Plasma Radical Edge Ring Barrier Seal

Abstract

A barrier seal ring for a plasma chamber includes an outer seal leg extending vertically downward from a top surface to a bottom surface along an outer diameter, and an inner seal leg extending downward from the top surface to an inner diameter. An upper leg portion of the inner seal leg extends at an angle relative to the outer seal leg, and a lower leg portion extends downward from a bottom of the upper leg portion, defining an interface between the upper leg portion and the lower leg portion. The interface allows the inner seal leg to fold inwardly toward an inner surface of the outer seal leg during installation within a groove in a base ring disposed in a lower electrode of the plasma chamber.

Description

[Technical field]

[0001] The present disclosure relates to providing a seal ring in a semiconductor process module. [Background technology]

[0002] In semiconductor processing, wafers are subjected to various operations to form features that define integrated circuits. For example, in a plasma etching operation, the wafer is contained within a plasma chamber and exposed to a plasma that is generated in a plasma processing region defined within the plasma chamber. The plasma interacts with material on the surface of the wafer, removing or modifying the material and ultimately removing it from the surface. Depending on the type of feature to be formed, a particular type of reactive gas is supplied to the chamber and a radio frequency (RF) signal from an RF power source is applied to activate the particular reactive gas to generate a plasma. The RF signal is supplied through the plasma processing region containing the reactive gas.

[0003] The plasma is controlled in the plasma processing region such that the radicals of the plasma are confined to an area above the wafer, resulting in an optimal plasma etching operation. An edge ring is defined to surround a wafer support (e.g., an electrostatic chuck) defined in a lower electrode. Constant exposure to highly reactive plasma radicals erodes the edge ring, limiting its useful life. As the surface of the edge ring erodes, other components below the edge ring (such as the thermal gasket that supports the edge ring on the lower electrode) are exposed to the highly reactive radicals of the plasma that also damage these components. When the edge ring reaches the end of its useful life, it must be replaced. Along with the edge ring, the thermal gasket must also be replaced.

[0004] The RF signal transmission path affects how the plasma is generated and how the plasma sheath is managed. For example, reactant gases may be more activated in certain parts of the plasma processing volume where more RF signal power is delivered, leading to spatial non-uniformity in the plasma characteristics across the plasma processing volume. Plasma characteristics that cause spatial non-uniformity include non-uniformity in ion density, ion energy, reactant gas density, etc. Spatial non-uniformity in the plasma characteristics can lead to non-uniformity in the plasma processing results across the wafer.

[0005] To address spatial non-uniformity and control the plasma sheath profile, a tunable edge sheath (TES) assembly is defined that independently powers edge electrodes. The edge electrodes are separate from the main electrodes that are used to deliver RF signals to power the reactant gases received in the plasma processing region. The TES assembly includes multiple quartz parts / elements, a ceramic support, and an edge electrode connected to an RF power source, providing RF power to the plasma processing region through an edge ring. With the introduction of the TES assembly, additional parts (e.g., plastic parts) that are susceptible to attack by plasma radicals were also introduced. Erosion of these TES assembly parts by radical attack has become a limiting factor affecting the mean time between cleanings and adds costly consumables.

[0006] It is against this background that implementations of the present invention arise. Summary of the Invention

[0007] In various implementations discussed herein, a barrier seal ring is introduced into an adjustable edge sheath (TES) assembly defined in a lower portion of a plasma processing chamber (or simply referred to as a "plasma chamber"). The lower portion of the plasma chamber includes a lower electrode powered by a radio frequency (RF) power source in some implementations, and the TES assembly is defined below an edge ring surrounding a wafer support surface (e.g., an electrostatic chuck (ESC)) defined in the lower electrode. The TES assembly is introduced into the plasma chamber to better control the profile of the plasma sheath covering the edge of the wafer. The TES assembly is provided to independently power an edge electrode (different from a main electrode that powers the ESC (i.e., lower electrode) in the plasma chamber) located below the edge ring. The barrier seal ring is incorporated into the TES assembly and is used to seal gaps between some components of the TES assembly to effectively prevent plasma radicals from reaching other underlying components (e.g., plastic components) of the TES assembly. The barrier seal ring is made of a material with a low erosion rate. Blocking the pathways to the TES assembly components results in improved service life for additional components, reduced consumable costs, and improved mean time between cleaning of the TES assembly components.

[0008] Typically, edge rings are designed to include gaps between the edge ring and the various components adjacent to the edge ring. These gaps are introduced to allow for thermal expansion and / or mechanical tolerances. The downside of having gaps between the edge ring and the various components adjacent to the edge ring is that the gaps allow plasma radicals to follow the path of least resistance and attack materials located below the edge ring in the plasma chamber. Prior to the introduction of the TES assembly in the plasma chamber, the gaps between the various components of the edge ring assembly did not affect the integrity of the various components of the plasma chamber below the edge ring because the various components of the lower electrode were not susceptible to attack from the plasma radicals. However, with the introduction of the TES assembly, insulating components such as plastic components were introduced to encase the conductive rods that provide power to the edge electrode. The gaps between the edge ring and the adjacent components allowed plasma radicals to flow through the gaps and attack the susceptible plastic components, resulting in a reduction in the mechanical strength of the components and visible erosion of the enclosed parts (e.g., the conductive rods).

[0009] To prevent attack of sensitive insulating components (e.g., plastic components), a barrier seal ring is introduced above the plastic components of the TES assembly to block the flow of plasma radicals toward the plastic components. The barrier seal ring is incorporated into a groove defined in a base ring of the TES assembly disposed below the edge ring. The base ring is made of quartz. The barrier seal ring is made of a material that is not susceptible to plasma radicals and is flexible so that it can be easily pressed into the groove defined in the base ring. The base ring is disposed adjacent to and surrounds the TES ring and a portion of the ceramic support element disposed below the TES ring. The insulating material (e.g., plastic or ceramic components) of the TES assembly is embedded in the ceramic support element defined below the TES ring and surrounds the ESC. The barrier seal ring is used to seal the gap between the TES ring and the base ring. By successfully sealing the gap, the barrier seal ring prevents plasma radicals from reaching the insulating material embedded in the ceramic support element of the TES assembly, preserving the integrity of the insulating material and the conductive rods encapsulated therein. By preventing erosion of insulation, barrier seal rings improve the mean time between cleanings and reduce consumable costs because insulation such as plastic parts can be reused for multiple wet cleanings.

[0010] In one implementation, a barrier seal ring for a plasma chamber is disclosed. The barrier seal ring includes an outer seal leg extending vertically downward along an outer diameter. The outer seal leg includes an upper chamfer and a lower chamfer defined along an outer diameter of the barrier seal ring. The inner seal leg is connected with an upper portion of the outer seal leg. The inner seal leg is oriented at an angle relative to the outer seal leg. The inner seal leg includes an upper leg portion and a lower leg portion. The lower leg portion of the inner seal leg forms an initial gap of a first distance with the outer seal leg. The lower leg portion is configured to deflect toward the outer seal leg to form a second gap less than the initial gap first distance but greater than zero. The barrier seal ring is configured to seat within a groove in the first ring and to seal when the inner seal leg is pressed against the second ring. The first ring and the second ring are part of a plasma chamber. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a simplified block diagram of the lower portion of a plasma chamber employing a barrier seal ring in an adjustable edge sheath assembly according to one implementation.

[0012] [Diagram 2] FIG. 2 is a side perspective view of a base ring having a groove for receiving the barrier seal ring of FIG.

[0013] [Diagram 3] FIG. 3 is an enlarged cross-sectional view of the barrier seal ring of FIG.

[0014] [Figure 4] FIG. 4 is an enlarged cross-sectional view of the barrier seal ring of FIG. 3 with some dimensions identified.

[0015] [Diagram 5] FIG. 5 is an enlarged cross-sectional view of the barrier seal ring of FIG. 3 with a location profile identified.

[0016] [Figure 6] FIG. 6 is a top perspective view of the barrier seal ring of FIG.

[0017] [Figure 7] FIG. 7 is a side view of the barrier seal ring of FIG.

[0018] [Figure 8] FIG. 8 is a top view of the barrier seal ring of FIG.

[0019] [Figure 9] FIG. 9 is a bottom view of the barrier seal ring of FIG.

[0020] [Figure 10A] FIG. 10A is a side view of FIG. 7 and is used to provide an enlarged cross-sectional view of the barrier seal ring of FIG.

[0021] [Figure 10B] FIG. 10B is an enlarged cross-sectional view of the barrier seal ring of FIG. 10A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The features of various components of a barrier seal ring used in a plasma process module (alternatively referred to herein as a "process module") to block the flow of plasma radicals toward and prevent attack of various underlying components of a plasma chamber defined in the process module are described in detail. The barrier seal ring is incorporated in a first ring that is adjacent to and surrounds a second ring defined in a lower portion of the process module. In one implementation, the first ring is a base ring disposed below a first portion of an edge ring that surrounds a substrate support surface defined in the lower portion of the process module, and the second ring is an adjustable edge sheath (TES) ring of a TES assembly defined below a second portion of the edge ring. The barrier seal ring is used to effectively block a path between the first ring and the second ring through which the plasma radicals can be used to attack various underlying components such as insulating (e.g., plastic) components of the TES assembly. A groove is defined along an inner sidewall of the base ring. The groove is sized to accommodate the barrier seal ring. The barrier seal ring is made of a material that is flexible and not susceptible to erosion by fluorine and / or other components of the plasma radicals. Chamfers are provided at various outer corners (both top and bottom) of the barrier seal ring to allow the barrier seal ring to be pressed into place within the groove so that it seats and fully engages the interior side walls of the groove defined in the base ring. The size and flexibility of the barrier seal ring ensures that the barrier seal ring is fully received and held in place within the groove without causing interference with the lower outer corners of the groove or between the components of the barrier seal ring. Additionally, the size, shape and design of the barrier seal ring are defined to seal a path between the base ring and adjacent components at the bottom of the process module so that plasma radicals cannot attack the underlying components.

[0023] Broadly speaking, the plasma chamber includes an upper member (also referred to as "top"), a lower member (also referred to as "bottom"), and a sidewall extending between the upper member and the lower member to define a plasma processing region therein. The upper member is configured to be coupled to a gas source for supplying a reactive gas to the plasma processing region. The lower member includes at least an electrostatic chuck (ESC) coupled to a radio frequency (RF) power source, the RF power source providing power to the reactive gas through the ESC to generate a plasma in the plasma processing region. The RF power source providing power to the reactive gas through the ESC represents a main power source, with the ESC acting as a main electrode. In addition to the main power source, the lower member also includes a second RF power source used to provide RF power to control a plasma sheath profile above an edge ring disposed to surround the ESC. The second power source is coupled to an edge electrode embedded within an adjustable edge sheath (TES) ring of a TES assembly included in the lower member. The TES assembly is used to control the properties of the plasma sheath near the periphery of the wafer housed on the ESC and over the edge ring, such as plasma density, ion attraction or repulsion, etc. By controlling the properties of the plasma, the TES assembly allows tuning of the plasma sheath (i.e., influencing the plasma sheath profile) at the edge of the wafer to improve radial uniformity across the surface of the wafer. Improving radial uniformity results in higher yields and improved quality of devices formed on the wafer.

[0024] The introduction of the TES assembly in the lower member, however, also introduces plasma-susceptible elements (such as plastic parts) that are used to surround certain components of the TES assembly (e.g., the conductive rods connected to the second RF power source). For example, the plastic parts with the conductive rods are embedded in a ceramic support element disposed below the TES ring. The plastic parts act as insulators surrounding the conductive rods. The conductive rods are connected at a first end to the RF power source, extend through the plastic parts, and connect at a second end to edge electrodes embedded in the TES ring. The TES ring is defined below a portion of the edge ring that surrounds the ESC. As various wafers are processed using the plasma generated in the plasma processing region, the edge ring adjacent to the ESC that receives the wafer is constantly exposed to plasma radicals. This constant exposure erodes the surface of the edge ring. As the surface of the edge ring erodes, the gaps provided between the edge ring and adjacent components such as the cover ring and the TES ring (i.e., the connecting ring) begin to widen, and the plasma radicals begin to find their way through the gaps to the underlying components of the TES assembly. The clearance between the edge ring and the adjacent components is provided to allow for thermal expansion or mechanical tolerances. To prevent radical erosion of the underlying components of the TES assembly (especially the sensitive plastic components), improve the mean time between cleaning (MTBC) and reduce the cost of consumables (CoC), a barrier seal ring is introduced in the path above the plastic components to block the flow of plasma radicals toward the plastic components of the TES assembly and prevent the plasma radicals from attacking the plastic components. The barrier seal ring is received in a groove defined in the inner sidewall of a base ring (e.g., first ring) adjacent to and surrounding the TES ring (e.g., second ring).

[0025] The various parts (i.e. components) used to enclose the ESC were selected to close any high voltage paths between the ESC and the ground ring. To avoid the risk of arcing and to close the high voltage paths, the various parts were positioned to physically touch each other. For example, the edge ring was connected to the ESC using a thermal gasket. Alternatively, the edge ring was directly connected using an O-ring. The base ring was positioned below a portion of the edge ring. The other portion of the edge ring and the base ring both rested on a ceramic support (i.e., insulator ring) that encloses the ESC. This stacking of parts leaves gaps, especially between the bottom surface of the edge ring and the base ring. The challenge with the edge ring design is that there is no way to close the gap without flexible components. Thermal gaskets and other edge ring connection methods did not provide the necessary flexibility and chemical / mechanical strength because they were as susceptible to plasma radicals as the edge ring.

[0026] The barrier seal ring is designed to provide the necessary flexibility and chemical / mechanical strength to ensure that the passage is completely sealed to preserve the integrity of the plastic parts and other underlying components. The barrier seal ring includes an outer seal leg that extends to an outer diameter equal to the outer diameter of the groove defined in the base ring in which the barrier seal ring is housed, and an inner seal leg that extends to an inner diameter equal to the inner diameter of the groove. The width of the barrier seal ring is sized to ensure that the outer diameter of the barrier seal ring and the inner diameter of the groove in the base ring are in contact at all times, and that the inner diameter of the barrier seal ring and the outer diameter of the adjacent TES ring are in contact. The outer diameter of the barrier seal ring is sized to ensure that the outer diameter of the barrier seal ring is compressed within the base ring during installation, ensuring that the seal is centered and in contact with the inner diameter of the groove in the base ring. The inner diameter of the barrier seal ring is sized to ensure an interference fit with the outer diameter of the TES ring, and is designed to flex to ensure that contact is maintained at all times. The material used to define the barrier seal ring is selected to be resistant to plasma radicals so that the barrier seal ring can be reused. The height of the outer seal leg at the outer diameter is defined to ensure that, at the operating temperature of the plasma chamber, the barrier seal ring does not overfill the height of the groove in the base ring in which it sits. The heights of the outer and inner seal legs of the barrier seal ring and the size of the groove are designed to ensure that the inner seal leg folds into the groove when deflected inward. A chamfer is defined at each outer corner of the barrier seal ring to ensure that the barrier seal ring can be received within the groove in the base ring without interference with the surfaces of the base ring that define the groove or between the inner seal leg and the inner seal leg. It should be noted that the use of the barrier seal ring in the TES assembly is one application of the barrier seal ring, to protect the underlying components from plasma attack.The barrier seal ring concept can be extended for use in fixed locations within plasma chambers other than the TES assembly to prevent the flow of plasma or other gases, or other gaseous by-products, from entering areas that should not receive such flow, and to better seal other areas.

[0027] FIG. 1 is a vertical cross-sectional view of a lower portion (i.e., lower member 102) of a plasma processing chamber (or simply referred to hereinafter as a "plasma chamber") of a process module 100 used in wafer processing according to some implementations. The plasma chamber of the process module 100 is designed to include a barrier seal ring 125 in a TES assembly defined in the plasma chamber to prevent plasma radicals from reaching the lower components of the TES assembly. The plasma chamber in the process module 100 includes an electrode 109, which in some implementations is formed of a conductive element such as aluminum. A ceramic layer 110 is formed on an upper surface of the electrode 109. The ceramic layer 110 is configured to receive and support a wafer W when the wafer W is subjected to a plasma processing operation. In some implementations, the ceramic layer 110, the electrode 109, and associated components define an electrostatic chuck (ESC).

[0028] Power is provided to the ESC from a radio frequency (RF) power source. In one implementation, the RF power source includes one or more RF signal generators that provide power(s) through a matching circuit, such as an impedance matching system (IMS) 140. In the exemplary implementation shown in FIG. 1, the RF power source includes two RF signal generators for providing power to the ESC. Thus, a first RF signal generator 141 is employed to provide RF power at about 60 MHz and a second RF signal generator 142 is employed to provide RF power at about 400 kHz to the electrode 109 through the impedance matching system (IMS) 140. It is defined that the RF power source including the first RF signal generator 141, the second RF signal generator 142, and the IMS 140 represents the main power source of the process module, and the electrode 109 is the main electrode. The RF power provided to the electrode 109 is applied to reactive gases (i.e., gaseous species) introduced into a plasma processing region 180 defined above the ceramic layer 110 to create a plasma for a wafer processing operation, such as etching. An edge ring 112 is defined to surround the ceramic layer 110 and is configured to facilitate expanding the plasma sheath radially outward beyond the periphery of the wafer W to improve process results near the periphery of the wafer W. In addition to the edge ring, ESCs, and RF power source, the lower member of the plasma chamber also includes a cover ring 114 defined adjacent to and surrounding the edge ring 112. The cover ring 114 is made of an insulating material. A gap is introduced adjacent to the edge ring 112 to allow for thermal expansion or mechanical tolerance allowances.

[0029] An adjustable edge sheath (TES) assembly is mounted on the lower member of the plasma chamber to better control the plasma sheath characteristics of the plasma generated in the plasma processing region 180. The TES assembly is disposed below the edge ring 112 to control the plasma sheath characteristics and thereby better control the plasma sheath profile, particularly at the peripheral region of the wafer W. The TES assembly includes a TES electrode (also referred to as an "edge electrode") 158 disposed (embedded) within a TES ring (also referred to herein as a "connecting ring") 150. The TES ring 150 is disposed below a first portion of the edge ring 112 and configured to surround at least a first portion of the electrode 109. In one implementation, an electrically conductive gel 113 or a thermal gasket (not shown) is used to seat the edge ring 112 over a portion of the top of the electrode 109 and the TES (connecting) ring 150. In another implementation, the edge ring 112 is directly attached to the TES ring 150. In other implementations, other mounting means may be engaged to mount the edge ring 112 over a portion of the electrode 109 and the TES ring 150. The ceramic support 118 is disposed below the TES ring 150 and configured to surround a second portion of the electrode 109. An insulating component is embedded within the ceramic support 118 and extends a first defined length from the top surface to the bottom surface of the ceramic support 118. In one implementation, the insulating component is a sleeve 122. In some implementations, the sleeve 122 is made of plastic or ceramic or other insulating material to protect and encapsulate the conductive rod 160. A TES radio frequency (RF) signal generator 154 is engaged to provide RF power to the TES electrode 158 through the TES impedance matching system (IMS) 152. Thus, a first end of the conductive rod 160 is coupled to the TES RF signal generator 154 through the TESIMS 152, and a second end of the conductive rod 160 is coupled to the TES electrode 158. In one implementation, power from a TESRF signal generator 154 is provided to a TES electrode 158 through a TESRF signal filter 156 .RF power generated by the TES RF signal generator 154 is transmitted through the TESIMS 152 and the TES RF signal filter 156 (if available) to the conductive rod 160. The conductive rod 160 extends a second length, which is defined to include the first length of the sleeve 122 within the ceramic support 118 and the length within the TES ring 150 from the bottom surface of the TES ring 150 to the bottom of the TES electrode 158. The TES assembly is used to control the properties of the plasma near the periphery of the wafer W, such as controlling the plasma sheath properties, plasma density, and ion attraction or repulsion. Applying RF power to the TES electrode 158 allows the TES system to tailor the plasma sheath profile at the edge of the wafer to improve radial uniformity.

[0030] The base ring 116 is defined below the second portion of the edge ring 112. The base ring 116 is disposed adjacent to and surrounds a portion of the TES ring 150 and the ceramic support 118 to electrically insulate the components of the TES assembly. In one implementation, the base ring 116 is made of quartz. The groove 117 is defined within a portion of an inner sidewall of the base ring 116 adjacent to the TES ring 150. The location of the groove 117 within the inner sidewall of the base ring 116 is specified to be above a top surface of the ceramic support 118. The groove 117 is defined to extend from a first inner diameter ("FID1") to a second inner diameter ("FID2") of the base ring 116, where FID2 is larger than FID1. The groove 117 is defined to have a dimension suitable to accommodate the barrier seal ring 125. The barrier-seal ring 125 is received within the groove 117 and blocks a path defined by a gap between the TES ring 150 and the base ring 116. The ground ring 120 is defined adjacent to and surrounding at least a portion of the cover ring 114, the base ring 116, and a portion of the ceramic support 118. The barrier-seal ring 125 is also referred to as a "plasma radical edge ring barrier seal" because the barrier-seal ring 125 is used to block a path for plasma radicals to pass through a gap defined between the edge ring and other components of the lower electrode.

[0031] Due to constant exposure to reactive radicals of the plasma, the surface of the edge ring 112 begins to erode. The gap between the edge ring 112 and adjacent components (e.g., the cover ring 114) that is determined by thermal expansion allowance or mechanical tolerance allows a path for the plasma radicals to move and erode weak materials along the way. In some implementations, the TES assembly incorporates a plastic shaft(s) in its design to encapsulate the conductive rod(s). Referring to FIG. 1, without the barrier seal ring 125, the plasma radicals can move along the gaps (e.g., the gap between the edge ring 112 and the cover ring 114, the gap between the edge ring 112 and the base ring 116, the gap between the coupling ring 150 and the base ring 116, etc.) and reach the sleeve 122. The plasma radicals can cause mechanical / material weakening of the sleeve 122, and such erosion can not only shorten the useful life of the sleeve 122 but also damage the conductive rod 160 encapsulated therein. As each process operation erodes the surface of the edge ring 112, the gap between the edge ring 112 and adjacent components widens, allowing radicals to move more freely toward their targets of attack (e.g., the sleeve 122 and the conductive rod 160).

[0032] In some implementations, the barrier seal ring 125 is installed on a portion of the base ring 116 above the sleeve 122 and is used to effectively seal the gap between the base ring 116 and the TES ring 150. The placement of the barrier seal ring 125 adjacent to the outer sidewall of the TES ring 150 prevents plasma radicals from reaching the underlying components of the TES assembly (such as the sleeve 122). Preventing the plasma radicals from traveling beyond the confines of the barrier seal ring 125 ensures that the sleeve 122 is not exposed to plasma radicals and that the integrity of the sleeve 122 (which may be made of plastic) and the conductive rods embedded therein is maintained. Such a configuration improves the mean time between cleanings (MTBC) and reduces the replacement cost of the sleeve 122 (i.e., reduces the cost of consumables (CoC)). Thus, the stored sleeve 122 can be reused multiple times after each cleaning cycle.

[0033] In addition to the lower member 102, the plasma chamber of the process module 100 includes an upper member (not shown) for supplying reactive gases to the plasma processing region 180, and a sidewall that extends between the upper member and the lower member 102 and seals the plasma processing region 180. In some implementations, the lower member 102 also includes an exhaust port through which exhaust gases from the plasma processing operation are removed. In some implementations, the exhaust port may be connected to a vacuum device that provides a suction force to remove the exhaust gases. In some implementations, the plasma chamber in the process module 100 is formed from aluminum. However, in other implementations, the plasma chamber can be formed from essentially any material that provides sufficient mechanical strength, has thermal performance capabilities, and has chemical compatibility with gaseous materials and other materials exposed during plasma processing operations performed in the plasma chamber. At least one sidewall of the plasma chamber includes an opening operated by a door to introduce and remove the semiconductor wafer W into and from the plasma chamber. In some implementations, the door is configured as a slit valve door.

[0034] In some implementations, the semiconductor wafer W is a substrate undergoing a manufacturing procedure. For ease of understanding and discussion, the semiconductor wafer W is hereafter referred to simply as the wafer W. However, it should be understood that in various implementations, the wafer W can be essentially any type of substrate undergoing a plasma-based manufacturing process. For example, in some implementations, the wafer W can be a substrate formed from silicon, SiC, or other substrate material, and can include glass panels / substrates, metal foils, metal sheets, polymeric materials, and the like. Furthermore, in various implementations, the wafer W can vary in form, shape, and / or size. For example, in some implementations, the wafer W can correspond to a circular semiconductor wafer having integrated circuit devices defined thereon. In other implementations, the wafer W can correspond to a non-circular substrate (e.g., rectangular, elliptical, etc.), and the like. Similarly, in implementations where a circular wafer W is being processed, the wafer W can have a variety of diameters, such as 200 mm (millimeters), 300 mm, 450 mm, or other sizes.

[0035] In the plasma chamber of the process module 100, the electrode 109 is formed from aluminum in one implementation. In another implementation, the electrode 109 can be formed from other electrically conductive materials with comparable mechanical strength and suitable thermal and chemical performance characteristics. The ceramic layer 110 is configured to receive and support the wafer W during the performance of a plasma processing operation on the wafer W. In some implementations, the ceramic layer 110 includes a radial arrangement of two or more clamping electrodes (not shown) for generating an electrostatic force that holds the wafer W against the upper surface of the ceramic layer 110 during the plasma processing operation. In one implementation, the ceramic layer 110 includes two clamping electrodes (not shown) that are diametrically opposed to each other and configured to operate bipolarly to provide a clamping force to the wafer W during the process operation. The clamping electrodes are connected to a direct current (DC) power supply configured to generate a controlled clamping voltage to hold the wafer W against the upper surface of the ceramic layer 110. The DC power supply is electrically connected to the clamping electrodes through the ceramic layer 110 and the electrode 109. The DC power supply is connected to a control system (not shown) through one or more signal conductors so that the clamping force provided to the waver W can be controlled by the control system.

[0036] FIG. 2 shows an enlarged perspective view of a base ring 116 incorporating a barrier seal ring 125 in one implementation. A groove 117 is defined on an inner sidewall of the base ring 116. The groove 117 is positioned within the base ring 116 above an upper surface of a ceramic support 118 defined within a lower member 102 of a plasma chamber in a process module 100 (see, for example, FIG. 1). The groove 117 is defined to have an inner sidewall with a top inner radius defined at a top of the inner sidewall and a bottom inner radius defined at a bottom of the inner sidewall. The dimensions and geometry of the barrier seal ring 125 are designed to fit within the dimensions and geometry of the groove 117, allowing the barrier seal ring 125 to be easily and snugly and securely installed in the groove 117. The material of the barrier seal ring 125 is selected to withstand exposure to plasma radicals and is flexible, allowing it to be pressed into place within the groove 117 with the application of appropriate force. The design and flexibility of the barrier seal ring 125 ensures that the gap between the TES ring 150 and the base ring 116 is completely covered, thereby preventing plasma radicals from finding a path to attack the sleeve 122.

[0037] FIG. 3 is an enlarged vertical cross-sectional view of a barrier seal ring 125 used to seal a gap between a TES ring 150 and a base ring 116 of a TES assembly in one implementation. The barrier seal ring 125 is defined by an outer seal leg 126 and an inner seal leg 127. The outer seal leg 126 is defined to extend vertically downward along an outer diameter "OD" by an outer height "h1". In one implementation, the outer height h1 is defined to be about 4.7 mm to about 5.0 mm. In another implementation, the outer height h1 is defined to be about 4.85 mm. In one implementation, the outer seal leg 126 is uniform in thickness along the length of the outer seal leg 126. In one implementation, the thickness of the outer seal leg 126 is defined to be about 1.32 mm to about 1.72 mm. In another implementation, the thickness of the outer seal leg 126 can vary along the length of the outer seal leg 126. The top and bottom outer corners (i.e., corners along the outer diameter) of the outer seal leg 126 are designed to include chamfers (C1, C2). The profile of the chamfers (C1, C2) of the top and bottom outer corners of the outer seal leg 126 is designed to match the profile at the inner radius of the corresponding top and bottom corners of the inner sidewall of the groove 117 in which the barrier seal ring 125 is housed. The profile of the chamfer includes at least the angle and length between adjacent faces. In one implementation, the length of the top outer chamfer C1 is defined to be equal to the length of the bottom outer chamfer C2. In this implementation, the length of the chamfers C1, C2 is defined to be about 0.60 mm to about 1.0 mm. In another implementation, the length of the chamfers C1, C2 is defined to be about 0.8 mm. In other implementations, the length of the top outer chamfer C1 differs from the length of the bottom outer chamfer C2, with the difference in length being determined by the contour of the groove 117 and the inner radii of the top and bottom corners of the interior sidewall of the groove 117. In one implementation, the angles of the top outer chamfer C1 and the bottom outer chamfer C2 are defined as being equal. In some implementations, the angles of the chamfers C1 and C2 are defined relative to the outer diameter of the barrier seal ring (e.g., the angle of inclination of the chamfers C1 and C2 relative to the outer sidewall of the barrier seal ring).In another implementation, the angles of the chamfers C1 and C2 are defined relative to the top surface of the barrier seal ring 125. In some implementations, the angles of the chamfers C1, C2 are defined to be about 45°. In another implementation, the angles of the chamfers C1, C2 are equal but are greater than or less than 45° depending on the profile of the top and bottom corners of the interior sidewall of the groove 117. In one implementation, the top and bottom corners of the interior sidewall of the groove 117 are defined to be right angles. In another implementation, the angle of the top corner of the groove 117 is different from the angle of the bottom corner, and each of the angles of the top and bottom corners is less than 90°. In this implementation, the angle of the top outer chamfer C1 and the angle of the bottom outer chamfer C2 are defined to closely match the angle profile of the top and bottom corners of the interior sidewall of the groove 117, and the angle of the top outer chamfer C1 is different from the angle of the bottom outer chamfer C2.

[0038] The inner seal leg 127 is defined to extend an inner height "h2" from a top portion of the inner surface of the outer seal leg 126. In some implementations, the profile of the inner seal leg 127 is defined to be different from the profile of the outer seal leg 126. In one implementation, the profile of the inner seal leg 127 is angled relative to the top surface, while the profile of the outer seal leg 126 is straight (i.e., perpendicular to the top surface). In one implementation, the inner height h2 of the inner seal leg 127 is defined to be different from the outer height h1 of the outer seal leg 126. In one implementation, the height h2 is less than the height h1. In one implementation, the inner height h2 of the inner seal leg 127 is defined to be about 4.45 mm to about 4.75 mm. In other implementations, the inner height h2 of the inner seal leg 127 is defined to be about 4.6 mm. The inner seal leg 127 is defined by an upper leg portion 128, a lower leg portion 129, and an interface connecting the upper leg portion 128 and the lower leg portion 129. The upper leg portion 128 is connected to an upper portion of the inner surface of the outer seal leg 126 and is oriented at an angle relative to the outer seal leg 126 to define an initial gap 131 between the inner surface of the outer seal leg 126 and the inner surface of the lower leg portion 129 of the inner seal leg 127. In one implementation, the angle at which the upper leg portion 128 extends relative to the inner surface of the outer seal leg 126 is defined as an acute angle. In one implementation, the lower leg portion 129 extends downward from a bottom surface of the upper leg portion 128 such that the inner surface of the lower leg portion 129 extends vertically downward and is substantially parallel (±5%) to the inner surface of the outer seal leg 126. The outer surface of the lower leg portion includes a lower leg top portion and a lower leg bottom portion. The lower leg top portion extends a first leg height "h5" and the bottom leg portion extends a second leg height "h6". In one implementation shown in Figure 3, the outer surface of the lower leg top portion follows the contour of the outer surface of the upper leg portion 128 and the outer surface of the lower leg bottom portion extends vertically downward from the bottom of the lower leg top portion such that it is substantially parallel (±5%) with the inner surface of the outer seal leg 126.It should be noted that the outer and inner seal leg profiles defined herein are exemplary and other profiles are contemplated.

[0039] In one implementation, the thickness of the inner seal leg 127 is uniform throughout the inner height h2. In another implementation, the thickness of the upper leg portion 128 of the inner seal leg 127 is different from the thickness of the lower leg portion 129. In one implementation, the thickness of the upper leg portion 128 is uniform (shown in FIG. 3 ) and the thickness of the lower leg portion 129 is uniform (not shown). However, the thickness of the upper leg portion 128 is greater or less than the thickness of the lower leg portion 129 in some implementations. In another implementation, the thickness of the upper leg portion 128 gradually increases from the top surface to the bottom surface of the upper leg portion 128. Similarly, the thickness of the lower leg portion 129 gradually increases from the top surface to the bottom surface of the lower leg portion 129, with the thickness of the lower leg portion 129 at the top surface being equal to the thickness of the upper leg portion 128 at the bottom surface. As will be appreciated, the barrier seal ring 125 can have a variety of profiles, each profile being defined by, in part, the outer shape and dimensions of the inner seal leg 127 and the outer seal leg 126, the angle at which the upper leg portion 128 is disposed in relation to the inner surface of the outer seal leg 126, the amount of initial gap desired between the outer seal leg 126 and the inner seal leg 127, the profile of the outer surface of the inner seal leg, etc.

[0040] The initial gap 131 can be adjusted by applying a force at the inner seal leg to deflect the inner seal leg toward the outer seal leg. This force is applied during installation of the TES ring 150 in one example. In one implementation, the initial gap 131 is reduced by the inner seal leg deflecting inwardly to define the fold gap 132 (shown in FIG. 5 ). In one implementation, the degree of inward deflection varies between the upper leg portion 128 and the lower leg portion 129. For example, the upper leg portion 128 deflects inwardly less than the lower leg portion 129. In this example, the height h1 does not change when the inner seal leg 127 is bent toward the outer seal leg 126. That is, the top surface of the barrier seal ring 125 is configured not to nudge or protrude upwardly when the inner seal leg 127 is moving toward the outer seal leg 126. Similarly, when the inner seal leg 127 is relaxed (ie, separated) from the outer seal leg 126, the top surface of the barrier seal ring 125 must not collapse.

[0041] The bottom inner corner of the lower leg portion 129 is defined to include a chamfer C3. In one implementation, the length of the chamfer C3 at the bottom inner corner of the inner seal leg 127 is defined to be about 0.4 mm to about 0.6 mm. In another implementation, the length of the chamfer C3 is defined to be about 0.5 mm. In one implementation, the angle of the chamfer C3 is defined to allow the lower leg portion 129, and therefore the inner seal leg 127, to easily flex.

[0042] In one implementation, the angular profile of the inner seal leg 127 results in different widths along the top and bottom surfaces of the barrier seal ring 125. In one implementation, the barrier seal ring 125 extends an upper width "w1" at the top surface and a lower width "w2" at the bottom surface. In one implementation, the upper width w1 is defined to be about 2.4 mm to about 2.8 mm. In another implementation, the upper width w1 is defined to be about 2.65 mm. In one implementation, the lower width w2 is defined to be about 4.2 mm to about 4.6 mm. In another implementation, the lower width w2 is defined to be about 4.4 mm.

[0043] In one implementation, the groove 117 defined on the inner sidewall of the base ring 116 extends from a first inner diameter "FID1" to a second inner diameter "FID2", where FID1 of the groove 117 is smaller than FID2. FID1 of the groove 117 is larger than the inner diameter "ID" of the barrier seal ring 125. Furthermore, in one implementation, FID2 of the groove 117 is equal to the outer diameter "OD" of the barrier seal ring 125. In another implementation, FID2 of the groove 117 is smaller than the OD of the barrier seal ring 125. In this implementation, when the barrier seal ring 125 is installed, a force presses the OD against the inner sidewall of the groove 117. In one implementation, the outer diameter OD of the barrier seal ring 125, the inner diameter ID, the first inner diameter (FID1) and the second inner diameter (FID2) of the groove 117 depend on the size of the ESC. In one implementation, the outer diameter OD of the barrier seal ring 125 is defined to be about 350 mm to about 355 mm. In other implementations, the outer diameter OD of the barrier seal ring 125 is defined to be about 352 mm. In yet other implementations, the outer diameter OD of the barrier seal ring 125 is defined to be about 383 mm to about 387 mm. In some implementations, the outer diameter OD of the barrier seal ring 125 is defined to be about 385.5 mm.

[0044] The interface defined between the upper leg portion 128 and the lower leg portion 129 of the inner seal leg 127 is configured to allow the inner seal leg 127 to flex inwardly toward the inner surface of the outer seal leg 126. During installation, a force "F" is applied along the inner diameter ID of the barrier seal ring 125 (i.e., at the outer surface of the lower leg portion 129) and the design and materials used for the barrier seal ring 125 can cause the inner seal leg 127 to flex and fold inwardly into the initial gap 131 and toward the outer seal leg 126. In one implementation, the extent to which the inner seal leg 127 can fold is limited to a fold angle. The fold angle, in one implementation, is defined to maintain a fold gap 132 between the tip of the outer seal leg 126 and the inner surface of the inner seal leg 127. The fold gap 132 is smaller than the initial gap 131 and is defined in one implementation such that deflection of the inner seal leg 127 does not cause interference with the parts / surfaces of the outer seal leg 126 and the groove 117, the surface of the base ring 116. In another implementation, the inner seal leg 127 can be folded such that the bottom inner corner of the inner seal leg 127, where the chamfer C3 is defined, abuts the inner wall of the outer seal leg 126 without leaving a fold gap 132. The degree to which the inner seal leg 127 can be folded is defined to ensure that a sufficient amount of the inner seal leg extends toward the TES ring 150 to close the gap between the TES ring 150 and the base ring 116. Force is applied to the barrier seal ring 125 during installation to ensure that the barrier seal ring 125 is properly seated in the groove 117 and that the outer surface of the outer seal leg 126 fits perfectly against the inner sidewall of the groove 117. In one implementation, the term "full fit" is defined by the length of the outer wall of the outer seal leg 126 being fully abutted against the length of the inner sidewall of the groove 117. The chamfers C1, C2 further aid in positioning the barrier seal ring 125 within the groove 117, and the chamfer C3 aids in flexing of the inner seal leg 127.

[0045] 4 illustrates additional features of the barrier seal ring 125 in one implementation. As shown, the inner seal leg 127 includes an upper leg portion 128 and a lower leg portion 129. The upper leg portion 128 extends downward from a top surface of the barrier seal ring 125 by a height "h3", and the lower leg portion 129 extends downward from a bottom surface of the upper leg portion 128 by a height "h4". In this implementation, the heights (h3, h4) of the upper leg portion 128 and the lower leg portion 129 together define an inner height "h2" of the inner seal leg 127. In one implementation, the height h4 of the lower leg portion 129 is defined such that there is enough space in the initial gap 131 to accommodate the folded lower leg portion 129 without touching (i.e., contacting) the outer seal leg 126. This deflection allows a portion of the lower leg portion 129 to be received in the groove 117 while ensuring that the inner seal leg 127 of the barrier seal ring 125 completely fills the gap between the TES ring 150 and the base ring 116. The length and angle of the inner corner chamfer C3 allows the lower leg portion 129 to easily fold into the initial gap 131 without interfering with the lower outer corner of the groove 117 while extending outward to fill the gap between the TES ring 150 and the base ring 116. Without the inner corner chamfer C3, the degree to which the outer seal leg 127 can be bent may be limited by one or more of the thickness of the lower leg portion 129 of the outer seal leg 127, the outer and outer seal leg heights h1, h2, and the height of the groove 117. In other words, the bottom surface of the outer seal leg 127 may hit the lower outer corner of the groove 117, preventing the barrier seal ring from being fully seated in the groove 117 during installation. Further, in one implementation, the heights (h3, h4) of the upper and lower leg portions (128, 129) and the degree of deflection of the lower leg portion 129 are determined to ensure that the lower leg portion 129 does not exceed the outer height h1 of the outer seal leg 126 when folded. In one implementation, the heights (h3, h4) of the upper and lower leg portions (128, 129) depend on the angle at which the upper leg portion 128 is disposed relative to the inner surface of the outer seal leg 126.In one implementation, the height h3 of the upper leg portion 128 is greater than the height h4 of the lower leg portion 129. In another implementation, the height h3 of the upper leg portion 128 is equal to or less than the height h4 of the lower leg portion 129. In one implementation, the height h3 of the upper leg portion 128 is defined to be about 2.5 mm to about 2.7 mm. In another implementation, the height h3 of the upper leg portion 128 is defined to be about 2.62 mm. In one implementation, the height h4 of the lower leg portion 129 is defined to be about 1.85 mm to about 2.05 mm. In another implementation, the height h4 of the lower leg portion 129 is defined to be about 1.95 mm. In one implementation, the angle at which the upper leg portion 128 extends from the inner surface of the outer seal leg 126 is defined by "α°", where α° is an acute angle. In one implementation shown in FIG. 4, α° is about 24°. In another implementation shown in FIG. 5, α° is about 20°.

[0046] The interface represents the interface between the upper leg portion 128 and the lower leg portion 129. In one implementation, the interface is located at a height h3 (i.e., the height of the upper leg portion 128) from the top surface of the barrier seal ring 125. This interface allows the inner seal leg 127 to flex inwardly when a force F is applied to the outer surface of the lower leg portion 129.

[0047] FIG. 5 illustrates different position profiles of the barrier seal ring in one implementation. The inner seal leg 127 is represented in both solid and dashed lines. The inner seal leg 127 represented in solid lines corresponds to the barrier seal ring 125 when in a relaxed position, and the dashed lines correspond to a deflected position. The barrier seal ring 125 is moved to a deflected position by applying a force "F" to the outer surface of the lower leg portion 129 when the TES ring 150 is seated adjacent to the inner diameter of the barrier seal ring 125 housed within a groove 117 defined in the base ring 116. In the implementation illustrated in FIG. 5, the upper leg portion 128 of the barrier seal ring 125 is oriented at an angle α° relative to the inner surface of the outer seal leg 126, where α° is defined to be an acute angle. When the force F is applied, the inner seal leg 127 is pushed inward toward the outer seal leg 126. As a result, the upper leg portion 128 and the lower leg portion 129 are pushed inward. In one implementation, the amount that the upper leg portion 128 is pushed inward is less than the amount that the lower leg portion 129 is pushed inward. The degree to which the upper leg portion 128 and the lower leg portion 129 of the inner seal leg 127 are deflected is limited by the interface. In one implementation, the angled profile of the inner seal leg 127 causes the upper leg portion 128 of the inner seal leg 127 to be pushed inward (i.e., deflect) by a first fold angle "a°", while the lower leg portion 129 of the inner seal leg 127 is deflected / pushed inward by a second fold angle "A°". In one implementation, the first fold angle a° of the upper leg portion 128 is less than the second fold angle A° of the lower leg portion 129. In another implementation, the first fold angle a° of the upper leg portion 128 is equal to the second fold angle A° of the lower leg portion 129. In one implementation, the first fold angle a° of the upper leg portion 128 is less than the angle α° at which the upper leg portion 128 is disposed relative to the inner surface of the outer seal leg 126. In one implementation, the second fold angle A° of the lower leg portion 129 is greater than the angle α° at which the upper leg portion 128 is disposed relative to the inner surface of the outer seal leg 126.In another implementation, the second fold angle A° of the lower leg portion 129 is less than or equal to the angle α° at which the upper leg portion 128 is disposed relative to the inner surface of the outer seal leg 126 . In some implementations, a first and second fold angle (a°, A°) at which the upper and lower leg portions (128, 129) can be deflected / pushed is determined based on a height h3 of the upper leg portion 128, a height h4 of the lower leg portion 129, an initial angle α° at which the upper leg portion 128 extends from an inner surface of the outer seal leg 126, an amount of initial gap 131 defined between the inner seal leg 127 and the outer seal leg 126 when the barrier seal ring 125 is in a relaxed position, an amount of fold gap 132 that needs to be left between the inner seal leg 127 and the outer seal leg 126 when the barrier seal ring 125 is in a deflected position, and an amount of force F applied to the outer surface of the lower leg portion 129. The fold gap 132 is determined to prevent interference between the outer seal leg 126 and the inner seal leg 127. Additionally, the first and second fold angles and the dimensions of the outer seal leg 126 and the inner seal leg 127 (i.e., upper leg portion 128, lower leg portion 129) are dimensioned to ensure that there is no interference between the surface of the barrier seal ring 125 and the surfaces of the groove 117 and the base ring 116. In one implementation, interference, as used herein, refers to the amount or degree to which the outer seal leg is prevented from bending, for example, by a lower outer corner of the groove 117, thereby preventing the outer seal leg from being forced into a position within the groove 117. Additionally, the first and second fold angles, the height h3 of the upper leg portion 128, and the height h4 of the lower leg portion 129 are all dimensioned to ensure that the lower leg portion 129 does not exceed the outer height h1 of the outer seal leg 126 when in the flexed position.

[0048] It should be noted that the design, dimensions, and materials used to define the barrier seal ring 125 are all provided as examples and should not be considered exhaustive or limiting. Additionally, it should be noted that the use of the term "about" in defining the various dimensions (length and angle) of the barrier seal ring 125 may include a variation of ±10-15% of the listed dimensions. In one implementation, the barrier seal ring 125 is made from a material that is not susceptible to attack by fluorine and / or other reactive components of plasma radicals and is flexible to be pressed into position within the groove of the base ring 116 so that the barrier seal ring 125 can be reused in multiple operations. In some implementations, the barrier seal ring 125 is made from polytetrafluoroethylene (PTFE) or perfluoroelastomer (FFKM) materials. In another implementation, the barrier seal ring 125 may be made from the same or similar material as O-rings used in plasma chambers to prevent leakage of gases and fluids. The barrier seal ring 125 is not limited to the aforementioned materials, but may be made of any other material with the same or comparable thermal and chemical properties.

[0049] In one implementation, the barrier seal ring 125 may be subjected to annealing to maintain its original size when placed in the groove. The environment in the plasma chamber in which the barrier seal ring 125 is used may change based on the operation being performed. As a result, the barrier seal ring 125 may shrink, and the barrier seal ring 125 may not be able to prevent plasma radicals from flowing towards and attacking the underlying parts, such as insulating (plastic) parts. To prevent affecting the size and shape of the barrier seal ring 125 when used in the plasma chamber, the barrier seal ring is subjected to an annealing process before being placed in the groove 117 of the base ring 116. By undergoing annealing, the outer shape of the barrier seal ring 125 is maintained during use, which ensures that the function of the barrier seal ring 125 is not adversely affected by the conditions in the plasma chamber. The annealing process allows the barrier seal ring to retain its structure and size. The temperature and time used for annealing depend on the material used, and the aforementioned temperature and time ranges are provided as examples and should not be considered limiting.

[0050] 6 is a side view of a top perspective view of a plasma radical edge ring barrier seal 125 that can be used in a plasma chamber. The barrier seal 125 is ring-shaped and is therefore also referred to as a "barrier seal ring" 125 throughout this application. The barrier seal ring 125 is configured to be incorporated into a groove 117 defined on an inner surface of a base ring 116 disposed below an edge ring 112 that surrounds an electrostatic chuck that is part of the lower electrode of a plasma chamber of a process module 100. The barrier seal ring 125 is used to seal a gap between the base ring 116 and an adjustable edge sheath (TES) ring 150 that is part of a TES assembly disposed below the edge ring 112, and the TES assembly is used to provide power to control the plasma sheath profile on the edge ring 112. Although various implementations have been described with reference to the barrier seal ring 125 sealing the gap between the base ring 116 and the TES ring 150, the barrier seal ring 125 can also be used to seal gaps between the edge ring 112 and the cover ring 114, between the edge ring 112 and the base ring 116, between the cover ring 114 and the base ring 116, etc.

[0051] FIG. 7 is a side view of a barrier seal ring 125 configured to seal the gap between the base ring 116 and other components disposed below the edge ring 112.

[0052] Figure 8 is a top view of the barrier seal ring 125 and Figure 9 is a bottom view of the barrier seal ring 125 used in a plasma chamber. A more detailed view of the barrier seal ring 125 is shown and described with reference to Figures 10A and 10B.

[0053] Figure 10A is a side view of the barrier seal ring 125, showing the position where an enlarged cross-sectional view of the barrier seal ring is provided in Figure 10B. Referring simultaneously to Figures 10A and 10B, the barrier seal ring 125 includes a pair of legs, an outer seal leg 126 defined at an outer diameter OD and including a sidewall having chamfers (C1, C2) defined at a top and bottom surface of the sidewall, and an inner seal leg 127 defined to extend to an inner diameter ID and includes an upper leg portion 128 and a lower leg portion 129. The upper leg portion 128 extends at an angle from a top of the outer seal leg 126 to define an initial gap 131 between the outer seal leg 126 and the inner seal leg 127. An interface 130 is defined between the upper leg portion 128 and the lower leg portion 129, and is configured to allow the inner seal leg 127 to flex inwardly toward the outer seal leg 126 at the interface 130. The flexure of the inner seal leg 127 is limited to define a fold gap 132 between the outer seal leg 126 and the inner seal leg 127. The fold gap 132 is to ensure that the outer seal leg 126 and the lower leg portion 129 of the inner seal leg 127 do not come into contact. The flexure allows the barrier seal ring 125 to fit snugly within the groove 117, maximizing the height h1 of the outer seal leg 126 and minimizing the clearance of the base ring 116 within the groove 117. Additionally, the outer height h1 of the outer seal leg 126 is dimensioned to ensure that the barrier seal ring 125 does not overfill the height of the groove when the barrier seal ring 125 is exposed to temperatures in the plasma chamber. The outer diameter OD of the barrier seal ring 125 is dimensioned to ensure that sealing compression occurs during installation to allow reuse and easy installation of the barrier seal ring 125. The chamfers (C1, C2) on the outer corners of the outer seal leg 126 ensure that the barrier seal ring 125 fits perfectly against the inner surface of the groove 117 during installation (i.e., the chamfers C1, C2 abut the length of the inner sidewall of the groove 117 except for the defined top and bottom outer corners).The chamfer C3 on the inner corner of the lower leg portion 129 of the inner seal leg 127 allows the inner seal leg 127 to easily flex without contacting the outer corner of the groove 117 of the base ring 116 (i.e., the lower outer corner facing the TES ring 150). Without the chamfer C3, in some instances, flexing of the inner seal leg 127 may damage the barrier seal ring 125 at the inner corner of the inner seal leg 127 or make it difficult to push the inner seal leg 127 inward. The lower width w2 of the barrier seal ring 125 is set to ensure contact between the barrier seal ring 125 and the TES ring 150 and to close the gap between the TES ring 150 and the base ring 116. The inner height h2 is set to provide a space for the inner seal leg 127 to be folded into the groove 117.

Claims

1. 1. A barrier seal ring for a plasma chamber, comprising: an outer seal leg extending vertically downwardly at an outer diameter, the outer seal leg having upper and lower chamfers on an outer surface thereof; an inner seal leg connected to an upper portion of the outer seal leg, the inner seal leg being oriented at an angle to the outer seal leg and including an upper leg portion and a lower leg portion, the lower leg portion of the inner seal leg forming an initial gap of a first distance with the outer seal leg; the lower leg portion is configured to deflect toward the outer seal leg and form a second gap less than the first distance of the initial gap but greater than zero; A barrier seal ring, the barrier seal ring being seated in a groove in a first ring and configured to seal when the inner seal leg is pressed against a second ring, the first ring and the second ring being part of the plasma chamber.

2. 2. The barrier seal ring of claim 1, wherein the inner seal leg is oriented at an acute angle relative to the outer seal leg; A barrier seal ring, wherein the first ring is a base ring disposed below an edge ring surrounding a substrate support surface disposed at the bottom of the plasma chamber, and the second ring is a connecting ring that is part of a adjustable edge sheath (TES) assembly disposed adjacent to and surrounded by the base ring.

3. 2. The barrier seal ring of claim 1, wherein an interface within the inner seal leg connects the upper leg portion and the lower leg portion, the inner seal leg deflecting inwardly along the interface, the degree of deflection being different for each of the upper leg portion and the lower leg portion.

4. 4. The barrier seal ring of claim 3, wherein the upper leg portion is deflected at a first fold angle and the lower leg portion is deflected at a second fold angle, the first fold angle being less than the second fold angle.

5. 4. The barrier seal ring of claim 3, wherein an inner surface of the lower leg portion extends vertically downward and is parallel to an inner surface of the outer seal leg; a barrier seal ring, wherein an outer surface of the lower leg portion includes a top and a bottom, the top extending a first height to follow the contour of the outer surface of the upper leg portion and the bottom extending vertically downward a second height to an inner diameter of the barrier seal ring.

6. 4. The barrier seal ring of claim 3, wherein the outer seal leg at the outer diameter extends a first height and the inner seal leg extends a second height to the inner diameter, the first height being greater than the second height; a barrier seal ring, wherein the upper leg portion extends a third height and the lower leg portion extends a fourth height, the third height and the fourth height defining the second height of the inner seal leg.

7. 10. The barrier seal ring of claim 1, wherein the inner seal leg has an inner chamfer defined in an inner surface.

8. 2. The barrier seal ring of claim 1, wherein the profiles of the upper and lower chamfers match the profiles of corresponding inner radii of top and bottom corners of an inner sidewall of the groove of the first ring.

9. 10. The barrier seal ring of claim 1, wherein a top width of the barrier seal ring is less than a bottom width of the barrier seal ring.

10. 2. The barrier seal ring of claim 1, wherein the groove is defined on an inner sidewall of the first ring disposed in the lower portion of the plasma chamber, the groove extending inwardly from a first inner diameter to a second inner diameter; a second inner diameter of the groove of the first ring equal to the outer diameter of the barrier seal ring, and the upper and lower chamfers of the outer seal leg of the barrier seal ring are defined to fully fit the outer seal leg at the outer diameter against the inner side wall of the groove defined in the first ring.

11. 2. The barrier seal ring of claim 1, wherein a height of the groove defined in the first ring is equal to a first height of the outer seal leg at the outer diameter.

12. 11. The barrier seal ring of claim 10, wherein the first ring and the second ring are part of a adjustable edge sheath (TES) assembly defined within a lower portion of the plasma chamber, the TES assembly comprising: a first ring disposed below a first portion of an edge ring surrounding an electrostatic chuck (ESC) disposed centrally in a lower portion of the plasma chamber; a second ring disposed below a second portion of the edge ring, the second ring including a coupler embedded within the second ring and proximate a top surface of the second ring; a ceramic support element disposed below the second ring and surrounding the ESC, the ceramic support element including a sleeve housed in a vertical shaft extending the height of the ceramic support element, the sleeve being an insulating component configured to enclose a conductive rod; a radio frequency (RF) power source having a matching network; a first end of the conductive rod coupled to the RF power source through the matching network and a second end of the conductive rod coupled to the coupler embedded in the second ring, the conductive rod extending through the insulating piece to a base of the coupler in the second ring, and configured to transfer power from the RF power source to the edge ring to affect a sheath profile of a plasma generated in a plasma processing region of the plasma chamber and extending to the edge ring.

13. 13. The barrier seal ring of claim 12, wherein a second RF power source is coupled to the ESC through a second matching network to provide power to the ESC to generate the plasma in the plasma processing region.

14. 10. The barrier seal ring of claim 1, wherein the barrier seal ring is annealed during use to prevent shrinkage of the barrier seal ring.

15. 10. The barrier seal ring of claim 1, wherein the barrier seal ring is made from a polytetrafluoroethylene or perfluoroelastomer material.

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