Wafer chuck assembly with insulation for RF connection

Abstract

A wafer chuck assembly is described that includes a platen having one or more plasma electrodes and an RF assembly that includes at least one radio frequency (RF) conductor electrically coupled to the one or more plasma electrodes. The at least one RF conductor includes a rod having a rod tip coupled to the one or more plasma electrodes and a rod stem mechanically coupled to a thermal choke having a hollow interior. The rod includes a first conductive material and has a first width and a first length. The thermal choke includes a second conductive material and has a second width and a second length, the second width being equal to or greater than the first width.

Description

[Background technology]

[0001] [Priority claim] This application claims priority to U.S. Provisional Patent Application No. 63 / 267,423, entitled “METHOD AND APPARATUS FOR THERMAL INSULATION FOR RF CONNECTIONS,” filed February 1, 2022, which is incorporated by reference in its entirety.

[0002] Substrate processing systems are used to perform processes such as deposition and etching of films on substrates, such as semiconductor wafers. For example, deposition may be performed using chemical vapor deposition (CVD), plasma-enhanced CVD (PECVD), atomic layer deposition (ALD), plasma-enhanced ALD (PEALD), and / or other deposition processes to deposit conductive, dielectric, or other types of films. During deposition, the substrate may be supported in a wafer chuck on a pedestal. Many deposition tools include components that deliver radio frequency power to an electrode embedded in the pedestal to generate and enable sputter deposition of, for example, dielectric materials.

[0003] Current wafer chuck component designs may have latent defects that can cause premature failure of key components after a deposition tool has been in use for a short period of time. Assembly and disassembly procedures for the wafer chuck pedestal for service and repair may be overly difficult or risk damage to the pedestal components due to suboptimal component design or layout. [Brief description of the drawings]

[0004] The materials described herein are illustrated by way of example, and not by way of limitation, in the accompanying figures. For simplicity and clarity of illustration, elements shown in the figures are not necessarily drawn to scale. For example, dimensions of some elements may be exaggerated relative to other elements for clarity. Also, for clarity of illustration, various physical features may be represented in their simplified "ideal" forms and geometries, but it will nevertheless be understood that actual implementations may only approximate the illustrated ideals. For example, smooth surfaces and square intersections may be depicted while ignoring finite roughness, rounded corners, and imperfect angular intersections that are characteristic of structures formed by nanofabrication techniques. Additionally, where considered appropriate, reference labels are repeated among the figures to indicate corresponding or similar elements.

[0005] [Figure 1A] FIG. 1A is a cross-sectional view of a radio frequency (RF) assembly according to at least one embodiment.

[0006] [Figure 1B] FIG. 1B is a cross-sectional view of a wafer chuck assembly including the RF assembly shown in FIG. 1A according to at least one embodiment.

[0007] [Figure 1C] FIG. 1C is a detailed cross-sectional view of the wafer chuck assembly shown in FIG. 1B according to at least one embodiment.

[0008] [Diagram 2] FIG. 2 is a cross-sectional view of an RF conductor of the RF assembly shown in FIG. 1A according to at least one embodiment.

[0009] [Figure 3A] FIG. 3A is a top view of an RF assembly clamp according to at least one embodiment.

[0010] [Figure 3B] FIG. 3B is a cross-sectional exploded view of the RF assembly clamp shown in FIG. 3A according to at least one embodiment.

[0011] [Figure 3C] FIG. 3C is a top view of an alternative embodiment of an RF assembly clamp according to at least one embodiment.

[0012] [Figure 3D] FIG. 3D is a cross-sectional view of the RF assembly clamp shown in FIG. 3A supporting multiple RF conductors in an O-ring retainer according to at least one embodiment.

[0013] [Figure 3E] FIG. 3E is a cross-sectional view of a second embodiment of an RF assembly clamp including a ball and socket retainer according to at least one embodiment.

[0014] [Figure 4] FIG. 4 is an exploded 3D cross-sectional view of an adapter tube assembly with an RF assembly according to at least one embodiment.

[0015] [Figure 5A] FIG. 5A is an orthogonal cross-sectional view of a wire harness according to at least one embodiment.

[0016] [Figure 5B] FIG. 5B is a top view of the wire harness shown in FIG. 5A according to at least one embodiment.

[0017] [Figure 5C] FIG. 5C is a cross-sectional view of an alternative embodiment of the wire harness shown in FIG. 5A according to at least one embodiment.

[0018] [Figure 6A]FIG. 6A is a top view of a spacer plate for separating RF conductors and heater wires according to at least one embodiment.

[0019] [Figure 6B] FIG. 6B is a cross-sectional view of the spacer plate of FIG. 6A according to at least one embodiment.

[0020] [Figure 7A] FIG. 7A is a top view of an upper clamp ring of a column clamp assembly according to at least one embodiment.

[0021] [Figure 7B] FIG. 7B is an orthogonal cross-sectional view of the upper clamp ring of FIG. 7A according to at least one embodiment.

[0022] [Figure 8A] FIG. 8A is a plan view of a lower clamp ring of a column clamp assembly showing the top surface according to at least one embodiment.

[0023] [Figure 8B] FIG. 8B is a top view of the lower clamp ring showing the underside, according to at least one embodiment.

[0024] [Figure 8C] FIG. 8C is a cross-sectional view of the lower clamp ring of FIGS. 8A and 8B according to at least one embodiment.

[0025] [Figure 9] FIG. 9 is a 3D cross-sectional view of an upper wafer chuck assembly according to at least one embodiment.

[0026] [Figure 10] FIG. 10 illustrates a semiconductor processing tool including the wafer chuck assembly shown in FIG. 1C in accordance with at least one embodiment.

[0027] [Figure 11] FIG. 11 is an exemplary flowchart summarizing a method for assembling a wafer chuck assembly according to at least one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] In the following description, numerous specific details, such as construction schemes, are set forth to provide a thorough understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that the embodiments of the present disclosure may be practiced without these specific details. In other instances, well-known features, such as gas line fittings, heating elements, and snap switches, are not described in particular detail so as not to unnecessarily obscure the embodiments of the present disclosure. Furthermore, it should be understood that the various embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale.

[0029] In some cases, in the following description, well-known methods and devices are shown in block diagram form rather than in detail to avoid obscuring the disclosure. Throughout this specification, reference to "one embodiment," "one embodiment," "at least one embodiment," or "some embodiments" means that a particular feature, structure, function, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Thus, the phrases "in one embodiment," "in one embodiment," "in at least one embodiment," or "some embodiments" appearing in various places throughout this specification do not necessarily refer to the same embodiment of the present disclosure. Furthermore, particular features, structures, functions, or characteristics can be combined in any suitable manner in one or more embodiments. For example, a first embodiment may be combined with a second embodiment, unless particular features, structures, functions, or characteristics associated with the two embodiments are mutually exclusive.

[0030] The terms "coupled" and "connected," along with their derivatives, may be used herein to describe a functional or structural relationship between components. These terms are not intended as synonyms for each other. Rather, in certain embodiments, "connected" may be used to indicate that two or more elements are in direct physical, optical, or electrical contact with each other. "Coupled" may be used to indicate that two or more elements are in direct or indirect (with other elements between them) physical, electrical, or magnetic contact with each other and / or that two or more elements cooperate or interact with each other (e.g., in a causal relationship).

[0031] The terms "on," "under," "between," and "on" may generally refer to the relative location of one component or material with respect to other components or materials for which such physical relationship is noteworthy. Unless these terms are modified with "direct" or "directly," one or more intervening components or materials may be present. A similar distinction is made with respect to component assemblies. As used throughout this specification and claims, a list of items joined by the terms "at least one of" or "one or more of" may mean any combination of the listed terms.

[0032] Unless otherwise specified by the explicit context in which they are used, the terms "substantially equal," "substantially identical," "approximately equal," "nearly equal," and "approximately equal" mean that there is only an accidental variation between the two objects so described. In at least one embodiment, the accidental variation is typically no more than + / -10% of a reference or target value. Here, "substantially," "close," "approximately," "near," and "about" may generally refer to being within + / -10% of a target value.

[0033] The term "adjacent" may generally refer to the location of something that is next to (e.g., immediately adjacent or nearby with one or more objects between) or in close proximity to (e.g., abutting) another thing.

[0034] In at least one embodiment, a wafer chuck assembly is disclosed that includes a high temperature (e.g., temperature greater than 500° C.) radio frequency (RF) assembly with enhanced thermal and mechanical characteristics. In at least one embodiment, the RF assembly includes one or more RF conductor assemblies that include a metal rod welded or brazed to a thermal choke. In at least one embodiment, the thermal choke includes a thin-walled tubular body that is coaxial with the rod to which it is welded. In at least one embodiment, an electrical RF connector can be attached to the base of the thermal choke. In at least one embodiment, the thermal choke and rod assembly conducts RF energy to a plasma discharge electrode in the wafer chuck. In at least one embodiment, the rod is in contact with the wafer chuck pedestal platen.

[0035] The RF conductor may be hot because it may be heated by contact with the pedestal platen, which may be heated to a substantially elevated temperature, e.g., above 700° C., to facilitate the formation of the deposition film. Through mechanical contact with the heated pedestal, the RF conductor may carry significant heat by conduction down the pedestal column and ultimately to the RF connector. The RF connector and other components within the stem and housing may not be able to withstand high temperatures. For example, the RF connector should not exceed 150° C. The thermal choke can significantly limit the heat transfer down the rod assembly and protect the connection. For example, the RF conductor rod may have a temperature of 650° C. at its tip, decaying (exponentially) to approximately 500° C. at the junction with the thermal choke. The temperature profile along the thermal choke may decay exponentially from approximately 500° C. at the attachment point of the connector (e.g., at the base of the thermal choke) to a temperature below 150° C. The insulator sleeve can protect temperature-sensitive components within the wafer chuck assembly from heat damage.

[0036] In at least one embodiment, the thermal choke may have a large length to diameter ratio (e.g., 5:1 or greater) to maximize thermal resistance. In at least one embodiment, the thermal resistance of the thermal choke may protect a connector attached to the lower end from excessive heat transferred from the platen. In at least one embodiment, the rod may have a length substantially shorter than the thermal choke in the RF conductor assembly. In at least one embodiment, the length of the rod may be limited to effectively maintain an axially uniform temperature. In at least one embodiment, the rod, which includes a ferromagnetic material such as iron or nickel, may be maintained at a temperature above the Curie temperature to reduce resistive losses due to magnetic effects on the RF skin depth.

[0037] In at least one embodiment, the thermal choke can be welded or brazed to the rod to enhance the mechanical, electrical, and thermal coupling between the rod and the thermal choke. In at least one embodiment, the welded bond assembly can be an RF conductor with high RF electrical conductance but also high thermal resistance. In at least one embodiment, the thermal choke can be gold coated to enhance electrical conductivity. In at least one embodiment, the RF assembly can further comprise a dielectric sleeve over the rod / thermal choke assembly. In at least one embodiment, the dielectric sleeve can include a ceramic material that thermally and electrically insulates the rod / thermal choke assembly from heat radiated by other rod / thermal choke assemblies. In at least one embodiment, the sleeve can also insulate heat sensitive components lower in the pedestal column (further away from the heated pedestal) from heat radiated by the rod and thermal choke. In at least one embodiment, the RF assembly can be housed within a tubular column coupled to the pedestal.

[0038] In at least one embodiment, the RF assembly may be housed within an adapter tube as part of a wafer chuck assembly. In at least one embodiment, the wafer chuck assembly may include a pedestal stem (integral with the pedestal platen) clamped to a flange on the adapter tube. In at least one embodiment, the adapter tube includes features that may enable enhancement of the RF assembly in embodiments disclosed herein.

[0039] In at least one embodiment, the RF assembly comprises an RF assembly clamp assembly that holds a plurality of RF conductors and constrains lateral and vertical movement of such RF conductors but allows limited pivotal movement of the RF conductors. In at least one embodiment, the RF assembly clamp may be located within an adapter tube. In at least one embodiment, the RF assembly clamp may enable compensation for lateral misalignment of the plurality of RF conductors with their attachment points on the wafer pedestal by allowing pivotal movement of the RF conductors held by the clamp.

[0040] In at least one embodiment, there may be a small lateral misalignment between the rod attachment points on the pedestal platen (e.g., the location of the plasma electrodes embedded in the platen) and the axial center of the RF conductor. In at least one embodiment, such lateral misalignment may cause bending strain of the entire RF conductor assembly, including the rods and thermal chokes, potentially leading to failure of the rod assemblies. In at least one embodiment, tolerances in the lateral or vertical displacement of the individual rod assemblies may compromise the performance of the wafer chuck assembly by potentially cracking or breaking the RF assemblies. In at least one embodiment, the RF rods may be displaced from their contact points with the wafer pedestal due to vibration or thermal expansion. In at least one embodiment, the RF assembly clamps can compensate for such displacements in real time.

[0041] In at least one embodiment, a column clamp assembly is disclosed that includes an upper clamp ring and a lower clamp ring. In at least one embodiment, the column clamp assembly facilitates coupling of a wafer pedestal stem to an adapter tube. In at least one embodiment, the adapter tube compresses a flange at a top portion. In at least one embodiment, the pedestal stem includes a retaining lip. In at least one embodiment, the column clamp assembly secures the retaining lip to the adapter tube flange. In at least one embodiment, the adapter tube flange includes a mounting structure (e.g., a groove) for a vacuum seal. In at least one embodiment, the retaining lip compresses the vacuum seal when the column clamp assembly is bolted to the flange. In at least one embodiment, an outer portion of the lower clamp ring is bolted to the flange. In at least one embodiment, an inner portion of the lower clamp ring is cantilevered to the outer portion of the lower clamp ring. In at least one embodiment, the lower clamp ring is operable to conform to non-planarity of the flange surface by flexing upward. In at least one embodiment, the lower clamp ring comprises a metal alloy or composition (e.g., aluminum) that has a lower yield stress than the material (e.g., steel) in the upper clamp ring. In at least one embodiment, the lower yield stress allows for lower torque to be applied to the retaining bolts during assembly of the wafer chuck assembly, thereby allowing flexure of the lower clamp ring without stressing or damaging the adapter tube flange or the adapter tube itself.

[0042] Here, "RF assembly" may generally refer to a system that includes a conductive structure operable to conduct radio frequency voltages and currents, such as an assembly that includes a rod and a thermal choke. In at least one embodiment, the RF assembly may include a thermal choke as part of the conductive structure. In at least one embodiment, the RF assembly may, for example, deliver RF power to a plasma discharge electrode.

[0043] Here, "RF conductor" may generally refer to a component that carries RF current, such as an assembly that includes a thermal choke and a rod that are mechanically and electrically coupled to one another. In at least one embodiment, the rod may extend from the thermal choke. In at least one embodiment, the rod and the thermal choke may be coaxial.

[0044] Here, a "rod" may generally refer to a portion of a conductive structure that is electrically coupled to a thermal choke, such as a tubular or non-tubular rigid component of an RF conductor. In at least one embodiment, the rod may be a solid structure. In at least one embodiment, the rod may include a stem portion that is inserted into a hollow interior of a tubular body of the thermal choke.

[0045] Here, "tip" or "rod tip" may generally refer to the end of the rod that is distal to a thermal choke in an RF conductor, such as the terminal portion of the rod. In at least one embodiment, the tip may contact a plasma generating electrode in a platen of a wafer chuck assembly.

[0046] Here, "rod stem" may generally refer to the end of a rod proximal to the thermal choke to which it is coupled, such as the portion of the rod that can be inserted into the hollow interior of the thermal choke.

[0047] Here, "insertion stop" may generally refer to a ledge on the stem of the rod, such as a widened segment of the rod that acts as an insertion stop to limit the length of the rod that can be inserted into the thermal choke.

[0048] Here, a "thermal choke" may generally refer to a tubular structure that retards heat transfer in the axial direction of the tubular structure, such as a hollow tube mechanically coupled to a rod. In at least one embodiment, the thermal choke may be a thin-walled tube that includes an electrically conductive material. In at least one embodiment, the wall of the tubular structure may have a cross-sectional area that is small enough to allow for a large thermal resistance in the axial direction of the tubular structure.

[0049] Here, "tubular body" may generally refer to a tubular structure that is part of a component of an RF assembly, such as a thermal choke. In at least one embodiment, the body is tubular because it may be hollow. In at least one embodiment, the tubular body may comprise a cylindrical wall surrounding a hollow interior and may be referred to as a "hollow tubular body." In at least one embodiment, a thermal choke is an example of a structure that comprises a tubular body.

[0050] Here, "hollow interior" may generally refer to the interior of a tubular body that is hollow, such as the interior of a thermal choke.

[0051] Here, a "bond" may generally refer to a joint formed between two or more structures, such as a welded or brazed bond. In at least one embodiment, the bond may permanently join the structures.

[0052] As used herein, a "weld bond" may generally refer to a welded joint that joins two or more metal structures.

[0053] Here, a "braze bond" may generally refer to a braze joint that joins two or more metal structures. In at least one embodiment, a braze bond may be defined as an atomic bond between the surfaces of two or more metal structures. In at least one embodiment, a braze bond may be formed by reflowing a layer of a low melting point metal (e.g., solder) at the interface of the two structures.

[0054] Here, "conductive coating" may generally refer to a coating that increases the surface conductivity of a conductor, such as a silver or gold coating to increase the surface conductivity of a thermal choke. In at least one embodiment, RF energy travels primarily on the surface of the conductor (e.g., skin effect). In at least one embodiment, the conductive coating may be a thin (e.g., 20 microns or less) coating of gold or other precious metal on the outer wall of the thermal choke to increase the surface conductivity.

[0055] Here, "conductive" may generally refer to the property of a material, such as a metal, semimetal, or semiconductor, to conduct electricity.

[0056] Here, "non-conductive" may generally refer to the property of a material not conducting electricity, such as a ceramic, glass, or a non-conductive polymer. In at least one embodiment, many materials that are electrically insulating are also thermally insulating.

[0057] Here, a "sleeve" may generally refer to a tubular structure that includes a thermally and electrically insulating material, such as an electrically and thermally insulating tubular jacket around a thermal choke. For example, the sleeve may surround the thermal choke as an electrically and thermally insulating jacket. In at least one embodiment, the sleeve may mitigate radiative heat transfer from the thermal choke wall.

[0058] Here, "nose" may generally refer to a terminal portion of a sleeve that tapers inwardly, such as a tapered end of the sleeve. In at least one embodiment, the diameter of the nose is smaller than the diameter of the sleeve. In at least one embodiment, the nose of the sleeve may guide the sleeve surrounding the rod into a counterbore in a platen of the wafer chuck assembly. In at least one embodiment, the counterbore in the platen exposes a portion of a plasma electrode embedded in the platen and allows the rod tip of the RF conductor to contact the exposed plasma electrode.

[0059] Here, "conductive material" may generally refer to a material that has the property of being highly electrically conductive (e.g., 10 mho or greater), such as a metal or a doped semiconductor. In at least one embodiment, many conductive materials are also thermally conductive.

[0060] Here, an "RF assembly clamp" may generally refer to a specialized clamp that holds an RF assembly, such as a clamp that includes a retention structure. In at least one embodiment, the RF assembly clamp may fit around a thermal choke portion of the RF assembly.

[0061] Here, "spacer plate" may generally refer to a plate within the base stem that maintains separation of multiple RF conductors extending from the adapter tube through the base stem to the platen, e.g., a plate with through holes through which the RF conductors can pass.

[0062] Here, "retaining structure" may generally refer to a part of an RF assembly clamp, such as a ball retainer or flexible rim, that can limit lateral or pivotal movement to allow for slight position corrections and enable self-alignment of the RF assembly.

[0063] Here, a "flexible rim" may generally refer to a flexible and / or deformable retention structure, such as a pliable ring, which in at least one embodiment may be placed around a thermal choke portion of an RF assembly.

[0064] Here, a "ring" may generally refer to one type of retaining structure. In at least one embodiment, the ring may be an annular structure that includes a pliable material, such as a flexible rim. In at least one embodiment, the ring may include an elastomeric material (e.g., rubber). One example of a ring is an O-ring. In at least one embodiment, the O-ring may act as a flexible rim around the RF assembly in the RF assembly clamp. In at least one embodiment, the O-ring material may be flexible and allow the RF assembly to pivot while constraining lateral and vertical movement of the RF assembly in the RF assembly clamp.

[0065] Here, "elastomeric material" may generally refer to organic polymeric materials, such as rubber, that exhibit a large elastic region in stress-strain space. In at least one embodiment, a large elastic region for an elastomeric material is an elongation strain ε ≥ 100% of its original length before the yield point (a threshold known as yield strength or tensile strength), measured as the stress in megapascals (MPa) at which the elastomer breaks. max (Some elastomeric materials may have an ε max (It may have a strain of 1% (traditionally 0.2% for metals, or ε<0.002) before its yield point (a threshold measured in MPa) at which the material begins to plastically deform. In at least one embodiment, elastomers such as most rubber compounds can undergo macroscopic elastic deformation by straining (e.g., elongating) at relatively low levels of stress. In at least one embodiment, a low level of stress may be a yield strength of 10 MPa that causes a strain of more than 100% for an elastomer, compared to an applied stress of over 200 MPa that would cause a steel rod to elongate 0.2% of its initial length.

[0066] Here, "ball retainer" may generally refer to a special retaining structure, such as a ball and socket joint, that has limited rotational motion and allows slight position correction of the RF assembly by pivoting the RF assembly for self-alignment.

[0067] Here, "aperture" may generally refer to an opening, such as a hole. In at least one embodiment, the aperture may refer to an opening in a retaining structure through which the RF assembly can extend.

[0068] Here, "upper portion" and "lower portion" may generally refer to adjacent pieces of an RF assembly clamp, such as a lower clamp ring and an upper clamp ring.

[0069] Here, "electrical connector" may generally refer to an electrical connector attached to an RF assembly, such as an RF connector. In at least one embodiment, the electrical connector may be located at the base of the RF assembly.

[0070] Here, a "threaded barrel" may generally refer to a movable electrical connector that can mate with a stationary electrical connector attached to an RF assembly, such as a connector component that threads into the electrical connector. In at least one embodiment, the threaded barrel may be threadably attached to a threaded portion of the stationary electrical connector.

[0071] Here, the term "wafer chuck assembly" may generally refer to a structure operable to support a wafer substrate within a vacuum chamber of a processing tool. In at least one embodiment, the wafer may be a semiconductor wafer supported by a wafer chuck.

[0072] As used herein, "wafer chuck" may generally refer to a structure, such as a pedestal assembly, that includes a platen that holds a wafer for processing, such as an electrostatic chuck (ESC).

[0073] Here, "pedestal stem" may generally refer to a portion of the pedestal that extends below the wafer chuck, such as a tube that is mechanically coupled to the wafer chuck. In at least one embodiment, the pedestal stem may include structures that carry electrical conductors and gas lines to the wafer chuck.

[0074] Here, the term "pedestal" may generally refer to a structure including a wafer chuck and a stem attached to the wafer chuck.

[0075] Here, a "vacuum chamber" may generally refer to a chamber of a processing tool, such as an enclosed space operable to hold a high vacuum (e.g., <<1 torr). In at least one embodiment, the vacuum chamber may provide a reduced pressure space in which chemical vapor deposition, etching, and other processes requiring high vacuum may occur.

[0076] Here, "platen" may generally refer to a component of a wafer chuck assembly operable to hold a wafer, such as a flat horizontal portion of the wafer chuck. In at least one embodiment, the platen may include a clamping mechanism to firmly hold the wafer. In at least one embodiment, the clamping structure may be, for example, an electrostatic clamping mechanism including electrodes embedded within the platen to electrostatically attract the semiconductor wafer. In at least one embodiment, the platen may have a temperature control element embedded within its structure, as well as a plasma discharge electrode for plasma generation.

[0077] Here, "RF" may generally refer to radio frequency. In at least one embodiment, radio frequency in the MHz range, for example, in the range of 10 MHz to 100 MHz, may be used in the plasma process.

[0078] Here, a "radio frequency (RF) power source" may generally refer to a power generator in the form of radio frequency energy, such as an RF power amplifier coupled to an RF oscillator. In at least one embodiment, the RF power source may be coupled to an RF assembly as defined herein to supply RF power (voltage and current) to a plasma electrode in a platen of a wafer chuck assembly.

[0079] Here, "column" may generally refer to a tubular housing that underlies the platen, such as the stem and adapter tube of a wafer chuck assembly. In at least one embodiment, the column may house an RF assembly and associated components, such as an RF assembly clamp. In at least one embodiment, the column may include a pedestal stem and an adapter tube clamped to the pedestal stem.

[0080] Here, "adapter tube" may refer generally to a lower portion of a column portion of a wafer chuck assembly, such as a tubular structure designed to accommodate an RF assembly. In at least one embodiment, the column portion of the wafer chuck assembly may generally comprise a pedestal stem and an adapter tube clamped to the pedestal stem by a column clamp as defined herein.

[0081] Here, "ledge" may generally refer to a structural shelf or step, such as an adapter tube flange.

[0082] Here, "lip" or "retaining lip" may generally refer to a narrow rim, such as a narrow rim around the end of a pedestal stem of a wafer chuck pedestal. In at least one embodiment, the lip may allow for attachment of the pedestal stem to an adapter tube. In at least one embodiment, the retaining lip may serve to compress a vacuum seal installed in a groove in the adapter tube flange.

[0083] Here, a "vacuum seal" may generally refer to a gasket or compression ring that is compressed within a groove or ledge on a flange, such as an adapter tube flange, to form an airtight seal against atmospheric pressure at a joint, such as the joint between a pedestal stem and an adapter tube. In at least one embodiment, a wafer chuck assembly column comprises a pedestal stem and an adapter tube joined together. In at least one embodiment, the column may be held under vacuum such that a vacuum seal may be present at the joint to form a vacuum-tight seal.

[0084] Here, "flange" may generally refer to a wide rim around the end of an adapter tube, such as an adapter tube flange. In at least one embodiment, the flange may include bolt holes distributed around the flange for mounting a pedestal stem via a column clamp. In at least one embodiment, the bolt holes may be threaded or non-threaded.

[0085] Here, "column clamp" may generally refer to a specialized clamp for attaching a column to an adapter tube of a wafer chuck assembly, such as a ring clamp secured to an adapter tube flange. In at least one embodiment, the column clamp may include two components, e.g., an upper clamp ring and a lower clamp ring.

[0086] As used herein, the term "clamp assembly" may generally refer to a column clamp, such as a column clamp, that includes multiple parts.

[0087] Here, "upper clamp ring" and "lower clamp ring" may generally refer to the first component of a column clamp as defined herein. In at least one embodiment, the upper clamp ring may comprise a rigid material, such as steel. In at least one embodiment, the upper clamp ring may have an annular form factor.

[0088] Here, "lower clamp ring" may generally refer to the second component of a column clamp. In at least one embodiment, the lower clamp ring may be below the upper clamp ring in an assembled column clamp. In at least one embodiment, the lower clamp ring comprises two identical pieces having a semi-annular form factor. In at least one embodiment, the lower clamp ring comprises a material, such as aluminum, that is less stiff than steel and therefore more flexible.

[0089] Here, "semi-annular" may generally refer to a form factor that is one half of a ring or annular structure, such as a semi-annular segment of a lower clamp ring. In at least one embodiment, the annulus has an outer diameter and an inner diameter.

[0090] Here, "semi-annular segment" may generally refer to a semicircular half portion of the lower clamp ring (as an independent structure), the half portion having a semi-annular structure. In at least one embodiment, the lower clamp ring may comprise two semi-annular halves that are joined together at their ends when assembled.

[0091] Here, "beveled portion" may generally refer to a beveled sidewall, such as a chamfered portion of a sidewall. In at least one embodiment, the upper clamp ring has a beveled portion of an inner wall. Here, "beveled" may refer to a slope or taper. In at least one embodiment, a portion of the sidewall of the upper clamp ring is beveled.

[0092] Here, "through holes" may generally refer to openings or holes in the upper and lower clamp rings, such as bolt holes that allow a bolt to pass through the through holes to a threaded hole in the adapter tube flange.

[0093] Here, a "semicircular groove" may generally refer to a groove formed in a semi-annular half of a lower clamp ring, such as a groove separating an inner sidewall and an outer sidewall. In at least one embodiment, the semicircular groove may have a semicircular shape, as opposed to a straight groove. In at least one embodiment, the semicircular groove may have an inner sidewall and an outer sidewall.

[0094] Here, "side wall" may generally refer to the bottom wall of a groove, such as a semicircular groove, as defined herein. In at least one embodiment, the side wall may intersect the inner and outer side walls of the semicircular groove.

[0095] Here, "outer" may generally refer to the outside or peripheral portion of a circular object, such as an annular ring or semi-annular structure. In at least one embodiment, the sidewall may be referred to as the "outer sidewall," where the sidewall is the outer sidewall of a semi-annular or annular structure.

[0096] Here, "inner" may generally refer to the inside or central portion of a circular object, such as a ring. In at least one embodiment, the sidewall may be referred to as the "inner sidewall," where the sidewall is the inner sidewall of a semi-annular or annular structure.

[0097] Here, "radius" may generally refer to the distance between the center of a circular or semicircular object and an arc on the object, such as the mid-distance between the inner and outer diameters. In at least one embodiment, the radius may be located between the inner and outer sidewalls of a semi-annular structure, such as the semi-annular half of a lower clamp ring. In at least one embodiment, the radius may be contained between the inner and outer sidewalls of an annular structure, such as the upper clamp ring.

[0098] Here, the term "oblique angle" may generally refer to an angle that is not a right angle, such as an acute angle or an obtuse angle.

[0099] Here, a "countersink" may generally refer to a recessed hole in the bottom of a platen, such as an opening into which a rod of an RF assembly may be inserted. In at least one embodiment, the rod may be electrically coupled to a plasma discharge electrode in the platen.

[0100] Here, "plasma discharge electrode" may generally refer to an electrode (or electrodes) embedded within a platen that is electrically coupled to a rod portion of an RF assembly, such as an electrode in contact with an RF conductor.

[0101] Here, "contour" may generally refer to the three-dimensional (3D) shape of the inner wall of the adapter tube, such as the curved portion of the inner wall of the adapter tube. In at least one embodiment, the 3D shape may include circular and non-circular arcs.

[0102] Here, "curvature" may generally refer to the curvature of a profile, such as a portion of an interior wall that has a varying diameter.

[0103] 1A illustrates a cross-sectional view in the xz plane of a radio frequency (RF) assembly 100, shown in at least one embodiment as an isolated unit. In at least one embodiment, the RF assembly 100 may be implemented in a semiconductor wafer processing tool, such as a plasma etch tool or a plasma enhanced chemical vapor deposition (PECVD) tool. In at least one embodiment, the RF assembly 100 may be housed in a wafer chuck pedestal, as described below (see, e.g., FIGS. 1B and 1C).

[0104] In at least one embodiment, RF assembly 100 comprises one or more RF conductors, such as RF conductor 102, and an RF assembly clamp 104 mechanically coupled to RF conductor 102. In at least one embodiment, RF assembly clamp 104 includes a retaining structure, such as retaining structure 106 depicted by a dashed box, for each RF conductor 102. In at least one embodiment, retaining structure 106 is an internal structure within RF assembly clamp 104. In at least one embodiment, retaining structure 106 comprises one or more openings 108 through which RF conductor 102 extends. In at least one embodiment, retaining structure 106 is operable to laterally restrain RF conductor 102, but allows limited pivotal movement of RF conductor 102 within RF assembly clamp 104.

[0105] In at least one embodiment, a spacer plate 110 is included to stabilize the RF conductors 102 and maintain the spacing s1 between the RF conductors 102. In at least one embodiment, the RF conductors 102 comprise rods 112 mechanically and electrically coupled to thermal chokes 114. In at least one embodiment, the rods 112 are welded or brazed to the thermal chokes 114. In at least one embodiment, the RF conductors 102 comprise insulating sleeves 116. In some embodiments, the sleeves 116 surround the thermal chokes 114 as shown. In at least one embodiment, the sleeves 116 can extend to surround the rods 112. The RF conductors 102 can be operable to handle high RF power (e.g., 1-5 kilowatts). In at least one embodiment, the RF conductors 102 can carry RF power to a plasma discharge electrode embedded within the wafer chuck to enable plasma etching or plasma enhanced deposition processes.

[0106] 1B illustrates a cross-sectional view of a wafer chuck assembly 120 including an RF assembly 100 housed within a column 122 according to at least one embodiment. In at least one embodiment, the wafer chuck assembly 120 includes a pedestal 124 including a platen 126 and a stem 128 mechanically coupled to the platen 126 and extending below the platen 126. In at least one embodiment, the stem 128 may be integral with the platen 126 as shown. In at least one embodiment, the platen 126 may include a counterbore 130 into which the rod tip 118 is inserted. In at least one embodiment, a plasma electrode 132 may be embedded within the platen 126 and positioned above the counterbore 130 for electrically coupling to the rod tip 118. In at least one embodiment, the platen 126 may include a plasma discharge electrode (not shown) for electrostatic clamping (ESC) of a wafer substrate 134 on an upper surface 136. In at least one embodiment, the platen 126 may include one or more embedded heating elements (not shown) for desired heating of the platen 126 and the wafer substrate 134 during the etching or PECVD process. In at least one embodiment, the platen 126 may be heated to temperatures in excess of 700° C. during operation.

[0107] In at least one embodiment, the stem 128 may be mechanically coupled to an adapter tube, such as adapter tube 138. In at least one embodiment, the adapter tube 138 may have an internal geometry that allows for the installation of the RF conductor 102, as described below. In at least one embodiment, the stem 128 is clamped to the adapter tube 138 by a column clamp assembly 140. In at least one embodiment, the column clamp assembly 140 comprises a rigid upper ring and a more resilient ceramic lower ring, as described below. In at least one embodiment, the adapter tube 138 may comprise a ceramic material, such as, but not limited to, polycrystalline alumina, alumina composite, silica, silicate glass, aluminum nitride, or a composite including silicate, alumina, and / or aluminum nitride.

[0108] FIG. 1C illustrates a detailed cross-sectional view of the wafer chuck assembly 120 including the RF assembly 100 according to at least one embodiment. In at least one embodiment, the stem 128 may be mechanically coupled to the adapter tube 138. As shown in FIG. 1C, a retaining lip 142 of the stem 128 engages a ledge 144 in the adapter tube flange 146 when assembled. In at least one embodiment, the stem 128 may be secured to the adapter tube 138 by a column clamp assembly 140 mounted on the adapter tube flange 146. In at least one embodiment, the column clamp assembly 140 includes an upper clamp ring 148 mounted on a lower clamp ring 150. In at least one embodiment, the upper clamp ring 148 may include a hardened metal such as, but not limited to, a case-hardened steel alloy or a non case-hardened steel alloy. The upper clamp ring 148 is described in more detail below according to at least one embodiment (see FIGS. 7A and 7B). In at least one embodiment, lower clamp ring 150 comprises two halves that are assembled together in wafer chuck assembly 120 (see, e.g., FIGS. 8A-8C). In at least one embodiment, lower clamp ring 150 may comprise a metallic material having a lower yield stress than upper clamp ring 148. In at least one embodiment, lower clamp ring 150 may comprise a flexible material such as, but not limited to, aluminum or copper. Column clamp assembly 140 is described in more detail below in accordance with at least one embodiment (see, e.g., FIGS. 7A-7B, 8A-8C).

[0109] In at least one embodiment, the upper clamp ring 148 and the lower clamp ring 150 are fastened to the adapter tube flange 146 by bolts 152. In at least one embodiment, tightening the bolts 152 compresses the retaining lip 142 toward the ledge 144. In at least one embodiment, the retaining lip 142 can compress a vacuum seal 154 mounted on the ledge 156. In at least one embodiment, the ledge 156 may be countersunk adjacent the adapter tube flange 146 below the ledge 144. In at least one embodiment, the vacuum seal 154 may be a strip of hard elastomer or a ring seal (e.g., an O-ring) comprising a malleable metal such as bronze, copper, or steel alloy. In at least one embodiment, the vacuum seal 154 may be mounted within a round or V-shaped groove (not shown) on the ledge 156.

[0110] In at least one embodiment, bolts 152 can be torqued to ensure proper pressure against vacuum seal 154 by transferring the clamping force from upper clamp ring 148 through lower clamp ring 150 to vacuum seal 154. In at least one embodiment, lower clamp ring 150 can deform under pressure from upper clamp ring 148. In at least one embodiment, lower clamp ring 150 can deform to distribute the clamping force evenly across retaining lip 142 and vacuum seal 154.

[0111] In at least one embodiment, the RF assembly 100 may be housed within the column 122 of the wafer chuck assembly 120. In at least one embodiment, the RF assembly 100 may be inserted into an adapter tube 138 during assembly. In at least one embodiment, an inner wall 139 of the adapter tube 138 may have an inner wall shaped to orient and position the RF assembly 100 within the column 122. In at least one embodiment, the RF assembly 100 may be inserted into the adapter tube 138 toward the central rod tip 118 within the counterbore 130. In at least one embodiment, a spacer plate, such as spacer plate 110, may be installed within the stem 128 and / or may be installed on a ledge 156 below the inner ledge 144 of the adapter tube flange 146.

[0112] In at least one embodiment, the spacer plate 110 may include openings or recesses through which the RF conductors 102 can pass. In at least one embodiment, the spacer plate 110 can stabilize the RF conductors 102 in the upper portion of the column 122. In at least one embodiment, the spacer plate 110 can also maintain the spacing s1 and parallelism between the individual RF conductors 102. In at least one embodiment, the spacer plate 110 can also include additional openings (described below) for passing the heater conductors 158 extending from the heater wires 160 to the platen 126.

[0113] In at least one embodiment, manufacturing tolerances may result in a misalignment offset between the rod tip 118 and the center of the counterbore 130. In at least one embodiment, the positioning of the RF conductor 102 may be determined at least in part by the spacing between the apertures 108 of the RF assembly clamp 104. In at least one embodiment, the centering offset may be further caused or exacerbated by heating cycles of the platen 126. In at least one embodiment, the RF conductor 102 is also heated to high temperatures during operation of the wafer chuck assembly 120.

[0114] In implementations where such offset misalignment exists or is potentially induced by platen heating, bending strains may be induced in the RF conductor 102. The bending strains may ultimately lead to breakage or failure of the RF conductor 102. In at least one embodiment, the retaining structure 106 may be advantageously operable to allow limited pivoting of the RF conductor to reduce bending upon repeated heating to compensate for the centering offset between the center of the counterbore 130 and the center of the aperture 108.

[0115] 2 illustrates a cross-sectional view of RF conductor 102, according to at least one embodiment. In at least one embodiment, RF conductor 102 comprises rod 112 and thermal choke 114 mechanically and electrically coupled to rod 112. In at least one embodiment, rod 112 may be a solid structure, while thermal choke 114 may be a tubular structure with a hollow interior 115. In at least one embodiment, rod 112 may be coaxial with thermal choke 114.

[0116] In at least one embodiment, the rod 112 can have an overall length (e.g., from the apex 121 to the base 119 of the tip 118) L1 of 40-100 mm. For example, L1 may be 50 mm. In at least one embodiment, the rod 112 can have a width (e.g., diameter) w1 of 4-5 mm. As noted above, the rod 112 includes a tip 118 having a width (e.g., diameter) w2. In at least one embodiment, the tip 118 has a configuration as shown in FIG. 2, where w2 is smaller than w1 of the rod 112. In at least one embodiment, the tip can have a different configuration, for example, as shown in FIG. 1A, where w2 is greater than or equal to w1. In at least one embodiment, the tip 118 can extend through a counterbore 130 in the platen 126 and contact a plasma electrode 132 (see, e.g., FIGS. 1B and 1C).

[0117] In at least one embodiment, width w2 may be greater than width w1. For example, width w2 may range from 5 mm to 7 mm. In at least one embodiment, rod 112 may include a conductive material such as, but not limited to, nickel and nickel alloys, steel alloys, or copper. In at least one embodiment, steel and nickel alloys may be magnetized under the influence of an RF current flowing through rod 112. In at least one embodiment, magnetization may reduce the conductivity of rod 112. In at least one embodiment, rod 112 may be maintained above the Curie temperature of the material to mitigate the magnetization of rod 112.

[0118] In at least one embodiment, the thermal choke 114 comprises a tubular body with a hollow interior 115. In at least one embodiment, the thermal choke 114 has an overall length L2 and a width (e.g., outer diameter) w3. In at least one embodiment, the width w3 may be in the range of 4 mm to 6 mm. In at least one embodiment, the width w3 is 5 mm. In at least one embodiment, the length L2 may be in the range of 180 to 200 mm. In at least one embodiment, the rod 112 can be coupled to the thermal choke by inserting the rod stem 162 into the hollow interior 115 of the thermal choke 114. In at least one embodiment, the rod 112 can include an insertion stop 164 that extends from the rod stem 162 of the rod 112 and abuts the rim 117 of the thermal choke 114. In at least one embodiment, the insertion stop 164 may be at the top of the rod stem 162 a distance L3 away from the base 119 of the rod stem 162 to limit the insertion length L3 of the rod stem 162. In at least one embodiment, the length L1 of the rod 112 may be approximately 20%-50% of the length L2 of the thermal choke 114. In at least one embodiment, the length L1 of the rod 112 may be determined by the nature and temperature of the material of the rod 112. In at least one embodiment, the length L1 of the rod 112 may be optimized to keep substantially the entire length of the rod 112 above the Curie point of the material. In at least one embodiment, the selection of L1 may be based on the known pedestal temperature and thermal conductivity of the rod material.

[0119] In at least one embodiment, the thermal choke 114 can have a wall thickness t1 between 1 mm and 2 mm. In at least one embodiment, the wall thickness t1 extends between the inner wall 166 and the outer wall 170 of the thermal choke 114 as shown. In at least one embodiment, the wall thickness t1 can be optimized to maximize thermal resistance in the axial direction (e.g., z-direction in the figure). In at least one embodiment, during operation, heat from the platen 126 is thermally coupled to the rod 112 through the tip 118 by contact and radiation, which can significantly increase heating of the rod 112 during operation. In at least one embodiment, a temperature gradient can be established within the rod 112 due to heat loss from the surface of the rod 112. In at least one embodiment, the tip 118 can be heated to 650° C., while the rod stem 162 at the base of the rod 112 can be 500° C. (e.g., for a nickel composition or alloy, the rod 112 exceeds the Curie point for nickel, 354° C., in this example).

[0120] In at least one embodiment, the length L3 of the rod stem 162 inserted into the thermal choke 114 may be limited to a small fraction of L1 to limit conductive heat transfer from the heated wafer chuck platen (e.g., platen 126 of the wafer chuck assembly 120 of FIGS. 1B and 1C) through the RF conductor 102 to the base of the thermal choke 114. In at least one embodiment, the length L3 may be 10% or less of the length L1 of the rod 112 to limit surface area overlap between the rod stem 162 and the thermal choke 114, thereby mitigating heat transfer along the rod 112 to the thermal choke 114 (e.g., from the heated platen 126). In at least one embodiment, the length L3 of the rod stem 162 may be 5% or less of the length L1 to further minimize surface area overlap between the rod 112 and the thermal choke 114. In at least one embodiment, the length L3 of the rod stem 162 may be 2% or less of the length L1, further minimizing the surface area overlap between the rods 112. Minimizing the surface area overlap between the rods 112 and the thermal choke 114 challenges the manufacturability / integrity of the RF conductor 102. The smaller the surface area overlap, the more susceptible the RF conductor 102 is to fracture when the joint is under high stress (thermal / mechanical stress in assembly and operation). By having an L3 less than 10% of the L1 of the rods 112, the RF conductor 102 can significantly reduce heat transfer from the rods 112 to the base of the thermal choke 114 while maintaining its resistance to the thermal / mechanical stresses required for semiconductor fabrication.

[0121] In at least one embodiment, the mechanical and electrical performance and reliability of RF conductor 102 may be enhanced by integrally coupling rod 112 to thermal choke 114. In at least one embodiment, during assembly of RF conductor 102, rod 112 may be coupled to thermal choke 114 by brazing rod stem 162 to inner wall 166 of thermal choke 114. In at least one embodiment, a brazed or welded bond (both types of bonds represented by joint 168) may provide better mechanical and electrical performance than removable coupling methods (e.g., collets or compression fittings, etc.).

[0122] In at least one embodiment, the wall thickness t1 may also be optimized to provide sufficient tensile strength and stiffness to avoid shape distortion and breakage. In at least one embodiment, the optimal figure of merit for thickness t1 may be 1 mm. In at least one embodiment, high strength alloys as described herein may be used to allow for minimization of wall thickness while maintaining adequate robustness. In at least one embodiment, the thermal choke 114 may include a high strength material such as steel or an Inconel alloy. In at least one embodiment, the thermal choke 114 may include Inconel 625 to withstand high temperatures.

[0123] In at least one embodiment, temperatures below 100° C. to 150° C. may be used at the interface level to interface additional components, such as wire connectors, to the RF assembly 100. In at least one embodiment, by optimizing the thickness t1 and length L2, the thermal choke 114 may have sufficient thermal resistance to reduce the temperature of its junction with the rod 112 from 500° C. to a temperature that can be tolerated by ancillary components, such as wire connectors (e.g., wire harness 500, described below) attached to the base 172 of the thermal choke 114. In at least one embodiment, optimizing the thickness t1 and length L2 may take into account, for example, the Young's modulus of the material to determine a minimum wall thickness t1 in order to maintain a minimum mechanical strength and stiffness of the thermal choke 114. In at least one embodiment, the thermal choke 114 is capable of attenuating the rod temperature to below 150° C. that can be tolerated by the wire connectors at the base 172 of the thermal choke 114.

[0124] In at least one embodiment, high frequency current (e.g., RF frequency of approximately 27 MHz) entering the RF conductor 102 can travel through the conductive thermal choke and rod from the connector to the electrode 132 in the platen (e.g., platen 126). In at least one embodiment, RF current of up to 20 amps can flow into the RF conductor 102. In at least one embodiment, the rod 112 can be kept above the Curie point to avoid skin depth reduction due to magnetic induction and also to increase RF conductivity. In at least one embodiment, high RF current can cause some Joule heating of the RF conductor, but the temperature rise due to Joule heating can be relatively small (e.g., up to approximately 50° C.). In at least one embodiment, heat transfer from contact with the wafer chuck platen during operation can dominate the temperature profile of the RF conductor 102.

[0125] In at least one embodiment, the thermal choke 114 can include a coating or conductive layer 174 on an outer wall 170 of the thermal choke 114, as shown in the inset of the figure. In at least one embodiment, the conductive layer 174 can enhance RF conductivity at the surface. In at least one embodiment, the conductive layer 174 can include, for example, electroplated gold to enhance RF conductivity. In at least one embodiment, the conductive layer 174 can have a thickness in the range of 5 to 20 microns.

[0126] In at least one embodiment, the thermal choke 114 can limit axial heat conduction to the rod assembly, but the thermal choke 114 as well as the rod 112 can radiate significant heat to surrounding components in the wafer chuck assembly column (e.g., column 122). If the pedestal column is under vacuum, heat transfer by convection can be slight or nonexistent. This can result in overheating of nearby components, ultimately leading to damage and failure. In at least one embodiment, the RF conductor 102 further comprises an insulating sleeve 116 (hereinafter sleeve) that extends over the thermal choke 114 and / or the rod 112. In at least one embodiment, the sleeve 116 can include a dielectric material, such as a ceramic or composite ceramic material. In at least one embodiment, the dielectric material can include aluminum (e.g., aluminum oxide) or aluminum nitride. In at least one embodiment, the sleeve 116 can insulate the RF conductor 102 during operation. In at least one embodiment, the sleeve 116 can inhibit radiative heat transfer from the surface of the RF conductor 102 and protect surrounding temperature sensitive components.

[0127] In at least one embodiment, the sleeve 116 can further provide electrical insulation for the thermal choke 114 and the rod 112. In at least one embodiment, short circuits between adjacent RF conductors or between the RF rod assembly and a ground plane can also be prevented by the sleeve 116.

[0128] In at least one embodiment, sleeve 116 may have a length L4 that may be substantially equal to at least length L2 of thermal choke 114. In at least one embodiment, length L2 may extend at least partially beyond rod 112, for example, to an additional distance L1. In at least one embodiment, sleeve 116 has a nominal wall thickness t2 of 1 mm to 2 mm. In at least one embodiment, sleeve 116 includes a narrow wall region at nose 176 at a terminal portion of sleeve 116. For example, nose 176 may have a wall thickness t3 that may be less than thickness t1. In at least one embodiment, the smaller wall thickness t3 may enable nose 176 to be inserted into a counterbore, such as counterbore 130 in platen 126 (e.g., as described below). In at least one embodiment, sleeve 116 has a width w4 (e.g., outer diameter, OD) in the range of 7 mm to 8 mm. In at least one embodiment, sleeve 116 may have an inner diameter (ID) of approximately 5 mm. In at least one embodiment, as shown in the inset, a gap 178 between an inner wall 180 of sleeve 116 and an outer wall 170 of thermal choke 114. In at least one embodiment, gap 178 has a spacing s2 (see inset) that may range from 100 microns to 1 mm. In at least one embodiment, spacing s2 may be adjusted to accommodate thermal expansion of thermal choke 114.

[0129] In at least one embodiment, high frequency current (e.g., RF frequency of approximately 27 MHz) entering the integrated RF socket can be conducted from the connector through the conductive thermal choke and rod to the plasma discharge electrode in the platen. In at least one embodiment, RF current of up to 20 amps can flow into the RF conductor 102. In at least one embodiment, the thermal choke 114 can include a conductive layer 174 (e.g., including gold) to increase RF conductivity at the surface, and the rod 112 can be kept above the Curie point of nickel (or other ferromagnetic material) to avoid magnetically induced skin depth reduction and also increase RF conductivity. Although high RF currents can cause some Joule heating of the RF conductor 102, the temperature rise due to Joule heating can be relatively small (e.g., up to approximately 50° C.). In at least one embodiment, heat transfer from contact with the platen 126 during operation can dominate the temperature profile of the RF conductor 102 including the rod 112 and thermal choke 114.

[0130] 3A illustrates a top view of the RF assembly clamp 104 according to at least one embodiment. In at least one embodiment, the RF assembly clamp 104 includes sidewalls 302 and 304 according to at least one embodiment. In at least one embodiment, the sidewalls 302 and 304 are straight. In at least one embodiment, the sidewalls 302 and 304 may be contoured, for example, as shown. In at least one embodiment, the sidewalls 306 and 308 may be substantially orthogonal to the sidewalls 302 and 304. In at least one embodiment, the sidewalls 306 and 308 may be straight as shown or contoured as described below. Although a particular shape or curvature of the RF assembly clamp 104 is illustrated, in at least one embodiment, the RF assembly clamp 104 may have any suitable shape. In at least one embodiment, the RF assembly clamp 104 may have an asymmetric shape. In at least one embodiment, the shape of the sidewalls 302 and 304 can facilitate the orientation and alignment of an RF conductor (eg, RF conductor 102) relative to a plasma discharge electrode in a wafer chuck platen (eg, platen 126).

[0131] In at least one embodiment, the asymmetry of the shape of the RF assembly clamp 104 may allow for a fixed orientation of the rod assembly clamp when inserted into a wafer chuck assembly (e.g., wafer chuck assembly 120). In at least one embodiment, the RF assembly clamp 104 may be inserted into a groove or may conform to a contour within an adapter tube (e.g., the contour of the inner wall 139 of the adapter tube 138 in FIG. 4). In at least one embodiment, the RF conductor rod tip (e.g., rod tip 118) may be substantially centered with a counterbore in the wafer chuck platen (e.g., platen 126). In at least one embodiment, the inner wall of the adapter tube (e.g., inner wall 139) may have an asymmetric contour pattern complementary to the side walls 302 and 304 such that the RF assembly clamp 104 may be inserted in a unique orientation.

[0132] In at least one embodiment, the clamp body 300 comprises an inorganic or organic dielectric material. In at least one embodiment, the dielectric material includes a polymer, such as, but not limited to, polyetheretherketone (PEEK), polyimide (e.g., Ultem), polyamideimide (e.g., Torlon), polyphenylene sulfide (e.g., Ryton, PPS), and blends or composites including any of the aforementioned polymers. In at least one embodiment, the dielectric material includes a ceramic, such as, but not limited to, polycrystalline alumina and silica or silicate glass.

[0133] In at least one embodiment, the RF assembly clamp 104 may include one or more apertures 108 through which an RF conductor (e.g., RF conductor 102) of an RF assembly (e.g., RF assembly 100) may extend. In at least one embodiment, the aperture 108 may have a diameter D1 that may be nominally larger than w4 of the RF conductor's sleeve (e.g., sleeve 116). In at least one embodiment, a positive tolerance of the diameter D1 relative to the width w4 may allow the RF conductor to pivot within the aperture 108 to a limited extent (e.g., 5 degrees). In at least one embodiment, the aperture 108 extends through a retaining structure (e.g., retaining structure 106 in FIG. 1A) depicted by a dashed circle surrounding the aperture 108. In at least one embodiment, the retaining structure may constrain lateral movement of the RF conductor while allowing limited pivoting movement within the aperture 108 for misalignment compensation, as described above.

[0134] In at least one embodiment, a small pivot angle (e.g., 5° or less) may allow the RF conductor to assume a small tilt angle when the contact point (e.g., counterbore 130) is misaligned with the center of aperture 108. In at least one embodiment, a small tilt may mitigate bending of the RF conductor that may induce strain and potentially lead to failure.

[0135] In at least one embodiment, the apertures 108 are equidistant and have a center-to-center spacing s1 that may be 1-3 cm. In at least one embodiment, the spacing s1 may be substantially equal to the center-to-center spacing between the rod tip insertion points (e.g., counterbore holes 130) on the wafer chuck platen (e.g., platen 126). In at least one embodiment, the apertures 108 are collinear, however, the apertures 108 may be configured in any suitable non-collinear pattern, according to at least one embodiment. In at least one embodiment, the particular configuration of the apertures 108 may mirror the configuration of the rod attachment points (e.g., counterbore holes 130) on the wafer chuck platen to ensure alignment of the RF conductors.

[0136] In at least one embodiment, the RF assembly clamp 104 includes an additional aperture 310 between the one or more apertures 108. In at least one embodiment, the aperture 310 may be a through hole for a fastener such as a screw or bolt.

[0137] 3B shows a cross-sectional exploded view of the RF assembly clamp 104 including the upper clamp piece 312 and the lower clamp piece 314 according to at least one embodiment. In at least one embodiment, the upper groove 316 and the lower groove 318 may extend around the rim of the aperture 108 in the upper mating face 320 and the rim of the aperture 109 in the lower mating face 322 of the upper clamp piece 312 and the lower clamp piece 314, respectively. In at least one embodiment, the upper and lower grooves 316 and 318 form a cavity around the aperture 108 when the upper and lower mating faces 320 and 322, respectively, contact. In at least one embodiment, the cavity can capture the retaining structure 106. In at least one embodiment, the retaining structure 106 may comprise an O-ring as shown in FIG. 3C, or a ball-and-socket joint as shown in FIG. 3D. In at least one embodiment, the retaining structure 106 includes an opening 107 that may be coaxially aligned with openings 108 and 109 .

[0138] In at least one embodiment, the lower piece 314 can include an opening 324 that can be used as a through hole for a fastener. In at least one embodiment, the opening 324 can align with the opening 310 in the upper clamp piece 312 to pass a fastener, such as a bolt, for fastening the upper clamp piece 312 to the lower clamp piece 314. In at least one embodiment, the recess 326 can provide, for example, a countersink for the head of a bolt.

[0139] 3C illustrates a top view of an alternative embodiment of the RF assembly clamp 104, according to at least one embodiment. In at least one embodiment, the RF assembly clamp 104 may be substantially similar to the RF assembly clamp 104 illustrated in FIGS. 3A and 3B. In at least one embodiment, the RF assembly clamp 104 comprises a front lobe 332 and a rear lobe 334. In at least one embodiment, the front lobe 332 may comprise an opening 336 for routing a heater wire (e.g., heater wire 160). In at least one embodiment, the rear lobe 334 may comprise an opening 338 for passing a gas purge tube (not shown).

[0140] 3D illustrates a cross-sectional view of an alternative embodiment of the RF assembly clamp 104, according to at least one embodiment. In at least one embodiment, the RF assembly clamp 104 includes an O-ring 340 (depicted by a dashed box) as an example of a retaining structure (e.g., retaining structure 106). In at least one embodiment, as shown in FIG. 3B, the RF assembly clamp 104 includes an upper clamp piece 312 and a lower clamp piece 314. In at least one embodiment, the upper and lower clamp pieces 312 and 314 can be fastened together by a bolt 342 extending through the openings 310 and 324. In at least one embodiment, the bolt 342 can include, for example, a hex head 346 seated in the recess 326. A nut 344 seated in the opening 310 can capture the bolt 342 for tightening.

[0141] In at least one embodiment, the upper and lower circular grooves 316 and 318 can respectively form upper and lower portions of a cavity 348 that can have a torus-like shape around the respective opening(s) 108. In at least one embodiment, an O-ring 340 can be placed within the cavity 348. In at least one embodiment, the O-ring 340 can include an elastomeric material that deforms under pressure. In at least one embodiment, when the upper and lower pieces 312 and 314 are fastened together, the upper and lower grooves 316 and 318 can compress the O-ring 340 and cause the O-ring 340 to expand a distance beyond a sidewall 350 of the opening(s) 108 and form a constriction within the opening(s) 108.

[0142] In at least one embodiment, the O-ring 340 can form a constriction around the sleeve 116 of the RF conductor 102 extending through the opening 108, such that movement of the captured RF conductor is substantially constrained laterally but may be permitted rotationally.

[0143] In at least one embodiment, RF conductor 102 may be limited in rotational motion about multiple rotation axes that extend in the xy plane and coincide with the interface between mating surfaces 320 and 322. In at least one embodiment, the maximum pivot angle β of RF conductor 102 may be limited at least in part by s3, where s3 is the width of the gap between sleeve sidewall 350 and sleeve 116 (e.g., D1-w4). In at least one embodiment, the maximum pivot angle β may be limited at least in part by elastic deformation of O-ring 340. For example, the compression of O-ring 340 may be 10-15%.

[0144] 3E illustrates a cross-sectional view of an alternative embodiment of the RF assembly clamp 104, according to at least one embodiment. In at least one embodiment, the RF assembly clamp 104 includes a ball retainer 358 (depicted by a dashed circle) as an example of a retaining structure (e.g., retaining structure 106). In at least one embodiment, the RF assembly clamp 104 includes an upper clamp piece 312 and a lower clamp piece 314. In at least one embodiment, the upper and lower clamp pieces 312 and 314 can include hemispherical grooves 352 and 354, respectively. In at least one embodiment, in an assembled state, the hemispherical grooves 352 and 354 combine into a substantially spherical socket 356 (depicted by a cut-out circle) that captures the ball retainer 358. In at least one embodiment, the ball retainer 358 can rotate freely within the spherical socket 356. In at least one embodiment, the ball retainer 358 includes an opening 360 extending through the center of the ball retainer 358 .

[0145] In at least one embodiment, the RF conductor 102 is retained by a ball retainer 358. In at least one embodiment, the RF conductor 102 extends through an opening 360 in the ball retainer 358. In at least one embodiment, the opening 360 has a diameter D2 that may be approximately equal to a width w4 of the sleeve 116. In at least one embodiment, the diameter D2 may have a positive tolerance that may be adjusted to provide a tight press fit onto the sleeve 116. In at least one embodiment, the press fit provided by the ball retainer 358 may restrain lateral and vertical movement of the RF conductor 102 within the opening 360. In at least one embodiment, the ball retainer 358 may include an elastomeric material. In at least one embodiment, the diameter D2 may be slightly smaller than the width w4 of the sleeve 116. In at least one embodiment, the RF conductor 102 may be inserted through the opening 360 and retained by, for example, an interference fit between the opening 360 and the sleeve 116.

[0146] In at least one embodiment, the ball retainer 358 can rotate freely in any direction within the socket 356. In at least one embodiment, the ball retainer 358 can allow limited rotation of the RF conductor 102 within the fixed aperture(s) 108. In at least one embodiment, the RF conductor 102 can pivot at a maximum angle γ that can be limited by a distance s4 between the aperture(s) 108 and the sleeve 116. In at least one embodiment, the maximum angle γ can be optimized to allow alignment between the RF conductor 102 and a rod insertion point (e.g., counterbore 130) on the wafer chuck assembly platen (e.g., platen 126).

[0147] FIG. 4 illustrates an exploded 3D cross-sectional view of an adapter tube assembly 400 including an RF conductor 102 and a rod assembly clamp 104 within an adapter tube 138 according to at least one embodiment. The dashed lines indicate the approximate alignment of an RF conductor (e.g., RF conductor 102) with an aperture 108. FIG. 4 illustrates the sleeve 116 of the RF conductor. In at least one embodiment, the adapter tube 138 includes an inner wall 139 within a lower portion 402. In at least one embodiment, the inner wall 139 includes a contour 404. In at least one embodiment, the contour 404 may have a curvature complementary to the curvature of the upper and lower clamp pieces 312 and 314, respectively. In at least one embodiment, the contour 404 may also conform to the shape of the side walls 302 and 304 and the lobe 332. In at least one embodiment, the RF assembly clamp 104 may be fixed in a particular orientation within the adapter tube 138 by the contour 404. In at least one embodiment, at least one of the contours 404 may have a substantially different curvature relative to the other contours to enable fixation, such that the RF assembly clamp 104 can have a unique orientation within the adapter tube 138.

[0148] In at least one embodiment, the RF conductor 102 (e.g., represented by sleeve 116) is shown aligned with the openings 108 in the upper and lower clamp body pieces 312 and 314. In at least one embodiment, an O-ring 340 surrounds the sleeve 116. In at least one embodiment, the O-ring 340 may be located in the upper and lower circular grooves 316 and 318, respectively. In at least one embodiment, the RF conductor 102 may extend beyond the adapter tube flange 146 (e.g., to the stem 128 in FIG. 1B). In at least one embodiment, the RF assembly clamp 104 may have an orientation that allows the RF conductor 102 to align with an attachment point on the wafer chuck platen (e.g., platen 126). In at least one embodiment, the RF conductor 102 may be further supported and stabilized within the adapter tube 138 by a spacer plate 110 (e.g., which may be located on ledge 156), as described below.

[0149] 5A illustrates a cross-sectional view of a wire harness 500 in at least one embodiment. In at least one embodiment, the wire harness 500 includes a sleeve well 502 for seating a bottom portion of an RF conductor sleeve (e.g., sleeve 116). In at least one embodiment, the wire harness 500 includes a connector port 504 for seating an RF connector 506 below the sleeve well 502. In at least one embodiment, the wire harness 500 may include a high temperature polymer, such as, but not limited to, PEEK, polyfluorocarbon (e.g., Teflon), polyimide (e.g., Ultem), polyamideimide (e.g., Torlon), polyphenylene sulfide (e.g., Ryton, PPS), and blends or composites including any of the aforementioned polymers. In at least one embodiment, the sleeve well 502 and the connector port 504 may be separated by a ledge 508. In at least one embodiment, the ledge 508 may border an opening 510. In at least one embodiment, the ledge 508 can facilitate alignment of the RF conductor 102. In at least one embodiment, a thermal choke (e.g., thermal choke 114) of the RF conductor 506 can extend through the opening 510 and be placed into a socket 512 of the RF connector 506. In at least one embodiment, the socket 512 can have a conductive sidewall 514 for electrically coupling to the thermal choke (e.g., base 172 of thermal choke 114).

[0150] In at least one embodiment, the connector port 504 comprises an internally threaded portion 516 near a bottom sidewall 518 of a frame 520. In at least one embodiment, the frame 520 interconnects the connector port 504 with an adjacent sleeve well 502. In at least one embodiment, the RF connector 506 comprises a threaded barrel 522 with external threads that mate with the internally threaded portion 516. In at least one embodiment, the threaded barrel 522 comprises a cap 524. In at least one embodiment, the cap 524 comprises a hexagonal sidewall 526 with flat sides that facilitate access by a tool (e.g., a wrench) to tighten the threaded barrel 522. In at least one embodiment, the RF connector 506 can be connected or disconnected from the RF wire harness 500 by manually rotating the threaded barrel 522. In at least one embodiment, the RF connector 506 can be secured within the connector port 504 by tightening the threaded barrel 522 to force the RF connector socket 512 against the ledge 508. In at least one embodiment, the RF connector 506 can be a collet-style connector (e.g., an ODU™ Springtac connector or a Lamtac connector). In at least one embodiment, the sleeve 116 can be placed through the opening 510 into the socket 512. In at least one embodiment, the prongs 528 can secure the sleeve base within the RF connector socket 512 and also electrically couple to the thermal choke. In at least one embodiment, the RF connector 506 can include a stem 530 that extends into the threaded barrel 522 below the RF connector socket 512. In at least one embodiment, the stem 530 can include a solder well 532 at the bottom of the stem 530. In at least one embodiment, a wire 534 may be soldered to the stem 530 by inserting a bare end 536 into the solder well 532, resulting in a solder bond.

[0151] 5B shows a top plan view of wire harness 500 with wall 538 surrounding sleeve well 502, according to at least one embodiment. Wall 538 can have a suitable thickness t6. In at least one embodiment, ledge 508 can include opening 510 between sleeve well 502 and connector port 504. In at least one embodiment, prong 528 can be at the bottom of connector port 504.

[0152] In at least one embodiment, the frame 520 may interconnect adjacent sleeve wells 502 and connector ports 504. In at least one embodiment, the frame 520 may have a thickness t7 that may be tailored to optimize the strength and flexibility of the RF wire harness 500. In at least one embodiment, the wire harness 500 has an overall length L that may be substantially equal to a length L8 of the RF rod assembly clamp (e.g., rod assembly clamp 104). 10 In at least one embodiment, the wire harness 500 can be installed within a base of an adapter tube (e.g., adapter tube 138).

[0153] 5C shows, in at least one embodiment, a cross-sectional view of an alternative embodiment of wire harness 550. In at least one embodiment, frame 520 includes a slot 540 approximately centered between sleeve wells 502. In at least one embodiment, slot 540 can have a length L9 that can be adjusted to provide flexibility to wire harness 500.

[0154] 6A shows a plan view of the spacer plate 110 according to at least one embodiment. In at least one embodiment, the spacer plate 110 may be substantially disk-shaped with openings 602 and 604 extending through the disk 600 for passing an RF conductor (e.g., RF conductor 102) and a heater wire 160, as described below. In at least one embodiment, the spacer plate 110 may have a diameter D3 that may be sized to fit within an inner diameter of a pedestal stem (e.g., stem 128). In at least one embodiment, the diameter D3 may also be adjusted to allow the spacer plate 110 to be seated on a ledge 156 within an adapter tube flange 146 of an adapter tube 138 (see, e.g., FIG. 1C). In at least one embodiment, the opening 602 may have a diameter D4 that may be slightly larger than a width w4 of the sleeve 116. In at least one embodiment, the offset of the opening 602 can provide adequate clearance for pivoting movement of the RF conductor for optimal alignment with a contact point on the wafer chuck platen (eg, platen 126).

[0155] In at least one embodiment, opening 604 has a diameter D5. In at least one embodiment, diameter D5 may be substantially smaller than diameter D4 of opening 602. In at least one embodiment, opening 604 may allow the heater conductor and ESC rod (e.g., heater conductor 158 of FIG. 1C ) to pass through to the pedestal stem (e.g., stem 128 of FIG. 1C ). In at least one embodiment, openings 602 and 604 may be arranged in any suitable pattern.

[0156] In at least one embodiment, the spacer plate 110 can include a dielectric material such as ceramic or glass. In at least one embodiment, the spacer plate 110 includes alumina, aluminum nitride, amorphous silica, or silicate glass. In at least one embodiment, the spacer plate 110 provides electrical (and thermal) insulation between the rods (e.g., rods 112) and the low frequency AC carrying conductors (e.g., heater conductors 158). In at least one embodiment, the spacer plate 110 can also maintain alignment of the RF conductors and heater conductors with the contact points on the wafer chuck platen.

[0157] In at least one embodiment, wall 606 can extend above and below opening 602 (e.g., as shown in FIG. 6B). In at least one embodiment, wall 606 has a thickness t8 that can be adjusted for optimal strength of wall 606. In at least one embodiment, wall 606 aids in stabilizing the RF conductor.

[0158] FIG. 6B illustrates a cross-sectional view of the spacer plate 110 according to at least one embodiment. In at least one embodiment, the disk 600 has a thickness t9. In at least one embodiment, the thickness t9 can be sized to optimize the strength of the spacer plate 110. In at least one embodiment, the walls 606 surrounding the opening 602 can extend above and below the disk 600 by a height h2. In at least one embodiment, the RF conductor 102 can engage the spacer plate 110 by insertion through the opening 602. In at least one embodiment, the spacer plate 110 can include an opening 602 that can be sized to accommodate a small tilt of the RF conductor.

[0159] In at least one embodiment, a sleeve nose (e.g., nose 176) may be inserted into opening 602 such that a gap exists between the sleeve nose and wall 606. In at least one embodiment, RF conductor 102 is allowed to pivot substantially freely within opening 602. In at least one embodiment, the sleeve of the RF conductor may extend completely through opening 602 and into the counterbore of the platen.

[0160] FIG. 7A shows a top view of the upper clamp ring 148 of the column clamp assembly 140, according to at least one embodiment. In at least one embodiment, the upper clamp ring 148 has a width w5 between an outer sidewall 702 and an inner sidewall 704 surrounding an opening 706. In at least one embodiment, the width w5 may be in a range of approximately 7 cm to 25 cm. In at least one embodiment, the upper clamp ring 148 has an outer diameter D6 in a range of approximately 7 cm to 15 cm. In at least one embodiment, the upper clamp ring 148 has an inner diameter D7. The annular width w5 of the upper clamp ring 148 may be the arithmetic difference between D6 and D7. In at least one embodiment, the upper clamp ring 148 includes a plurality of through holes 708. In at least one embodiment, the through holes 708 allow for the passage of bolts (e.g., bolts 152 of FIG. 1C) to provide a clamping force against the lower clamp ring 150 (discussed below). In at least one embodiment, the through holes 708 are distributed in a symmetrical pattern to provide a symmetrical distribution of the force applied by a bolt (eg, bolt 152).

[0161] In at least one embodiment, upper clamp ring 148 comprises an upper surface 718 and a lower surface 720 (shown in FIG. 7B). In at least one embodiment, lower surface 720 is a contact surface (hereinafter contact surface 720). In at least one embodiment, upper clamp ring 148 comprises six equally spaced through holes 708 extending from upper surface 718 to lower surface 720. In at least one embodiment, through holes 708 have an azimuth angle spacing of 60 degrees. In at least one embodiment, the center of through hole 708 is coincident with a radius R1 that is smaller than a radius halfway between outer diameter D6 and inner diameter D7 (e.g., closer to inner diameter D7). In at least one embodiment, positioning through hole 708 inwardly allows the bolt to pass through a chamfered portion of upper clamp ring 148 (see FIG. 7B). Thus, in at least one embodiment, the downward force on the inner portion of lower clamp ring 150 is reduced, allowing lower clamp ring 150 to flex upward (discussed below).

[0162] In at least one embodiment, the upper clamp ring 148 comprises a metal having a high elastic modulus for rigidity. In at least one embodiment, materials such as, but not limited to, steel alloys, tungsten, or titanium can be used for the upper clamp ring 148.

[0163] FIG. 7B shows an orthogonal cross-sectional view of upper clamp ring 148, according to at least one embodiment. The cross-section is taken along section line A-A' of FIG. 7A. In at least one embodiment, upper clamp ring has a height h3 that may be in the range of approximately 1 cm to 3 cm. In at least one embodiment, inner sidewall 704 includes a bevel 710. In at least one embodiment, bevel 710 reduces the area of ​​contact surface 720 relative to the outer circumference of upper clamp ring 148. As described below, an inner portion of lower clamp ring 150 is cantilevered to allow upward flexure to accommodate non-planarity of adapter tube flange 146 (see FIG. 1C). In at least one embodiment, bevel 710 has an angle θ that may be adjusted to confine contact surface 720 to an outer portion of lower clamp ring 150. In at least one embodiment, angle θ may be adjusted to optimize width w6 of contact surface 720 relative to outer diameter D6. In at least one embodiment, width w6 can be adjusted to optimize the surface area of ​​contact surface 720 of upper clamp ring 148 for optimal force applied to lower clamp ring 150. In at least one embodiment, width w6 can be adjusted such that the surface area of ​​upper surface 718 is greater than the surface area of ​​contact surface 720. In at least one embodiment, the ratio of the area of ​​upper surface 718 to lower surface 720 can be adjusted to optimize the force applied to lower clamp ring 150, as described below.

[0164] FIG. 8A illustrates a top plan view of lower clamp ring 150, according to at least one embodiment. In at least one embodiment, lower clamp ring 150 may be a unitary annular structure. In at least one embodiment, lower clamp ring may comprise two mating semi-annular halves or segments (referred to as semi-annular segment 802A and semi-annular segment 804B). In at least one embodiment, semi-annular segment 802A is substantially identical to semi-annular segment 802B. In at least one embodiment, lower clamp ring comprises aluminum or other suitable metal alloy. In at least one embodiment, semi-annular segments 802A and 802B each comprise a top surface 804A / 804B that extends between outer sidewall 806A / 806B, respectively, and inner sidewall 808A / 808B, respectively. In at least one embodiment, width w7 of halves 802A and 802B may be in the range of approximately 1 cm to 3 cm. In at least one embodiment, the outer sidewall 806A / 806B extends along an outer radius R2, hi at least one embodiment, the inner sidewall 808A / 808B extends along an inner radius R3.

[0165] In at least one embodiment, semi-annular segment 802A includes a plurality of through holes 814A. In at least one embodiment, semi-annular segment 802B includes a plurality of through holes 814B. In at least one embodiment, through holes 814A / B serve as unthreaded bolt holes to allow passage of bolts from upper clamp ring 148 to adapter tube flange 146 to secure stem 128 to adapter tube 138 in wafer chuck assembly 120 (see FIG. 1C ).

[0166] In at least one embodiment, the through holes 814A / B can be evenly distributed along a radius extending through the semi-annular segments 802A and 802B, respectively. In at least one embodiment, the semi-annular segments 802A and 802B can each include three through holes 814A and 814B, respectively, angularly spaced by 60 degrees. In at least one embodiment, the centers of the holes 814A / B can coincide with the radius R4. In at least one embodiment, the radius R4 can be greater than halfway between the outer radius R2 and the inner radius R3. In at least one embodiment, the radius R4 can be closer to the radius R2 than to the radius R3. In at least one embodiment, the asymmetric centering of the holes 810A / B on the radius R4 can allow for a greater force (e.g., pressure from the upper clamp ring 148) to be applied to an outer portion of the lower clamp ring 150 compared to an inner portion of the lower clamp ring. In at least one embodiment, the outer portion of the lower clamp ring 150 may be between radius R4 and outer radius R2. In at least one embodiment, the inner portion (e.g., between radius R4 and inner radius R3) is cantilevered since this portion is not contacted by the upper clamp ring 148. In at least one embodiment, the cantilevering of the inner portion of the lower clamp ring 150 may allow the lower clamp ring 150 to elastically or plastically deform out of plane to conform to non-planarity of the adapter tube flange 146. In at least one embodiment, bending stresses on the lower clamp ring 150 and the adapter tube flange 146 may be reduced by deformation when bolted together to the wafer chuck assembly 120 (see FIG. 1C). In at least one embodiment, the induced bending may curve the lower clamp ring 150, reducing the contact area and displacing the contact area to the periphery, thereby allowing optimal force distribution through the lower surfaces 818A / B and 819A / B. In at least one embodiment, a metallic material having a lower modulus of elasticity than that of upper clamp ring 148 may be used.

[0167] In at least one embodiment, the material of construction of the lower clamp ring 150 may have a lower yield strength than the material in the upper clamp ring 148. The lower yield strength may allow for plastic deformation of the lower clamp ring 150 at lower levels of mechanical stress (e.g., lower bolt torque on the upper clamp ring 148) to avoid cracking or damaging the weaker adapter tube flange 146 and adapter tube 138. In at least one embodiment, the adapter tube 138 comprises a ceramic material. In at least one embodiment, the lower clamp ring may comprise aluminum (e.g., approximately 130 megapascals (MPa) yield strength) and the upper clamp ring 148 may comprise a steel alloy (e.g., approximately 230 MPa yield strength for mild steel).

[0168] While the lower clamp ring 150 is shown with two semi-annular segments, in at least one embodiment, the lower clamp ring 150 includes four quarter-annular segments (not shown). In at least one embodiment, structures such as holes 814A / B described above may be distributed in a similar or identical configuration on the four quarter-annular segments. In at least one embodiment, the first quarter-annular segment includes a first end and a second end. In at least one embodiment, the second quarter-annular segment includes a third end and a fourth end. In at least one embodiment, the third quarter-annular segment includes a fifth end and a sixth end. In at least one embodiment, the fourth quarter-annular segment includes a seventh end and an eighth end. In at least one embodiment, the second end is adjacent to the third end. In at least one embodiment, the fourth end is adjacent to the fifth end. In at least one embodiment, the sixth end is adjacent to the seventh end. In at least one embodiment, the eighth end is adjacent to the first end.

[0169] 8B illustrates a bottom plan view of lower clamp ring 150, according to at least one embodiment. In at least one embodiment, lower clamp ring 150 may be assembled by abutting ends 810A and 810B, and 812A and 812B, of semi-annular segments 802A and 802B, as shown. In at least one embodiment, ends 810A and 810B are interlocked. For example, end 810A may include one or more protruding structures (not shown), such as one or more tabs or tongues extending from end 810A, and end 810B may include one or more recessed areas (not shown), such as one or more notches or grooves that receive the one or more protruding structures, extending inwardly from end 810B. In at least one embodiment, the recessed areas may have a similar or the same shape as the protruding structures, such that semi-annular segments 802A and 802B may be interlocked by fitting the protruding structures into the recessed areas in a key-and-lock manner. In at least one embodiment, end 810A may include a protruding pin and end 810B may include a hole through which the protruding pin is inserted to interlock semi-annular segments 802A and 802B.

[0170] In at least one embodiment, the grooves 816A / B extend into the lower surfaces 818A / B of the semi-annular segments 802A and 802B, respectively. In at least one embodiment, the lower surfaces 818A / B are substantially planar and parallel to the upper surfaces 804A / B, respectively. In at least one embodiment, the grooves 816A / B follow a semi-circular arc between the outer sidewalls 806A / B and the inner sidewalls 808A / B of the semi-annular segments 802A and 802B, respectively. In at least one embodiment, the grooves 816A / B can combine to form a single circular groove when the lower clamp ring 150 is assembled. In at least one embodiment, the grooves 816A / B can have a width w8. In at least one embodiment, the upper surfaces 808A / B can be substantially coplanar when the lower clamp ring 150 is assembled into the wafer chuck assembly 120 (see FIG. 1C). For example, during construction of wafer chuck assembly 120, semi-annular segments 802A / B may be inserted between upper clamp ring 148 and adapter tube flange 146 and abut one another. When assembled, lower clamp ring 150 may have an outer diameter D8 (e.g., the sum of radii R2) and an inner diameter D9 (e.g., the sum of radii R3). In at least one embodiment, lower surfaces 818A / B may also be substantially coplanar when lower clamp ring 150 is assembled to wafer chuck assembly 120.

[0171] In at least one embodiment, the grooves 816A / B each include an inner sidewall 820A / B and an outer sidewall 822A / B. In at least one embodiment, the grooves 816A / B may include a lateral wall 824A / B between the inner sidewall 820A / B and the outer sidewall 822A / B. In at least one embodiment, a portion of the through-hole 810A / B may pass through the outer sidewall 822A / B. In at least one embodiment, the outer sidewall 822A / B may be curved (see FIG. 8C). In at least one embodiment, the intersection of the outer sidewall 822A / B and the lateral wall 824A / B may have a non-zero radius. In at least one embodiment, the outer sidewall 822A / B may be tapered as it approaches the lateral wall 824A / B to provide a reinforced cantilever joint to the lateral wall 824A / B. In at least one embodiment, the outer sidewalls 822A / B asymptotically join the lateral walls 824A / B at an oblique angle and can have a curvature at the intersection. In at least one embodiment, the maximum taper width w9 of the outer sidewalls 822A / B can be adjusted to allow for a desired cantilever deflection of the lateral walls 826A / B. In at least one embodiment, the widths w8 and w9 can be adjusted for optimal force distribution on the interfacing surfaces, as described herein.

[0172] In at least one embodiment, the overall width w7 of the semi-annular segments 802A / B may be adjusted to undergo a desired cantilever deflection when a normal force acts on the inner ridges 828A / B. In at least one embodiment, the width w7 may be adjusted for optimal distribution of forces applied to adjacent interfaces (e.g., the retaining lip 142 and the adapter tube flange 146) to optimize the thermal-mechanical performance of the column clamp assembly 140. In at least one embodiment, the inner side walls 820A / B can each include a flat portion 826A / B. In at least one embodiment, the location and length L of the flat portions 826A / B are 10may be adjusted to abut guide structure that may be present on the adapter tube flange 146. Such guide structure may facilitate orienting and / or centering the lower clamp ring 150 on the adapter tube flange 146.

[0173] FIG. 8C illustrates an orthogonal cross-sectional view of lower clamp ring 150 taken along section line A-A' shown in FIG. 8B, according to at least one embodiment. In at least one embodiment, lower clamp ring 150 comprises assembled semi-annular segments 802A and 802B adjacent at abutting ends 812A and 812B, respectively. In at least one embodiment, lower clamp ring 150 has a thickness h4. In at least one embodiment, thickness h4 is in the range of approximately 0.5-2 cm. In at least one embodiment, lateral walls 824A / B may be recessed below lower surfaces 818A / B and 819A / B, respectively, by a depth h5. In at least one embodiment, h5 is the depth of grooves 816A / B. In at least one embodiment, depth h5 may be in the range of 0.5 cm to approximately 75% of thickness h4. In at least one embodiment, depth h5 may be adjusted for optimal performance of lower clamp ring 150. In at least one embodiment, the adjustment may depend on the material, width w7, and vertical offset between lower surfaces 818A / B and 819A / B. In at least one embodiment, depth h5 may be optimized to allow the cantilevered portion of lower clamp ring 150 to bend at the desired clamping force on upper surfaces 808A / B to accommodate non-planarity of adapter tube flange 146. In at least one embodiment, deformation of lower clamp ring 150 may prevent damage to adapter tube flange 146 and adapter tube 138 (see FIG. 1C ) distributed between inner and outer contact surfaces 816 and 818, respectively.

[0174] In at least one embodiment, outer side walls 822A / B may each have an expanding taper approaching lateral walls 824A / B at an oblique angle. In at least one embodiment, outer side walls 822A / B asymptotically merge with lateral walls 824A / B to form a rounded (curved) joint. In at least one embodiment, the intersection between outer side walls 822A / B and lateral walls 824A / B has a non-zero circular radius of curvature r, as shown in the inset.

[0175] FIG. 9 illustrates a 3D cross-sectional view of an upper wafer chuck assembly 900 according to at least one embodiment. In at least one embodiment, the upper wafer chuck assembly 900 can extend between the platen 126 and an upper portion of the adapter tube 138. In at least one embodiment, the RF conductor 102 can extend from a lower portion of the adapter tube 138 to the platen 126 at the top of the stem 128. In at least one embodiment, the sleeve 116 can extend substantially the entire length of the rod 112 and provide thermal insulation for temperature regulation of the rod. In at least one embodiment, the tip 118 of the rod 112 can extend above the nose 176 of the sleeve 116. In at least one embodiment, the tip 118 of the rod 112 can be located within the counterbore 130. In at least one embodiment, the tip 118 can be attached to a plasma discharge electrode (not shown) within the platen 126 located above the counterbore 130. In at least one embodiment, the nose 176 can be seated in a counterbore 130 in the bottom surface of the plate 126 to align the RF conductor 102. In at least one embodiment, the counterbore 130 can be sized to allow clearance for pivoting movement of the RF conductor 102.

[0176] In at least one embodiment, the spacer plate 110 may be seated within the base of the stem 128 inside the retaining lip 142. In at least one embodiment, the RF conductor 102 may pass through an opening 602 in the spacer plate 110. In at least one embodiment, the diameter D4 of the opening 602 may be adjusted for clearance between the width w4 of the sleeve 116 and the diameter D4 of the opening 602. In at least one embodiment, the clearance may allow for pivoting of the RF conductor 102 and accommodate thermal expansion of the sleeve 116. In at least one embodiment, the heater conductor 158 may extend from the wire attachment lug 902 below the spacer plate 110 (e.g., extending from the heater wire 160 at the lower portion of the adapter tube 138). In at least one embodiment, the heater conductor 158 may extend through the opening 604 to the stem 128. In at least one embodiment, the heater conductor 158 may be attached to a heating element in the platen 126 (connection not shown). In at least one embodiment, the spacer plate 110 can provide electrical and thermal insulation between the sleeve 116 and the heater conductor 158 .

[0177] In at least one embodiment, the stem 128 may be attached to the adapter tube 138 by a column clamp assembly 140 including an upper clamp ring 148 and a lower clamp ring 150. In at least one embodiment, a clamping force from a tightened bolt 152 may be transferred through the column clamp assembly 140 to a retaining lip 142, compressing a vacuum seal 154 against a ledge 156. In at least one embodiment, the upper and lower clamp rings 148 and 150, respectively, may distribute the force such that compression of the vacuum seal 154 is even. In at least one embodiment, the vacuum seal 154 may be designed as a high vacuum or ultra-high vacuum seal.

[0178] FIG. 10 illustrates a semiconductor processing tool 1000 including a wafer chuck assembly 120 depicted by a dashed box according to at least one embodiment. In at least one embodiment, the semiconductor processing tool 1000 may be a wafer processing tool such as, but not limited to, a plasma enhanced chemical vapor deposition (PECVD) tool, an atomic layer deposition tool, an RF sputtering tool, a dry etching tool, or a plasma cleaning tool. In at least one embodiment, the wafer chuck assembly 120 including the platen 126 may be housed within a vacuum chamber 1002. In at least one embodiment, the vacuum chamber 1002 may be a high vacuum chamber or an ultra-high vacuum chamber. In at least one embodiment, the column 122 including the stem 128 and the adapter tube 138 may be housed within a cabinet 1006 below the vacuum chamber 1002. In at least one embodiment, the pedestal 126 may be on a top surface 1008 of the cabinet 1006 as shown. In at least one embodiment, the pedestal 126 may be recessed (not shown) below the top surface 1008. In at least one embodiment, the cabinet 1006 may be under a vacuum during operation of the semiconductor processing tool 1000.

[0179] In at least one embodiment, the RF conductor 102 is connected to the RF power source 1010 by a wire 534 attached to a feedthrough connector 1012. In at least one embodiment, the feedthrough connector 1012 can split the RF power from a coaxial cable extending from the RF power source 1010. In at least one embodiment, the RF power can be coupled to the thermal choke 114 via a wire harness 500.

[0180] 11 shows an example flowchart 1100 summarizing a method for assembling a wafer chuck assembly (e.g., wafer chuck assembly 120) according to at least one embodiment. In at least one embodiment, flowchart 1100 begins with operation 1102. In at least one embodiment, a wafer chuck pedestal assembly may be prepared for assembly. In at least one embodiment, the wafer chuck pedestal assembly may include a pedestal platen (e.g., platen 126) and an integral pedestal stem (e.g., stem 128). In at least one embodiment, an adapter tube housing may also be prepared for assembly to the wafer chuck pedestal.

[0181] In at least one embodiment, in operation 1104, an RF assembly comprising one or more RF conductors (e.g., RF conductor 102) clamped in an RF assembly clamp (e.g., RF assembly clamp 104) may be inserted into the base of the adapter tube housing. In at least one embodiment, the body of the RF assembly clamp comprises a contour (e.g., side walls 302, 304) that matches a contour (e.g., inner wall 139 and contour 404) in the inner wall of the adapter tube (e.g., adapter tube 138). In at least one embodiment, the RF rod assembly clamp may have an asymmetric shape so that it can be inserted in a unique (e.g., fixed) orientation. In at least one embodiment, the contours 404 may have a corresponding asymmetry relative to one another so that the RF assembly clamp 104 may be inserted in a fixed orientation. In at least one embodiment, the fixed orientation may ensure alignment of the RF conductors with contact points (e.g., counterbore 130) on the pedestal platen when the adapter tube housing is attached to the pedestal stem, as described below.

[0182] In at least one embodiment, the individual RF conductors may comprise a conductive rod (e.g., rod 112) integrally coupled (e.g., welded) to a conductive thermal choke (e.g., thermal choke 114), as described above in accordance with at least one embodiment. In at least one embodiment, the integral structure comprising the rod and thermal choke may be insulated by a dielectric cylindrical sleeve (e.g., sleeve 116). In at least one embodiment, the insulating sleeve may provide both thermal and electrical insulation for the rod / thermal choke structure. In at least one embodiment, the RF conductors may further comprise an RF electrical connector (e.g., wire harness 500) attached to a base portion (e.g., base 172) of the thermal choke.

[0183] In at least one embodiment, the RF conductor may be constrained in the RF rod assembly clamp by a deformable O-ring stretched around the dielectric sleeve. In at least one embodiment, the O-ring may allow rocking or pivoting movement of the RF conductor to compensate for misalignment of the rod with the contact point (e.g., counterbore 130) at the bottom of the pedestal platen. In at least one embodiment, the RF conductor may be held in a ball retainer captured in a spherical socket in the body of the RF rod assembly clamp. In at least one embodiment, the ball and socket joint may be rotatable to allow limited pivoting movement of the RF conductor while constraining lateral and vertical movement.

[0184] In at least one embodiment, in operation 1106, the wafer chuck pedestal can be attached to the adapter tube housing. In at least one embodiment, the pedestal stem can include a lip (e.g., retaining lip 142) at its base that sits on a ledge (e.g., ledge 144) in the top end of the adapter tube housing. In at least one embodiment, the top end of the adapter tube housing can approach the base of the pedestal stem during the assembly procedure. In at least one embodiment, the individual RF conductors can be inserted through openings in a spacer plate (e.g., opening 602 in spacer plate 110) that is seated in the base of the pedestal stem. In at least one embodiment, the spacer plate can be seated on a ledge inside the lip of the pedestal stem.

[0185] In at least one embodiment, the base of the pedestal stem can be inserted into the upper end of the adapter tube housing. In at least one embodiment, once the pedestal stem is inserted into the adapter tube housing, a clamp (e.g., column clamp assembly 140) including an upper clamp ring (e.g., upper clamp ring 148) and a lower clamp ring (e.g., lower clamp ring 150) can be bolted to the adapter tube flange (e.g., adapter tube flange 146). In at least one embodiment, the lower clamp ring straddles the flange and the pedestal stem lip. In at least one embodiment, the lower clamp ring comprises a material that is sufficiently elastic to be slightly deformed by tightening a number of clamp bolts (e.g., bolts 152) to distribute the clamping force transmitted by the upper clamp ring.

[0186] In at least one embodiment, an RF connection can be made to the wafer chuck pedestal assembly in operation 1108. In at least one embodiment, a wire harness (e.g., wire harness 500) with a dielectric (e.g., PEEK) body can be inserted into the base of the adapter tube housing. In at least one embodiment, the wire harness can have a contoured body that fits into a contoured recess (e.g., contour 404) in the interior wall of the adapter tube housing. In at least one embodiment, an RF connector (e.g., RF connector 506) may be inserted into a connector port (e.g., connector port 504) of a wire harness. In at least one embodiment, the wire harness may be inserted over an RF conductor. In at least one embodiment, a dielectric sleeve of the RF conductor may be placed into a well (e.g., sleeve well 502) of the wire harness. In at least one embodiment, a thermal choke may extend through an opening in the bottom of the well (e.g., through opening 510) and be placed in a receptacle (e.g., socket 512) of the RF connector. In at least one embodiment, the thermal choke may be electrically coupled to the RF connector. In at least one embodiment, a wire (e.g., wire 534) may be pre-soldered to the RF connector. In at least one embodiment, the wire may carry RF current to the connector. In at least one embodiment, the RF connector may include a threaded base (e.g., inner threaded portion 516) to which a threaded barrel may be attached. In at least one embodiment, the threaded barrel can be tightened to secure the RF connector within the wire harness.

[0187] In at least one embodiment, the structures of the various embodiments described herein can also be described as methods of forming those structures and methods of operating those structures.

[0188] The following examples are provided illustrating at least one embodiment. These examples may be combined with other examples. Thus, at least one embodiment may be combined with at least another embodiment without changing the scope of the invention.

[0189] Example 1 is a wafer chuck assembly comprising: a platen having one or more plasma electrodes; and at least one radio frequency (RF) conductor electrically coupled to the one or more plasma electrodes, the at least one RF conductor comprising a rod having a rod tip coupled to the one or more plasma electrodes and a rod stem mechanically coupled to a thermal choke having a hollow interior, the rod comprising a first conductive material and having a first width and a first length, the thermal choke comprising a second conductive material and having a second width and a second length, the second width being greater than or equal to the first width.

[0190] Example 2 includes all of the features of example 1, wherein the rod comprises a rod stem inserted into a tubular body of the thermal choke, the rod stem having a third length that is less than 10% of the first length.

[0191] Example 3 includes all of the features of example 1, wherein the rod further comprises an insertion stop on the stem portion, the insertion stop abutting a rim of the thermal choke.

[0192] Example 4 includes all of the features of example 1, wherein the first length is between 20% and 50% of the second length.

[0193] Example 5 includes all of the features of example 1, wherein an RF assembly clamp is coupled to the at least one RF conductor, the RF assembly clamp comprising at least one retaining structure through which the at least one RF conductor extends, the at least one retaining structure operable to pivotally engage the at least one RF conductor with the RF assembly clamp.

[0194] Example 6 includes all of the features of example 5, wherein the RF assembly clamp comprises a first portion and a second portion, the at least one retaining structure is between the first portion and the second portion, at least one first opening extends through the first portion and is substantially coaxial with at least one second opening extending through the second portion, and a third opening extends through the at least one retaining structure and is substantially coaxial with the at least one first opening and the at least one second opening.

[0195] Example 7 includes all of the features of Example 6, wherein the at least one retaining structure comprises a ball retainer pivotally engaged within a cavity of the RF assembly clamp, the third opening extending through the ball retainer, and the at least one RF conductor being laterally restrained within the third opening.

[0196] Example 8 includes all of the features of example 6, wherein the at least one retention structure comprises a ring surrounding the third opening, the at least one RF conductor is laterally restrained within the third opening, and the at least one RF conductor is pivotally engaged within the third opening.

[0197] Example 9 includes all of the features of example 8, wherein the ring comprises an elastomeric material, the elastomeric material deforms due to a pivotal force applied by the at least one RF conductor.

[0198] Example 10 includes all of the features of example 1, wherein the thermal choke is coupled to the rod by a welded or brazed bond.

[0199] Example 11 includes all of the features of example 1, wherein the first conductive material includes nickel, iron, or copper.

[0200] Example 12 includes all of the features of example 1, wherein the second conductive material includes an alloy of nickel, copper, or iron.

[0201] Example 13 includes all of the features of example 1, wherein the thermal choke comprises a conductive coating on an outer wall.

[0202] Example 14 includes all of the features of example 13, wherein the conductive coating includes gold, and the conductive coating has a thickness less than or equal to 20 microns.

[0203] Example 15 includes all of the features of example 1, wherein the thermal choke has a first end coupled to the rod and a second end coupled to an electrical connector, the electrical connector being electrically coupled to the thermal choke.

[0204] Example 16 includes all of the features of example 1, wherein the RF assembly further comprises a sleeve around the rod and the thermal choke, the sleeve comprising a non-conductive material, and the sleeve has a fourth length, the fourth length being equal to at least a portion of the sum of the first length and the second length.

[0205] Example 17 includes all of the features of example 16, wherein the non-conductive material includes an oxide of aluminum, an oxide of silicon, or an organic polymer.

[0206] Example 18 includes all of the features of example 16, wherein the sleeve comprises a nose having a first wall thickness that is less than the second wall thickness of the sleeve.

[0207] Example 19 is a system including a vacuum chamber; a wafer chuck assembly within the vacuum chamber, the wafer chuck assembly including a pedestal having a stem coupled to a platen, the platen including a pedestal having at least one plasma discharge electrode, a column including an adapter tube coupled to the stem, and a radio frequency (RF) assembly including at least one RF conductor, the at least one RF conductor including a rod mechanically coupled to a thermal choke, and a sleeve extending at least partially along a length of the at least one RF conductor, the at least one RF conductor including a sleeve coupled to the at least one RF conductor. and a wafer chuck assembly comprising an RF assembly clamp comprising an RF assembly clamp having at least one retaining structure within a clamp body, the at least one retaining structure comprising an opening through which the at least one RF conductor extends, the at least one retaining structure operable to pivotally engage the at least one RF conductor with the clamp body, the at least one RF conductor extending through the column, the at least one RF conductor electrically coupled to the at least one plasma discharge electrode.

[0208] Example 20 includes all of the features of example 19, wherein an RF power source is electrically coupled to the at least one RF conductor.

[0209] Example 21 includes all of the features of example 19, wherein the platen comprises at least one counterbore on a lower surface of the platen, the at least one counterbore extending to the at least one plasma discharge electrode, and a tip of the rod extends through the at least one counterbore and contacts the at least one plasma discharge electrode.

[0210] Example 22 includes all of the features of example 19, wherein a column clamp assembly connects the stem of the base to the adapter tube, the column clamp assembly including an upper clamp ring above a lower clamp ring.

[0211] Example 23 includes all of the features of example 19, wherein the RF assembly clamp is mounted within the adapter tube, the adapter tube comprising an inner wall comprising one or more contours.

[0212] Example 24 is a method for assembling a wafer chuck assembly, the method including receiving the wafer chuck assembly with a stem, the stem attached to a platen at a first end and having a lip at a second end, an adapter tube having a flange at a third end and a base at a fourth end; placing a spacer plate at the second end of the stem, the spacer plate having one or more openings; placing a radio frequency (RF) assembly at the base of the adapter tube, the RF assembly having one or more RF conductors extending through openings in an RF assembly clamp, the RF assembly clamp having a unique orientation within the adapter tube, the one or more RF conductors extending through the spacer plate; and clamping the flange to the end of the stem.

[0213] Example 25 includes all of the features of example 24, further including coupling the RF assembly to an RF power source, the RF power source electrically coupled to an RF connector that is electrically coupled to the RF assembly.

[0214] Example 26 includes all of the features of Example 24, wherein mounting the RF assembly to the base of the adapter tube includes mounting the RF assembly to the RF assembly clamp, the RF assembly clamp substantially constraining lateral movement of the one or more RF conductors, and the one or more RF conductors are pivotally engaged within the RF assembly clamp.

[0215] Example 27 includes all of the features of Example 24, wherein the one or more RF conductors include a rod having a tip, and placing the RF assembly at the base of the adapter tube includes contacting the tip with the platen.

[0216] Example 28 is a lower clamp ring comprising a first surface and a second surface opposite the first surface and separated from the first surface by a thickness, the first and second surfaces extending between an outer radius and an inner radius, and a circular groove in the second surface, the circular groove having a width extending partially between the outer radius and the inner radius, the circular groove each having an outer sidewall and an inner sidewall, the circular groove having a lateral wall extending between the inner sidewall and the outer sidewall, the outer sidewall extending inwardly from the second surface toward the lateral wall at an oblique angle, an intersection of the outer sidewall and the lateral wall being rounded, and a plurality of holes extending from the first surface into the circular groove.

[0217] Example 29 includes all of the features of example 28, wherein centers of the holes are coincident with a third radius that is greater than half the distance between the first radius and the second radius, and the holes are azimuthally spaced apart by about 60 degrees.

[0218] Example 30 includes all of the features of example 28, wherein the inner sidewall comprises a flat portion.

[0219] Example 31 includes all of the features of example 28, and further includes a first semi-annular segment and a second semi-annular segment, the first semi-annular segment having a first end and a second end, the second semi-annular segment having a third end and a fourth end, the first end adjacent to the third end and the second end adjacent to the fourth end.

[0220] Example 32 includes all of the features of example 28, except that the first quarter-ring segment, a second quarter-ring segment, a third quarter-ring segment, and a fourth quarter-ring segment, the first quarter-ring segment having a first end and a second end, the second quarter-ring segment having a third end and a fourth end, the third end adjacent to the second end, the third quarter-ring segment having a fifth end and a sixth end, the fifth end adjacent to the fourth end, the fourth quarter-ring segment having a seventh end and an eighth end, the seventh end adjacent to the sixth end, and the eighth end adjacent to the first end.

[0221] Example 33 is an upper clamp ring comprising: a first sidewall along an outer diameter; a second sidewall along an inner diameter, a first surface extending between the outer diameter and the inner diameter, the first surface being separated from a second surface by a thickness; and a plurality of through holes extending through the thickness between the first surface and the second surface.

[0222] Example 34 includes all of the features of example 33, except that centers of the through holes are coincident with a radius that is less than half the distance between the outer diameter and the inner diameter, and the holes are azimuthally spaced apart by 60 degrees.

[0223] Example 35 includes all of the features of example 33, wherein the second sidewall comprises a beveled portion, the beveled portion being chamfered at an angle such that the first surface has a first surface area that is greater than a second surface area of ​​the second surface.

[0224] Example 36 is a clamp assembly comprising: an upper clamp ring having at least one through hole and a chamfer at a bottom surface adjacent an inner radius of the upper clamp ring; and a lower clamp ring having a top surface, a bottom surface, and at least one through hole, the bottom surface comprising a groove bounded between an outer radius and an inner radius, the upper clamp ring and the lower clamp ring being bolted together by bolts through the through holes in the upper clamp ring and the lower clamp ring such that the bottom surface of the upper clamp ring is in direct contact with the top surface of the lower clamp ring.

[0225] Besides those described herein, various modifications can be made to the disclosed embodiments and implementations thereof without departing from the scope thereof. Therefore, the description of the embodiments herein should be construed as examples only, and not as limiting the scope of the present disclosure. The scope of the present invention should be judged solely by reference to the following claims.

Claims

1. 1. A wafer chuck assembly comprising: a platen having one or more plasma electrodes; 1. An RF assembly comprising at least one radio frequency (RF) conductor electrically coupled to the one or more plasma electrodes, the at least one RF conductor comprising: a rod having a rod tip coupled to said one or more plasma electrodes and a rod stem mechanically coupled to a thermal choke having a hollow interior; an RF assembly comprising: Equipped with the rod comprises a first conductive material and has a first width and a first length; the thermal choke includes a second conductive material and has a second width and a second length; The second width is greater than or equal to the first width. Wafer chuck assembly.

2. 2. The wafer chuck assembly of claim 1, the rod comprises a rod stem inserted into a tubular body of the thermal choke, the rod stem having a third length that is less than 10% of the first length.

3. 2. The wafer chuck assembly of claim 1, The wafer chuck assembly, wherein the rod further comprises an insertion stop on the rod stem, the insertion stop abutting a rim of the thermal choke.

4. 2. The wafer chuck assembly of claim 1, The first length is between 20% and 50% of the second length.

5. 2. The wafer chuck assembly of claim 1, a wafer chuck assembly, wherein an RF assembly clamp is coupled to the at least one RF conductor, the RF assembly clamp comprising at least one retention structure through which the at least one RF conductor extends, the at least one retention structure operable to pivotally engage the at least one RF conductor with the RF assembly clamp.

6. 6. The wafer chuck assembly of claim 5, a wafer chuck assembly, the RF assembly clamp comprising a first portion and a second portion, the at least one retaining structure being between the first portion and the second portion, at least one first opening extending through the first portion and coaxial with at least one second opening extending through the second portion, and a third opening extending through the at least one retaining structure and substantially coaxial with the at least one first opening and the at least one second opening.

7. 7. The wafer chuck assembly of claim 6, a wafer chuck assembly, wherein the at least one retaining structure comprises a ball retainer pivotally engaged within a cavity of the RF assembly clamp, the third opening extending through the ball retainer, and the at least one RF conductor being laterally restrained within the third opening.

8. 7. The wafer chuck assembly of claim 6, the at least one retaining structure comprises a ring surrounding the third opening, the at least one RF conductor being laterally constrained within the third opening, and the at least one RF conductor being pivotally engaged within the third opening.

9. 9. The wafer chuck assembly of claim 8, The wafer chuck assembly, wherein the ring comprises an elastomeric material, the elastomeric material deforming due to a pivotal force applied by the at least one RF conductor.

10. 2. The wafer chuck assembly of claim 1, The wafer chuck assembly, wherein the thermal choke is coupled to the rod by a welded or brazed bond.

11. 2. The wafer chuck assembly of claim 1, The first conductive material comprises nickel, iron, or copper.

12. 2. The wafer chuck assembly of claim 1, the second conductive material comprises an alloy of nickel, copper, or iron.

13. 2. The wafer chuck assembly of claim 1, The thermal choke of the wafer chuck assembly includes a conductive coating on an outer wall.

14. 14. The wafer chuck assembly of claim 13, 11. A wafer chuck assembly, comprising: a conductive coating comprising gold, the conductive coating having a thickness of 20 microns or less.

15. 2. The wafer chuck assembly of claim 1, The thermal choke has a first end coupled to the rod and a second end coupled to an electrical connector, the electrical connector being electrically coupled to the thermal choke.

16. 2. The wafer chuck assembly of claim 1, the RF assembly further comprising a sleeve around the rod and the thermal choke, the sleeve comprising a non-conductive material, the sleeve having a fourth length, the fourth length being equal to at least a portion of the sum of the first length and the second length.

17. 17. The wafer chuck assembly of claim 16, The wafer chuck assembly, wherein the non-conductive material comprises an oxide of aluminum, an oxide of silicon, or an organic polymer.

18. 17. The wafer chuck assembly of claim 16, The sleeve includes a nose having a first wall thickness less than a second wall thickness of the sleeve.

19. 1. A system comprising: A vacuum chamber; a wafer chuck assembly within the vacuum chamber, the wafer chuck assembly comprising: a pedestal comprising a stem coupled to a platen, said platen comprising at least one plasma discharge electrode; an adapter tube connected to the stem; and 1. A radio frequency (RF) assembly comprising: at least one RF conductor comprising a rod mechanically coupled to a thermal choke and a sleeve extending at least partially along a length of the at least one RF conductor; an RF assembly clamp coupled to the at least one RF conductor, the RF assembly clamp comprising at least one retention structure within a clamp body; An RF assembly comprising: a wafer chuck assembly comprising: Equipped with the at least one retaining structure includes an opening through which the at least one RF conductor extends; the at least one retaining structure is operable to pivotally engage the at least one RF conductor with the clamp body; the at least one RF conductor extends through the adapter tube and the stem; the at least one RF conductor is electrically coupled to the at least one plasma discharge electrode. system.

20. 20. The system of claim 19, The system wherein an RF power source is electrically coupled to the at least one RF conductor.

21. 20. The system of claim 19, the platen comprises at least one counterbore on a lower surface of the platen, the at least one counterbore extending to the at least one plasma discharge electrode, and a tip of the rod extends through the at least one counterbore and contacts the at least one plasma discharge electrode.

22. 20. The system of claim 19, A column clamp assembly connects the stem of the base to the adapter tube, the column clamp assembly including an upper clamp ring above a lower clamp ring.

23. 20. The system of claim 19, The system, wherein the RF assembly clamp is mounted within the adapter tube, the adapter tube comprising an inner wall comprising one or more contours.

24. 1. A method for assembling a wafer chuck assembly, comprising: receiving the wafer chuck assembly comprising a pedestal stem, the pedestal stem attached to a platen at a first end and comprising a lip at a second end, an adapter tube comprising a flange at a third end and a base at a fourth end; placing a spacer plate on the second end of the pedestal stem, the spacer plate having one or more apertures; placing a radio frequency (RF) assembly at the base of the adapter tube, the RF assembly comprising one or more RF conductors extending through an opening in an RF assembly clamp, the RF assembly clamp having a specific orientation within the adapter tube, the one or more RF conductors extending through the spacer plate; clamping the flange onto an end of the base stem; A method comprising:

25. 25. The method of claim 24, The method further comprising coupling the RF assembly to an RF power source, the RF power source being electrically coupled to an RF connector that is electrically coupled to the RF assembly.

26. 25. The method of claim 24, The method of claim 1, wherein mounting the RF assembly to the base of the adapter tube includes mounting the RF assembly to the RF assembly clamp, the RF assembly clamp substantially constraining lateral movement of the one or more RF conductors, the one or more RF conductors being pivotally engaged within the RF assembly clamp.

27. 25. The method of claim 24, The method, wherein the one or more RF conductors comprise a rod having a tip, and placing an RF assembly at the base of the adapter tube includes contacting the tip to the platen.

28. A lower clamp ring, a first surface and a second surface opposite the first surface and separated from the first surface by a thickness, the first surface and the second surface extending between an outer radius and an inner radius; a circular groove in the second surface, the circular groove having a width extending partially between the outer radius and the inner radius, the circular groove having an outer sidewall and an inner sidewall; Equipped with the circular groove has a lateral wall extending between the inner sidewall and the outer sidewall, the outer sidewall extending inwardly from the second surface toward the lateral wall at an oblique angle, an intersection of the outer sidewall and the lateral wall being rounded; a plurality of holes extending from the first surface into the circular groove; Lower clamp ring.

29. 29. A lower clamp ring as in claim 28, a lower clamp ring, the centers of the holes being coincident with a third radius that is greater than half the distance between the outer radius and the inner radius, and the holes being azimuthally spaced apart by approximately 60 degrees.

30. 29. A lower clamp ring as in claim 28, The inner sidewall includes a flat portion.

31. 29. A lower clamp ring as in claim 28, a lower clamp ring comprising a first semi-annular segment and a second semi-annular segment, the first semi-annular segment having a first end and a second end, the second semi-annular segment having a third end and a fourth end, the first end adjacent the third end and the second end adjacent the fourth end.

32. 29. A lower clamp ring as in claim 28, a first quarter-ring segment, a second quarter-ring segment, a third quarter-ring segment, and a fourth quarter-ring segment; the first quarter-annular segment having a first end and a second end; the second quarter-annular segment having a third end and a fourth end, the third end adjacent the second end; the third quarter-annular segment having a fifth end and a sixth end, the fifth end being adjacent to the fourth end; the fourth quarter-annular segment comprises a seventh end and an eighth end, the seventh end adjacent the sixth end and the eighth end adjacent the first end; Lower clamp ring.

33. An upper clamp ring, a first sidewall along an outer diameter; a second sidewall along the inner diameter, a first surface extending between the outer diameter and the inner diameter, the first surface being separated from a second surface by a thickness; a plurality of through holes extending through the thickness between the first surface and the second surface; An upper clamp ring comprising:

34. 34. An upper clamp ring as in claim 33, comprising: an upper clamp ring, wherein centers of said plurality of through holes are coincident with a radius that is less than half the distance between said outer diameter and said inner diameter, and said holes are azimuthally spaced apart by approximately 60 degrees.

35. 34. An upper clamp ring as in claim 33, comprising: the second sidewall includes a beveled portion, the beveled portion being chamfered at an angle such that the first surface has a first surface area that is greater than a second surface area of ​​the second surface.

36. 1. A clamp assembly comprising: an upper clamp ring having at least one through hole and a chamfer on a bottom surface adjacent an inner radius of the upper clamp ring; a lower clamp ring having a top surface, a bottom surface, and at least one through hole, the bottom surface comprising a groove bounded between an outer radius and an inner radius; Equipped with the upper clamp ring and the lower clamp ring are bolted through the through holes in the upper clamp ring and the lower clamp ring by bolts such that the bottom surface of the upper clamp ring is in direct contact with the top surface of the lower clamp ring; Clamp assembly.

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