RF Filters for Multi-Frequency Radio Frequency (RF) Bias

Abstract

A radio frequency (RF) filter includes an inductive element having multiple coil sections collectively forming an unsplit coil of a twisted magnetic wire cable. At least two adjacent coil sections have different winding pitches. The twisted magnetic wire cable is configured for at least one channel, with two wires per channel. The twisted magnetic wire cable is configured for connection to an electrical component that will receive power from a power source at a first end of the inductive element. The twisted magnetic wire cable is configured for connection to a power source at a second end of the inductive element. Terminating capacitive elements are electrically connected between a reference ground potential and each wire of the twisted magnetic wire cable at respective locations between the second end of the inductive element and the power source. [Selected Figure] Figure 3C

Description

[Technical field]

[0001] The present disclosure relates to semiconductor manufacturing equipment. [Background technology]

[0002] In various semiconductor manufacturing processes, radio frequency (RF) power is transmitted to a processing chamber to generate a plasma and / or generate a bias voltage. One or more other electrically powered components, such as a heater assembly, may be operated under exposure to RF power. For example, the heater assembly may be configured and arranged to heat a component or region in the processing chamber. The RF power used to generate the plasma and / or the bias voltage may interfere with and / or damage the power source. It is necessary to prevent the RF power from interfering with and / or damaging the power source. In addition, connecting a heater power source to a heating element embedded in an RF electrode in a processing chamber may load the RF power and reduce its efficiency. An RF filter is required to isolate the RF electrode from the heater power source, which may be either AC (alternating current) or DC (direct current), so that AC or DC power may be provided to the heating element in the RF electrode without RF power entering the AC or DC supply path. It is in this context that the present disclosure arises. Summary of the Invention

[0003] In an exemplary embodiment, a radio frequency (RF) filter is disclosed. The RF filter includes an inductive element including at least two coil sections that collectively form an unsplit coil of the cable of twisted magnetic wire. Each coil section includes a portion configured with a corresponding winding pitch as a portion of the unsplit coil of the cable of twisted magnetic wire. At least two adjacent coil sections have different winding pitches. The cable of twisted magnetic wire is configured for at least one channel, including two wires per channel. The cable of twisted magnetic wire is configured for connection to an electrical component at a first end of the inductive element. The electrical component is to receive power from a power source, which is either a DC power source or an AC power source. The cable of twisted magnetic wire is configured for connection to a power source at a second end of the inductive element. The RF filter also includes a set of termination capacitive elements including a separate termination capacitive element for each wire of the cable of twisted magnetic wire. Each termination capacitive element is electrically connected between a reference ground potential and a respective wire of the cable of twisted magnetic wire at a location between the second end of the inductive element and the power source.

[0004] In an exemplary embodiment, a method for filtering RF power is disclosed. The method includes having an RF filter between a power source and an electrical component that will receive power from the power source. The power source is either a DC power source or an AC power source. The RF filter includes an inductive element having at least two coil sections that collectively form an unsplit coil of a cable of twisted magnetic wire. Each coil section includes a portion configured with a corresponding winding pitch as a portion of the unsplit coil of the cable of twisted magnetic wire. At least two adjacent coil sections have different winding pitches. The cable of twisted magnetic wire includes two wires per channel and is configured for at least one channel. The cable of twisted magnetic wire is connected to an electrical component at a first end of the inductive element. The cable of twisted magnetic wire is connected to a power source at a second end of the inductive element. The RF filter also includes a separate termination capacitive element for each wire of the cable of twisted magnetic wire. Each termination capacitive element is electrically connected between a reference ground potential and a respective wire of the cable of twisted magnetic wire at a location between the second end of the inductive element and the power source.

[0005] In an exemplary embodiment, a method for filtering RF power is disclosed. The method includes transmitting power from a power source to wires in an input configuration. The wires are connected to respective capacitive elements. Each separate pair of wires is designated to supply power to an electrical component exposed to the RF power. The method also includes transmitting power from the wires in the input configuration to corresponding magnetic wires in the cable of twisted magnetic wire at an input of the inductive element. The inductive element includes at least two coil sections that collectively form an unsplit coil of the cable of twisted magnetic wire between the input of the inductive element and an output of the inductive element. Each coil section includes a portion configured with a corresponding winding pitch as a portion of the unsplit coil of the cable of twisted magnetic wire. At least two adjacent coil sections have different winding pitches. The method also includes transmitting power from the magnetic wires in the cable of twisted magnetic wire to corresponding wires connected to an electrical component exposed to the RF power at an output of the inductive element.

[0006] Other aspects and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, provided by way of example. [Brief description of the drawings]

[0007] [Figure 1A] FIG. 1A is an exemplary cross-sectional side view of a CCP processing chamber according to some embodiments of the present disclosure.

[0008] [Figure 1B] FIG. 1B is an exemplary cross-sectional side view of an ICP processing chamber according to some embodiments of the present disclosure.

[0009] [Figure 1C] FIG. 1C is a top view of an exemplary heater assembly including four concentrically arranged and positioned heating elements according to some embodiments of the present disclosure.

[0010] [Diagram 2]FIG. 2 is an electrical schematic diagram of an RF filter connected between a power supply and a heater assembly in the exemplary embodiment of FIG. 1C, according to some embodiments of the present disclosure.

[0011] [Figure 3A] FIG. 3A is an isometric view of an inductor according to some embodiments of the present disclosure.

[0012] [Figure 3B] FIG. 3B illustrates a bare coilform according to some embodiments of the present disclosure.

[0013] [Figure 3C] FIG. 3C illustrates a non-split coil of a cable of twisted magnetic wire formed by winding the cable of twisted magnetic wire around a coil form, according to some embodiments of the present disclosure.

[0014] [Figure 3D] FIG. 3D is a vertical cross-sectional view through the center of an inductor according to some embodiments of the present disclosure.

[0015] [Figure 4] FIG. 4 illustrates a plot of impedance as a function of RF frequency at the higher primary RF frequency of 13.56 MHz for each of the wires supplying current flow to a given heating element in a heater assembly in accordance with some embodiments of the present disclosure.

[0016] [Diagram 5] FIG. 5 illustrates a plot of impedance as a function of RF frequency at a lower primary RF frequency of 1 MHz for each of the wires supplying current flow to a given heating element in a heater assembly according to some embodiments of the present disclosure.

[0017] [Figure 6]FIG. 6 presents a method for filtering RF power according to some embodiments of the present disclosure.

[0018] [Figure 7] FIG. 7 presents a diagram illustrating a method for filtering RF power according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one of ordinary skill 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 in order not to unnecessarily obscure the present disclosure.

[0020] In the semiconductor industry, semiconductor substrates are processed in capacitively coupled plasma (CCP) and inductively coupled plasma (ICP) processing chambers. ) ProcessingManufacturing operations can be performed in various types of plasma chambers, such as CCP and ICP process chambers. Both CCP and ICP process chambers use radio frequency (RF) power to energize a process gas and convert the process gas into a plasma. Reactive and / or charged species in the plasma are intended to interact with the substrate to modify the state of the substrate, for example, by modifying materials present on the substrate or depositing material on the substrate or removing / etching material from the substrate. CCP and ICP process chambers can also include one or more electrodes that receive RF power to generate a bias voltage to accelerate the charged species from the plasma toward the substrate. CCP and ICP process chambers can also include one or more electrically powered components (such as a heater assembly) that receive power from one or more power sources, each of which is either a DC (direct current) or AC (alternating current) power source. It is necessary to ensure that the RF power used to generate the plasma and / or the bias voltage does not get transferred to the power source (DC or AC power source) used to power the one or more electrically powered components (such as the heater assembly). Various embodiments of the RF filters and associated inductors disclosed herein are suitable for preventing RF power associated with the operation of CCP and ICP processing chambers from being transmitted to DC and / or AC power sources.

[0021] 1A illustrates an exemplary vertical cross-sectional view of a CCP processing chamber 101, according to some embodiments of the present disclosure. The CCP processing chamber 101 defines a process volume in which a plasma 123 is generated during exposure to a substrate 105 to affect a change in the substrate 105 in a controlled manner. In various manufacturing processes, the change in the substrate 105 can be a change in the material or surface condition on the substrate 105. For example, in various manufacturing processes, the change in the substrate 105 can be the etching of material from the substrate 105, the deposition of material onto the substrate 105, or the removal of material present on the substrate 105. FeeThe substrate 105 may include one or more of the following modifications: a) a substrate 105 is a semiconductor wafer undergoing a manufacturing process; b) a substrate 105 is ...

[0022] In various embodiments, the CCP processing chamber 101 operates by flowing one or more process gases into a processing volume during exposure of the substrate 105 and applying RF power to the one or more process gases to convert the one or more process gases into a plasma 123 to affect material or surface state changes on the substrate 105. The CCP processing chamber 101 includes a substrate support structure 103 on which the substrate 105 is positioned and supported during processing operations. In some embodiments, an electrode 107 is disposed within the substrate support structure 103 and transmits RF power from the electrode 107 through the processing volume to generate the plasma 123 and / or control ion energy. The electrode 107 is connected to receive RF power through an RF feed structure 109, which is connected to one or more RF power generators 111 via one or more impedance match systems 113. The impedance matching system 113 includes an arrangement of capacitors and inductors that are configured such that the impedance seen by the RF power generator 111 at the input of the impedance matching system 113 is sufficiently close to the output impedance that the RF power generator 111 is designed to operate with (typically 50 ohms). As a result, the RF power generated and transmitted by the RF power generator 111 is transmitted efficiently (e.g., without unacceptable or undesirable reflections) to the process volume.

[0023] Also, in some embodiments, an upper electrode 115 may be provided. In various embodiments, the upper electrode 115 may provide an electrical ground electrode or may be used to transmit RF power to the processing volume. In some embodiments, the upper electrode 115 is connected to receive RF power through an RF feed structure 117, which is connected to one or more RF power generators 121 via one or more impedance matching systems 119. The impedance matching system 119 includes an arrangement of capacitors and inductors configured such that the impedance seen by the RF power generator 121 at the input of the impedance matching system 119 is sufficiently close to the output impedance at which the RF power generator 121 is designed to operate (typically 50 ohms). As a result, the RF power generated and transmitted by the RF power generator 121 is efficiently transmitted (e.g., without unacceptable or undesirable reflections) to the processing volume.

[0024] In some embodiments, a heater assembly 125 is disposed within the substrate support structure 103 to provide temperature control for the substrate 105. The heater assembly 125 is electrically connected to receive power through electrical connection 127, which is provided from a power source 131 through electrical connection 137 to an RF filter 129 and through the RF filter 129 to the electrical connection 127. In some embodiments, the power source 131 is an alternating current (AC) power source. In some embodiments, the power source 131 is a direct current (DC) power source. In some embodiments, the heater assembly 125 includes a plurality of electrical resistive heating elements. The RF filter 129 is configured to prevent RF power from entering the power source 131 while allowing transmission of electrical current between the power source 131 and the electrical connection 127.

[0025] In some embodiments, the heater assembly 125 includes multiple heating elements. FIG. 1C is a top view of an exemplary heater assembly 125 including four concentrically configured and positioned heating elements 132, 133, 134, 135 according to some embodiments of the present disclosure. The heating element 132 corresponds to an inner heating zone that is substantially centered horizontally with respect to an area of ​​the substrate support structure 103 configured to receive and support the substrate 105. The heating element 133 corresponds to an intermediate inner heating zone configured to radially surround the inner heating zone. The heating element 134 corresponds to an intermediate outer heating zone configured to radially surround the intermediate inner heating zone. The heating element 135 corresponds to an outer heating zone configured to radially surround the intermediate outer heating zone. In the exemplary heater assembly 125 of FIG. 1C, each of the heating elements 132, 133, 134, 135 is connected to receive separate and independently controlled power from the power source 131. More specifically, each of the heating elements 132, 133, 134, 135 is exclusively connected to two wires in the electrical connection 127. Thus, to accommodate the four heating elements 132, 133, 134, 135, the electrical connection 127 includes eight wires 132A, 132B, 133A, 133B, 134A, 134B, 135A, 135B, as shown in FIG. Also, in the example of FIG. 1C, each of the eight wires 132A, 132B, 133A, 133B, 134A, 134B, 135A, 135B is connected through the RF filter 129 to eight wires 137A, 137B, 137C, 137D, 137E, 137F, 137G, 137H (137A-137H) that form an electrical connection 137 between the power source 131 and the RF filter 129. It should be understood that the heater assembly 125 of FIG. 1C is shown as an example. In various embodiments, the heater assembly 125 can include less than four heating elements or more than four heating elements, with each heating element having a dedicated wire pair for receiving power from the power source 131 through the RF filter 129.

[0026] FIG. 1B illustrates an exemplary vertical cross-sectional view of an ICP processing chamber 151 according to some embodiments of the present disclosure. An ICP processing chamber may also be referred to as a transformer coupled plasma (TCP) processing chamber. For ease of description herein, ICP processing chamber shall be used to refer to both ICP and TCP processing chambers. The ICP processing chamber 151 defines a processing volume in which a plasma 123 is generated during exposure to the substrate 105 to affect changes in the substrate 105 in a controlled manner. In various manufacturing processes, the changes in the substrate 105 may be changes in materials or surface conditions on the substrate 105. For example, in various manufacturing processes, the changes in the substrate 105 may include etching of materials from the substrate 105, deposition of materials onto the substrate 105, or the removal of materials present on the substrate 105. Fee The compound may include one or more of the following modifications:

[0027] It should be understood that the ICP processing chamber 150 can be any type of ICP processing chamber in which RF power is transmitted from a coil 155 disposed outside the ICP processing chamber 151 to a process gas in the ICP processing chamber 151 to generate a plasma 123 within the ICP processing chamber 151. An upper window structure 153 is provided to allow RF power to be transmitted from the coil 155 through the upper window structure 153 to a processing volume of the ICP processing chamber 151. The ICP processing chamber 150 operates by flowing one or more process gases into the processing volume during exposure of the substrate 105 and applying RF power from the coil 155 to the one or more process gases to convert the one or more process gases into a plasma 123 to affect a change in a material or surface condition on the substrate 105. The coil 155 is disposed above the upper window structure 153. 1B, the coil 155 is formed as a radial coil assembly, with the shaded portions of the coil 155 indicating a direction from the front of the page to the rear of the page, and the unshaded portions of the coil 155 indicating a direction from the rear of the page to the front of the page. However, it should be understood that in other embodiments, the coil 155 can have essentially any configuration suitable for transmitting RF power through the upper window structure 153 to the plasma processing volume. In various embodiments, the coil 155 can have any number of turns and any cross-sectional size and shape (circular, elliptical, rectangular, trapezoidal, etc.) as needed to transmit RF power through the upper window structure 153 to the processing volume as desired.

[0028] The coil 155 is connected through an RF power supply structure 161 to one or more RF power generators 157 via one or more impedance matching systems 159. The impedance matching system 159 includes an arrangement of capacitors and / or inductors configured such that the impedance seen by the RF power generator 157 at the input of the impedance matching system 159 is sufficiently close to the output impedance at which the RF power generator 157 is designed to operate (typically 50 ohms). As a result, RF power supplied by the RF power generator 157 to the coil 155 is efficiently (i.e., without unacceptable or undesirable reflections) transmitted to the process volume. Also, in some embodiments, the ICP process chamber 151 can include an electrode 107, an RF power feed structure 109, an impedance matching system 113, and an RF power generator 111, as previously described with respect to FIG. 1A.

[0029] Additionally, in some embodiments, the ICP processing chamber 151 may include a heater assembly 125 disposed within the substrate support structure 103 to provide temperature control for the substrate 105. As described with respect to the ICP processing chamber 101 of FIG. 1A, the heater assembly 125 of the ICP processing chamber 151 is electrically connected to receive electrical power through electrical connection 127, which is provided from a power source 131 through electrical connection 137 to an RF filter 129 and through the RF filter 129 to the electrical connection 127.

[0030] 2 shows an electrical diagram of an RF filter 129 connected between the power supply 131 and the heater assembly 125 in the exemplary embodiment of FIG. 1C in accordance with some embodiments of the present disclosure. The RF filter 129 includes a separate wire for each wire connected between the power supply 131 and the heater assembly 125. Specifically, the RF filter 129 includes a wire 142A that connects a wire 137A from the output of the power supply 131 to a wire 132A that is connected to an input to the heater assembly 125. The RF filter 129 also includes a wire 142B that connects a wire 137B from the output of the power supply 131 to a wire 132B that is connected to an input to the heater assembly 125. The RF filter 129 also includes a wire 142C that connects a wire 137C from the output of the power supply 131 to a wire 133A that is connected to an input to the heater assembly 125. The RF filter 129 also includes a wire 142D that connects a wire 137D from the output of the power supply 131 to a wire 133B that is connected to an input to the heater assembly 125. The RF filter 129 also includes a wire 142E connecting a wire 137E from the output of the power supply 131 to a wire 134A that is connected to the input to the heater assembly 125. The RF filter 129 also includes a wire 142F connecting a wire 137F from the output of the power supply 131 to a wire 134B that is connected to the input to the heater assembly 125. The RF filter 129 also includes a wire 142G connecting a wire 137G from the output of the power supply 131 to a wire 135A that is connected to the input to the heater assembly 125. The RF filter 129 also includes a wire 142H connecting a wire 137H from the output of the power supply 131 to a wire 135B that is connected to the input to the heater assembly 125.

[0031] Each of the wires 142A, 142B, 142C, 142D, 142E, 142F, 142G, 142H (142A-142H) passing through the RF filter 129 forms a portion of an inductor 141 within the RF filter 129. At a first end of the inductor 141, each of the wires 142A-142H is connected to the heater assembly 125 through an electrical connection 127. At a second end of the inductor 141, each of the wires 142A-142H is connected to the power source 131 through an electrical connection 137. Within the inductor 141, the wires 142A-142H are twisted together to form a cable of twisted magnetic wires 142 that can be mechanically / spatially manipulated as a single cable. Within the inductor 141, the cable of twisted magnetic wires 142 is formed into a helical coil shape that extends between a first end of the inductor 141 (the electrical connection 127 connected to the heater assembly 125) and a second end of the inductor 141 (the electrical connection 137 connected to the power source 131). Each of the wires 142A-142H is formed as an electrical conductor coated with an electrically insulating coating material. Thus, when the wires 142A-142H are twisted together to form the cable of twisted magnetic wires 142, the electrically insulating coating material of each wire 142A-142H prevents inter-wire conduction of low frequency currents, such as direct current (DC) and alternating current (AC), associated with power transmission. Also, in some embodiments, the electrically insulating coating material of each wire 142A-142H is a material that is semi-permeable to RF power that may travel along the wires 142A-142H. In these embodiments, RF power can travel along the cable of twisted magnetic wires 142 as if it were traveling in a monolithic conductor cable, while low frequency (DC / AC) currents simultaneously flowing through the wires 142A-142H are prevented from flowing between the wires 142A-142H in the cable of twisted magnetic wires 142. This reduces or even eliminates channel-to-channel variations in impedance of the RF filter 129. In the RF filter 129, a given channel corresponds to a given pair of wires 142A-142H that supplies current flow to a given heating element 132, 133, 134, 135 in the heater assembly 125.In some embodiments, the wires 142A-142H are copper wires coated with a high temperature electrically insulating polymeric material, however, it should be understood that in various embodiments, the wires 142A-142H can be formed of conductive materials other than copper and coated with electrically insulating coating materials other than a high temperature electrically insulating polymeric material.

[0032] Each of the wires 142A-142H is electrically connected to a respective termination capacitor 143A, 143B, 143C, 143D, 143E, 143F, 143G, 143H (143A-143H) at a respective location between the inductor 141 and the electrical connection 137 to the power source 131. Specifically, the wire 142A is electrically connected to a first terminal of the termination capacitor 143A through the wire 144A, and the second terminal of the termination capacitor 143A is electrically connected to the reference ground potential 145. The wire 142B is electrically connected to a first terminal of the termination capacitor 143B through the wire 144B, and the second terminal of the termination capacitor 143B is electrically connected to the reference ground potential 145. The wire 142C is electrically connected to a first terminal of the termination capacitor 143C through a wire 144C, and the second terminal of the termination capacitor 143C is electrically connected to the reference ground potential 145. The wire 142D is electrically connected to a first terminal of the termination capacitor 143D through a wire 144D, and the second terminal of the termination capacitor 143D is electrically connected to the reference ground potential 145. The wire 142E is electrically connected to a first terminal of the termination capacitor 143E through a wire 144E, and the second terminal of the termination capacitor 143E is electrically connected to the reference ground potential 145. The wire 142F is electrically connected to a first terminal of the termination capacitor 143F through a wire 144F, and the second terminal of the termination capacitor 143F is electrically connected to the reference ground potential 145. Wire 142G is electrically connected to a first terminal of termination capacitor 143G through wire 144G, and a second terminal of termination capacitor 143G is electrically connected to reference ground potential 145. Wire 142H is electrically connected to a first terminal of termination capacitor 143H through wire 144H, and a second terminal of termination capacitor 143H is electrically connected to reference ground potential 145. Between electrical connection 137 to power source 131 and inductor 141, wires 142A-142H, wires 144A-144H, termination capacitors 143A-143H and reference ground potential 145 may collectively be referred to as an input configuration of RF filter 129.

[0033] The termination capacitors 143A-143H have a sufficiently high capacitance such that their presence in combination with the inductor 141 causes RF power entering the RF filter 129 from the heater assembly 125 to follow a transmission path to the reference ground potential 145 rather than to the power supply 131. In some embodiments, the termination capacitors 143A-143H each have a capacitance within a range extending from about 3000 picofarads (pF) to about 5000 pF, or about 0.1 microfarads (μF). Also, because the termination capacitors 143A-143H have such a large capacitance, manufacturing variations in the termination capacitors 143A-143H do not essentially affect the impedance uniformity between channels. Thus, manufacturing variations in the termination capacitors 143A-143H do not essentially affect the overall unit-to-unit (RF filter 129-RF filter 129) impedance uniformity.

[0034] FIG. 3A illustrates an isometric view of an inductor 141 according to some embodiments of the present disclosure. The example inductor 141 of FIG. 3A is configured for use with the example heater assembly 125 of FIG. 1C to filter RF power of two different RF frequencies. The inductor 141 includes a coilform 305 formed of an electrically insulating material. In some embodiments, the electrically insulating material of the coilform 305 is a polymeric material capable of withstanding high temperatures. For example, in some embodiments, the electrically insulating material of the coilform 305 is a fluoropolymer of tetrafluoroethylene, such as polytetrafluoroethylene (PTFE), e.g., Teflon™. However, it should be understood that in other embodiments, the electrically insulating material of the coilform 305 can be essentially any other solid material that is electrically non-conductive, can withstand the operating temperatures of the cable of the twisted magnetic wire 142, and is chemically compatible with the cable of the twisted magnetic wire 142 and other interface materials when installed for operation in a plasma processing chamber. For example, in some embodiments, the electrically insulating material of the coil form 305 may be one or more of acrylonitrile-butadiene-styrene (ABS), acetate, acrylic, beryllium oxide, ceramic, Delrin™, epoxy, fiberglass, glass, Kynar™, Lexan™, Merlon™, melamine, mica, Nomex™, nylon, polyethylene terephthalate (PET), phenolic, polyester, polyolefin, polystyrene, polyurethane, polyvinyl chloride (PVC), thermoplastic, polysulfone, polyetherimide, polyamideimide, polyphenylene, Noryl™, Ultem™, Udel™, Vespel™, Torlon™, vinyl, and the like.

[0035] The example coilform 305 of Figure 3A is formed as a hollow cylinder having an inner diameter 307 and an outer diameter 309. It should be appreciated that the inductance of the inductor 141 is a partial function of the outer diameter 309 of the coilform 305, as the cable of twisted magnetic wire 142 is wrapped around the outer surface of the coilform 305. In various embodiments, the outer diameter 309 of the coilform 305 is within a range extending from about 4 inches to about 6 inches.

[0036] In some embodiments, the inner diameter 307 of the coilform 305 is defined to provide for cooling airflow through the coilform 305. Additionally, the inner diameter 307 of the coilform 305 is defined so that the coilform 305 has sufficient mechanical strength to provide a rigid structure to maintain the spatial configuration of the cable of twisted magnetic wire 142 coiled on the outer surface of the coilform 305. Additionally, the inner diameter 307 of the coilform 305 can be defined to reduce the overall weight of the inductor 141, which may benefit the physical mounting of the inductor 141. In various embodiments, the inner diameter 307 of the coilform 305 is within a range ranging from about 3 inches to about 5 inches.

[0037] In general, the inductor 141 includes a number of coil sections corresponding to a number of substantially different RF frequencies to be filtered by the RF filter 129. In the example of FIG. 3A, the inductor 141 is configured to filter RF power at two substantially different RF frequencies. Thus, the exemplary inductor 141 of FIG. 3A has two coil sections, a first coil section 301 and a second coil section 303. Each coil section of the inductor 141, e.g., 301, 303, extends along a respective portion of the total axial length of the inductor 141. In the example of FIG. 3A, the total axial length of the inductor 141 is measured in the z-direction, and the inner diameter 307 and the outer diameter 309 are measured in the x-y plane. Each coil section of the inductor 141, e.g., 301, 303, is configured to have a particular inductance characteristic defined to filter RF power at or near a particular RF frequency intended to be filtered by the RF filter 129.

[0038] The particular inductance provided by a given coil section, e.g., 301, 303, of the inductor 141 is a function of the outer diameter 309 of the coilform 305, the axial length of the given coil section, the winding pitch between adjacent turns (wrapped around the coilform 305) of the cable of the twisted magnetic wire 142 in the given coil section, and the number of turns (wrapped around the coilform 305) of the cable of the twisted magnetic wire 142 in the given coil section. In the example of Figure 3A, the first coil section 301 has a winding pitch 311 measured between adjacent turns of the cable of the twisted magnetic wire 142 and the second coil section 303 has a winding pitch 313 measured between adjacent turns of the cable of the twisted magnetic wire 142. It should be understood that the winding pitch is measured for adjacent turns of the cable of the twisted magnetic wire 142 wound around the coilform 305, measured parallel to the z-direction between the centerlines of the cable of the twisted magnetic wire 142 and at the same azimuthal position about the z-axis of the coilform 305. The winding pitch between adjacent turns of the cable of the twisted magnetic wire 142 in a given coil section, e.g., 301, 303, e.g., 311, 313, affects the resonant frequency of the given coil section. In other words, the winding pitch between adjacent turns of the cable of the twisted magnetic wire 142 in a given coil section, e.g., 311, 313, determines the RF frequencies that are filtered by the given coil section. The smaller the winding pitch between adjacent turns of the cable of the twisted magnetic wire 142 in a given coil section, e.g., 301, 303, e.g., 311, 313, the higher the inductance provided in the given coil section. And the larger the turn pitch between adjacent turns of the cable of twisted magnetic wire 142 in a given coil section, e.g., 301, 303, e.g., 311, 313, the lower the inductance provided in that given coil section.

[0039] For higher RF frequencies, less inductance is required in a given coil section, and for lower RF frequencies, more inductance is required in a given coil section, to obtain a particular impedance for a given coil section, e.g., 301, 303. Thus, for higher RF frequencies, less inductance is required in a given coil section, which corresponds to a larger turn pitch, e.g., 311, 313, between adjacent turns of the cable of the twisted magnetic wire 142 in a given coil section, e.g., 301, 303. And, for lower RF frequencies, more inductance is required in a given coil section, which corresponds to a smaller turn pitch, e.g., 311, 313, between adjacent turns of the cable of the twisted magnetic wire 142 in a given coil section, e.g., 301, 303. Thus, in the example inductor 141 of Figure 3A, the first coil section 301, which has a larger winding pitch 311 between adjacent turns of the cable of the twisted magnetic wire 142, provides a lower inductance and resonates with a higher RF frequency. And, in the example inductor 141 of Figure 3A, the second coil section 303, which has a smaller winding pitch 313 between adjacent turns of the cable of the twisted magnetic wire 142, provides a higher inductance and resonates with a lower RF frequency. It should be appreciated that the cable of the twisted magnetic wire 142 is continuous throughout the inductor 141 from a first end of the inductor 141, which is connected to the heater assembly 125, to a second end of the inductor 141, which is connected to the power source 131. Thus, at each transition between adjacent coil sections, e.g., 301, 303, the cable of twisted magnetic wire 142 is wound around the coilform 305 without interruption, with the winding pitch between adjacent turns of the cable of twisted magnetic wire 142 being adjusted.

[0040] FIG 3B illustrates the coilform 305 in its bare state, according to some embodiments of the present disclosure. FIG 3C illustrates an unsplit coil of the cable of the twisted magnetic wire 142 formed by winding the cable of the twisted magnetic wire 142 around the coilform 305, according to some embodiments of the present disclosure. In the example of FIG 3B, a continuous groove is formed in the outer surface of the coilform 305 to precisely position the cable of the twisted magnetic wire 142 around the coilform 305 and to maintain the spatial configuration of the unsplit coil of the cable of the twisted magnetic wire 142 formed by winding the cable of the twisted magnetic wire 142 around the coilform 305. 3B illustrates that the continuous groove includes a first groove portion 315 formed in the first coil section 301 and a second groove portion 317 formed in the second coil section 303 with a smooth transition between the first groove portion 315 and the second groove portion 317 at the transition between the first coil section 301 and the second coil section 303. However, it should be understood that in other embodiments, the coilform 305 can be configured without a continuous groove on its outer surface. For example, in some embodiments, the coilform 305 can have a substantially smooth outer surface and use an electrically insulating spacer to separate adjacent turns of the cable of the twisted magnetic wire 142 wound around the coilform 305. In these embodiments, the electrically insulating spacer can be formed of essentially any material that can be used to form the coilform 305, such as those listed above as examples.

[0041] It should be understood that while the illustrated exemplary coilform 305 has an outer surface that is in the shape of a right cylinder (except for the presence of the continuous grooves), in other embodiments, the outer surface of the coilform 305 can have other cross-sectional shapes in the x-y plane, such as an oval, a rectangle, a square, a triangle, a polygon, a star, an x-shape, a cross, etc. Also, in some embodiments, the cross-sectional shape and / or size of the outer surface of the coilform 305 in the x-y plane can be different / varying along the axial length of the coilform 305. For example, the cross-sectional shape and / or size of the outer surface of the coilform 305 in the x-y plane can be different / varying for each coil section, e.g., 301, 303. For example, in some embodiments, the coilform 305 can be configured to have a first value of outer diameter 309 for the first coil section 301 and a second value of outer diameter 309 for the second coil section 303, where the second value of outer diameter 309 is different from the first value of outer diameter 309. It should also be appreciated that in some embodiments, the coilform 305 of the inductor 141 can have a solid configuration without a hollow interior region.

[0042] In addition, each coil section of the inductor 141, e.g., 301, 303, can include one or more windings of the cable of the twisted magnetic wire 142. For example, in the inductor 141, as shown in FIG. 3A, the first coil section 301 has one winding of the cable of the twisted magnetic wire 142, and the second coil section 303 has two windings of the cable of the twisted magnetic wire 142. FIG. 3D shows a vertical cross-section through the center of the inductor 141, according to some embodiments of the present disclosure. FIG. 3D shows that the cable of the twisted magnetic wire 142 is variously wound around the coilform 305. The first coil section 301 shown in FIG. 3D has one winding of the cable of the twisted magnetic wire 142. And the second coil section 303 shown in FIG. 3D has two windings of the cable of the twisted magnetic wire 142. Specifically, the second coil section 303 has a first winding 303A of the cabled twisted magnetic wire 142 formed on the outer surface of the coilform 305 and a second winding 303B of the cabled twisted magnetic wire 142 formed outside / on the first winding 303A of the cabled twisted magnetic wire 142. It should be appreciated and understood that in various embodiments, any coil section of the inductor 141, e.g., 301, 303, may be configured to include one or more layers of cabled twisted magnetic wire 142 windings as appropriate to provide a desired level of inductance. It should also be appreciated that multiple layers of cabled twisted magnetic wire 142 windings in a given coil section, e.g., 301, 303, may reduce the overall size of the inductor 141 and provide a higher inductance for a given coil section compared to a single winding for the same length of cabled twisted magnetic wire 142 for that given coil section.

[0043] In an exemplary embodiment, the inductor 141 is configured to filter RF frequencies at or about 1 MHz and at or about 13.56 MHz. In this exemplary embodiment, the first coil section 301, which has a larger winding pitch 311 between adjacent turns of the cable of the twisted magnetic wire 142, is configured to filter the higher RF frequency of 13.56 MHz. And, the second coil section 303, which has a smaller winding pitch 313 between adjacent turns of the cable of the twisted magnetic wire 142, is configured to filter the lower RF frequency of 1 MHz. In this exemplary embodiment, the first coil section 301 includes 13 turns of the cable of the twisted magnetic wire 142. Also, in this embodiment, the first winding layer 303A of the second coil section 303 includes 21 turns of the cable of the twisted magnetic wire 142. And, in this embodiment, the second winding layer 303B of the second coil section 303 includes a cable of 18 turns of twisted magnetic wire 142. Additionally, in this exemplary embodiment, each of the termination capacitors 143A-143H has a capacitance value of approximately 0.1 microfarads.

[0044] It should be appreciated that the inductor 141 can be configured to filter two or more different RF frequencies, and the frequencies of 1 MHz and 13.56 MHz in the above exemplary embodiment are mentioned as examples. For example, assuming that the inductor 141 is configured to filter three different RF frequencies (e.g., 400 kilohertz (kHz), 1 MHz, and 13.56 MHz), the inductor 141 will include three coil sections (e.g., coil sections 301, 303, and another coil section extending from coil section 303). Also, the winding pitch between adjacent turns of the cable of the twisted magnetic wire 142 can be different in each of the three coil sections, so as to be suitable for resonating with the three different RF frequencies, respectively. And the number of turns of the cable of the twisted magnetic wire 142 in each of the three coil sections can be appropriately set to establish a desired inductance in each of the three coil sections. And, as mentioned above, in some embodiments, the outer diameter 309 of the coilform 305 may be different in one or more of the three coil sections, if appropriate to obtain a desired inductance in that particular coil section.

[0045] In some embodiments, when the inductor 141 has two coil sections 301 and 303, and the coil section 301 has a larger winding pitch 311 between adjacent turns of the cable of the twisted magnetic wire 142, the number of turns in the coil section 301 is in a range ranging from about 10 to about 15. Also, in this embodiment, the number of turns in the coil section 303 is in a range ranging from about 20 to about 25. Also, in this embodiment, the winding pitch 311 between adjacent turns of the cable of the twisted magnetic wire 142 in the coil section 301 is in a range ranging from about 0.4 inches to about 0.6 inches. Also, in this embodiment, the winding pitch 313 between adjacent turns of the cable of the twisted magnetic wire 142 in the coil section 303 is in a range ranging from about 0.2 inches to about 0.3 inches.

[0046] 3D also shows how the inductor 141 can be disposed within the outer housing 319. 319 The outer housing 319 provides physical protection for the inductor 141 and provides for mounting of the inductor 141 to other equipment and / or a rack, chassis, box, housing, etc. for equipment associated with the plasma processing chamber. In some embodiments, the outer housing 319 is configured as a substantially cylindrical structure having a flange 319A at at least one end for mounting to another surface. Also, in some embodiments, the outer housing 319 can have a built-in enclosure 320 for receiving the termination capacitors, e.g., 143A-143H, and a connector for receiving power from the power source 131. However, it should be understood that in other embodiments, the outer housing 319 can be formed to have essentially any shape suitable for physically protecting the inductor 141, cooling the inductor 141, and allowing the inductor 141 to be mounted within an existing system associated with the plasma processing chamber. FIG. 3D also illustrates how a fan 321 can be positioned proximate to the grate 325 to either blow cooling air into the inductor 141 as shown by arrow 323 or pull cooling air from the inductor 141 as shown by arrow 324.

[0047] During operation of the plasma processing chamber, e.g., 101, 151, the RF filter 129 appears as a load to the RF generator, e.g., 111, 121, 157. Thus, the higher the impedance of the RF filter 129, the lower the load it presents to the RF generator. Thus, in some embodiments, it is interesting that the RF filter 129 presents a high impedance to RF power transmission so that a smaller amount of RF power is lost in the RF filter 129. In some embodiments, the operating RF frequency of the RF power generator, e.g., 111, 121, 157, may change as a result of frequency tuning. In these embodiments, it may be desirable to have the RF filter 129 present at least a minimum specified impedance over the expected range of RF frequencies generated by the RF power generator during frequency tuning operations. In some embodiments, the impedance of the RF filter 129 is about 3 kilohms or greater to limit the expected range of RF frequencies generated by the RF power generator during frequency tuning operations. In this manner, the RF filter 129 is configured to present at least a minimum specified impedance to any RF frequencies generated during operation. It should also be appreciated that the impedance of the RF filter 129 is relatively high, e.g., 3 kilohms, so that less RF power is transmitted through the RF filter 129, improving the overall RF power efficiency of the plasma processing chamber, e.g., 101, 151.

[0048] As previously discussed, a given channel corresponds to a given pair of wires 142A-142H that provide current flow to a given heating element 132, 133, 134, 135 in the heater assembly 125. The RF filter 129 provides improved impedance uniformity between channels because the RF filter 129 is capable of blocking RF power transmission in a substantially similar manner for each channel present. FIG. 4 illustrates a schematic diagram of a pair of wires 132A, 132B, 132C, 132D, 132E, 132F, 132G, 132H that provide current flow to a given heating element 132, 133, 134, 135 in the heater assembly 125, according to some embodiments of the present disclosure. 133A, 133B, 134A, 134B, 135A, 135B4 shows a plot of impedance as a function of RF frequency at the upper primary RF frequency of 13.56 MHz for each of the wires 132A, 132B, 132C, 132D, 133D, 134D, 135E, 135F ... 133A, 133B, 134A, 134B, 135A, 135B 5 shows a plot of impedance as a function of RF frequency at the lower primary RF frequency of 1 MHz for each of the RF filters 129. FIG. 5 demonstrates how the RF filter 129 provides substantial channel-to-channel impedance uniformity at or near the lower RF frequency of 1 MHz. Because the RF filter 129 provides substantial channel-to-channel impedance uniformity, essentially the same amount of RF power is present in each of the power delivery channels of the heater assembly 125. This means that different heating elements, e.g., 132, 133, 134, 135, in various heating zones have a substantially uniform effect on the RF power transmission within their respective heating zones, thereby improving process uniformity across the substrate 105 with respect to RF power transmission / loss through the different heating elements, e.g., 132, 133, 134, 135. Also, by controlling the impedance uniformity between channels in the RF filter 129, it is possible to control the impedance uniformity between different units of the RF filter 129 installed in different plasma processing chambers, and thus the effect of the RF filter 129 on the impedance uniformity between chambers.

[0049] It should be understood that the RF filter (e.g., 129) is disclosed herein as including an inductive element (e.g., inductor 141) and a set of terminating capacitive elements (e.g., capacitors 143A-143H). The inductive element (e.g., 141) includes at least two coil sections (e.g., 301, 303) that collectively form an unsplit coil of the cable of twisted magnetic wire (e.g., 142). The unsplit coil of the cable of twisted magnetic wire (e.g., 142) has a continuous configuration through each transition between adjacent coil sections of the at least two coil sections (e.g., 301, 303). Each coil section (e.g., 301, 303) includes a portion of the unsplit coil of the cable of twisted magnetic wire (e.g., 142) configured with a corresponding winding pitch (e.g., 311, 313). At least two adjacent coil sections (e.g., 301, 303) have different winding pitches (e.g., 311, 313). A cable of twisted magnetic wire (e.g., 142) is configured for at least one channel, with two wires per channel. The cable of twisted magnetic wire (e.g., 142) is configured for connection at a first end of an inductive element (e.g., 141) to an electrical component (e.g., 125) that will receive power from a power source (e.g., 131). The cable of twisted magnetic wire (e.g., 142) is configured for connection at a second end of the inductive element (e.g., 141) to a power source (e.g., 131). A set of termination capacitive elements (e.g., 143A-143H) includes a separate termination capacitive element for each wire of the cable of twisted magnetic wire (e.g., 142). Each terminating capacitive element (e.g., 143A-143H) is electrically connected between a reference ground potential (e.g., 145) and a respective wire of the cable of twisted magnetic wires (e.g., 142) at a location between the second end of the inductive element (e.g., 141) and the power source (e.g., 131).

[0050] In some embodiments, the number of at least two coil sections (e.g., 301, 303) corresponds to a number of different RF frequencies filtered by the RF filter (e.g., 129). Also, in some embodiments, the winding pitch (e.g., 311, 313) of a given coil section (e.g., 301, 303) is set so that the given coil section (e.g., 301, 303) resonates with one of the number of different RF frequencies filtered by the RF filter (e.g., 129). In some embodiments, each wire (e.g., 142A-142H) of the cable of twisted magnetic wire (e.g., 142) is an electrical conductor coated with an electrically insulating coating material. In some embodiments, the electrically insulating coating material prevents wire-to-wire conduction of low frequency currents while allowing wire-to-wire transmission of RF power. In some embodiments, the inductive element (e.g., 141) includes a coilform (e.g., 305) around which the unsplit coil of the cable of twisted magnetic wire (e.g., 142) is wound. In some embodiments, the coilform (e.g., 305) has a hollow right cylindrical shape. In some embodiments, a continuous groove is formed in the outer surface of the coilform (e.g., 305), the continuous groove being configured to receive the cable of twisted magnetic wires (e.g., 142) and maintain the spatial configuration of the unsplit coils of the cable of twisted magnetic wires (e.g., 142).

[0051] In some embodiments, at least one coil section (e.g., 301, 303) includes multiple windings of the cable of twisted magnetic wire (e.g., 142). In some embodiments, the multiple windings are stacked radially relative to the axis of the inductive element (e.g., 141). In some embodiments, at least two coil sections (e.g., 301, 303) have different lengths measured along the axis of the inductive element (e.g., 141). In some embodiments, the non-split coil of the cable of twisted magnetic wire (e.g., 142) has different winding diameters (e.g., 309) of at least two coil sections (e.g., 301, 303). In some embodiments, the non-split coil of the cable of twisted magnetic wire (e.g., 142) has different winding shapes of at least two coil sections (e.g., 301, 303). In some embodiments, the cable of twisted magnetic wire (e.g., 142) includes eight wires (e.g., 142A-142H) and is configured for four channels, and the number of at least two coil sections (e.g., 301, 303) in the inductive element (e.g., 141) is two. In some embodiments, the unsplit coil of the cable of twisted magnetic wire (e.g., 142) has a winding diameter (e.g., 309) that is substantially the same in the two coil sections (e.g., 301, 303), and the winding pitch (e.g., 311) of the first coil section (e.g., 301) that connects to the first end of the inductive element (e.g., 141) is larger than the winding pitch (e.g., 313) of the second coil section (e.g., 303) that connects to the second end of the inductive element (e.g., 141). In some embodiments, the first coil section (e.g., 301) has one winding of a cable of twisted magnetic wire (e.g., 142) and the second coil section (e.g., 303) has two windings (e.g., 303A, 303B) of a cable of twisted magnetic wire (e.g., 142).In some embodiments, the first coil section (e.g., 301) has about 13 turns of twisted magnetic wire (e.g., 142) in one winding layer, the second coil section (e.g., 303) has about 21 turns of twisted magnetic wire (e.g., 142) in an inner winding layer (e.g., 303A) of two winding layers, and the second coil section (e.g., 303) has about 18 turns of twisted magnetic wire (e.g., 142) in an outer winding layer (e.g., 303B) of two winding layers, and each termination capacitance element (e.g., 143A-143H) of the set of termination capacitance elements has a capacitance value of about 0.1 microfarads.

[0052] FIG. 6 presents a method for filtering RF power according to some embodiments of the present disclosure. The method includes connecting an RF filter (e.g., 129) between a power source (e.g., 131) and an electrical component (e.g., 125) that will receive power from the power source (e.g., 131). In the method of FIG. 6, the RF filter (e.g., 129) includes an inductive element (e.g., 141) having at least two coil sections (e.g., 301, 303) that collectively form an unsplit coil of a cable of twisted magnetic wire (e.g., 142). Each coil section (e.g., 301, 303) includes a portion configured with a corresponding winding pitch (e.g., 311, 313) as a portion of the unsplit coil of the cable of twisted magnetic wire (e.g., 142). At least two adjacent coil sections (e.g., 301, 303) have different winding pitches (e.g., 311, 313). A cable of twisted magnetic wires (e.g., 142) includes two wires per channel and is configured for at least one channel. The cable of twisted magnetic wires (e.g., 142) is connected to an electrical component (e.g., 125) at a first end of an inductive element (e.g., 141). The cable of twisted magnetic wires (e.g., 142) is connected to a power source (e.g., 131) at a second end of the inductive element (e.g., 141). The RF filter (e.g., 129) includes a separate terminating capacitive element (e.g., 143A-143H) for each wire (e.g., 142A-142H) of the cable of twisted magnetic wires (e.g., 142). Each terminating capacitive element (e.g., 143A-143H) is electrically connected between a reference ground potential (e.g., 145) and a respective wire (e.g., 142A-142H) of the cable of twisted magnetic wires (e.g., 142) at a location between the second end of the inductive element (e.g., 141) and the power source (e.g., 131). In some embodiments, the number of at least two coil sections (e.g., 301, 303) corresponds to a number of different RF frequencies that are filtered by the RF filter (e.g., 129).In some embodiments, the winding pitch (e.g., 311, 313) of a given coil section (e.g., 301, 303) is set so that the given coil section (e.g., 301, 303) resonates with one of a number of different RF frequencies that are filtered by the RF filter (e.g., 129). In some embodiments, each wire (e.g., 142A-142H) of the cable of twisted magnetic wires (e.g., 142) is an electrical conductor coated with an electrically insulating coating material that prevents wire-to-wire conduction of low frequency currents while allowing wire-to-wire transmission of RF power.

[0053] 7 presents a method for filtering RF power according to some embodiments of the present disclosure. The method includes an operation 701 for transmitting power from a power source (e.g., 131) to wires (e.g., 142A-142H) in an input configuration. The wires (e.g., 142A-142H) are connected to respective capacitive elements (e.g., 143A-143H). Each separate pair of wires (e.g., 142A-142H) is designated to supply power to an electrical component (e.g., 125) that is exposed to RF power. The method also includes an operation 703 for transmitting power from the wires (e.g., 142A-142H) in the input configuration to corresponding magnetic wires in a cable of twisted magnetic wires (e.g., 142) at the input of the inductive element (e.g., 141). The inductive element (e.g., 141) includes at least two coil sections (e.g., 301, 303) that collectively form an unsplit coil of the cable of twisted magnetic wire (e.g., 142) between an input of the inductive element (e.g., 141) and an output of the inductive element (e.g., 141). Each coil section (e.g., 301, 303) includes a portion of the unsplit coil of the cable of twisted magnetic wire (e.g., 142) configured with a corresponding winding pitch (e.g., 311, 313). At least two adjacent coil sections (e.g., 301, 303) have different winding pitches (e.g., 311, 313). The method also includes an operation 705 for transmitting power at the output of the inductive element (e.g., 141) from the magnetic wires in the cable of twisted magnetic wires (e.g., 142) to corresponding wires (e.g., 132A, 132B, 133A, 133B, 134A, 134B, 135A, 135B) connected to electrical components (e.g., 125) that are exposed to RF power.

[0054] To understand some advantages of the RF filter 129, it is useful to contrast the RF filter 129 with other possible RF filter configurations. For the purpose of filtering two or more different primary RF frequencies, some other possible RF filter configurations may implement physically separate sets of inductors and termination capacitors for each of the different primary RF frequencies. For example, in the case of two primary RF frequencies, other possible RF filter configurations may implement one set of inductors and termination capacitors for the first primary RF frequency and one physically separate set of inductors and termination capacitors for the second primary RF frequency. Compared to the RF filter 129, this other possible RF filter configuration has twice the number of inductors and twice the number of termination capacitors. It should be understood and appreciated that the RF filter 129 differs from this other possible RF filter configuration in that the different coil sections of the RF filter 129, e.g., 301, 303, are part of the same coil winding and are not physically separate inductors. RF filter 129 further differs from other possible RF filter configurations in that a single set of termination capacitors 143A-143H is used regardless of the number of different coil sections, eg, 301, 303.

[0055] Additionally, in other possible RF filter configurations, some termination capacitors may have relatively low capacitance values ​​and relatively high manufacturing tolerances on capacitance, up to a few percent or more. These manufacturing tolerances on the capacitance of the termination capacitors may combine to essentially limit the channel-to-channel impedance uniformity achievable in other possible RF filter configurations. Also, in other possible RF filter configurations, separate inductors defined for filtering lower RF frequencies may be configured (by necessity) to have ferrite cores wrapped with untwisted conductors. The ferrite cores in this other possible RF filter configuration may have a large unit-to-unit permeability variation, up to 30%, essentially limiting the achievable impedance uniformity between different RF filter units. Reducing the unit-to-unit permeability variation of the ferrite core material may be costly and may require the use of larger ferrite core structures. For other possible RF filter configurations, manufacturing variations in the capacitance of the small termination capacitors and manufacturing variations associated with the permeability of the ferrite core material of the low frequency windings collectively increase chamber-to-chamber variations in the RF filter characteristics and performance (such as the impedance presented by the RF filter to the RF generator), which in turn affect the RF power transfer characteristics. Also, for other possible RF filter configurations, failure of any component of the RF filter often results in replacement of the entire RF filter. Thus, for other possible RF filter configurations, a higher number of termination capacitors may result in a higher failure rate.

[0056] Compared to other possible RF filter configurations described above, the RF filter 129 disclosed herein does not include multiple sets of termination capacitors. The large overall inductance provided by the RF filter 129 disclosed herein avoids the need to use smaller capacitance termination capacitors and avoids the need to form an inductor around a ferrite core. The RF filter 129 disclosed herein includes a set of termination capacitors 143A-143H at respective locations between the inductor 141 and the electrical connection 137 to the power source 131. Also, compared to other possible RF filter configurations described above, the RF filter 129 disclosed herein does not utilize termination capacitors that have relatively low capacitance and high manufacturing tolerances. Thus, the RF filter 129 disclosed herein can improve impedance uniformity between channels as well as improve impedance uniformity between corresponding chambers. Also, compared to other possible RF filter configurations described above, the RF filter 129 disclosed herein does not include a ferrite core structure for an inductor defined to filter lower RF frequencies, thereby avoiding the large manufacturing variations in permeability associated with the ferrite core structure and improving impedance uniformity between chambers.

[0057] In addition, it should be appreciated that the RF filter 129 disclosed herein uses a cable of twisted assemblies of wires 142 in the inductor 141 to improve impedance uniformity and repeatability between channels, minimizing loading effects on process uniformity. The RF filter 129 eliminates the effect of capacitance tolerances on unit-to-unit variations. The RF filter 129 eliminates the effect of permeability tolerances of ferrite core magnetic materials on unit-to-unit variations. The RF filter 129 can achieve higher impedance with a wide bandwidth to enable frequency tuning. The RF filter 129 provides repeatability between channels, minimizing loading effects on process uniformity. The RF filter 129 can achieve higher RF power efficiency by minimizing RF power losses in the RF filter 129. The RF filter 129 provides high impedance (up to 3 kilohms or more), which minimizes loading effects of the RF filter 129, and provides wide bandwidth to enable frequency tuning operation in plasma processes using level-to-level RF power pulsing. Because RF filter 129 does not use interstage capacitors and does not use ferrite core construction, the effects of capacitance and permeability tolerances on unit-to-unit variations are eliminated in RF filter 129. Additionally, the use of twisted magnetic wire in the windings of inductor 141 in RF filter 129 minimizes channel-to-channel variations and therefore minimizes inter-channel loading effects on plasma process uniformity.

[0058] Although the foregoing disclosure includes certain details 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. Thus, the present embodiments should be considered as illustrative and not restrictive, and the claims should not be limited to the details given herein, but can be modified within the scope and equivalents of the described embodiments. The present disclosure may be realized in the following forms. [Form 1] 1. A radio frequency (RF) filter comprising: an inductive element including at least two coil sections collectively forming an unsplit coil of a cable of twisted magnetic wire, each coil section including a portion of the unsplit coil of the cable of twisted magnetic wire configured with a corresponding winding pitch, at least two adjacent coil sections having different winding pitches, the cable of twisted magnetic wire configured for at least one channel including two wires per channel, the cable of twisted magnetic wire configured for connection at a first end of the inductive element to an electrical component that will receive power from a power source, and the cable of twisted magnetic wire configured for connection to the power source at a second end of the inductive element; a set of termination capacitance elements including a separate termination capacitance element for each wire of the cable of twisted magnetic wires, each termination capacitance element being electrically connected between a reference ground potential and a respective wire of the cable of twisted magnetic wires at a location between the second end of the inductive element and the power source; An RF filter comprising: [Form 2] 2. The RF filter according to claim 1, An RF filter, wherein the unsplit coil of the cable of twisted magnetic wire has a continuous configuration through each transition between adjacent coil sections of the at least two coil sections. [Form 3] 2. The RF filter according to claim 1, An RF filter, wherein the at least two coil sections are associated with corresponding RF frequencies that are filtered by the RF filter. [Form 4] 4. The RF filter according to claim 3, An RF filter, wherein the winding pitch of a given coil section is set such that the given coil section resonates with one of the corresponding RF frequencies filtered by the RF filter. [Form 5] 2. The RF filter according to claim 1, 4. An RF filter, in which each wire of said twisted magnetic wire cable is an electrical conductor coated with an electrically insulating coating material. [Form 6] 6. The RF filter according to claim 5, The electrically insulating coating material is an RF filter that prevents the conduction of low frequency current between wires while allowing the transmission of RF power between wires. [Form 7] 2. The RF filter according to claim 1, An RF filter, wherein at least one coil section includes multiple windings of the twisted magnetic wire cable, the multiple windings being stacked radially relative to an axis of the inductive element. [Form 8] 2. The RF filter according to claim 1, At least two coil sections have different lengths measured along an axis of the inductive element. [Form 9] 2. The RF filter according to claim 1, The unsplit coil of the twisted magnetic wire cable has at least two coil sections with different winding diameters. [Form 10] 2. The RF filter according to claim 1, The RF filter, wherein the unsplit coil of the twisted magnetic wire cable has a different winding shape in at least two coil sections. [Form 11] 2. The RF filter according to claim 1, An RF filter, wherein the cable of twisted magnetic wires includes eight wires and is configured for four channels, and the number of the at least two coil sections is two. [Form 12] 2. The RF filter according to claim 1, 1. An RF filter, wherein the unsplit coil of the cable of twisted magnetic wire has a winding diameter that is substantially the same in the at least two coil sections, and the winding pitch of a first coil section that connects to the first end of the inductive element is greater than the winding pitch of a second coil section that connects to the second end of the inductive element. [Form 13] 13. The RF filter according to claim 12, an RF filter, the first coil section having one winding of the twisted magnetic wire cable and the second coil section having two windings of the twisted magnetic wire cable; [Form 14] 14. The RF filter according to claim 13, 1. An RF filter, wherein the first coil section has approximately 13 turns of the twisted magnetic wire cable in one of the winding layers, the second coil section has approximately 21 turns of the twisted magnetic wire cable in an inner winding layer of the two winding layers, and the second coil section has approximately 18 turns of the twisted magnetic wire cable in an outer winding layer of the two winding layers, and each termination capacitance element of the set of termination capacitance elements has a capacitance value of approximately 0.1 microfarads. [Form 15] 2. The RF filter according to claim 1, The inductive element includes a coilform around which the unsplit coil of the twisted magnetic wire cable is wound. [Form 16] 16. The RF filter according to claim 15, An RF filter, wherein the coilform has a hollow right circular cylinder shape. [Form 17] 17. The RF filter according to claim 16, 11. An RF filter comprising: a continuous groove formed within an outer surface of the coilform, the continuous groove configured to receive the twisted magnetic wire cable and maintain a spatial configuration of the unsplit coils of the twisted magnetic wire cable. [Form 18] 1. A method for filtering radio frequency (RF) power, comprising: having an RF filter between a power source and an electrical component that will receive power from the power source, the RF filter including an inductive element having at least two coil sections collectively forming an unsplit coil of a twisted magnetic wire cable, each coil section including a portion of the unsplit coil of the twisted magnetic wire cable configured with a corresponding winding pitch, at least two adjacent coil sections having different winding pitches, the twisted magnetic wire cable including two wires per channel and configured for at least one channel, the twisted magnetic wire cable connected to the electrical component at a first end of the inductive element, the twisted magnetic wire cable connected to the power source at a second end of the inductive element, the RF filter including a separate termination capacitive element for each wire of the twisted magnetic wire cable, each termination capacitive element electrically connected between a reference ground potential and a respective wire of the twisted magnetic wire cable at a location between the second end of the inductive element and the power source. A method comprising: [Form 19] 19. A method for filtering RF power as recited in claim 18, comprising: A method according to claim 1, wherein the number of the at least two coil sections corresponds to a plurality of different RF frequencies to be filtered, and the winding pitch of a given coil section is set such that the given coil section resonates with one of the plurality of different RF frequencies to be filtered. [Form 20] 20. A method for filtering RF power as recited in claim 19, comprising: A method wherein each wire of said cable of twisted magnetic wires is an electrical conductor coated with an electrically insulating coating material that prevents inter-wire conduction of low frequency currents while allowing inter-wire transmission of RF power. [Form 21] 1. A method for filtering radio frequency (RF) power, comprising: transmitting power from a power source to wires in an input arrangement, the wires being connected to respective capacitive elements, each separate pair of the wires being designated to supply power to an electrical component exposed to RF power; Sending power from the wires in the input arrangement at an input of an inductive element to corresponding magnetic wires in a cable of twisted magnetic wire, the inductive element including at least two coil sections collectively forming an unsplit coil of the cable of twisted magnetic wire between the input of the inductive element and an output of the inductive element, each coil section including a portion of the unsplit coil of the cable of twisted magnetic wire configured with a corresponding winding pitch, at least two adjacent coil sections having different winding pitches; transmitting power at the output of the inductive element from the magnetic wires in the cable of twisted magnetic wires to corresponding wires connected to the electrical components that are exposed to RF power; A method comprising:

Claims

1. 1. A radio frequency (RF) filter comprising: an inductive element including a coilform and at least two coil sections collectively forming an unsplit coil of a cable of twisted magnetic wire wound on the coilform, the coilform being a hollow cylinder having an inner diameter and an outer diameter, the inner diameter of the coilform being defined to provide cooling air flow through the coilform, each coil section including a portion of the unsplit coil of the cable of twisted magnetic wire configured with a corresponding winding pitch, at least two adjacent coil sections having different winding pitches, the cable of twisted magnetic wire including two wires per channel and configured for at least one channel, the cable of twisted magnetic wire configured for connection to an electrical component that will receive power from a power source at a first end of the inductive element, and the cable of twisted magnetic wire configured for connection to the power source at a second end of the inductive element; a set of termination capacitive elements including a separate termination capacitive element for each wire of the cable of twisted magnetic wires, each termination capacitive element being electrically connected between a reference ground potential and a respective wire of the cable of twisted magnetic wires at a location between the second end of the inductive element and the power source; a fan disposed at an end of the coilform for moving a cooling airflow through the coilform; Equipped with the unsplit coil of the cable of twisted magnetic wire has the same winding diameter in the at least two coil sections, the winding pitch of a first coil section that connects to the first end of the inductive element being greater than the winding pitch of a second coil section that connects to the second end of the inductive element; an RF filter, the first coil section having one winding of the twisted magnetic wire cable and the second coil section having two windings of the twisted magnetic wire cable;

2. 2. The RF filter of claim 1, An RF filter, wherein the unsplit coil of the cable of twisted magnetic wire has a continuous configuration through each transition between adjacent coil sections of the at least two coil sections.

3. 2. The RF filter of claim 1, An RF filter, wherein the at least two coil sections are associated with corresponding RF frequencies that are filtered by the RF filter.

4. 4. The RF filter of claim 3, An RF filter, wherein the winding pitch of a given coil section is set such that the given coil section resonates with one of the corresponding RF frequencies filtered by the RF filter.

5. 2. The RF filter of claim 1, An RF filter wherein each wire of said cable of twisted magnetic wires is an electrical conductor coated with an electrically insulating coating material.

6. 6. The RF filter of claim 5, The electrically insulating coating material prevents conduction of low frequency current between wires while allowing transmission of RF power between wires, an RF filter.

7. 2. The RF filter of claim 1, An RF filter, wherein at least one coil section includes multiple windings of the twisted magnetic wire cable, the multiple windings being stacked radially relative to an axis of the inductive element.

8. 2. The RF filter of claim 1, An RF filter, wherein at least two coil sections have different lengths measured along an axis of the inductive element.

9. 2. The RF filter of claim 1, An RF filter, wherein the unsplit coil of the twisted magnetic wire cable has different winding diameters in at least two coil sections.

10. 2. The RF filter of claim 1, An RF filter, wherein the unsplit coil of the cable of twisted magnetic wire has a different winding shape in at least two coil sections.

11. 2. The RF filter of claim 1, An RF filter, wherein the cable of twisted magnetic wires includes eight wires and is configured for four channels, and the at least two coil sections are two in number.

12. 2. The RF filter of claim 1, 1. An RF filter, wherein the first coil section has 13 turns of the twisted magnetic wire cable in one of the winding layers, the second coil section has 21 turns of the twisted magnetic wire cable in an inner winding layer of the two winding layers, and the second coil section has 18 turns of the twisted magnetic wire cable in an outer winding layer of the two winding layers, and each termination capacitance element of the set of termination capacitance elements has a capacitance value of 0.1 microfarads.

13. 2. The RF filter of claim 1, 11. An RF filter comprising: a continuous groove formed within an outer surface of the coilform, the continuous groove configured to receive the twisted magnetic wire cable and maintain a spatial configuration of the unsplit coils of the twisted magnetic wire cable.

14. 1. A method for filtering radio frequency (RF) power, comprising:

1. An RF filter between a power source and an electrical component that will receive power from the power source, the RF filter comprising an inductive element having a coilform and at least two coil sections collectively forming an unsplit coil of a cable of twisted magnetic wire wound on the coilform, the coilform being a hollow cylinder having an inner diameter and an outer diameter, the inner diameter of the coilform comprising an inductive element defined to provide cooling air flow through the coilform, each coil section including a portion of the unsplit coil of the cable of twisted magnetic wire configured with a corresponding winding pitch, and at least two adjacent coil sections including a portion of the unsplit coil of the cable of twisted magnetic wire configured with a corresponding winding pitch. the coil sections have different winding pitches, the twisted magnetic wire cable includes two wires per channel and is configured for at least one channel, the twisted magnetic wire cable is connected to the electrical component at a first end of the inductive element, the twisted magnetic wire cable is connected to the power source at a second end of the inductive element, the RF filter includes a separate termination capacitive element for each wire of the twisted magnetic wire cable, each termination capacitive element being electrically connected between a reference ground potential and a respective wire of the twisted magnetic wire cable at a location between the second end of the inductive element and the power source; operating a fan disposed at an end of the coilform to move a cooling airflow through the coilform; Including, the unsplit coil of the cable of twisted magnetic wire has the same winding diameter in the at least two coil sections, the winding pitch of a first coil section that connects to the first end of the inductive element being greater than the winding pitch of a second coil section that connects to the second end of the inductive element; The method of claim 1, wherein the first coil section has one winding of the twisted magnetic wire cable and the second coil section has two windings of the twisted magnetic wire cable.

15. 15. A method for filtering RF power as recited in claim 14, comprising: A method according to claim 1, wherein the number of the at least two coil sections corresponds to a plurality of different RF frequencies to be filtered, and the winding pitch of a given coil section is set such that the given coil section resonates with one of the plurality of different RF frequencies to be filtered.

16. 16. A method for filtering RF power as recited in claim 15, comprising: A method wherein each wire of said cable of twisted magnetic wires is an electrical conductor coated with an electrically insulating coating material that prevents inter-wire conduction of low frequency currents while allowing inter-wire transmission of RF power.

17. 1. A method for filtering radio frequency (RF) power, comprising: transmitting power from a power source to wires in an input arrangement, the wires being connected to respective capacitive elements, each separate pair of the wires being designated to supply power to an electrical component exposed to RF power; at an input of an inductive element, transmitting power from the wires in the input arrangement to corresponding magnetic wires in a cable of twisted magnetic wire, the inductive element including a coilform and at least two coil sections collectively forming an unsplit coil of the cable of twisted magnetic wire wound around the coilform between the input of the inductive element and an output of the inductive element, the coilform being a hollow cylinder having an inner diameter and an outer diameter, the inner diameter of the coilform being defined to provide cooling air flow through the coilform, each coil section including a portion of the unsplit coil of the cable of twisted magnetic wire configured with a corresponding winding pitch, at least two adjacent coil sections having different winding pitches; transmitting power at the output of the inductive element from the magnetic wires in the cable of twisted magnetic wires to corresponding wires connected to the electrical components that are exposed to RF power; operating a fan disposed at an end of the coilform to move a cooling airflow through the coilform; Including, the unsplit coil of the cable of twisted magnetic wire has the same winding diameter in the at least two coil sections, the winding pitch of a first coil section that connects to a first end of the inductive element being greater than the winding pitch of a second coil section that connects to a second end of the inductive element; The method of claim 1, wherein the first coil section has one winding of the twisted magnetic wire cable and the second coil section has two windings of the twisted magnetic wire cable.

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