Radio Frequency Distribution Circuit Including a Transformer and / or a Transformer-Coupled Combiner - Patent application

Abstract

The transformer includes a primary coil and a secondary coil. The primary coil includes a first shield of a first coaxial cable, a second shield of a second coaxial cable, and a conductive interconnector connecting the first shield to the second shield. The secondary coil includes a first core of the first coaxial cable, a second core of the second coaxial cable, and a pair of conductive wires connecting the first core to the second core.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 62 / 908,846, filed October 1, 2019. The above-referenced related applications are hereby incorporated by reference in their entireties.

[0002] The present disclosure relates to apparatus for semiconductor and solid state device manufacturing and processing, and more particularly to radio frequency (RF) distribution circuits for substrate processing systems. [Background technology]

[0003] The description of the background art provided herein is intended to provide a general overview of the contents of the present disclosure, and the work of the inventors named herein is not admitted, expressly or impliedly, as prior art against the present disclosure, to the extent described in this Background section, as well as aspects of the description that may not be considered prior art at the time of filing.

[0004] Substrate processing systems may be used to process substrates, such as semiconductor wafers. Examples of substrate processing include etching, deposition, etc. During processing, the substrate is placed on a substrate support, such as an electrostatic chuck (ESC), and one or more process gases may be introduced into the processing chamber.

[0005] One or more process gases may be supplied to the processing chamber by a gas supply system. In some systems, the gas supply system includes a manifold connected to a showerhead located in the processing chamber. As an example, during an etching process, a substrate may be placed on the ESC of the substrate processing system, and a thin film on the substrate is etched. As another example, a thin film is deposited on the substrate using atomic layer deposition (ALD). During processing of the substrate, one or more RF signals may be supplied to the electrodes of the showerhead to adjust the plasma ionization density and ionization energy. Summary of the Invention

[0006] A transformer is provided, comprising a primary coil and a secondary coil, the primary coil comprising a first shield of a first coaxial cable, a second shield of a second coaxial cable, and a conductive interconnect connecting the first shield to the second shield, the secondary coil comprising a first core of the first coaxial cable, a second core of the second coaxial cable, and a pair of conductive wires connecting the first core to the second core.

[0007] In other features, the first coaxial cable extends parallel to the second coaxial cable. In other features, a sum of the lengths of the first core, the second core and the pair of conductive wires is at least one of a multiple of and equal to the length of each of the first coaxial cable and the second coaxial cable. In other features, a length of each of the first coaxial cable and the second coaxial cable is at least one of a fractional multiple of a wavelength of a radio frequency signal transmitted by the transformer.

[0008] In other features, a radio frequency distribution circuit is provided, comprising a radio frequency generator and the transformer, the radio frequency generator for generating a first radio frequency signal having frequency components at a radio frequency, the transformer for converting the first radio frequency signal to a second radio frequency signal, the second radio frequency signal having frequency components at the first radio frequency.

[0009] In other features, a substrate processing system is provided, comprising the radio frequency distribution circuit, a process chamber, a showerhead, and a substrate support, the showerhead including an electrode and mounted within the process chamber, the substrate support mounted within the process chamber adjacent the showerhead, and the transformer for providing the second radio frequency signal to the electrode.

[0010] In other features, a radio frequency distribution circuit is provided, comprising a first filter, a second filter, a first matching network, a second matching network, and a transformer coupled combiner. The first filter is for receiving a first radio frequency signal and a second radio frequency signal from at least one radio frequency generator and filtering out the first radio frequency signal, the first radio frequency signal being at a first frequency and the second radio frequency signal being at a second frequency, the second frequency being less than the first frequency. The second filter is for receiving the first radio frequency signal and the second radio frequency signal from at least one radio frequency generator and filtering out the first radio frequency signal. The first matching network is for matching an output of the at least one radio frequency generator to an input of the first filter. The second matching network is for matching an output of the at least one radio frequency generator to an input of the second filter. The transformer coupled combiner is for converting the first radio frequency signal to a third radio frequency signal, converting the second radio frequency signal to a fourth radio frequency signal, and either combining the first radio frequency signal with the second radio frequency signal or combining the third radio frequency signal with the fourth radio frequency signal. The third radio frequency signal includes a frequency component at the first radio frequency. The fourth radio frequency signal includes a frequency component at the second radio frequency.

[0011] In other features, the transformer coupled combiner includes a first transformer to receive an output of the first filter and a second transformer to receive an output of the second filter.

[0012] In other features, the first transformer includes a primary coil and a secondary coil. The primary coil is connected to the first filter. The second transformer includes a primary coil and a secondary coil. The primary coil is connected to the second filter and to the primary coil of the first transformer. The secondary coil is connected to the secondary coil of the first transformer.

[0013] In other features, the primary coil and the secondary coil of the first transformer are connected to a ground reference, and the primary coil and the secondary coil of the second transformer are connected to the ground reference.

[0014] In other features, the first transformer includes a primary coil and a secondary coil, the primary coil includes a first shield of a first coaxial cable, a second shield of a second coaxial cable, and a conductive interconnector connecting the first shield to the second shield, and the secondary coil includes a first core of the first coaxial cable, a second core of the second coaxial cable, and a pair of conductive wires connecting the first core to the second core.

[0015] In other features, the first coaxial cable extends parallel to the second coaxial cable. In other features, a sum of the lengths of the first core, the second core and the pair of conductive wires is at least one of a multiple of and equal to the length of each of the first coaxial cable and the second coaxial cable. In other features, a length of each of the first coaxial cable and the second coaxial cable is at least one of a fractional multiple of the wavelength of the first radio frequency signal.

[0016] In other features, the transformer coupled combiner includes a first transformer including a first primary coil connected to the first filter, a second primary coil connected to the second filter, a first secondary coil connected to receive the third radio frequency signal, and a second secondary coil connected to receive the fourth radio frequency signal.

[0017] In other features, the first transformer includes a third secondary coil for receiving a fifth radio frequency signal including a frequency component at the first frequency and a frequency component at the second frequency.

[0018] In other features, the transformer coupled combiner includes a first primary coil, a second primary coil, a first secondary coil, and a second secondary coil. The first primary coil is coupled to the first filter. The second primary coil is coupled to the second filter. The first secondary coil outputs the third radio frequency signal. The third radio frequency signal includes frequency components at the first radio frequency and the second radio frequency, respectively. The second secondary coil outputs the fourth radio frequency signal. The fourth radio frequency signal includes frequency components at the first radio frequency and the second radio frequency, respectively.

[0019] In other features, the transformer coupled combiner includes a third secondary coil and a fourth secondary coil. The third secondary coil outputs a fifth radio frequency signal. The fifth radio frequency signal includes frequency components at the first radio frequency and the second radio frequency, respectively. The fourth secondary coil outputs a sixth radio frequency signal. The sixth radio frequency signal includes frequency components at the first radio frequency and the second radio frequency, respectively.

[0020] In other features, a substrate processing system is provided, comprising the radio frequency distribution circuit, a process chamber, a showerhead, and a substrate support, the showerhead including the electrode and mounted within the process chamber, and the substrate support mounted within the process chamber adjacent the showerhead.

[0021] Also provided in the substrate processing system is an RF distribution circuit for supplying RF power to an electrode, the RF distribution circuit including a first RF generator, a first filter, a first matching network, and a first transformer. The first RF generator generates a first RF signal having a frequency component at a first RF. The first filter filters out one or more RF signals generated in the substrate processing system other than the first RF signal. The first matching network matches an output of the first RF generator to an input of the first filter. The first transformer converts the first RF signal to a second RF signal, where the second RF signal has a frequency component at the first RF, and supplies the second RF signal to the electrode to adjust plasma ionization density and ionization energy in a process chamber of the substrate processing system.

[0022] In other features, a substrate processing system is provided, comprising the RF distribution circuit, the process chamber, a showerhead, the showerhead including the electrode, and a substrate support mounted within the process chamber, the substrate support mounted within the process chamber adjacent the showerhead.

[0023] In other features, the transformer includes a primary coil and a secondary coil. The primary coil includes a first shield of a first coaxial cable, a second shield of a second coaxial cable, and a conductive interconnect connecting the first shield to the second shield. The secondary coil includes a first core of the first coaxial cable, a second core of the second coaxial cable, and a pair of conductive wires connecting the first core to the second core. In other features, the first coaxial cable runs parallel to the second coaxial cable.

[0024] In other features, a sum of the lengths of the first core, the second core and the pair of conductive wires is equal to four times the length of each of the first coaxial cable and the second coaxial cable. In other features, a length of each of the first coaxial cable and the second coaxial cable is equal to one-quarter of a wavelength of the first RF signal.

[0025] In other features, the RF distribution circuit further includes a second RF generator for generating a third RF signal having frequency components at a second RF, where the second RF is less than the first RF, a second filter for filtering the first RF signal, where the first filter filters out the third RF signal, and a second matching network for matching an output of the second RF generator to an input of the second filter.

[0026] In other features, the RF distribution circuit further includes a second transformer to receive an output of the second filter, convert the third RF signal to a fourth RF signal, and provide the fourth RF signal to the electrode.

[0027] In other features, a substrate processing system is provided, comprising the RF distribution circuit, the process chamber, a showerhead including the electrode and mounted within the process chamber, and a substrate support mounted within the process chamber adjacent to the showerhead.

[0028] In other features, the first transformer includes a primary coil connected to the first filter and a secondary coil connected to the electrode, and the second transformer includes a primary coil connected to the second filter and the primary coil of the first transformer, and a secondary coil connected to the secondary coil of the first transformer and the electrode.

[0029] In other features, the primary coil and the secondary coil of the first transformer are connected to a ground reference, and the primary coil and the secondary coil of the second transformer are connected to the ground reference.

[0030] In another feature, the first transformer includes a primary coil and a secondary coil. The primary coil includes a first shield of a first coaxial cable, a second shield of a second coaxial cable, and a conductive interconnect connecting the first shield to the second shield. The secondary coil includes a first core of the first coaxial cable, a second core of the second coaxial cable, and a pair of conductive wires connecting the first core to the second core. In another feature, the first coaxial cable runs parallel to the second coaxial cable. In another feature, a sum of the lengths of the first core, the second core, and the pair of conductive wires is equal to four times the length of each of the first coaxial cable and the second coaxial cable. In another feature, a length of each of the first coaxial cable and the second coaxial cable is equal to one-quarter of a wavelength of the first RF signal.

[0031] In other features, the first transformer includes a first primary coil connected to the first filter, a second primary coil connected to the second filter, and a first secondary coil connected to the electrode for receiving the first RF signal and the third RF signal. In other features, the electrode is a first electrode. The first transformer includes a second secondary coil connected to a second electrode for receiving the second RF signal and the fourth RF signal.

[0032] In other features, a substrate processing system is provided, comprising the RF distribution circuit, the process chamber, a showerhead, the showerhead including the electrode, and a substrate support mounted within the process chamber, the substrate support mounted within the process chamber adjacent the showerhead.

[0033] In other features, the first transformer includes a third secondary coil connected to a third showerhead for receiving the second RF signal and the fourth RF signal. In other features, the first transformer includes a first primary coil connected to the first filter, a second primary coil connected to the second filter, a first secondary coil connected to the electrode for outputting the second RF signal, where the second RF signal includes frequency components at the second RF and the electrode is a first electrode, and a second secondary coil connected to a second electrode for outputting a fourth RF signal. The fourth RF signal includes frequency components at the first RF and the second RF, respectively.

[0034] In other features, the first transformer includes a third secondary coil that outputs a fifth RF signal to a third electrode, the fifth RF signal including frequency components at the first RF and the second RF, and a fourth secondary coil that outputs a sixth RF signal to a fourth electrode, the sixth RF signal including frequency components at the first RF and the second RF,

[0035] In another feature, a substrate processing system is provided with an RF distribution circuit for supplying RF power to an electrode, the RF distribution circuit comprising an RF generator, a transformer, and a matching network. The RF generator is for generating a first RF signal. The transformer is for converting the first RF signal to a second RF signal and supplying the second RF signal to the electrode to adjust plasma ionization density and ionization energy in a process chamber of the substrate processing system. The matching network is for matching an output of the RF generator to an input of the transformer. In another feature, a substrate processing system is provided, the substrate processing system comprising the RF distribution circuit, the process chamber, a showerhead, and a substrate support. The showerhead includes the electrode and is mounted in the process chamber. The substrate support is mounted in the process chamber adjacent to the showerhead.

[0036] Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims and the drawings. The detailed description and specific examples are for purposes of illustration only and are not intended to limit the scope of the present disclosure. [Brief description of the drawings]

[0037] The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

[0038] [Figure 1A] FIG. 1A is a Smith chart illustrating an example input impedance of a non-transformer-based RF distribution circuit relative to a first load impedance.

[0039] [Figure 1B] FIG. 1B is a Smith chart illustrating another example input impedance of an RF distribution network relative to a second load impedance.

[0040] [Figure 1C] FIG. 1C is a Smith chart illustrating another example input impedance of an RF distribution network for a third load impedance.

[0041] [Diagram 2] FIG. 2 is a functional block diagram of an example substrate processing system incorporating an RF distribution circuit including a transformer in accordance with one embodiment of the present disclosure.

[0042] [Diagram 3] FIG. 3 is a functional block diagram of an example of an RF distribution circuit including a transformer in accordance with one embodiment of the present disclosure.

[0043] [Figure 4A] FIG. 4A is a Smith chart illustrating an example of the input impedance of the RF distribution circuit of FIG. 3 relative to a first load impedance.

[0044] [Figure 4B] FIG. 4B is a Smith chart illustrating another example input impedance of the RF distribution circuit of FIG. 3 for a second load impedance.

[0045] [Diagram 5] FIG. 5 is a functional block diagram of an example of a dual RF distribution circuit including a transformer-coupled combiner according to one embodiment of the disclosure.

[0046] [Figure 6] FIG. 6 is a Smith chart showing the short circuit, open circuit, and 50 Ω input impedances that provide the load impedances for the low frequency (LF) and high frequency (HF) paths of the dual RF distribution circuit of FIG.

[0047] [Figure 7] FIG. 7 is a functional block diagram of an example of a quad RF divider circuit including a transformer-coupled combiner according to one embodiment of the disclosure.

[0048] [Figure 8] FIG. 8 is a side view of an exemplary transformer for high frequency RF signals in an RF distribution circuit according to one embodiment of the present disclosure.

[0049] In the drawings, reference numbers may be reused to refer to similar and / or identical elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0050] In semiconductor processing systems, it is common to provide two different RF frequencies to provide independent control of plasma ionization density and ionization energy. The substrate processing system may include a processing chamber having a certain number of stations (e.g., four stations). Each of the stations may include a substrate support and a showerhead, respectively. The showerheads receive RF power from an RF combiner and a distribution circuit, respectively. Each of the RF combiner and distribution circuit may include an LF and HF path. The LF path generates an RF signal having a lower frequency than the RF signal generated by the HF path. As an example, the LF path may generate a 400 kilohertz (kHz) RF signal and the HF path may generate a 13.56 megahertz (MHz) RF signal. The LF generator generates an LF signal, which is provided to a first matching network, which feeds each of the LF paths of the RF combiner and distribution circuit. The first matching network collectively matches the impedance of the output of the LF generator to the input impedance of the LF path. The HF generator generates an HF signal that is provided to a second matching network that feeds each of the HF paths of the RF combiner and distribution circuit, the second matching network collectively matching the impedance of the output of the HF generator to the input impedance of the HF paths.

[0051] Each LF path includes an LF ballast and an LF filter for filtering the HF signal so that it is not received at the LF generator. Each HF path includes an HF ballast and an HF filter for filtering the LF signal so that it is not received at the HF generator. The LF and HF ballast may include inductors and / or capacitors to (i) isolate each of the stations from the other stations, and (ii) isolate the inputs of the combiner and RF distribution circuit from load variations.

[0052] Each of the RF combiner and distribution circuits includes a switch for switching between a dummy load and the LF and HF paths. The dummy load is used when the corresponding station is not in use. This maintains approximately equal loads across the stations. For example, when one or more of the stations are not in use, the switch of the station that is in use is switched to allow the LF and HF signals to pass from the RF generator to the coaxial cable that feeds the corresponding one of the electrodes of the station. The switch of the unused station or stations is switched to the dummy load to prevent the LF and HF signals from passing through the coaxial cable to the corresponding electrode of the station or stations.

[0053] The RF combiner and distribution circuit is designed to resonate at high frequencies, which helps to develop high voltage across the electrodes, which may refer to the electrodes (or grounded conductive elements) in the showerhead and the station's substrate support.

[0054] RF combiner and splitter circuits experience large input impedance variations as a result of small changes in load impedance. As an example, FIGS. 1A-1C show three different input impedances for three different load impedances. FIGS. 1A-1C include Smith charts 100, 104, 108, which are logarithmic representations of possible input impedance values. As an example, the load impedance (or the impedance at the showerhead) may be 132 picofarads (pF), which results in an input impedance shown by dot 102 in FIG. 1A. The load impedance may change to 230 pF, which may result in a change in input impedance, as shown by dot 106 in FIG. 1B. The load impedance may change again to 240 pF, which may result in a change in input impedance, as shown by dot 110 in FIG. 1C. As shown by these plots, small changes in the load impedance result in large position changes in the Smith charts 100, 104, 108 of the dots 102, 106, 110, which correspond to large variations in the input impedance. In a processing chamber containing multiple stations, a change in the load impedance of one station can also adversely affect the performance of the other stations.

[0055] Since the RF combiner and distribution circuits exhibit large changes in input impedance as a result of small changes in load impedance, automatic matching circuits are used to adjust the matching network. Also, automatic matching circuits with large adjustment ranges are used to perform different types of substrate processing using the same substrate processing tool. Furthermore, the RF combiner and distribution circuits require high impedance ballast devices for isolation. High impedance ballast devices reduce the current flow to the corresponding stations. Also, the size of the matching network components, ballast devices, and filter components increases as the power increases. The topology of the RF combiner and distribution circuits is inherently unbalanced.

[0056] When a process is performed that does not utilize all stations of the process chamber, the required tuning range of the automatic matching circuit increases substantially. A multi-station tool, unlike a single station tool, includes multiple showerheads, each of which receives the generated RF signal. When one or more of the stations is not utilized, the load impedance of that station is substantially different from the load impedance of the other stations. This requires the automatic matching circuit for a station to have a wider tuning range to compensate for the imbalance in the load of that station.

[0057] Examples described herein overcome the above-mentioned shortcomings and provide a substrate processing system including an RF distribution circuit including one or more transformers and / or transformer-coupled combiners. The transformers and / or transformer-coupled combiners minimize input impedance variations as a result of changes in load impedance. Some of the disclosed RF distribution circuits include efficient combiner circuits. As used herein, a "combiner circuit" combines two or more RF signals into a single RF signal.

[0058] The RF distribution circuit provides station-to-load, station-to-station, and input-to-output isolation to minimize the impact of load impedance variations at another station on a particular station. The RF distribution circuit exhibits reduced sensitivity to load impedance variations, allows a wide range of recipes for substrate processing with a wide range of corresponding load impedances, experiences minimal input impedance variations due to substrate loading and unloading from the processing chamber, and provides a self-sustaining system that allows each leg (or RF signal path to each station) to resonate or near-resonate for fast and smooth ignition associated with plasma generation. In certain embodiments, the RF combiner and distribution circuit combines two or more RF frequency signals and provides a signal having two or more frequencies to one or more stations. The RF distribution circuit allows impedance matching for both LF and HF signals. Other advantages and aspects of the RF distribution circuit described herein are further described below.

[0059] 2 is a functional block diagram of an example of a substrate processing system 200 incorporating an RF distribution circuit 201 including a transformer 202. The RF distribution circuit 201 may be configured the same as or similar to any of the RF distribution circuits disclosed herein. The transformer 202 may be configured as any of the transformers and / or transformer-coupled combiners disclosed herein. Figure 2 Although a capacitively coupled plasma (CCP) system is shown, the embodiments disclosed herein are applicable to other plasma processing systems. The embodiments are applicable to deposition, etching, and other substrate processing processes, including plasma-enhanced atomic layer deposition (PEALD) and plasma-enhanced chemical vapor deposition (PECVD) processes.

[0060] The substrate processing system 200 includes one or more stations, each having a substrate support, such as an electrostatic chuck (ESC) 204. The one or more stations are disposed within a processing chamber 205. The ESC 204 may include a top plate 206 and a base plate 207. Other components, such as an upper electrode 208, may be disposed within the processing chamber 205. During operation, a substrate 209 is placed on and electrostatically clamped to the top plate 206 of the ESC 204, and an RF plasma is generated within the processing chamber 205.

[0061] As an example, the upper electrode 208 may include a showerhead 210 for introducing and distributing gases. The showerhead 210 may include a stem portion 211 with one end connected to the top surface of the processing chamber 205. The showerhead 210 is generally cylindrical and extends radially outward from the opposing end of the stem portion 211 at a location spaced from the top surface of the processing chamber 205. The substrate-facing surface of the showerhead 210 includes holes through which process or purge gases flow. Alternatively, the upper electrode 208 may include a conductive plate, and gases may be introduced in another manner. One or both of the plates 206, 207 may function as the lower electrode.

[0062] One or both of the plates 206, 207 may include temperature control elements (TCEs). An intermediate layer 214 is disposed between the plates 206 and 207. The intermediate layer 214 may bond the top plate 206 to the base plate 207. The base plate 207 may include one or more gas channels and / or one or more coolant channels for flowing a backside gas to the backside of the substrate 209 and for flowing a coolant through the base plate 207.

[0063] The RF generation system 220 generates and outputs an RF voltage to the upper electrode 208. The RF generation system 220 may generate and output an RF voltage to the ESC 204. One of the upper electrode 208 and the ESC 204 may be DC grounded, AC grounded, or at floating potential. As an example, the RF generation system 220 may include one or more RF generators 223 (e.g., capacitively coupled plasma RF power generators and / or other RF power generators) that generate an RF voltage, which is supplied to the upper electrode 208 by one or more matching networks 227 and the RF distribution circuit 201. The RF generator 223 may be a high-power RF generator that generates, for example, 6 to 10 kilowatts (kW) or more of power. The RF generators 223 may generate respective RF signals having frequency components at respective RF frequencies.

[0064] The gas delivery system 230 includes one or more gas sources 232-1, 232-2, ..., and 232-N (collectively, gas sources 232), where N is an integer greater than 0. The gas sources 232 provide one or more precursors and their gas mixtures. The gas sources 232 may also provide etching gases, carrier gases, and / or purge gases. Vaporized precursors may also be used. The gas sources 232 are connected to a manifold 240 by valves 234-1, 234-2, ..., and 234-N (collectively, valves 234) and mass flow controllers 236-1, 236-2, ..., and 236-N (collectively, mass flow controllers 236). The output of the manifold 240 is provided to the process chamber 204. In one example, the manifold 240 may include a valve 234-1, a valve 234-2, ..., and 234-N. 240 The output of the condenser 212 is fed to the showerhead 210.

[0065] The substrate processing system 200 further includes a cooling system 241 including a temperature controller 242, which may be connected to the TCEs. Although shown separate from the system controller 260, the temperature controller 242 may be implemented as part of the system controller 260. One or more of the plates 206, 207 may include multiple temperature control zones (e.g., four zones, where each of the zones includes four temperature sensors).

[0066] The temperature controller 242 may control the operation of the TCEs, and therefore the temperature, to control the temperature of the plates 206, 207 and the substrate (e.g., substrate 209). The temperature controller 242 and / or the system controller 260 may control the flow of gas from one or more of the gas sources 232 to the gas channels to cool the substrate. Gas channel inside ESC204The temperature controller 242 may also control the flow rate of the backside gas (e.g., helium) to the ESC 204. The temperature controller 242 may also communicate with the coolant assembly 246 to control the flow (pressure and flow rate of the cooling fluid) of the first coolant through the channels in the ESC 204. The first coolant assembly 246 may receive the cooling fluid from a reservoir (not shown). For example, the coolant assembly 246 may include a coolant pump and a reservoir. The temperature controller 242 operates the coolant assembly 246 to flow the coolant through the channels 216 to cool the base plate 207. The temperature controller 242 may control the rate at which the coolant flows and the temperature of the coolant. The temperature controller 242 controls the current supplied to the TCEs and the pressure and flow rate of the gas and / or coolant supplied to the channels based on parameters detected from a sensor 243 in the process chamber 205. The temperature sensor 243 may include a resistive temperature device, a thermocouple, a digital temperature sensor, and / or other suitable temperature sensor. During the etching process, the substrate 209 may be heated to a predetermined temperature (e.g., 120 degrees Celsius (°C)) in the presence of a high power plasma. The flow of gas and / or coolant through the channels reduces the temperature of the base plate 207, thereby reducing the temperature of the substrate 209 (e.g., cooling from 120°C to 80°C).

[0067] Valves 256 and pumps 258 may be used to evacuate reactants from the process chamber 205. A system controller 260 may control the components of the substrate processing system 200, including controlling the RF power levels delivered, the pressure and flow rates of the gases delivered, RF matching, etc. The system controller 260 controls the states of the valves 256 and pumps 258. A robot 270 may be used to deliver substrates onto and remove substrates from the ESC 204. For example, the robot 270 may transport substrates between the ESC 204 and a load lock 272. The robot 270 may be controlled by the system controller 260. The system controller 260 may control the operation of the load lock 272.

[0068] The power source 280 may provide power, including high voltage, to electrodes in the ESC 204 to electrostatically clamp the substrate 209 to the top plate 206. The power source 280 may be controlled by the system controller 260.

[0069] The valves, gas and / or coolant pumps, power sources, RF generators, etc. may be referred to as actuators. The TCEs, gas channels, coolant channels, etc. may be referred to as temperature adjustment elements.

[0070] 2 and 3, an RF distribution circuit 300 is shown, which may include an RF generator 302, a matching network 304, a filter 306, a transformer 308, and a load 310. In one embodiment, the filter 306 is not included. The load 310 is shown as a capacitor, which may represent, for example, an impedance between the showerhead 210 and the ground reference 316. The RF generator 302 may be one of the RF generators 223 and generates an RF signal. The matching network 304 may be one of the matching networks 227 and matches the impedance of (i) the output of the RF generator 302 and (ii) the input of the filter 306 and / or the transformer 308. The matching network 304 may perform an automatic matching operation, which includes adjusting one or more components, to impedance match the output of the RF generator 302 and the input of the filter 306 and / or the transformer 308. This may include, for example, adjusting the capacitors of the matching network 304 .

[0071] If included, filter 306 may filter out one or more RF signals generated by one or more other RF generators other than RF generator 302. Filter 306 allows the RF signals generated by the RF generators to pass through to transformer 308.

[0072] The transformer 308 includes a primary coil 312 and a secondary coil 314 having corresponding windings and / or voltage transformation ratios. As some examples, the ratio may be 3:4 or 1:2. The transformer 308 may convert a first radio frequency signal at a frequency received from the matching network 304 or the filter 306 to a second radio frequency signal at the same frequency. The transformer 308 may then provide the second radio frequency signal to, for example, an electrode and / or a showerhead to adjust the plasma ionization density and ionization energy in the process chamber.

[0073] The transformer 308 provides multiple functions including providing ballast and isolation between the primary and secondary sides of the transformer 308, and thus between (i) the RF generator 302 and the matching network 304, and (ii) the load 310. In one embodiment, no ballast device is connected between (i) the RF generator 302 and the matching network 304, (ii) the matching network 304 and the filter 306, (iii) the filter 306 and the transformer 308, and / or (iv) the matching network 304 and the transformer 308. The described isolation reduces the effect of load impedance changes on the corresponding input circuit (or the RF generator 302 and the matching network 304). The impedance of the load 310 may change during processing of the substrate. The amount of variation is based on the recipe and the process being performed. By selecting an appropriate transformation ratio, the input impedance variation is also controlled. The input impedance refers to the impedance of the input of the filter 306 as seen by the matching network 304. The transformer 308 also allows for faster adjustment of the components of the matching network 304 because the associated changes in input impedance are reduced relative to changes in load impedance. The transformer 308 also minimizes the amount of reflected power received by the RF generator 302, allowing for high power (e.g., 10 KW) to be delivered to the load 310.

[0074] Although a single RF distribution circuit 300 is shown in Figure 3, multiple RF distribution circuits of the type shown in Figure 3 may be used to supply RF power to each station of the process chamber. A secondary winding of a transformer may supply power to the stations via a respective coaxial cable, as also shown in Figure 7. Also, as shown in Figure 7, a switch and corresponding dummy load may be included in each of the stations. The switch may be controlled by one of the controllers 242, 260 of Figure 2.

[0075] 4A and 4B show Smith charts 400, 402 illustrating an example input impedance of the RF distribution circuit 300 of FIG. 3 for a first load impedance and a second load impedance. The input impedances are represented by dots 404, 406. In the example shown, the first load impedance is 130 picofarads (pF) and the second load impedance is 3,000,000 pF. As can be seen from the Smith charts 400, 402, the distance between the dots 404, 406, and therefore the difference in the input impedance, is minimal compared to the difference in the load impedances.

[0076] 5 shows a dual RF distribution circuit 500 including a first (or high) RF path 502 and a second (or low) RF path 504. The first RF path 502 includes a first RF generator 506, a first matching network 508, a first filter 510, and a first transformer 512 having a first transformation ratio. The second RF path 504 includes a second RF generator 520, a second matching network 522, a second filter 524, and a second transformer 526 having a second transformation ratio. The first transformer 512 is connected to the second transformer 526. The transformers 512, 526 provide a transformer-coupled combiner that combines the two RF signals generated by the RF paths 502, 504 to provide a single RF signal to a load 530. The single RF signal has frequency components of the two RF signals. The transformers 512, 526 convert the two RF signals into a single RF signal. This may include, for example, modifying the amplitude of the two RF signals to provide a single RF signal having a different amplitude than the two RF signals. The load 530 is shown, for example, as a capacitor representing a load impedance between the showerhead 210 and the ground reference 540 in FIG. 2. The load 530 may be one or more electrodes of one or more processing stations in one or more processing chambers, where each station may include one or more electrodes and each processing chamber may include one or more stations.

[0077] The RF generators 506, 520 each generate an RF signal. As an example, the first RF generator 506 may generate a 13.56 MHz RF signal, and the second RF generator 520 may generate a 400 kHz signal. The first matching network 508 may match the output impedance of the first RF generator 506 to the input impedance of the first filter 510. The second matching network 522 may match the output impedance of the second RF generator 520 to the input impedance of the second filter 524.

[0078] The first filter 510 functions as a high pass filter and (i) allows a path of the first RF signal generated by the first RF generator 506 to pass through to the first transformer 512, and (ii) prevents the RF signal generated by the second RF generator 520 from being received at the first RF generator 506. The second filter 524 functions as a low pass filter and (i) allows a path of the second RF signal generated by the second RF generator 520 to pass through to the second transformer 526, and (ii) prevents the RF signal generated by the first RF generator 506 from being received at the second RF generator 520. Both of the RF generators 506, 520 may be properly matched by including separate primary coils in the RF paths 502, 504 as shown, selecting an appropriate number of primary windings in each of the primary coils, and including appropriate matching circuits in the matching networks 508, 522.

[0079] The first transformer 512 includes a primary coil 532 and a secondary coil 534. The second transformer 526 includes a primary coil 536 and a secondary coil 538. A first end of the primary coils 532, 536 is connected to the filter 510, 524. In one embodiment, the filter 510, 524 is not included and the primary coils 532, 536 are connected to the matching network 508, 522. A second end of the primary coils 532, 536 is connected to a ground reference 540. A first end of the secondary coils 534, 538 is connected to the ground reference 540. A second end of the secondary coils 534, 538 is connected to the load 530. The first transformer 512 may convert a first radio frequency signal at a first frequency received from the first filter 510 to a second radio frequency signal at a first frequency. The second transformer 526 may convert the third radio frequency signal at the second frequency received from the second filter 524 to a fourth radio frequency signal at the second frequency. The transformers 512, 526 may then provide the second radio frequency signal and the fourth radio frequency signal to, for example, an electrode and / or a showerhead to adjust the plasma ionization density and ionization energy in the process chamber.

[0080] Input impedance of LF and HF paths Example is illustrated by the Smith chart 600 of FIG. 6. The Smith chart 600 illustrates the short circuit, open circuit, and 50 Ω input impedances that provide the load impedances for the LF and HF paths 502, 504 of FIG. 5. In FIG. 6, circular dots are shown, corresponding to the HF paths, and square dots are shown, corresponding to the LF paths. The Smith chart 600 is a logarithmic representation of the possible input impedance values. As the input impedance changes, the corresponding dot moves to a different position on the Smith chart.

[0081] Dots 602, 604, 606 represent a short circuit, an open circuit, and a 50Ω input impedance, respectively, that provide a load impedance for the HF path 502. A 50Ω load impedance refers to a load impedance that provides an input impedance of 50Ω. Dots 610, 612, 614 represent a short circuit, an open circuit, and a 50Ω input impedance that provide a load impedance for the LF path 504. A short circuit refers to a direct or indirect conductive connection (or path) between the showerhead 210 and the ground reference 540. A short circuit refers to a case where the load impedance is 0Ω. An open circuit refers to the absence of a conductive path between the showerhead 210 and the ground reference 540. This open circuit refers to a case where the load impedance approaches infinity. As can be seen from the Smith chart, the distance between the dots (or points) 602, 604, 606 and the distance between the dots (or points) 610, 612, 614 are minimal and are not located across the entire Smith chart, but rather in a small portion of the Smith chart. Therefore, the corresponding input impedance difference is also minimal.

[0082] The transformers 512, 526 provide multiple functions, including providing ballast and isolation between the primary and secondary sides of the transformers 512, 526, similar to the transformer 308 of Figure 3. In one embodiment, no ballast devices are connected (i) between the RF generators 506, 520 and the matching networks 508, 522, (ii) between the matching networks 508, 522 and the filters 510, 524, (iii) between the filters 510, 524 and the transformers 512, 526, and / or (iv) between the matching networks 508, 522 and the transformers 512, 526.

[0083] Although a single RF distribution circuit 500 is shown in FIG. 5, multiple RF distribution circuits of the type shown in FIG. 5 may be used to supply RF power to each station of the process chamber. A secondary winding of a transformer may supply power to the stations via corresponding coaxial cables, as also shown in FIG. 7. Also, as shown in FIG. 7, a switch and corresponding dummy load may be included for each of the stations. As an example, a switch may be connected downstream from terminal 550 to switch between (i) the respective coaxial cables connected to the electrodes and / or showerheads and (ii) the dummy load. The switch may be controlled by one of the controllers 242, 260 of FIG. 2.

[0084] 7 shows that the quad RF distribution circuit 700 includes a first (or high) RF path 702 and a second (or low) RF path 704. The first RF path 702 includes a first RF generator 706, a first matching network 708, and a first filter 710. The second RF path 704 includes a second RF generator 720, a second matching network 722, and a second filter 724. The quad RF distribution circuit 700 includes a transformer 712 having two inputs, four outputs, and a transformation ratio shared by the four outputs. The four outputs feed four channels that are connected to four loads (or showerheads) 750, 752, 754, 756 of four stations of a processing chamber.

[0085] The RF generators 706, 720 each generate an RF signal. As an example, the first RF generator 706 may generate a 13.56 MHz RF signal, and the second RF generator 720 may generate a 400 KHz signal. The first matching network 708 may match the output impedance of the first RF generator 706 to the input impedance of the first filter 710. The second matching network 722 may match the output impedance of the second RF generator 720 to the input impedance of the second filter 724. The first filter 710 functions as a high-pass filter, (i) allowing the path of the first RF signal generated by the first RF generator 706 to pass to the first transformer 712, and (ii) preventing the RF signal generated by the second RF generator 720 from being received by the first RF generator 706. The second filter 724 functions as a low pass filter to (i) allow the path of the second RF signal generated by the second RF generator 720 to pass through to the transformer 712, and (ii) prevent the RF signal generated by the first RF generator 706 from being received at the second RF generator 720. Both of the RF generators 706, 720 include separate primary coils (or primary windings) for the RF paths 702, 704 as shown, and may be properly matched by selecting an appropriate number of primary windings on each of the primary coils and including appropriate matching circuits in the matching networks 708, 722.

[0086] The transformer 712 is a transformer-coupled combiner that combines the two RF signals generated by the RF paths 702, 704 to provide four RF signals that are provided to loads 750, 752, 754, 756. The loads 750, 752, 754, 756 are shown as capacitors that represent load impedances between, for example, the showerhead and a ground reference 760. Although the transformer 712 is shown as having two inputs and four outputs, the transformer 712 may have more than two inputs and one or more outputs.

[0087] The transformer 712 includes a first primary coil 730, a second primary coil 732, a first secondary coil 734, a second secondary coil 736, a third secondary coil 738, and a fourth secondary coil 740. In one embodiment, the primary coils 730, 732 have the same number of windings and the secondary coils 734, 736, 738, 740 have the same number of windings. A first end of the primary coils 730, 732 is connected to the filter 710, 724. In one embodiment, the filter 710, 724 is not included and the first end of the primary coils 730, 732 is connected to the matching network 708, 722. A second end of the primary coils 730, 732 is connected to a ground reference 760. A first end of the secondary coils 734, 736, 738, 740 is connected to a load 750, 752, 754, 756, respectively. A second end of the secondary coils 734, 736, 738, 740 is connected to a ground reference 760. The transformer receives the RF signals from paths 702, 704, combines the signals, and provides the combined RF signal via the secondary coils 734, 736, 738, 740 to each of the loads 750, 752, 754, 756.

[0088] The transformer 712 may convert and combine the first radio frequency signal at the first frequency received from the first filter 710 and the second radio frequency signal at the second frequency received from the second filter 724 into a third radio frequency signal. The third radio frequency signal includes both the first radio frequency and the second radio frequency. The transformer 712 may then provide the third radio frequency signal to, for example, an electrode and / or a showerhead to adjust the plasma ionization density and ionization energy in the process chamber.

[0089] The transformer 712 provides multiple functions, including providing ballast and isolation between the primary and secondary sides of the transformer 712, similar to the transformer 308 of Figure 3. In one embodiment, no ballast device is connected (i) between the RF generators 506, 520 and the matching networks 508, 522, (ii) between the matching networks 508, 522 and the filters 510, 524, (iii) between the filters 510, 524 and the transformers 512, 526, and / or (iv) between the matching networks 508, 522 and the transformers 512, 526.

[0090] In one embodiment, the secondary coils 734, 736, 738, 740 may be connected to switches 762, 764, 766, 768 that can switch between the loads 750, 752, 754, 756 and the dummy loads 770, 772, 774, 776. In another embodiment, the switches 762, 764, 766, 768 and the dummy loads 770, 772, 774, 776 are not included. The secondary coils 734, 736, 738, 740 or the switches 762, 764, 766, 768 may be connected to the loads 750, 752, 754, 756 via coaxial cables 780, 782, 784, 786. The switches 762, 764, 766, 768 may be controlled by one of the controllers 242, 260 of FIG. One or more of the dummy loads 770, 772, 774, 776 may be connected when substrates are not being processed at the corresponding station or stations, for example, as described above.

[0091] Some of the RF combiner circuits disclosed herein, such as that shown in FIG. 7, provide a balanced distribution system that splits the combined RF signal into n equal channels, where n is an integer equal to or greater than 1. The outputs of the n channels are isolated from each other so that changes in one channel do not affect, or have minimal effect on, changes in the other channels. The inputs of the channels are isolated from the input of the transformer 712. The RF combiner circuit provides fast and smooth ignition for plasma generation.

[0092] 3, 5, and 7, each of the RF distribution circuits 300, 500, 700 is configured to be usable for a number of different substrate processes. The processes may include etching, deposition, and / or other substrate treatment processes.

[0093] FIG. 8 shows a side view of an exemplary transformer 800 that can be used for high frequency RF signals in an RF distribution circuit. As an example, the transformers 308, 512 of FIGS. 3 and 5 may each be replaced with the transformer 800. The transformer 800 may be a coaxial transformer and include a primary coil 802 and a secondary coil 804. The primary coil 802 includes (i) conductive shields 822, 832 of two coaxial cables 806, 810, and (ii) a conductive interconnector 808. The conductive interconnector 808 extends through the non-conductive sheaths 820, 830 of the coaxial cables 806, 810 and is connected to the conductive shields 822, 832. The conductive interconnector may be a conductive plate or other suitable interconnector that maintains the position of the second coaxial cable 810 relative to the first coaxial cable 806.

[0094] The coaxial cables 806, 810 run parallel to one another and are electrically conductively shielded by inner dielectric insulation 824, 834. Rudo 822, 832 The conductive cores 825, 835 are connected in a series loop by conductive lines 826A, 826B. The conductive line 826A connects a first end of the first coaxial cable 806 to a first end of the second coaxial cable 810. The first end of the second coaxial cable 810 is at an end of the conductive interconnector 808 opposite the first end of the first coaxial cable 806. The conductive line 826B connects a second end of the first coaxial cable 806 to a second end of the second coaxial cable 810. The second end of the second coaxial cable 810 is at an end of the conductive interconnector 808 opposite the second end of the first coaxial cable 806.

[0095] As an example, the conductive shields 822, 832, conductive cores 825, 835, and conductive lines 826A, 826B may be formed from copper and / or other suitable materials that exhibit a minimal amount of heating during use. The non-conductive sheaths 820, 830 may be formed from plastic. The inner dielectric insulators 824, 834 are non-conductive and may be formed from a variety of dielectric materials, such as polyethylene (PE) and polytetrafluoroethylene (PTFE). In one embodiment, as shown, the sheaths, shields and / or inner dielectric insulators are not on the conductive lines 826A, 826B.

[0096] It may be difficult to manufacture a low frequency transformer that can handle high frequencies, for example, above 1 megahertz (MHz), without overheating the transformer. The permeability (or distributed inductance) of the transformer may need to be reduced and the transformer may need to be made from special materials. The transformer 800 may be used for high frequencies, microwave frequencies, and the like. The length L1 of the coaxial cables 806, 810 may be based on and / or equal to a fractional multiple of the wavelength of the transmitted RF. As an example, the fractional multiple may be, for example, less than one-half (1 / 2) of the wavelength of the transmitted RF. In one embodiment, the length L1 of the coaxial cables 806, 810 is equal to one-quarter (1 / 4) of the wavelength of the transmitted RF. The quarter wavelength (or a multiple thereof) is advantageous in that it transforms the corresponding impedance of the transformer from 0 Ohms (Ω) (or a short circuit) to infinite Ω (or an open circuit) or vice versa, depending on the circuit. The total length of the series loop provided by the conductive cores 825, 835 and the conductive lines 826A, 826B may be based on and / or equal to a multiple of the length L1. In one embodiment, the total length of the series loop provided by the conductive cores 825, 835 and the conductive lines 826A, 826B is equal to four times the length L1 (or 4L1). As an example, the transformation ratio of the transformer 800 may be 1:2 between the primary and secondary windings, where the primary winding is implemented as the primary coil 802 and comprises the input of the transformer 800, and the secondary winding is implemented as the secondary coil 804 and provides the output of the transformer 800. The coaxial cables 806, 810 may be formed similarly to RG58C coaxial cables, although RG58C coaxial cables may not be suitable for high power applications, such as those associated with substrate processing systems. The size and / or material of the coaxial cables 806, 810 may be different than that of the RG58C coaxial cable.

[0097] The disclosed RF distribution circuit exhibits high isolation between input and output, improved station-to-station isolation, and impedance matching for the LF and HF paths such that the input impedance is less sensitive to changes in load impedance. The disclosed RF distribution circuit is also robust and provides improved reliability over conventional RF combiners and distribution circuits. The disclosed RF distribution circuit includes balanced stations, exhibits fast adjustment, allows for RF signals to be fed to multiple stations, exhibits low reflected power to both LF and HF generators, and provides an unconditionally stable system. The RF distribution circuit is also capable of feeding high power (e.g., 10 kilowatts (KW) HF and 8 KW LHF) RF signals.

[0098] The foregoing description is merely exemplary 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 various forms. Thus, while this disclosure includes specific examples, the true scope of the disclosure should not be limited to such examples, since other modifications will become apparent upon review of the drawings, specification, and the following claims. It should be understood that one or more steps in a method may be performed in different orders (or simultaneously) without altering the principles of the disclosure. Furthermore, although each of the embodiments is described above as having certain features, any one or more of these features described with respect to any embodiment of the disclosure may be implemented in other embodiments and / or combined with any features of the other embodiments, even if such combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with each other remain within the scope of the disclosure.

[0099] Spatial and functional relationships between elements (e.g., between modules, between circuit elements, between semiconductor layers, etc.) are described using various terms, including "connected," "engaged," "coupled," "adjacent," "next to," "on top of," "above," "below," and "disposed." When a relationship between a first element and a second element is described in the above disclosure, unless expressly described as "direct," the relationship may be a direct relationship in which there are no other intervening elements between the first element and the second element, but also an indirect relationship in which there are one or more intervening elements (either spatial or functional) between the first element and the second element. As used herein, the phrase at least one of A, B, and C should be interpreted to mean a logic (A or B or C) using a non-exclusive logical OR, and not to mean "at least one of A, at least one of B, and at least one of C."

[0100] In some implementations, the controller is part of a system, which may be part of the examples described above. Such systems may include semiconductor processing equipment, including one or more processing tools, one or more chambers, one or more processing platforms, and / or specific processing components (wafer pedestals, gas flow systems, etc.). These systems may be integrated with electronics for controlling system operations before, during, and after processing of a semiconductor wafer or substrate. This electronics may be referred to as a "controller" and may control various components or subparts of one or more systems. The controller may be programmed to control any of the processes disclosed herein depending on the processing requirements and / or type of system. Such processes may include supply of process 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 settings, fluid supply settings, position and motion settings, wafer loading and unloading into and from tools and other transport tools, and / or load locks connected or coupled to a particular system.

[0101] Broadly, a controller may be defined as an electronic device having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, etc. 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 the program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files) that define operational parameters for performing a particular process on, for, or for a semiconductor wafer. In some embodiments, the operational parameters may be part of a recipe defined by a process engineer to accomplish one or more processing steps during the manufacture of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or dies of a wafer.

[0102] In some implementations, the controller may be part of or coupled to a computer that is interfaced with, coupled to, or otherwise networked to the system, or a combination thereof. For example, the controller may be in the "cloud" or may be all or part of a fab host computer system. This allows for remote access of wafer processing. The computer may allow remote access to the system to monitor the current progress of a manufacturing operation, examine the history of past manufacturing operations, examine trends or performance criteria from multiple manufacturing operations, modify parameters of a current process, set processing steps following a current process, or initiate a new process. In some examples, a remote computer (e.g., a server) may provide process recipes to the system over a network, which may include a local network or the Internet. The remote computer may include a user interface that allows entry or programming of parameters and / or settings, which are communicated from the remote computer to the system. In some examples, the controller receives instructions in the form of data, which identifies parameters for each of the processing steps that are performed during one or more operations. It should be understood that the parameters may be specific to the type of process being performed and the type of tool with which the controller is configured to interface or control. Thus, as discussed above, the controller may be distributed, such as by having one or more individual controllers networked together and cooperating toward a common purpose, such as the processes and controls described herein. One example of a distributed controller for such purposes would include one or more integrated circuits on the chamber that are located remotely (such as at the platform level or as part of a remote computer) and communicate with one or more integrated circuits coupled to control the process on the chamber.

[0103] Exemplary systems may include, but are not limited to, a plasma etch chamber or module, a deposition chamber or module, a spin rinse chamber or module, a metal plating chamber or module, a cleaning 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 tracking chamber or module, and any other semiconductor processing system that may be associated with or used in the fabrication and / or manufacturing of semiconductor wafers.

[0104] As described above, depending on the process step or steps being performed by the tool, the controller may communicate with one or more other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, a main computer, another controller, or tools used for material transport to and from tool locations and / or load ports in a semiconductor manufacturing factory. The present invention can be realized, for example, in the following manner. Application example 1: 1. A transformer comprising: A primary coil, a first shield of the first coaxial cable; a second shield of the second coaxial cable; and a conductive interconnect connecting the first shield to the second shield; A primary coil comprising: A secondary coil, a first core of the first coaxial cable; a second core of the second coaxial cable; a pair of conductive wires connecting the first core to the second core; a secondary coil comprising: A transformer comprising: Application example 2: A transformer according to Application Example 1, The first coaxial cable extends parallel to the second coaxial cable. Application example 3: A transformer according to Application Example 1, A transformer, wherein a sum of the lengths of the first core, the second core and the pair of conductive wires is at least one of based on or equal to a multiple of the lengths of each of the first coaxial cable and the second coaxial cable. Application example 4: A transformer according to Application Example 1, A transformer, wherein a length of each of the first coaxial cable and the second coaxial cable is at least one of based on or equal to a fractional multiple of a wavelength of a radio frequency signal transmitted by the transformer. Application example 5: 1. A radio frequency distribution circuit, comprising: a radio frequency generator for generating a first radio frequency signal having frequency components at radio frequencies; The transformer of Application Example 1 and wherein the transformer is for converting the first radio frequency signal to a second radio frequency signal, the second radio frequency signal including frequency components at the first radio frequency. Application example 6: 1. A substrate processing system, comprising: The radio frequency distribution circuit of Application Example 5; A process chamber; a showerhead including an electrode and mounted within the process chamber; a substrate support mounted within the process chamber adjacent to the showerhead; Equipped with The transformer is for providing the second radio frequency signal to the electrode. Example 7: 1. A radio frequency distribution circuit, comprising: a first filter for receiving a first radio frequency signal and a second radio frequency signal from at least one radio frequency generator and filtering out the first radio frequency signal, the first radio frequency signal being at a first frequency and the second radio frequency signal being at a second frequency, the second frequency being less than the first frequency; a second filter for receiving the first radio frequency signal and the second radio frequency signal from the at least one radio frequency generator and filtering out the first radio frequency signal; a first matching network for matching an output of the at least one radio frequency generator to an input of the first filter; a second matching network for matching the output of the at least one radio frequency generator to the input of the second filter; a transformer coupling combiner for converting the first radio frequency signal to a third radio frequency signal, converting the second radio frequency signal to a fourth radio frequency signal, and either combining the first radio frequency signal with the second radio frequency signal or combining the third radio frequency signal with the fourth radio frequency signal, wherein the third radio frequency signal includes frequency components at the first radio frequency and the fourth radio frequency signal includes frequency components at the second radio frequency; A radio frequency distribution circuit comprising: Application example 8: The radio frequency distribution circuit of Application Example 7, The transformer coupling combiner includes: a first transformer for receiving an output of the first filter; a second transformer for receiving the output of the second filter; and A radio frequency distribution circuit comprising: Example 9: The radio frequency distribution circuit of Application Example 8, The first transformer comprises: a primary coil connected to the first filter; Secondary coil and and The second transformer comprises: a primary coil connected to the second filter and the primary coil of the first transformer; a secondary coil connected to the secondary coil of the first transformer; A radio frequency distribution circuit comprising: Example 10: The radio frequency distribution circuit of Application Example 9, The primary coil and the secondary coil of the first transformer are connected to a ground reference; and The primary coil and the secondary coil of the second transformer are connected to the ground reference. Example 11: The radio frequency distribution circuit of Application Example 9, The first transformer comprises: A primary coil, a first shield of the first coaxial cable; a second shield of the second coaxial cable; and a conductive interconnect connecting the first shield to the second shield; A primary coil comprising: A secondary coil, a first core of the first coaxial cable; a second core of the second coaxial cable; a pair of conductive wires connecting the first core to the second core; a secondary coil comprising: A radio frequency distribution circuit comprising: Example 12: The radio frequency distribution circuit of Application Example 11, The first coaxial cable extends parallel to the second coaxial cable. Application example 13: The radio frequency distribution circuit of Application Example 11, A radio frequency distribution circuit, wherein a sum of the lengths of the first core, the second core and the pair of conductive wires is at least one of based on or equal to a multiple of the lengths of each of the first coaxial cable and the second coaxial cable. Example 14: The radio frequency distribution circuit of Application Example 11, A radio frequency distribution circuit, wherein a length of each of the first coaxial cable and the second coaxial cable is at least one of based on and equal to a fractional multiple of a wavelength of the first radio frequency signal. Example 15: The radio frequency distribution circuit of Application Example 7, the transformer coupling combiner comprises a first transformer; The first transformer comprises: a first primary coil connected to the first filter; a second primary coil connected to the second filter; a first secondary coil connected to receive the third radio frequency signal; a second secondary coil connected to receive the fourth radio frequency signal; and A radio frequency distribution circuit comprising: Application example 16: The radio frequency distribution circuit of application example 15, the first transformer includes a third secondary coil; the third secondary coil is for receiving a fifth radio frequency signal; and The fifth radio frequency signal includes a frequency component at the first frequency and a frequency component at the second frequency. Example 17: The radio frequency distribution circuit of Application Example 7, The transformer coupling combiner includes: a first primary coil connected to the first filter; a second primary coil connected to the second filter; a first secondary coil that outputs the third radio frequency signal, the third radio frequency signal including frequency components at the first radio frequency and the second radio frequency, respectively; a second secondary coil that outputs the fourth radio frequency signal, the fourth radio frequency signal including frequency components at the first radio frequency and the second radio frequency, respectively; A radio frequency distribution circuit comprising: Application example 18: The radio frequency distribution circuit of application example 17, The transformer coupling combiner includes: a third secondary coil outputting a fifth radio frequency signal, the fifth radio frequency signal including frequency components at the first radio frequency and the second radio frequency, respectively; a fourth secondary coil that outputs a sixth radio frequency signal, the sixth radio frequency signal including frequency components at the first radio frequency and the second radio frequency, respectively; A radio frequency distribution circuit comprising: Example 19: 1. A substrate processing system, comprising: The radio frequency distribution circuit of Application Example 7; A process chamber; a showerhead including an electrode and mounted within the process chamber; a substrate support mounted within the process chamber adjacent to the showerhead; A substrate processing system comprising: Example 20: 1. A radio frequency distribution circuit for supplying radio frequency power to an electrode in a substrate processing system, the radio frequency distribution circuit comprising: a radio frequency generator for generating a first radio frequency signal; a transformer for converting the first radio frequency signal to a second radio frequency signal and providing the second radio frequency signal to the electrode to adjust plasma ionization density and ionization energy within a process chamber of the substrate processing system; a matching network for matching the output of the radio frequency generator to the input of the transformer; A radio frequency distribution circuit comprising:

Claims

1. 1. A transformer comprising: A primary coil, a first shield of the first coaxial cable; a second shield of the second coaxial cable; and a conductive interconnect connecting the first shield to the second shield; a primary coil comprising: A secondary coil, a first core of the first coaxial cable; a second core of the second coaxial cable; a pair of conductive wires forming a direct loop connecting the first core to the second core; a secondary coil comprising: Equipped with A transformer, wherein the length of each of the first coaxial cable and the second coaxial cable is at least one of based on or equal to 1 / n times the wavelength of a radio frequency signal transmitted by the transformer, where n is a positive integer.

2. 2. The transformer of claim 1, The first coaxial cable extends parallel to the second coaxial cable.

3. 2. The transformer of claim 1, A transformer, wherein a sum of the lengths of the first core, the second core, and the pair of conductive wires is (i) equal to a multiple of the lengths of each of the first coaxial cable and the second coaxial cable, or (ii) a length determined based on said multiple.

4. 1. A radio frequency distribution circuit, comprising: a radio frequency generator for generating a first radio frequency signal having frequency components at radio frequencies; The transformer of claim 1; wherein the transformer is for converting the first radio frequency signal to a second radio frequency signal, the second radio frequency signal including frequency components at the radio frequency.

5. 1. A substrate processing system, comprising: The radio frequency distribution circuit of claim 4; A process chamber; a showerhead including an electrode and mounted within the process chamber; a substrate support mounted within the process chamber adjacent to the showerhead; Equipped with The transformer is for providing the second radio frequency signal to the electrode.

6. 1. A radio frequency distribution circuit, comprising: a first filter for receiving a first radio frequency signal and a second radio frequency signal from at least one radio frequency generator and filtering out the first radio frequency signal, the first radio frequency signal being at a first frequency and the second radio frequency signal being at a second frequency, the second frequency being less than the first frequency; a second filter for receiving the first radio frequency signal and the second radio frequency signal from the at least one radio frequency generator and filtering out the first radio frequency signal; a first matching network for matching an output of the at least one radio frequency generator to an input of the first filter; a second matching network for matching the output of the at least one radio frequency generator to the input of the second filter; a transformer-coupled combiner for converting the first radio frequency signal to a third radio frequency signal, converting the second radio frequency signal to a fourth radio frequency signal, and either combining the first radio frequency signal with the second radio frequency signal or combining the third radio frequency signal with the fourth radio frequency signal, wherein the third radio frequency signal includes frequency components at the first frequency and the fourth radio frequency signal includes frequency components at the second frequency; Equipped with The transformer coupling combiner includes: a first transformer for receiving an output of the first filter; a second transformer for receiving the output of the second filter; and Equipped with The first transformer comprises: a primary coil connected to the first filter; Secondary coil and and The second transformer comprises: a primary coil connected to the second filter and the primary coil of the first transformer; a secondary coil connected to the secondary coil of the first transformer; Equipped with The first transformer comprises: The primary coil, a first shield of the first coaxial cable; a second shield of the second coaxial cable; and a conductive interconnect connecting the first shield to the second shield; The primary coil comprises: The secondary coil, a first core of the first coaxial cable; a second core of the second coaxial cable; a pair of conductive wires forming a direct loop connecting the first core to the second core; The secondary coil comprises: A radio frequency distribution circuit comprising:

7. 7. A radio frequency distribution circuit as claimed in claim 6, comprising: The first coaxial cable extends parallel to the second coaxial cable.

8. 7. A radio frequency distribution circuit as claimed in claim 6, comprising: A radio frequency distribution circuit, wherein a sum of the lengths of the first core, the second core, and the pair of conductive wires is (i) equal to a multiple of the lengths of each of the first coaxial cable and the second coaxial cable, or (ii) a length determined based on said multiple.

9. 7. A radio frequency distribution circuit as claimed in claim 6, comprising: A radio frequency distribution circuit, wherein a length of each of the first coaxial cable and the second coaxial cable is at least one of based on and equal to a fractional multiple of a wavelength of the first radio frequency signal.

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