofrequency signal return paths of a plasma processing chamber. The method includes electrically connecting a plurality of variable resistance networks between a respective plurality of electrodes within a plasma processing chamber and a reference ground potential. Each of the plurality of variable resistance networks includes a corresponding plurality of resistance modules electrically connected in series and a corresponding plurality of relay modules to control activation and deactivation of respective ones of the corresponding plurality of resistance modules. The method also includes controlling the plurality of relay modules in each of the plurality of variable resistance networks to independently set a cumulative resistance of each of the plurality of variable resistance networks. The method also includes transmitting radiofrequency signals into the plasma processing chamber, such that at least a portion of the radiofrequency signals return through the plurality of electrodes and through the corresponding plurality of variable resistance networks to the reference ground potential. In some embodiments, the method also includes filtering radiofrequency signals between one or more of the plurality of electrodes and the corresponding plurality of variable resistance networks to block at least one specified frequency range of the radiofrequency signals.

[0007] Other aspects and advantages of the embodiments disclosed herein will become more apparent from the following detailed description and the accompanying drawings.Brief Description of the Drawings

[0008] Figure 1A shows a diagram of a variable resistance network, in accordance with some embodiments.

[0009] Figure IB shows a diagram of an example resistance module of the plurality of resistance modules, in accordance with some embodiments.

[0010] Figure 1C shows a diagram of an example relay module of the plurality of relay modules, in accordance with some embodiments.

[0011] Figure 2 shows a diagram of a plasma processing system for performing a plasma-driven fabrication process on a substrate, in accordance with some embodiments.

[0012] Figure 3A shows a diagram of a plasma processing system for performing a plasma- driven fabrication process on the substrate, in accordance with some embodiments.

[0013] Figure 3B shows a top view of the multiple electrode zones, referenced as view A-A in Figure 3 A, in accordance with some embodiments.

[0014] Figure 4A shows a cross-sectional diagram of an apparatus in which the variable resistance network is disposed within a housing structure, in accordance with some embodiments.

[0015] Figure 4B shows a variation of the apparatus Figure 4A in which liquid cooling is used instead of forced air cooling, in accordance with some embodiments.

[0016] Figure 5 shows a flowchart of a method for providing controlled variable electrical resistance, in accordance with some embodiments.

[0017] Figure 6 shows a flowchart of a method for operating the plasma processing chamber, in accordance with some embodiments.

[0018] Figure 7 shows a flowchart of a method for operating the plasma processing chamber, in accordance with some embodiments.Detailed Description of the Invention

[0019] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent, however, to one skilled in the art that embodiments of the present disclosure may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail so as to avoid unnecessarily obscuring the present disclosure.

[0020] Figure 1A shows a diagram of a variable resistance network 101, in accordance with some embodiments. The variable resistance network 101 includes a plurality of resistance modules 103-1 to 103-N, where N is an integer number greater than one. In some embodiments, each of the plurality of resistance modules 103-1 to 103-N includes one or more solid-state resistor(s). The plurality of resistance modules 103-1 to 103-N are electrically connected in series along an electrical conduction path between an input electrical node 109 and an output electrical node 111. Each of the plurality of resistance modules 103-1 to 103-N has an input (ires)and an output (ores). The input (ires) of a first resistance module 103-1 in the plurality of resistance modules 103-1 to 103-N is electrically connected to the input electrical node 109 of the variable resistance network 101. The output (ores) of a last resistance module 103-N in the plurality of resistance modules 103-1 to 103-N is electrically connected to the output electrical node 111.

[0021] Each resistance module 103-x of the plurality of resistance modules 103-1 to 103-N includes at least one fixed electrical resistor, where the at least one fixed electrical resistor is electrically connected between the input (ires) and the output (ores) of the resistance module 103- x. In some embodiments, the fixed electrical resistors in the resistance modules 103-1 to 103-N are solid-state resistors. In some embodiments, at least one of the plurality of resistance modules 103-1 to 103-N includes a plurality of fixed electrical resistors electrically connected between the input (ires) and output (ores) of said at least one of the plurality of resistance modules 103-1 to 103-N. In some embodiments, the plurality of fixed electrical resistors includes at least two fixed electrical resistors electrically connected in series. In some embodiments, the plurality of fixed electrical resistors includes at least two fixed electrical resistors electrically connected in parallel. In some embodiments, the plurality of fixed electrical resistors includes at least two fixed electrical resistors electrically connected in series and at least two fixed electrical resistors electrically connected in parallel. The configuration of fixed electrical resistors in any given one of the resistance modules 103-1 to 103-N defines an overall resistance of said given on of the resistance modules 103-1 to 103-N.

[0022] Figure IB shows a diagram of an example resistance module 103-x of the plurality of resistance modules 103-1 to 103-N, where x is an integer number within the range from 1 to N, in accordance with some embodiments. The example resistance module 103-x has the input (ires) and the output (ores). The example resistance module 103-x includes a resistor group 121 of parallel connected fixed resistors 129-1 to 129-X and 131-1 to 131-Y, where X is an integer number greater than zero, and where Y is an integer number greater than zero. The fixed resistors 129-1 to 129-X are electrically connected in parallel with the fixed resistors 131-1 to 131-Y. The example resistance module 103-x also includes a resistor group 123 of serially connected fixed resistors 133-1 to 133-Z, where Z is an integer number greater than zero. The resistor group 121 of parallel connected fixed resistors 129-1 to 129-X and 131-1 to 131-Y is electrically connected in series with the resistor group 123 of serially connected fixed resistors 133-1 to 133-Z between the input (ires) and the output (ores) of the example resistance module 103-x. It should be understood that the configuration of the example resistance module 103-x shown in Figure IB demonstrates one of many possible configurations of any one or more of the plurality of resistance modules 103-1 to 103-N. For example, an alternative configuration of the exampleresistance module 103-x includes just the resistor group 123, but not the resistor group 121. Another alternative configuration of the example resistance module 103-x includes just a single fixed resistor, e.g., 133-1, electrically connected between the input (ires) and the output (ores). Another alternative configuration of the example resistance module 103-x includes just the resistor group 121, but not the resistor group 123. Another example alternative configuration of the example resistance module 103-x includes just a pair of parallel connected fixed resistors, e.g., 129-1 and 131-1, electrically connected between the input (ires) and the output (ores). In another alternative configuration of the example resistance module 103-x, the resistor group 121 includes a pair of parallel connected fixed resistors, e.g., 129-1 and 131-1, and the resistor group 123 includes a single fixed resistor, e.g., 133-1, with the resistor group 121 and the resistor group 123 serially electrically connected between the input (ires) and the output (ores). It should be understood that each resistance module 103-x of the plurality of resistance modules 103-1 to 103-N can be configured to include any number of fixed resistors electrically connected together in any configuration as needed to achieve a desired overall resistance of the resistance module 103-x. It should also be understood that in various embodiments different ones of the plurality of resistance modules 103-1 to 103-N can be configured to include a different number and / or different electrical connectivity of fixed resistors as need to achieve a desired overall resistance of the resistance module 103-x. Also, it should be understood that the electrical resistance of each fixed resistor in each of the plurality of resistance modules 103-1 to 103-N is independently set as needed to achieve a desired overall resistance of the resistance module 103-x. In this manner, each fixed resistor in a given resistance module 103-x can have an electrical resistance that is the same or different than other fixed resistors in the given resistance module 103-x. In some embodiments, each one of the plurality of resistance modules 103-1 to 103-N provides a different fixed electrical resistance along the electrical conduction path through the variable resistance network 101.

[0023] As shown in Figure 1A, the variable resistance network 101 also includes a plurality of relay modules 105-1 to 105-N. The plurality of relay modules 105-1 to 105-N are electrically connected to control activation and deactivation of respective ones of the plurality of resistance modules 103-1 to 103-N within the variable resistance network 101. Each of the plurality of relay modules 105-1 to 105-N has an input (irei) electrically connected to the input (ires) of a respective one of the plurality of resistance modules 103-1 to 103-N. Each of the plurality of relay modules 105-1 to 105-N also has an output (orei) electrically connected to the output (ores) of said respective one of the plurality of resistance modules 103-1 to 103-N. For example, the relay module 105-1 has an input (irei) electrically connected to the input (ires) of the resistancemodule 103- 1 , and the relay module 105-1 has an output (orei) electrically connected to the output (Ores) of the resistance module 103-1. For a further example, the relay module 105-2 has an input (irei) electrically connected to the input (ires) of the resistance module 103-2, and the relay module 105-2 has an output (orei) electrically connected to the output (ores) of the resistance module 103- 2. This pattern of relay module 105-x bypass connection for each resistance module 103-x continues along the electrical conduction path between the input 109 and the output 111 of the variable resistance network, with the relay module 105-N completing the pattern. Specifically, the relay module 105-N has an input (irei) electrically connected to the input (ires) of the resistance module 103-N, and the relay module 105-N has an output (orei) electrically connected to the output (Ores) of the resistance module 103-N.

[0024] In a closed state of operation, each of the plurality of relay modules 105-1 to 105-N is configured to form a low resistance electrical conduction path around a respective one of the plurality of resistance modules 103-1 to 103-N to deactivate the respective one of the plurality of resistance modules 103-1 to 103-N within the variable resistance network 101. Also, in an open state of operation, each of the plurality of relay modules 105-1 to 105-N is configured to block the low resistance electrical conduction path around the respective one of the plurality of resistance modules 103-1 to 103-N so as to activate the respective one of the plurality of resistance modules 103-1 to 103-N within the variable resistance network 101. For example, when the relay module 105-1 is in the closed state of operation, the relay module 105-1 forms a low resistance electrical conduction path through the relay module 105-1 and around the resistance module 103-1, so as to allow electrical signals (RF signals) to bypass the resistance module 103-1 by traveling through the relay module 105-1 and around the resistance module 103-1 as the electrical signals travel through the variable resistance network 101 between the input electrical node 109 and the output electrical node 111. Also, when the relay module 105-1 is in the open state of operation, the relay module 105-1 blocks the low resistance electrical conduction path through the relay module 105-1, so as to force electrical signals (RF signals) to travel through the resistance module 103-1 as the electrical signals travel through the variable resistance network 101 between the input electrical node 109 and the output electrical node 111, which forces the electrical signals to encounter the electrical resistance provided by the resistance module 103-1.

[0025] Similarly, when the relay module 105-2 is in the closed state of operation, the relay module 105-2 forms a low resistance electrical conduction path through the relay module 105-2 and around the resistance module 103-2, so as to allow electrical signals (RF signals) to bypass the resistance module 103-2 by traveling through the relay module 105-2 and around theresistance module 103-2 as the electrical signals travel through the variable resistance network 101 between the input electrical node 109 and the output electrical node 111. Also, when the relay module 105-2 is in the open state of operation, the relay module 105-2 blocks the low resistance electrical conduction path through the relay module 105-2, so as to force electrical signals (RF signals) to travel through the resistance module 103-2 as the electrical signals travel through the variable resistance network 101 between the input electrical node 109 and the output electrical node 111, which forces the electrical signals to encounter the electrical resistance provided by the resistance module 103-2. This above-described functionality of the relay modules 105-x relative to the corresponding resistance modules 103-x continues along the electrical conduction path through the variable resistance network 101 between the input electrical node 109 and the output electrical node 111.

[0026] In this manner, when the relay module 105-N is in the closed state of operation, the relay module 105-N forms a low resistance electrical conduction path through the relay module 105- N and around the resistance module 103-N, so as to allow electrical signals (RF signals) to bypass the resistance module 103-N by traveling through the relay module 105-N and around the resistance module 103-N as the electrical signals travel through the variable resistance network 101 between the input electrical node 109 and the output electrical node 111. Also, when the relay module 105-N is in the open state of operation, the relay module 105-N blocks the low resistance electrical conduction path through the relay module 105-N, so as to force electrical signals (RF signals) to travel through the resistance module 103-N as the electrical signals travel through the variable resistance network 101 between the input electrical node 109 and the output electrical node 111, which forces the electrical signals to encounter the electrical resistance provided by the resistance module 103-N.

[0027] The variable resistance network 101 also includes a controller 107 electrically connected to each of the plurality of relay modules 105-1 to 105-N. The controller 107 is configured to transmit electrical control signals to each of the plurality of relay modules 105-1 to 105-N to independently control operation of each of the plurality of relay modules 105-1 to 105-N and correspondingly independently control activation and deactivation of the plurality of resistance modules 103-1 to 103-N. Each of the plurality of relay modules 105-1 to 105-N has a respective control input (ictri) that is electrically connected to the controller 107 by way of electrical connections 115-1 to 115-N, respectively. In some embodiments, the plurality of relay modules 105-1 to 105-N are configured to operate in accordance with digital control signals. In some embodiments, the plurality of relay modules 105-1 to 105-N are configured to operate in accordance with analog control signals.

[0028] Figure 1C shows a diagram of an example relay module 105-x of the plurality of relay modules 105-1 to 105-N, in accordance with some embodiments. The example relay module 105-x has the input (irei) and the output (orei). In some embodiments, the relay module 105-x includes an input connector 151, an output connector 153, and a switching device 155 electrically connected between the input connector 151 and the output connector 153. In some embodiments, the relay module 105-x includes a switch driver 157 configured to operate the switching device 155 in accordance with an electrical control signal (digital and / or analog) received from the controller 107 by way of the connection 115-x. Operation of the switch driver 157, by way of the controller 107, to close the switching device 155 causes the low resistance electrical conduction path to be formed through the relay module 105-x along the input connector 151, through the switching device 155, and along the output connector 153. Operation of the switch driver 157, by way of the controller 107, to open the switching device 155 causes the low resistance electrical conduction path through the relay module 105-x to be blocked, such that electrical signals (RF signals) do not travel from the input connector 151 to the output connector 153, which forces the electrical signals (RF signals) to travel through the corresponding resistance module 103-x. It should be appreciated that the variable resistance network 101 is scalable in terms of voltage, current, power, resistance.

[0029] Figure 2 shows a diagram of a plasma processing system 200 for performing a plasma- driven fabrication process on a substrate 205, in accordance with some embodiments. In some embodiments, the substrate 205 is a semiconductor wafer that includes integrated circuit devices in the form of multi-level structures defined on a silicon substrate. At a substrate level of the semiconductor wafer, transistor devices with diffusion regions are formed. In subsequent upper levels of the semiconductor wafer, interconnect metallization lines are patterned and electrically connected to the transistor devices to define a desired integrated circuit device. Electrically conductive vertical structures, such as vias and contacts, are formed to establish various vertical electrical connections with the semiconductor wafer. The interconnect metallization lines are insulated from other electrically conductive layers by intervening dielectric material.

[0030] The system 200 includes a radiofrequency (RF) power supply 211 an impedance matching network 213, a plasma processing chamber 201, and a computer 202. In some embodiments, the RF power supply 211 includes a low frequency RF generator having a low frequency of operation within a range extending from about 10 kilohertz (kHz) to about 2 megahertz (MHz). In some embodiments, the RF power supply 211 includes a low frequency RF generator having a selectable frequency of operation of one or more of 100 kHz, 400 kHz, 1 MHz, 2 MHz, and / or another frequency. In some embodiments, the RF power supply 211includes a high frequency RF generator having a high frequency of operation within a range extending from about 2 MHz to about 200 MHz. In some embodiments, the RF power supply 211 includes a high frequency RF generator having a selectable frequency of operation of one or more of 2 MHz, 13.56 MHz, 27 MHz, 60 MHz, 120 MHz, and / or another frequency. In some embodiments, the RF power supply 211 includes a combination of one or more low frequency RF generator(s) and / or one or more high frequency RF generator(s), such as those described above. In some embodiments, the low frequency RF generator is a primary RF generator with regard to generation of a plasma 209 within the plasma processing chamber 201, and the high frequency RF generator is an example of a secondary RF generator with regard to the plasma 209 generated within the plasma processing chamber 201.

[0031] An output of the RF power supply 211 is electrically connected to an input of the impedance matching network 213 through an electrical connection 215, e.g., RF cable. The impedance matching network 213 includes an arrangement of capacitors and / or inductors configured to ensure that an impedance seen at the output of the RF power supply 211 is sufficiently close to a load impedance for which the RF power supply 211 is designed to operate, so that RF signals generated and transmitted by the RF power supply 211 will be transmitted into the plasma 209 generated within the plasma processing chamber 201 in an efficient manner, i.e., without unacceptable reflection back toward the RF power supply 211.

[0032] The plasma processing chamber 201 includes a substrate support 203, such as an electrostatic chuck (ESC). The substrate 205 is disposed on a top surface of the substrate support 203 for processing. In some embodiments, the plasma processing chamber 201 includes a door 206 through which the substrate 205 is moved into and out of the plasma processing chamber 201. The substrate support 203 includes (or serves as) a lower electrode formed of an electrically conductive material, such as metal, e.g., aluminum, an alloy of aluminum, or other metal. In some embodiments, the substrate support 203 is formed in part by a ceramic, with the electrically conductive lower electrode embedded within the ceramic of the substrate support 203. In some embodiments, the ceramic of the substrate support 203 is aluminum oxide (AI2O3). An output of the impedance matching network 213 is electrically connected to the lower electrode within the substrate support 203 through an electrical connection 217, e.g., RF power transmission line.

[0033] In some embodiments, the plasma processing chamber 201 is a capacitively coupled plasma (CCP) chamber. More specifically, the plasma processing chamber 201 also includes an upper electrode 207 that is located above the substrate support 203, so as to form a gap 204 between the upper electrode 207 and the substrate support 203. The upper electrode 207 is formed of an electrically conductive material, such as metal, e.g., aluminum, an alloy ofaluminum, or other metal. The upper electrode 207 is electrically connected through an electrical connection 221 to the input electrical node 109 of the variable resistance network 101. The output electrical node 111 of the variable resistance network 101 is electrically connected through an electrical connection 223 to a reference ground potential 225. In this manner, the variable resistance network 101, as controlled by the controller 107, controls the electrical resistance on the RF signal return path from the upper electrode 207 to the reference ground potential 225.

[0034] In some embodiments, an optional RF signal filter 227 is electrically connected between the variable resistance network 101 and the upper electrode 207 along the electrical connection 221. In some embodiments, the RF signal filter 227 is configured to block at least one specified range of RF signal frequencies from reaching the variable resistance network 101. In some embodiments, the RF signals that are blocked by the RF signal filter 227 find RF signal return paths to a reference ground potential through the plasma processing chamber 201, rather than through the variable resistance network 101 by way of the upper electrode 207. In some embodiments, the RF signal filter 227 is configured as a notch filter.

[0035] The computer 202 is configured to control operation of the system 200, including operation of the controller 107 of the variable resistance network 101. In various embodiments, the computer 202 is configured and connected to control various parameters associated with operation of the plasma processing chamber 201, including delivery of process gases to the plasma processing chamber 201, temperature settings (e.g., heating and / or cooling) of the substrate support 203, pressure and / or vacuum settings within the plasma processing chamber 201, operational settings of the RF power supply 211 and of the matching network 213, and transfer of the substrate 205 into and out of the plasma processing chamber 201, among other parameters. Examples of the computer 202 include a desktop computer, a laptop computer, a tablet, a smart phone, and a controller. In some embodiments, the computer 202 includes a processor and a memory device. In various embodiments, the processor is one or more of a central processing unit (CPU), a graphical processing unit (GPU), a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a programmable logic device (PLD), and a microcontroller, among others. In various embodiments, the memory device includes one or more of a read-only memory (ROM) and a random access memory (RAM), among other types of computer memory. The processor is connected in bi-directional data communication with the memory device. In some embodiments, the computer 202 generates process recipe signals and sends the process recipe signals to each component involved in operation of the plasma processing chamber 201, including the RF power supply 211, processgas delivery components, the substrate support 203, the matching network 213, and the controller 107, among other components. The various components / equipment in the system 200 are integrated with electronics for controlling their operation before, during, and after processing of the substrate 205.

[0036] Broadly speaking, in various embodiments, the computer 202 includes electronics having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, and the like. In some embodiments, the integrated circuits include computer chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as ASICs, PLDs, and / or one or more microprocessors, or microcontrollers that execute program instructions, e.g., software. The program instructions are instructions communicated to the computer 202 in the form of various individual settings (or program files), defining the parameters, the factors, the variables, etc., for carrying out a particular plasma process on the substrate 205 within the plasma processing chamber 201 of the system 200. In some embodiments, the program instructions are 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 the substrate 205, e.g., semiconductor wafer.

[0037] In various embodiments, the computer 202 is integrated with or coupled to the system 200, or otherwise networked to the system 200, or a combination thereof. For example, in some embodiments, the computer 202 is implemented as a computing cloud or at least partially in a fab host computer system, which allows for remote access of the substrate 205 processing controls. In various embodiments, the computer 202 enables remote access to the system 200 to monitor current progress of substrate 205 plasma processing operations, examines a history of past substrate 205 fabrication operations, examines trends or performance metrics from a plurality of substrate 205 fabrication operations, to enable informed setting and / or adjustment of parameters associated with current plasma processing of the substrate 205, to set processing steps to follow in a recipe for a current plasma processing of the substrate 205, and / or to start a new plasma process on the substrate 205.

[0038] In some embodiments, a remote computer, e.g., a server, provides process recipes to the computer 202 of the system 200 over a network, which includes a local network or the Internet. The remote computer includes a user interface that enables entry or programming of parameters and / or settings, which are then communicated to the computer 202. In some examples, the computer 202 receives instructions in the form of data, which specify the parameters, factors,and / or variables for each of the plasma processing steps to be performed during one or more plasma processing operations on the substrate 205. In some embodiments, the computer 202 is implemented in a distributed manner, such as by including 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 computer 202 for such purposes includes one or more integrated circuits within the system 200 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 performed by the system 200.

[0039] Figure 3A shows a diagram of a plasma processing system 300 for performing a plasma- driven fabrication process on the substrate 205, in accordance with some embodiments. The system 300 is a variation of the system 200 described with regard to Figure 2. Specifically, in the system 300, the upper electrode 207 includes multiple electrode zones 207-1, 207-2, and 207-3. Figure 3B shows a top view of the multiple electrode zones 207-1, 207-2, and 207-3, referenced as view A- A in Figure 3 A, in accordance with some embodiments. It should be understood that the multiple electrode zones 207-1, 207-2, and 207-3 are shown by way of example. In various other embodiments, the upper electrode 207 can be configured to include either more than or less than three electrode zones. Each of the multiple electrode zones 207-1, 207-2, and 207-3 is electrically separated from others of the multiple electrode zones 207-1, 207- 2, and 207-3. In this manner, the RF signal return paths to the reference ground potential 225 that are respectively provided by the multiple electrode zones 207-1, 207-2, and 207-3 are separately and independently controllable.

[0040] The system 300 includes an RF return control system 301 that includes multiple variable resistance networks 101-1, 101-2, and 101-3 respectively electrically connected between the multiple electrode zones 207-1, 207-2, and 207-3 and the reference ground potential 225. An input electrical node 109-1 of the variable resistance network 101-1 is electrically connected to the electrode zone 207-1 through an electrical connection 221-1. An output electrical node 111- 1 of the variable resistance network 101-1 is electrically to the reference ground potential 225 through an electrical connection 223-1. An input electrical node 109-2 of the variable resistance network 101-2 is electrically connected to the electrode zone 207-2 through an electrical connection 221-2. An output electrical node 111-2 of the variable resistance network 101-2 is electrically to the reference ground potential 225 through an electrical connection 223-2. An input electrical node 109-3 of the variable resistance network 101-3 is electrically connected to the electrode zone 207-3 through an electrical connection 221-3. An output electrical node 111- 3 of the variable resistance network 101-3 is electrically to the reference ground potential 225through an electrical connection 223-3. It should be understood that each of the multiple electrode zones 207-1, 207-2, and 207-3 of the upper electrode 207 has its own separate variable resistance network 101-1, 101-2, and 101-3, respectively, for controlling the electrical resistance along the respective electrical conduction path between each of the multiple electrode zones 207- 1, 207-2, and 207-3 of the upper electrode 207 and the reference ground potential 225.

[0041] Each of the variable resistance networks 101-1, 101-2, and 101-3 is configured in the same manner as the variable resistance network 101 described with regard to Figures 1A, IB, and 1C. In this manner, each of the multiple variable resistance networks 101-1, 101-2, and 101- 3 includes a corresponding plurality of resistance modules 103-1 to 103-N electrically connected in series, and a corresponding plurality of relay modules 105-1 to 105-N electrically connected to control activation and deactivation of respective ones of the corresponding plurality of resistance modules 103-1 to 103-N. The controller 107 is electrically connected in a separate and independent manner to each relay module 105-1 to 105-N in the variable resistance network 101- 1 through an electrical connection bus 229-1. The controller 107 is also electrically connected in a separate and independent manner to each relay module 105-1 to 105-N in the variable resistance network 101-2 through an electrical connection bus 229-2. The controller 107 is also electrically connected in a separate and independent manner to each relay module 105-1 to 105- N in the variable resistance network 101-3 through an electrical connection bus 229-3. The controller 107 is configured to transmit electrical control signals to each of the plurality of relay modules 105-1 to 105-N in each of the variable resistance networks 101-1, 101-3, 101-3 to independently control operation of each of the plurality of relay modules 105-1 to 105-N and correspondingly control activation and deactivation of the plurality of resistance modules 103-1 to 103-N in each of the variable resistance networks 101-1, 101-2, and 101-3.

[0042] In some embodiments, an optional RF signal filter 227-1 is electrically connected between the variable resistance network 101-1 and the upper electrode zone 207-1 along the electrical connection 221-1. In some embodiments, an optional RF signal filter 227-2 is electrically connected between the variable resistance network 101-2 and the upper electrode zone 207-2 along the electrical connection 221-2. In some embodiments, an optional RF signal filter 227-3 is electrically connected between the variable resistance network 101-3 and the upper electrode zone 207-3 along the electrical connection 221-3. In some embodiments, each of the RF signal filters 227-1, 227-2, and 227-3 is configured to block at least one specified range of RF signal frequencies from reaching the variable resistance network 101-1, 101-2, and 101-3, respectively. In some embodiments, the RF signals that are blocked by any of the RF signal filters 227-1, 227-2, and 227-3 find other RF signal return paths to a reference ground potential,such as through the plasma processing chamber 201. In some embodiments, one or more of the RF signal filters 227-1, 227-2, and 227-3 is configured as a notch filter.

[0043] Figure 4A shows a cross-sectional diagram of an apparatus in which the variable resistance network 101 is disposed within a housing structure 401, in accordance with some embodiments. The resistance modules 103-1 to 103-N are electrically connected to a printed circuit board 405. The electrical conduction path between the input electrical node 109 and the output electrical node 111 is formed through the printed circuit board 405. In some embodiments, the relay modules 105-1 to 105-N are electrically connected to a printed circuit board 403, and the controller 107 is electrically connected to the printed circuit board 403. The printed circuit board 403 is configured to separately and independently provide for electrical connection of the controller 107 to each of the relay modules 105-1 to 105-N. Also, in some embodiments, the resistance modules 403-1 to 403-N are thermally connected to a heat transfer plate 407 formed of a thermally conductive material, such as metal. In some embodiments, the heat transfer plate 407 is thermally connected to an arrangement of heat transfer fins 407 A configured to move heat away from the heat transfer plate 407 and correspondingly away from the resistance modules 103-1 to 103-N. In some embodiments, a fan 409 is disposed to provide forced air flow through the housing structure 401 and over the heat transfer fins 407A, as indicated by arrows 411, to provide for cooling of the resistance modules 103-1 to 103-N and relay modules 105-1 to 105- N. In these embodiments, the combination of the fan 409, the heat transfer plate 407, and the heat transfer fins 407A forms a cooling system disposed in thermal connection with the plurality of resistance modules 103-1 to 103-N.

[0044] Figure 4B shows a variation of the apparatus Figure 4A in which liquid cooling is used instead of forced air cooling, in accordance with some embodiments. In the apparatus of Figure 4B, the plurality of resistance modules 103-1 to 103-N are thermally connected to a heat transfer plate 425. A tube 423 is disposed in thermal connection with the heat transfer plate 425. A liquid coolant system 421 is connected in fluid communication with the tube 423 to provide a controlled flow of cooling fluid through the tube 423, as indicated by arrows 427, and correspondingly through the heat transfer plate 425. The cooling fluid removes heat from the heat transfer plate 425, and correspondingly removes heat from the plurality of resistance modules 103-1 to 103- N. In some embodiments, a channel is formed within the heat transfer plate 425 to serve as the tube 423 within the heat transfer plate 425. In some embodiments, the fan of 409 of Figure 4A is implemented in conjunction with the liquid coolant system 421 of Figure 4B. Also, it should be understood that in various other embodiments other types of cooling systems / components, e.g., thermoelectric coolers, heat tubes, etc., can be implemented to remove heat from theplurality of resistance modules 103-1 to 103-N and / or from the plurality of relay modules 105-1 to 105-N.

[0045] Figure 5 shows a flowchart of a method for providing controlled variable electrical resistance, in accordance with some embodiments. The method includes an operation 501 for electrically connecting the plurality of resistance modules 103-1 to 103-N in series along an electrical conduction path between the input electrical node 109 and the output electrical node 111. The method also includes an operation 503 for electrically connecting the plurality of relay modules 105-1 to 105-N to control activation and deactivation of the plurality of resistance modules 103-1 to 103-N, such that a different one of the plurality of relay modules 105-1 to 105- N is electrically connected to control a correspondingly different one of the plurality of resistance modules 103-1 to 103-N. The method also includes an operation 505 for setting a cumulative resistance along the electrical conduction path between the input electrical node 109 and the output electrical node 111 by controlling each of the plurality of relay modules 105-1 to 105-N in an independent manner to activate or deactivate the corresponding one of the plurality of resistance modules 103-1 to 103-N to which said each of the plurality of relay modules 105-1 to 105-N is electrically connected to control. Activation of a given one of the plurality of resistance modules 103-1 to 103-N causes an electrical resistance of the given one of the plurality of resistance modules 103-1 to 103-N to be imparted along the electrical conduction path between the input electrical node 109 and the output electrical node 111. Deactivation of the given one of the plurality of resistance modules 103-1 to 103-N causes the electrical resistance of the given one of the plurality of resistance modules 103-1 to 103-N to not be imparted along the electrical conduction path between the input electrical node 109 and the output electrical node 111. In some embodiments, the method includes electrically connecting the input electrical node 109 to the electrode 207 within the plasma processing chamber 201, and electrically connecting the output electrical node 111 to the reference ground potential 225. In some embodiments, the method includes filtering electrical signals between the electrode 207 and the variable resistance network 101 to block at least one specified range of signal frequency from reaching the variable resistance network 101, such as by way of the RF signal filter 227.

[0046] Figure 6 shows a flowchart of a method for operating the plasma processing chamber 201, in accordance with some embodiments. The method includes an operation 601 for electrically connecting the plurality of resistance modules 103-1 to 103-N in series along an electrical conduction path between the electrode 207 within the plasma processing chamber 201 and the reference ground potential 225. The method also includes an operation 603 for electrically connecting the plurality of relay modules 105-1 to 105-N to control activation anddeactivation of the plurality of resistance modules 103-1 to 103-N, such that a different one of the plurality of relay modules 105-1 to 105-N is electrically connected to control a correspondingly different one of the plurality of resistance modules 103-1 to 103-N. The method also includes an operation 605 for setting a cumulative resistance along the electrical conduction path between the electrode 207 and the reference ground potential 225 by controlling each of the plurality of relay modules 105-1 to 105-N in an independent manner to activate or deactivate the corresponding one of the plurality of resistance modules 103-1 to 103-N. Activation of a given one of the plurality of resistance modules 103-1 to 103-N causes an electrical resistance of the given one of the plurality of resistance modules 103-1 to 103-N to be imparted along the electrical conduction path between the electrode 207 and the reference ground potential 225. Deactivation of the given one of the plurality of resistance modules 103-1 to 103-N causes the electrical resistance of the given one of the plurality of resistance modules 103-1 to 103-N to not be imparted along the electrical conduction path between the electrode 207 and the reference ground potential 225. The method also includes an operation 607 for transmitting RF signals into the plasma processing chamber 201, such that at least a portion of the RF signals return through the electrode 207 and through the cumulative resistance that is set by one or more of the plurality of resistance modules 103-1 to 103-N along the electrical conduction path between the electrode 207 and the reference ground potential 225. The method also includes an optional operation 609 for filtering RF signals between the electrode 207 and the plurality of resistance modules 103-1 to 103-N to block at least one specified frequency range of the RF signals.

[0047] Figure 7 shows a flowchart of a method for operating the plasma processing chamber 201, in accordance with some embodiments. The method includes an operation 701 for electrically connecting a plurality of variable resistance networks 101-1 to 101-V, where V is an integer number greater than one, between a respective plurality of electrodes 207-1 to 207-V within the plasma processing chamber 201 and the reference ground potential 225. Each of the plurality of variable resistance networks 101-1 to 101-V includes a corresponding plurality of resistance modules 103-1 to 103-N electrically connected in series and a corresponding plurality of relay modules 105-1 to 105-N to control activation and deactivation of respective ones of the corresponding plurality of resistance modules 103-1 to 103-N. The method also includes an operation 703 for controlling the plurality of relay modules 105-1 to 105-N in each of the plurality of variable resistance networks 101-1 to 101-V to independently set a cumulative resistance of each of the plurality of variable resistance networks 101-1 to 101-V. The method also includes an operation 705 for transmitting RF signals into the plasma processing chamber 201, such that at least a portion of the RF signals return through the plurality of electrodes 207-1 to 207-V and through the corresponding plurality of variable resistance networks 101-1 to 101- V to the reference ground potential 225. The method also includes an optional operation 707 for filtering RF signals between one or more of the plurality of electrodes 207-1 to 207-V and the corresponding plurality of variable resistance networks 101-1 to 101-V to block at least one specified frequency range of the RF signals.

[0048] It should be appreciated that without the variable resistance network 101 as disclosed herein, adjustment of resistance is done by either use of jumper wires or use of rotary resistors, which both have limitations and drawbacks. Resistance adjustment methods based on jumper wire manual selection rely on individuals physically connecting or disconnecting resistors using jumper wires. These jumper wire based methods for resistance adjustment not only require human intervention, but also involve demerging and remerging components, which is prone to human error. Also, the risk of selecting an incorrect resistance value is substantial in the jumper wire based methods for resistance adjustment. Resistance adjustments methods based on rotary resistors also come with challenges. Specifically, rotary resistors are inherently unstable, which leads to inconsistencies in resistance values. Users often attempt to address this inconsistency in resistance values by utilizing stepper motors to drive the rotary resistor. However, this solution is far from ideal. For example, the continuous movement of rotary resistors can generate conductive particles, which is a significant concern for long-term reliability and safety. Additionally, rotary resistors exhibit high parasitic inductance, which limits their utility in certain applications despite having low rated power levels.

[0049] The solid-state variable resistance network 101 disclosed herein offers a compelling alternative by combining multiple relay modules 105-1 to 105-N and resistance modules 103-1 to 103-N to create a highly stable and precisely controllable resistance system. With the ability to digitally toggle the relay modules 105-1 to 105-N on and off within the variable resistance network 101, users can achieve accurate resistance adjustments without the drawbacks of manual intervention or the wear and tear associated with rotary resistors. It should be appreciated that the variable resistance network 101 disclosed herein not only addresses the existing limitations of variable resistors but also opens up new possibilities across various industries, from electronics to automation.

[0050] The variable resistance network 101 allows users to manipulate the final resistance output by selectively activating or deactivating the individual relay modules 105-1 to 105-N. This dynamic control mechanism ensures precision and versatility in resistance adjustments within the variable resistance network 101. The variable resistance network 101 provides an extensive resistance tuning range, as determined by the number of relay modules 105-1 to 105-N and the corresponding number of resistance modules 103-1 to 103-N within the variable resistance network 101. In some embodiments, each resistance module 103-1 to 103-N in the variable resistance network 101 has a resistance value that is twice that of its preceding resistance module 103-1 to 103-N in the variable resistance network 101. For example, in these particular embodiments, if the variable resistance network 101 includes seven resistance modules 103-1 to 103-7, and the first resistance module 103-1 has a resistance value of 10 Ohms, the total resistance range provided by the variable resistance network 101 would extend from about 0 Ohm to about 1270 Ohms (10 Ohms + 20 Ohms + 40 Ohms + 80 Ohms + 160 Ohms + 320 Ohms + 640 Ohms = 1270 Ohms). It should be understood that this is just an example of how the variable resistance network 101 can be configured. In various embodiments, the variable resistance network 101 can be configured to include any number of resistance modules 103-1 to 103-N, where N is greater than one, and each of the resistance modules 103-1 to 103-N can be configured to have any resistance value as needed.

[0051] It should also be appreciated that with the variable resistance network 101, it is possible to control resistance remotely, which not only enhances user convenience but also opens up possibilities for automation and remote monitoring in a wide array of applications. Also, with the variable resistance network 101, the risk of human error in setting electrical resistance is significantly mitigated. The controller 107 of the variable resistance network 101 eliminates that need for manual interventions, such as insertion of jumper wires, which reduces the probability of selecting an incorrect resistance value due to human error, and which correspondingly provides a safer operating environment.

[0052] Also, the variable resistance network 101 is scalable to accommodate higher power ratings. This scalability is particularly valuable for applications requiring precise resistance control at elevated power levels, while maintaining a broad resistance tuning range. Also, the configuration of the variable resistance network 101 minimizes parasitic inductance, which makes the variable resistance network 101 particularly well-suited for high-frequency signal applications where inductance can be a significant factor. Also, due to its solid-state configuration, the variable resistance network 101 has an extended operational lifetime, which reduces the need for frequent resistor replacement and provides for lower maintenance and repair costs. It should be appreciated that, unlike rotary resistor implementations, the variable resistor network 101 does not include mechanical moving parts. Therefore, use of the variable resistor network 101 eliminates wear and tear issues associated with rotary resistor implementations and correspondingly provides improved reliability over a longer term.

[0053] It is further noted that in some embodiments, the variable resistance network 101 andthe various associated methods disclosed herein are applicable to several types of plasma chambers, e.g., a capacitively coupled plasma (CCP) chamber, a plasma chamber including an inductively coupled plasma (ICP) reactor, a transformer coupled plasma chamber, conductor tools, dielectric tools, a plasma chamber including an electron cyclotron resonance (ECR) reactor, among others. As noted above, depending on the process step or steps to be performed by the system 200 / 300, the computer 202 communicates 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 substrates 205 to and from tool locations and / or load ports in a semiconductor manufacturing factory.

[0054] The various embodiments disclosed herein may be practiced with various computer system configurations including hand-held hardware units, microprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers and the like. The various embodiments disclosed herein can also be practiced in distributed computing environments where tasks are performed by remote processing hardware units that are linked through a network.

[0055] Various embodiments described herein may also be practiced using various computer system configurations including hand-held hardware units, microprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers and the like. Embodiments described herein can also be practiced in distributed computing environments where tasks are performed by remote processing hardware units that are linked through a network. It should be understood that the embodiments described herein can employ various computer-implemented operations involving data stored in computer systems. These operations are those requiring physical manipulation of physical quantities. Any of the operations described herein that form part of the embodiments are useful machine operations. The embodiments also relate to a hardware unit or an apparatus for performing these operations. The apparatus may be specially constructed for a special purpose computer. When defined as a special purpose computer, the computer can also perform other processing, program execution or routines that are not part of the special purpose, while still being capable of operating for the special purpose. In some embodiments, the operations may be processed by a general purpose computer selectively activated or configured by one or more computer programs stored in the computer memory, cache, or obtained over a network. When data is obtained over a network, the data may be processed by other computers on the network, e.g., a cloud of computing resources.

[0056] Various embodiments described herein can be implemented through process control instructions instantiated as computer-readable code on a non-transitory computer-readable medium. The non-transitory computer-readable medium is any data storage hardware unit that can store data, which can thereafter be read by a computer system. Examples of the non- transitory computer-readable medium include hard drives, network attached storage (NAS), ROM, RAM, compact disc-ROMs (CD-ROMs), CD-recordables (CD-Rs), CD-rewritables (CD- RWs), magnetic tapes, and other optical and non-optical data storage hardware units. The non- transitory computer-readable medium can include computer-readable tangible medium distributed over a network-coupled computer system so that the computer-readable code is stored and executed in a distributed fashion.

[0057] The foregoing description of the embodiments has been provided for purposes of illustration and description, and is not intended to be exhaustive or limiting. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. In this manner, one or more features from one or more embodiments disclosed herein can be combined with one or more features from one or more other embodiments disclosed herein to form another embodiment that is not explicitly disclosed herein, but rather that is implicitly disclosed herein. This other embodiment may also be varied in many ways. Such embodiment variations are not to be regarded as a departure from the disclosure herein, and all such embodiment variations and modifications are intended to be included within the scope of the disclosure provided herein.

[0058] Although some method operations may be described in a specific order herein, it should be understood that other housekeeping operations may be performed in between method operations, and / or method operations may be adjusted so that they occur at slightly different times or simultaneously or may be distributed in a system which allows the occurrence of the processing operations at various intervals associated with the processing, as long as the processing of the method operations are performed in a manner that provides for successful implementation of the method.

[0059] Although the foregoing embodiments have been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications can be practiced within the scope of the appended claims. Accordingly, the embodiments disclosed herein are to be considered as illustrative and not restrictive, and are therefore not to be limited to just the details given herein, but may be modified within the scope and equivalents of the appended claims.

Claims

Claims1. A variable resistance network, comprising: a plurality of resistance modules electrically connected in series along an electrical conduction path between an input electrical node and an output electrical node; a plurality of relay modules electrically connected to control activation and deactivation of respective ones of the plurality of resistance modules; and a controller electrically connected to each of the plurality of relay modules, the controller configured to transmit electrical control signals to each of the plurality of relay modules to independently control operation of each of the plurality of relay modules and correspondingly control activation and deactivation of the plurality of resistance modules.

2. The variable resistance network as recited in claim 1, wherein each of the plurality of resistance modules includes at least one fixed electrical resistor.

3. The variable resistance network as recited in claim 2, wherein at least one of the plurality of resistance modules includes a plurality of fixed electrical resistors.

4. The variable resistance network as recited in claim 3, wherein the plurality of fixed electrical resistors includes at least two fixed electrical resistors electrically connected in series.

5. The variable resistance network as recited in claim 3, wherein the plurality of fixed electrical resistors includes at least two fixed electrical resistors electrically connected in parallel.

6. The variable resistance network as recited in claim 3, wherein the plurality of fixed electrical resistors includes at least two fixed electrical resistors electrically connected in series and at least two fixed electrical resistors electrically connected in parallel.

7. The variable resistance network as recited in claim 1, wherein each of the plurality of resistance modules has an input and an output, the input of a first resistance module in the plurality of resistance modules electrically connected to the input electrical node, the output of a last resistance module in the plurality of resistance modules electrically connected to the output electrical node, and wherein each of the plurality of relay modules has an input electrically connected to the input of a respective one of the plurality of resistance modules and an output electrically connected to the output of said respective one of the plurality of resistance modules.

8. The variable resistance network as recited in claim 7, wherein each of the plurality of relay modules is configured to form a low resistance electrical conduction path around said respective one of the plurality of resistance modules to deactivate said respectiveone of the plurality of resistance modules, and wherein each of the plurality of relay modules is configured to block the low resistance electrical conduction path around said respective one of the plurality of resistance modules to activate said respective one of the plurality of resistance modules.

9. The variable resistance network as recited in claim 1, further comprising: a printed circuit board to which the plurality of resistance modules are electrically connected, the electrical conduction path between the input electrical node and the output electrical node formed through the printed circuit board.

10. The variable resistance network as recited in claim 9, further comprising: a cooling system disposed in thermal connection with the plurality of resistance modules.

11. The variable resistance network as recited in claim 10, wherein the cooling system includes a heat transfer plate in thermal connection with the plurality of resistance modules.

12. The variable resistance network as recited in claim 11, wherein the cooling system includes one or more of a fan disposed to direct air flow over the heat transfer plate and a tube disposed to direct cooling fluid through the heat transfer plate.

13. A plasma processing system, comprising: a plasma processing chamber; an electrode disposed within the plasma processing chamber; and a variable resistance network electrically connected between the electrode and a reference ground potential, the variable resistance network including a plurality of resistance modules electrically connected in series, the variable resistance network also including a plurality of relay modules electrically connected to control activation and deactivation of respective ones of the plurality of resistance modules, the variable resistance network also including a controller electrically connected to each of the plurality of relay modules, the controller configured to transmit electrical control signals to each of the plurality of relay modules to independently control operation of each of the plurality of relay modules and correspondingly control activation and deactivation of the plurality of resistance modules.

14. The plasma processing system as recited in claim 13, wherein each of the plurality of resistance modules has an input and an output, each one of the plurality of resistance modules providing a different fixed electrical resistance along an electrical conduction path through the variable resistance network, and wherein each of the plurality of relay modules has an input electrically connected to the input of a respective one of the plurality of resistance modules and an output electrically connected to the output of said respective one of the plurality of resistancemodules.

15. The plasma processing system as recited in claim 14, wherein each of the plurality of relay modules is configured to form a low resistance electrical conduction path around said respective one of the plurality of resistance modules to deactivate said respective one of the plurality of resistance modules, and wherein each of the plurality of relay modules is configured to block the low resistance electrical conduction path around said respective one of the plurality of resistance modules to activate said respective one of the plurality of resistance modules.

16. The plasma processing system as recited in claim 13, further comprising: a radiofrequency signal filter electrically connected between the variable resistance network and the electrode, the radiofrequency signal filter configured to block at least one specified range of signal frequency from reaching the variable resistance network.

17. The plasma processing system as recited in claim 13, wherein the electrode includes multiple electrode zones, the multiple electrode zones electrically separated from each other, wherein said variable resistance network is one of multiple variable resistance networks, each one of the multiple variable resistance networks electrically connected between a respective one of the multiple electrode zones and the reference ground potential, each of the multiple variable resistance networks including a corresponding plurality of resistance modules electrically connected in series, each of the multiple variable resistance networks also including a corresponding plurality of relay modules electrically connected to control activation and deactivation of respective ones of the corresponding plurality of resistance modules, and wherein the controller is electrically connected to each relay module of the corresponding plurality of relay modules within the multiple variable resistance networks, the controller configured to transmit electrical control signals to each relay module to independently control operation of said relay module.

18. A method for providing controlled variable electrical resistance, comprising: electrically connecting a plurality of resistance modules in series along an electrical conduction path between an input electrical node and an output electrical node; electrically connecting a plurality of relay modules to control activation and deactivation of the plurality of resistance modules, such that a different one of the plurality of relay modules is electrically connected to control a correspondingly different one of the plurality of resistance modules; and setting a cumulative resistance along the electrical conduction path between the input electrical node and the output electrical node by controlling each of the plurality of relay modulesin an independent manner to activate or deactivate the corresponding one of the plurality of resistance modules to which said each of the plurality of relay modules is electrically connected to control, wherein activation of a given one of the plurality of resistance modules causes an electrical resistance of the given one of the plurality of resistance modules to be imparted along the electrical conduction path between the input electrical node and the output electrical node, and wherein deactivation of the given one of the plurality of resistance modules causes the electrical resistance of the given one of the plurality of resistance modules to not be imparted along the electrical conduction path between the input electrical node and the output electrical node.

19. The method as recited in claim 18, further comprising: electrically connecting the input electrical node to an electrode within a plasma processing chamber; and electrically connecting the output electrical node to a reference ground potential.

20. The method as recited in claim 19, further comprising: filtering electrical signals between the electrode and the variable resistance network to block at least one specified range of signal frequency from reaching the variable resistance network.

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