Grounding features for wafer processing equipment

Abstract

A process chamber used for processing multiple wafers includes a plurality of grounding features distributed uniformly to establish electrical connection between an upper chamber body and a lower chamber body. The grounding features are defined along each chamber rib that extends inward from a lateral sidewall of the chamber wall. The chamber ribs extend between adjacent pair of wafer processing stations defined in the lower chamber body of the process chamber. The electrical connection established between the upper and the lower chamber bodies defines a symmetric return path to ground for an electrical current flowing in the process chamber.

Description

GROUNDING FEATURES FOR WAFER PROCESSING EQUIPMENTBACKGROUND1. Field of the Invention

[0001] The present embodiments relate to semiconductor wafer processing equipment tools, and more particularly, to multi-station process chambers with grounding features to provide additional return paths to ground for an electrical connection established between a top portion and a bottom portion of the process chamber in order to improve electric field uniformity above the wafer.2. Description of the Related Art

[0002] In semiconductor processing, a wafer undergoes various operations to form features that define integrated circuits (IC). The wafer is received on a pedestal disposed in a lower portion of a process chamber. The pedestal provides a supporting surface to receive and reliably hold the wafer in place during process operations. Some of the operations performed on the wafer include deposition, etching, cleaning, etc. With respect to deposition, the wafer can undergo different types of depositions. One example deposition process is a plasma-enhanced chemical vapor deposition (PECVD) that uses plasma to deposit thin films on a surface of the wafer. In the plasma deposition, a gas chemistry is applied to the surface of the wafer (i.e., solid state) to deposit thin films. Another example of deposition process is an atomic layer deposition (ALD), which also uses plasma to deposit very thin films. In the ALD, volatile gases, solids or vapors are sequentially introduced over the surface of a heated wafer. A first precursor is introduced onto the surface of the wafer, where the first precursor is absorbed. The first precursor is then cleared and a second precursor is introduced onto the surface of the wafer. The second precursor reacts with the first precursor to define a layer of thin film. The second precursor is then removed from the chamber and the process of introducing the first precursor followed by the second precursor is repeated to define additional layers of thin film, one layer at a time.

[0003] Chambers used for performing various deposition operations require reliable and precision-based structural condition so that the layers deposited on the surface are uniform, leading to consistency in device performance and higher yield. However, the current process chambers have non-uniformity issues in relationto on-wafer thickness data, which can partly be attributed to non-uniformity in electrical field over the wafer. The non-uniformity in the electrical field translates on to the layers deposited on the surface of the wafer. Due to non-uniform electrical field over the wafer, the layers deposited can develop a tilt that is usually directed toward a grounding feature. In the cases where the grounding feature is disposed in the center of the lower chamber portion, the tilt is directed toward the center. The tilting of the layers are inconsistent and cannot be repeated.

[0004] It is in this context that embodiments of the invention arise.SUMMARY

[0005] Various implementations describe plasma process chamber that is used for processing semiconductor wafers. The process chamber is a multi-station process chamber and includes a symmetric return path to ground for an electrical current flowing between an upper chamber portion and a lower chamber portion of the process chamber. The symmetric return path to ground is defined by a plurality of actuated grounding features, such as a radio frequency (RF) fin, disposed between any pair of adjacent wafer processing stations of the multi-station process chamber. The symmetric return paths defined by the actuated grounding features are in addition to a return path defined by electrically grounded chamber walls of the process chamber. The symmetric return paths to ground are activated during process operation (e.g., thin film deposition operation, etc.), so as to electrically connect the upper chamber portion and the lower chamber portion. The symmetric return paths defined by the actuated grounding features ensure uniform electric field is maintained over the surface of the wafer, during wafer processing within the process chamber. As the grounding features (i.e., RF fin) provide the symmetric return paths, the grounding features are also referred to as “symmetry fins”.

[0006] The process chamber includes an upper chamber body in the upper chamber portion and a lower chamber body in the lower chamber portion. The upper chamber body is designed to include a showerhead for providing process gases over the surface of wafers. The lower chamber body is configured to include a plurality of wafer processing stations with each wafer processing station providing a wafer holding surface for receiving and holding a wafer during processing. In some implementations, the wafer processing station can be a pedestal (e.g., an electrostastic chuck). An outer boundary of the lower chamber body includes a chamber wall defined by a plurality of lateral sidewalls enclosing the wafer processing stations. Insome implementations, a chamber rib extends inward from a center of each lateral sidewall of the lower chamber body, such that it separates a corresponding pair of adjacent wafer processing stations. In other implementations, a chamber rib may extend inward to align with a center of each lateral sidewall but be separated from the lateral sidewall by a gap of predefined length. Each chamber rib includes a housing in which a grounding feature is disposed. In one implementation, each grounding feature is coupled to and operated by a distinct actuator. In alternate implementations, two or more of the plurality of grounding features are coupled to and operated by a single actuator. When the actuator coupled to the grounding feature is actuated (i.e., activated) during processing, the grounding feature is extended out of the housing to form a capacitive connection or an inductive connection between the upper and the lower chamber bodies. The electrical connection (either capacitive or inductive connection) established by the grounding features define additional paths to ground for the electrical current. The additional paths to ground for the electrical current improve the electric field uniformity over the surface of each wafer received on the wafer holding surface defined in the lower chamber body. Each grounding feature includes additional features, such as a chamfer edge, in a bottom portion, so as to increase surface contact area of the grounding feature and to better control the height to which the grounding feature can extend out of the housing to establish the electrical current return path between the upper chamber body and the lower chamber body.

[0007] After a wafer has been processed in one wafer processing station, the wafer may be moved to a different wafer processing station for further processing to define features. When the wafer is to be moved, the actuator is deactivated causing the actuator to retract the grounding feature into the housing. Once the grounding feature is moved out of the way, a wafer transfer mechanism moves the wafer unhindered around to the different wafer processing station. The process of moving the wafer to a different wafer processing station and performing wafer process operations continue till the features are formed. The features formed on the wafer surface using the process chamber equipped with additional grounding features, exhibit uniform thickness and are fairly evenly balanced (i.e., without any noticeable tilt).

[0008] In one implementation, a process chamber used for processing a plurality of wafers, is disclosed. The process chamber includes an upper chamber body and a lower chamber body. The upper chamber body includes a showerheadthat is configured to supply deposition gases to top surfaces of the plurality of wafers received in the process chamber. The lower chamber body includes a plurality of wafer processing stations. Each wafer processing station includes a wafer holding surface that is configured to receive and hold wafer for processing. The lower chamber body includes a chamber wall defining an outer boundary and having a plurality of lateral sidewalls. A chamber rib is located centrally and extend inwardly between a pair of adjacent wafer processing stations. A housing is defined within the chamber rib for storing a grounding feature. The grounding feature is configured to move between a raised position (i.e., extended state), when activated, and a retracted position (i.e., retracted state), when deactivated. The grounding feature provides an electrical current return path along the chamber rib for an electrical connection established between the upper chamber body and the lower chamber body. The grounding feature provides an electrical current return path to ground for the electrical current along the chamber rib disposed between an adjacent pair of wafer processing stations of the plurality of wafer processing stations, when the grounding feature is moved to the raised position.

[0009] In another implementation, a process chamber used for processing a plurality of wafers, is disclosed. The process chamber includes an upper chamber body and a lower chamber body. The upper chamber body is defined in an upper portion and includes a showerhead that is configured to supply deposition gases to top surfaces of the plurality of wafers received within the process chamber. The lower chamber body is defined in a lower portion and includes a plurality of wafer processing stations. Each wafer processing station includes a wafer holding surface for receiving a wafer for processing. The lower chamber body includes, an outer boundary defined by a chamber wall having a plurality of lateral sidewalls. A chamber rib extends inward for a first length from a center of each lateral sidewall. The chamber rib has a groove that extends along the chamber rib for a second length. A recess is defined in the center of each lateral sidewall of the lower chamber body and is aligned with the groove of the chamber rib. The recess provides a housing that is configured for storing a grounding feature that is configured to move between an installed position and a retracted position and is used for providing a return path, along the chamber rib, for an electrical connection established between the upper chamber body and the lower chamber body, when the grounding feature is moved to the installed position. An actuator is coupled to the grounding feature. The actuator,when activated, is configured to move the grounding feature to the installed position by sliding the grounding feature out of the housing in the recess and along the groove of the chamber rib and extending out of the groove, and, when deactivated, is configured to move to the retracted position by retracting the grounding feature into the groove and sliding along the groove back into the housing in the recess within the lateral sidewall of the plurality of lateral sidewalls.

[0010] In another implementation, a process chamber for processing a plurality of wafers, is disclosed. The process chamber includes an upper chamber body and a lower chamber body. The upper chamber body has a showerhead defined within. The showerhead is configured to supply deposition gases to top surfaces of the plurality of wafers received within the process chamber. The upper chamber body has an upper outer boundary defined by an upper chamber wall. The upper chamber wall is defined by a plurality of upper lateral sidewalls. The lower chamber body has a plurality of wafer processing stations with each wafer processing station having a wafer holding surface for receiving a wafer of the plurality of wafers, for processing. The lower chamber body has a lower outer boundary defined by a lower chamber wall. The lower chamber wall is defined by a plurality of lower lateral sidewalls. A plurality of grounding features is distributed within the process chamber. Each grounding feature is configured to move between a raised position and a retracted position and is used to provide a return path to ground for an electrical connection established between the upper chamber body and the lower chamber body, when the grounding feature is moved to the raised position.

[0011] In yet another implementation, a process chamber for processing a plurality of wafers, is disclosed. The process chamber includes an upper chamber body defining an upper portion of the process chamber and a lower chamber body defining a lower portion of the process chamber. The lower chamber body has a pair of wafer processing stations and a rib extending between the pair of wafer processing stations. A grounding feature is housed within the rib and is configured to move between a retracted state and an extended state relative to the rib. The grounding feature establishes an electrical current return path between the upper chamber body and the lower chamber body and along the rib, when the grounding feature is in the extended state.

[0012] In another implementation, a grounding feature for use in a process chamber used for processing a plurality of wafers, is disclosed. The groundingfeature includes an upper portion that extends for a first width, a lower portion that extends for a second width, and a chamfer edge disposed between the upper portion and the lower portion. The grounding feature is disposed in a first portion of the process chamber and is configured to move between an extended state and a retracted state. The grounding feature establishes an electrical current return path between the first portion and a second portion of the process chamber, when the grounding feature is moved to the extended state.

[0013] Other aspects will become apparent from the following detailed description, taken in conjunction with the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 illustrates a simplified high level block diagram of a semiconductor plasma process chamber that is used for processing a plurality of wafers received therein, in accordance with one implementation.

[0015] Figure 2 illustrates an overhead view of a multi-station process tool used for processing the plurality of wafers, in accordance with one implementation.

[0016] Figures 3 A-3D illustrate a simplified vertical cross-sectional view of a chamber rib extending out of a lateral sidewall of a bottom plate with a housing for accommodating a grounding feature and at least a portion of an actuator used for moving the grounding feature in and out of the housing, in accordance with some implementations.

[0017] Figure 4 illustrates a top perspective view of a multi-station process module showing the grounding features extending out of the respective housings, in some implementations.DESCRIPTION

[0018] Embodiments of the disclosure illustrate examples of a multistation process chamber that is used to process a plurality of wafers simultaneously. The multi-station process chamber includes an upper chamber body and a lower chamber body. The upper chamber body includes a showerhead that is designed to provide process gas(es) to top surfaces of wafers received within the process chamber. The lower chamber body includes a plurality of wafer processing stations. In some implementations, the multi-station process chamber is a quad-station module (QSM) that includes four wafer processing stations. In some implementations, the multistation process chamber is a dual-station module (DSM) having two wafer processing stations. In other implementations, the plurality of wafer processing stations includedin the multi-station process chamber is not restricted to include two or four wafer processing stations but can include any number of wafer processing stations that is greater than 2 and different from 2 or 4 wafer processing stations. A plurality of grounding features is defined in the lower chamber body. A grounding feature is defined between each pair of adjacent wafer processing stations and is configured to move between a raised position and a retracted position. The grounding features, when moved to the raised position, extend out of the housing and establish electrical current return path between the upper chamber body and the lower chamber body. The additional return paths result in establishing a more uniform electrical field over the surfaces of the wafers received on the wafer processing stations.

[0019] Conventional process chambers used a single grounding rod in the center of the lower chamber body or had the grounded chamber wall defining the outer boundary of the process chamber. Either cases led to non-uniformity of the electrical field over the wafer surfaces, which could be attributed to varying distance of the different sections of the wafer surface to the grounding / grounded component, such as the chamber wall or the central grounding rod. As a result, the mass of the layers deposited over the wafer surface tilted toward the grounding / grounded component (i.e., tilt toward the center in the case of the central grounding rod or the outside boundary in the case of the outside boundary of the bottom plate) leading to uneven thickness in the layers due to the tilt leading to devices with non-uniform structure. The tilting of the layers is inconsistent and cannot be replicated.

[0020] To avoid the tilting and to improve the uniformity of layers formed on the surfaces of the wafers, the lower chamber body of a multi-station process chamber is designed to include additional grounding features, wherein each additional grounding feature is defined between adjacent pair of wafer processing stations. The additional grounding features establish a tighter boundary condition around each wafer processing station defined in the lower chamber body by providing additional symmetrical grounding paths for the electrical connection established between the upper chamber body and the lower chamber body. The symmetrical grounding paths established by the grounding features improve uniformity of the electrical field over the surfaces of the wafers, eliminate or at least substantially reduce the tilt in the layers formed on the surface of the wafers to define devices, leading to uniformity in the thickness of the layers formed on the wafer surface that can be repeated.Uniformity of the features leads to improved device performance thereby improving device yield.

[0021] It should be appreciated that the present embodiments can be implemented in numerous ways, such as a process, an apparatus, a system, a device, or a method. Several embodiments are described below.

[0022] Figure 1 illustrates a simplified block diagram of a substrate processing system 100, which is used to process a plurality of wafers 101. The substrate processing system 100 shown depicts a portion of a multi-station process chamber, wherein the number of stations can be 2, 4 or any number greater than 1. In the substrate processing system 100 of Figure 1, a portion of chamber 102 is shown. The portion of chamber 102 includes an upper chamber body 102a and a lower chamber body 102b. A wafer processing station (e.g., a pedestal) 320 is disposed in the portion of the lower chamber body 102b. The wafer processing station 320 includes a wafer support surface configured to receive and support a wafer 101 received for processing. In one implementation, the wafer processing station (e.g., pedestal) 320 is a powered electrode. Consequently, the wafer processing station 320 is electrically coupled to a power and control circuitry, which includes at least a power source (not shown), such as a radio frequency (RF) power supply, (e.g., RF generators), a wafer transfer mechanism, and a controller to control the various process parameters (e.g., power levels, timing parameters, type, combination and a flow rate of process gases, and the movement of the wafer). As the process chamber is a multi-station process chamber with a plurality of wafer processing stations, each of the wafer processing stations is electrically coupled to the power and control circuitry. Where the power source used to power the wafer processing station 320 is a RF power supply, the power and control circuitry also includes a corresponding match network to couple the RF power supply to the wafer processing station 320. The process parameters are used to control deposition of layers (i.e., to form films) over the surface of the wafer 101 via one of the deposition methods (e.g., ALD method, PECVD method, etc.).

[0023] The upper chamber body 102a includes a showerhead 150 that is coupled to one or more gas sources and is configured to supply process gas(es) to a process region defined between a bottom surface of the showerhead 150 and a top surface of each wafer processing station 320. Appropriate valving and mass flow control mechanisms may be employed to control a type, combination and flow rate ofthe gases that are delivered during the deposition and plasma treatment phases of the process and to draw the gases out of the process region.

[0024] Figure 2 illustrates a simplified overhead view of a multi-station processing system 100, wherein four wafer processing stations 320a-320d are provided to allow simultaneous processing of 4 wafers. This top view is of the lower chamber body 102b (e.g., with the top chamber body 102a removed for illustration). The chamber with the four wafer processing stations is also referred to as a Quad- Station Module (QSM). The wafer processing stations (320a-320d) can be accessed using a wafer transfer mechanism, such as a spindle 342, with wafer supporting components, such as paddles (not shown). The spindle 342 is disposed in the center and is configured to move up and down along a vertical axis and rotate along a horizontal axis. The spindle 342 with the paddles are capable of transporting multiple wafers simultaneously. The paddles include end-effectors that are configured to hold and support the wafers as the wafers are simultaneously moved to the different wafer processing stations (320a-320d) so that further plasma processing, treatment and / or film deposition can take place on the respective wafers 101. It should be noted that not all wafer processing stations may have a wafer received thereon. The implementations of the wafer transfer mechanism is not restricted to the spindle 342 and / or the components is not restricted to paddles or spider forks, and that other types of the wafer transfer mechanism and the components of the wafer transfer mechanism can also be envisioned.

[0025] In the implementations where multiple wafer processing stations are disposed, the wafer transfer mechanism can be indexed to move the components (e.g., paddles or spider forks) to a pre-set location within the chamber 102, and is therefore also referred to as a “wafer indexer”. The pre-set location can correspond with a wafer processing station or an input / output port. The wafer transfer mechanism can be coupled to and controlled by signals from the power and control circuitry (shown in Figure 1).

[0026] The wafer may be moved into and out of the chamber 102 and from one wafer processing station to another wafer processing station on its own or using another component, such as a carrier ring 200. In the case where the carrier ring 200 is used, the carrier ring 200 can be a fixed component of the wafer processing station or a moveable component. In the case of the carrier ring 200 being a fixed component, a carrier ring 200 may be disposed in each wafer processing station 320a-320d defined in the lower chamber body 102b, such that it is adjacent to and coplanar with the surface of a wafer 101, when the wafer 101 is received in the wafer processing station. In such cases, the wafer 101 is lifted, supported and moved by itself using components of the wafer transfer mechanism. In the case where the carrier ring 200 is a moveable component, a wafer 101 is received and supported on the carrier ring 200 and the components of the wafer transfer mechanism (e.g., spindle 342) are used to move the carrier ring 200 with the wafer 101 received thereon as a unit to a different wafer processing station, or into or out of the chamber 102. In some cases, not all the carrier rings 200 may carry a wafer 101 while in other cases all the carrier rings 200 may be carrying a wafer 101 for processing.

[0027] In the multi-station processing tool shown in Figure 2, the four wafer processing stations 320a-320d defined in the lower chamber body 102b is encompassed by a chamber wall defining an outer boundary. The chamber wall is defined by a plurality of lateral sidewalls 325. A chamber rib 322 extends inward toward a center of the bottom plate 103b from a center of each lateral sidewall 325. In some implementations, each of the lateral sidewalls 325 of the chamber wall is equal in length and the chamber rib 322 extends inward from the center of each lateral sidewall 325 for a length. For example, each lateral sidewall 325 extends for a first length and the chamber rib 322 extends from the center of each lateral sidewall 325 for a second length and the second length of the chamber rib 322 is less than half of the first length of each lateral sidewall 325. In other implementations, the second length of the chamber ribs can be of a different length than the first length of the lateral sidewall 325 and can be defined based on a number and size of the wafer processing stations (320a-320d) defined in the lower chamber body 102b. Thus, each wafer processing station (320) is encircled by a pair of adjacent lateral sidewalls 325 and the corresponding pair of chamber ribs 322 that extend from the pair of adjacent lateral sidewalls 325.

[0028] In some implementations, a chamber rib may extend inwardly and be located centrally between each pair of adjacent wafer processing stations disposed in the lower chamber body 102b (not shown). In such implementations, the chamber rib is defined to extend inwardly to align to a center of each lateral sidewall 325 of the chamber wall so as to define a gap of predefined length between the lateral sidewall 325 and the chamber rib. In some implementation, the length of the chamber rib extends inwardly and the predefined length are defined, based on the size of thechamber 102, the size of each wafer processing station and a size of grounding feature that is to be stored in the chamber rib.

[0029] Each chamber rib 322 includes a housing with an opening 327 defined in a portion of a top surface of the chamber rib 322. The opening 327 in the housing is disposed at a defined length from the lateral sidewall and is sized to accommodate a grounding feature. In some implementations, the opening 327 of the housing can be disposed in the middle of the chamber rib 322. In alternate implementations, the opening 327 can be located on the chamber rib 322 at any suitable distance from the lateral sidewall 325. In some implementations, each grounding feature is coupled to a distinct actuator (not shown in Figure 2) disposed in the respective housing. When the actuator is activated (i.e., actuated), the actuator extends the grounding feature out of the housing to a raised position, and when the actuator is deactivated, the grounding feature is retracted into the housing to a retracted position. The grounding features disposed along the chamber ribs of the bottom plate 103b provide additional ground return paths to ensure symmetric discharge of the electric current so that the top surfaces of the wafers 101 can experience uniform electric field. More details of the grounding feature and the role of the grounding features during processing of the wafer to provide symmetric ground return paths will be discussed with reference to Figures 3 A-3D.

[0030] Each wafer processing station (320a-320d) depicted in Figure 2 includes a wafer holding surface 321 defined to receive and hold a wafer 101 during processing. The showerhead (150 of Figure 1) defined in the upper chamber body 102a includes sets of gas delivery inlets along the bottom surface of the showerhead 150, wherein a number of sets of gas delivery inlets defined in the showerhead corresponds with number of wafer processing stations defined in the lower chamber body 102b. Each set of gas delivery inlets is oriented over a corresponding wafer processing station and is configured to deliver the process gas to a process region defined between the bottom surface of the showerhead 150 and a top surface of the wafer received on the wafer holding surface 321.

[0031] A wafer is brought into the chamber 102, aligned over a wafer processing station 320, and lowered onto the wafer holding surface 321 defined in the wafer processing station 320 by the wafer transfer mechanism 342. The alignment over the wafer processing station 320 is done by indexing the wafer transfer mechanism (i.e., wafer indexer) 342. After the wafer is lowered, the wafer transfermechanism (i.e., wafer indexer) 342 moves the components (e.g., paddles or spider forks) used to support and transport the wafer out of the way so that a process operation can be performed on the surface of the wafer. In some implementations, the components are moved out and aligned with a corresponding chamber rib 322, where they rest during process operation. When preparing the wafer for a process operation, the actuator is activated so as to cause the grounding feature to extend out of the opening 327 of the housing and to make electrical contact with a surface of the top plate 103a. In some implementations, the actuator is automatically activated upon detecting the upper chamber body 102a is lowered and engaged with the lower chamber body 102b. As earlier noted, in Figure 2, the upper chamber body 102a has been removed to provide a clear overview of the wafer processing stations 320a-320d, whereas, in reality, the upper chamber body 102a is lowered to isolate the chamber 102 in preparation for processing the wafers. The grounding features extended out of the housing provide additional return paths to ground for the electrical current in addition to the return paths defined via the lateral sidewalls 325 of the chamber wall, which is electrically grounded. The additional ground return paths provide ground return symmetry, resulting in improved electrical field uniformity over the wafer surface. Uniformity in the electrical field on the wafer surface results in the uniformity of the layers deposited over the wafer surface, which, in turn, leads to predictable device performance and repeatable device features.

[0032] Figures 3 A-3D illustrate cross-sectional views of a chamber rib322 defined in the lower chamber body 102b with a housing 323 for storing an actuated grounding feature 330, in accordance with some implementations. In some implementations, the chamber rib 322, as noted, extends from a lateral sidewall 325 of a chamber wall enclosing the wafer processing stations (32 la-32 Id) in the lower chamber body 102b. The housing 323 is defined along the length of the chamber rib 322. In some implementations, the housing 323 is defined at a center of each chamber rib 322. In alternate implementations, the housing 323 may be defined at a different length from the lateral sidewall 325. In some implementations as illustrated in Figures 3A-3D, only one grounding feature 330 is shown to be disposed along the length of the chamber rib 322. In some implementations, additional sets of grounding features (330) may be defined either along the length of the chamber rib 322 or in the center portion of the lower chamber body 102b and the housing 323 for storing each additional grounding feature (330) is defined at the corresponding locations of theadditional set of grounding features. In some implementations, the additional grounding features (330) and the corresponding housing (323) may be defined in the chamber rib 322 in addition to the grounding features 330. In some implementations, the additional grounding features may be defined at different lengths from the grounding features 330 along the chamber rib 322 so as to provide symmetric return paths for the electric current and the different lengths may be defined based on the number and size of the grounding features and the additional grounding features (330). In one example, the housings 323 defined in adjacent pair of chamber ribs 322 for housing the grounding features 330 can be defined to be equidistant from the corresponding lateral sidewall and from each other. By defining the chamber ribs to be equidistant from the lateral sidewall 325 and from each other, optimal symmetry of the ground return paths can be realized.

[0033] Each wafer processing station 321 is enclosed by portions of adjacent pair of lateral sidewalls of the chamber wall and the grounding features 330 extending out of the housings in the consecutive pair of chamber ribs 322 extending from the adjacent pair of lateral sidewalls 325. The enclosure created by the grounding features 330 and the portions of the lateral sidewalls establish localized boundary conditions that result in the establishment of efficient localized return paths to ground for the power (e.g., radio frequency (RF) power) applied in the process chamber. By tightening (i.e., reducing) the boundary conditions surrounding each wafer processing station using the grounding features along the chamber ribs 322, the distance for the return path to ground is reduced leading to substantial improvement in electrical field uniformity over the wafer surface. The improved electrical field uniformity over the wafer surface correlates to reduction in the tilt of features formed on the wafer surface.

[0034] In some implementations, the grounding features 330 are designed to have a distinct profile defined to increase the surface contact area. The distinct profile is defined, in some implementations, with the introduction of a chamfer edge 331. In some implementations, the grounding feature 330 includes a top or an upper portion defined to have a first width, a bottom or a lower portion defined to have a second width and the chamfer edge 331 defined between the upper portion and the lower portion. The chamfer edge increases the surface contact area that is used when moving the grounding feature 330 to a raised position. For instance, the increased surface contact area may be used to limit the extent to which the grounding feature330 can be extended out of the housing 323, when the grounding feature 330 is moved to the raised position. The second width of the bottom portion below the chamfer edge 331 is greater than the first width of the top portion of the grounding feature 330 above the chamfer edge 331. The opening 327 of the housing 323 is defined to correspond with a size of the top portion of the grounding feature 330 and the width of the bottom portion would limit the grounding feature 330 from extending out of the housing 323 beyond the top portion. In some implementations, the grounding feature 330 is defined in the form of a fin. Since the grounding feature 330 offers symmetric return path to ground for the electrical current between the upper and the lower chamber bodies, the fin is also referred to as “symmetry fin”. In other implementations, the grounding feature 330 can be in the form of a series of pins or posts defined along the length of the chamber rib 322.

[0035] Figure 3 A shows the grounding feature 330 in a retracted state or position, wherein the grounding feature is fully retracted into a housing 323 defined in the chamber rib 322, in one implementation. The dotted line surrounding the grounding feature and the actuator 332 is to indicate that it is within the housing 323 or below the top surface of the lower chamber body 102b. Figure 3A further shows an inset 348 defined on a top surface of the chamber rib 322. An opening of the housing 323 is defined on the bottom inner surface of the inset 348. A bottom side 330b of the grounding feature 330 is coupled to an actuator 332 that is configured to move along a vertical axis, when activated. The actuator 332 is coupled to a controller (not shown) of the process chamber and is activated via a signal from the controller. The actuator 332 is configured to move the grounding feature 330 coupled thereon between a raised position and a retracted position. When activated, the actuator 332 extends the grounding feature 330 out of the housing 323 to the raised position so that the top side 330a of the grounding feature 330 makes electrical connection with a surface of the upper chamber body 102a. Figure 3B shows an example where the grounding feature 330 is being extended out of the opening 327 in the housing 323 as it is being moved to the raised position and is about half way out. The solid line in the top portion of the grounding feature 330 indicates that the top portion of the grounding feature 330 has extended out of the housing 323 while the bottom portion shown in dotted lines indicates that the bottom portion is still inside the housing 323.

[0036] In some implementations, similar to the chamber rib 322 defined in the lower chamber body 102b, an upper chamber rib 352 is defined to extend from a center of an upper lateral sidewall 326 of the upper chamber body 102a for a length that corresponds with the length of the chamber rib 322. In some implementations, the top surface of the chamber rib (i.e., the lower chamber rib) 322 in the lower chamber body 102b has a flat profile and the opening 327 to the housing 323 is defined in a portion of the top surface of the chamber rib 322. In some other implementations, the top surface of the chamber rib 322 in the lower chamber body 102b includes a distinct profile defined by an inset 348 and the opening 327 of the housing 323 is defined in the inset 348. Along similar lines, the surface of the upper chamber rib 352 in the upper chamber body 102a, in some implementations, can have a flat profile. In some other implementations, the upper chamber rib 352 can include a pocket 350 defined on a surface of the top chamber rib 352 and oriented opposite to and aligned with the housing 323 of the chamber rib (lower or bottom chamber rib) 322 in the lower chamber body 102b, wherein the alignment causes the opening of the pocket 350 to align with the opening 327 of the housing 323. In some implementations, the lower chamber rib 322 can have a flat profile while the upper chamber rib 352 includes a pocket 350. In alternate implementations, both the bottom surface of the upper chamber rib 352 facing the lower chamber body 102b and the top surface of the lower chamber rib 322 can include a profile. For example, the upper chamber rib 352 can have the pocket 350 and the lower chamber rib can have the inset 348, wherein the profile of the inset 348 is similar to the profile of the pocket 350. Figures 3 A-3D illustrate one such implementation, wherein the lower chamber rib 322 includes the inset 348 and the upper chamber rib 352 includes a pocket 350.

[0037] When the actuator 332 is activated, the actuator 332 extends the grounding feature 330 through the opening 327 and out of the housing 323 to the fully raised position (i.e., extended state) and when the actuator 332 is deactivated, the grounding feature 330 is retracted back into the housing 323 to a retracted position or retracted state. In some implementations, upon detecting the process chamber 100 is closed to perform a process operation (i.e., upon detecting the upper chamber body 102a has been lowered and is engaged with the lower chamber body 102b), the actuator 332 is automatically activated (e.g., in response to a signal from a controller) causing the grounding feature 330 to extend out of the housing 323 and establish the electrical connection between the top plate 103a and the bottom plate 103b. Uponcompletion of the process operation and the wafer 101 is to be moved from one wafer processing station 320 to another or when the wafer 101 is to be moved into or out of the process chamber 100, the actuator 332 is automatically deactivated, wherein the grounding feature 330 is automatically retracted back into the housing 323 (i.e., moved to the retracted position or state) so as to avoid interfering with the wafer transfer mechanism. In some implementations, sensors may be provided on the chamber ribs 322 of the lower chamber body 102b and / or on the inner surface (e.g., corresponding rib surfaces) of the pocket 350 defined in the upper chamber body 102a to sense when the upper chamber body 102a engages or disengages with the lower chamber body 102b, so that the grounding feature 330 can be appropriately moved to establish or disconnect the electrical connection.

[0038] In the fully raised position, the grounding feature 330 establishes electrical connection between the upper chamber body 102a and the lower chamber body 102b. Since the implementations illustrated in Figures 3C and 3D include the pocket 350 in the upper chamber rib 352 and an inset 348 in the lower chamber rib 322, the grounding feature 350 is shown to establish the electrical connection with an inner surface of the pocket 350. In alternate implementations where the upper chamber rib 352 has a flat profile, the grounding feature establishes electrical connection with the surface of the upper chamber rib 352 of the top plate 103 a.

[0039] In Figures 3C and 3D, the grounding feature is shown to be in the fully raised position. This is shown by the solid lines in the top portion of the grounding feature 330 indicating that the top portion of the grounding feature 330 has fully extended out of the housing 323 and the dotted line having the chamfer edge 331 is inside the housing 323. In the fully raised position, the grounding feature 330 establishes the electrical connection, wherein the electrical connection is one of a capacitive connection or an inductive connection. In the implementation illustrated in Figure 3C, the grounding feature 330 is extended into the pocket 350 to make contactless electrical connection (i.e., capacitive connection). In this implementation, the grounding feature 330 is extended into the pocket 350 so that a gap exists between the top surface of the grounding feature 330 and the inner surface of the pocket 350. The size of the gap is defined to ensure capacitive connection can be established. In an alternate implementation illustrated in Figure 3D, the grounding feature is extended into the pocket 350 to make contact electrical connection (e.g., an inductiveconnection - with low impedance), wherein the top surface of the grounding feature 330 makes contact with the inner surface of the pocket 350.

[0040] In some implementations, the chamber rib 322 defined in the lower chamber body 102b may have a plain, level surface (i.e., without any inset). In such implementations, a strike plate (not shown) may be disposed on the top surface of the chamber rib 322. In some implementations, in addition to the strike plate, components of the wafer transfer mechanism may also be received on the top surface of the chamber rib 322. For example, the paddle, spider fork or other wafer carrying components of the wafer transfer mechanism (342 of Figure 2) can be moved to rest on top of the strike plate defined on the top surface of the chamber rib 322, during process operation. The strike plate and, where present, the components of the wafer transfer mechanism may both include an opening that corresponds and aligns with the opening 327 of the housing 323 so as to allow the grounding feature 330 to extend out of the housing 323 to make the electrical connection.

[0041] In some implementations (e.g., implementations illustrated in Figures 3A-3D) where the chamber rib (i.e., lower chamber rib) 322 includes an inset 348, a strike plate (not shown) may be disposed in the inset 348 on the top surface of the housing 323. In some implementations, a depth of the inset 348 is defined to correspond with a depth of the strike plate. In some implementations, in addition to the strike plate, the inset can also be designed to accommodate some of the components of the wafer transfer mechanism, such as the paddles. In such implementations, the depth of the inset 348 can be defined to accommodate both the strike plate and the components of the wafer transfer mechanism.

[0042] In Figures 3 A-3D, the depth of the inset 348 is shown to be exaggerated for illustration purposes, whereas, in reality the depth of the inset 348 can be much smaller. In the implementation where the strike plate is received on the top surface of the chamber rib 322, a size of an opening of the strike plate is defined to at least match with the opening 327 of the housing 323 defined in the chamber rib 322. The strike plate, in some implementations, can be defined to assist in establishing electrical connection between the upper chamber body 102a and the lower chamber body 102b, when the upper chamber body 102a is engaged with the lower chamber body 102b during processing of the wafer 101. In some implementations, the profile of the strike plate matches the profile of the top surface of the chamber rib 322 in the section where the strike plate is disposed. In alternate implementations, the strikeplate 324 can have a rectangular or any other shaped profile so long no surface of the strike plate overhangs or otherwise hinders in the process of establishing electrical connection or during wafer movement.

[0043] In some implementations, a second strike plate (not shown) may be disposed along the upper chamber rib 352 defined in the upper chamber body 102a. If the upper chamber rib 352 includes the pocket 350, the second strike plate may be disposed on the inside surface of the pocket 350. If the upper chamber rib 352 is level and does not include the pocket 350, the second strike plate may be defined on the surface of the upper chamber rib 352 that is facing the chamber rib 322 of the lower chamber body 102b so as to align with the opening in the housing 323 of the chamber rib 322 defined in the lower chamber body 102b. In some implementations, the second strike plate may be in addition to a first strike plate defined over the housing 323 on the top surface of the chamber rib 322. In other implementations, the second strike plate may be provided in the upper chamber body 102a in place of the first strike plate in the lower chamber body 102b. The first and / or the second strike plates may be provided for establishing reliable electrical connection between the upper chamber body 102a and the lower chamber body 102b so as to have symmetric return paths to ground.

[0044] In the implementations where the upper chamber rib 352 is defined to have a plain, level surface, the capacitive coupling or the inductive coupling is established between a top surface of the grounding feature 330 and the bottom surface of the upper chamber rib 352 facing the corresponding chamber rib 322 defined in the lower chamber body 102b. In the implementations where the upper chamber rib 352 is defined to include a pocket 350, the capacitive coupling or the inductive coupling is established between the top surface of the grounding feature and the inner surface of the pocket 350.

[0045] Figure 4 illustrates a top perspective view of the lower chamber body 102b showing the different wafer processing stations and the grounding features 330 in the raised position. In this view, as with the implementations illustrated in Figures 3A-3D, the upper chamber body 102a has been removed to provide a better view of the wafer processing stations with all the grounding features 330 extended out of the housing 323. The lower chamber body 102b is a multi-station module, such as a quad station module (QSM), with four wafer processing stations (320a-320d). In the implementations illustrated in Figure 4, the grounding features 330 are defined inthe chamber ribs 322 that are extending from center of the lateral sidewalls 325 of the lower chamber body 102b. In alternate implementations, the chamber ribs are defined to extend inwardly and to align with a center of the lateral sidewalls 325. The chamber ribs, in these implementations, are independent of and separated from the lateral sidewalls by a predefined length. Although the perspective view shows the grounding features 330 exposed when extended out of the housing, in reality, the grounding features 330, when extended out of the housing 323 to the fully raised position (i.e., moved to the extended state), are making contact or contactless electrical connection with the bottom surface or with the strike plate defined on the bottom surface of the upper chamber body 102a, or the inside surface of the pocket 350. A wafer transfer mechanism 342 disposed in the center of the lower chamber body 102b is used to move the wafers from one wafer processing station to another and to move the wafers into and out of the process chamber. As noted, the extension of the grounding features 330 out of the housing 323 is done when the upper chamber body 102a is engaged with the lower chamber body 102b and such engagement is done during wafer processing.

[0046] The actuator 332 includes components that assist in moving the grounding features along a vertical axis. In some implementations, the actuator 332 includes at least a linear guide defined in a bottom portion and an actuator rod disposed above the linear guide. The top of the actuator rod is coupled to the grounding feature 330, such as a radio frequency (RF) fin (also referred to as symmetry fin), 330. In some implementations, the housing 323 is defined to include sufficient depth to fully accommodate the grounding feature 330. In the implementations where the housing can accommodate only a portion of the actuator 332 along with the grounding feature 330, a first portion of the actuator 332 is disposed within the housing 323 while a second portion of the actuator 332 is disposed below the housing 323 of the lower chamber body 102b. In some implementations, the first portion includes a top portion of the actuator rod that is coupled to the grounding feature 330. In these implementations, the remaining portion of the actuator rod along with the linear guide is disposed below the lower chamber body 102b. In alternate implementations, the first portion can include the actuator rod and a portion of the linear guide that is received in the housing 330 with the grounding feature 330. The second portion disposed below the lower chamber body 102b includes the remaining portion of the linear guide. The linear guide is usedto guide the actuator rod 333 into and out of the housing 323 taking the grounding feature 330 with it.

[0047] In some implementations, the lower chamber body 102b can include a RF liner (not shown) disposed on a top surface of the bottom plate 103b so as to cover the horizontal surfaces of the chamber ribs 322 and any horizontal surfaces of the lateral sidewalls 325, in some implementations. In the implementations where the lower chamber body 102b includes a RF liner, the RF liner includes an opening that aligns with the opening 327 of the housing 323, so that when the grounding feature 330 is extended out of the housing 323 by the actuator 332, the grounding feature 330 can extend through the opening 327 of the housing 323 and of the RF liner to electrically connect the lower chamber body 102b with a surface of the upper chamber body 102a. When the lower chamber body 102b includes a strike plate on a top surface of the housing 323, the strike plate is disposed below the RF liner and the opening of the strike plate aligns with the opening of the housing 323 and the opening of the RF liner. In some implementations, where the wafer transfer mechanism (e.g., spindle) is used to move the wafer into and out of a wafer processing station defined in the multi-station process chamber 100, the components of the wafer transfer mechanism (e.g., paddles or other wafer supports) are moved out of the way and are stored on the chamber rib 322, such that the components rest on top of the RF liner 336. In such implementations, openings are defined in the components so as to align with the openings in the RF liner, the opening in the strike plate, and the opening in the housing 323, so that the grounding feature can move freely into and out of the housing 323.

[0048] In some implementations, the depth of the lower chamber body 102b is defined so as to be able to accommodate the housing 323 for fully receiving the grounding feature 330, when moved to retracted position. In such implementations, the lower chamber body 102b is defined to have sufficient depth to also include at least some portion of the actuator 332. In the implementations where an inset is defined on the top surface of the lower chamber body 102b, the depth of the inset 348 is defined to accommodate one or more of the components, such as strike plate, components of a wafer transfer mechanism, liner, etc. The depth of the lower chamber body 102b, in such implementations, is defined by taking into account the depth of the inset 348 and the height of the grounding feature 330 so that thehousing 323 defined in the lower chamber body 102b can fully accommodate at least the grounding feature 330.

[0049] In some implementations, the actuator 332 and the grounding feature 330 are designed to make a capacitive connection (i.e., contactless electrical connection) between the upper and the lower chamber body (102a, 102b), so as to prevent exposing any surface of the grounding feature to particle residues that make their way from the process chamber to the inside surfaces of the pocket 350. In some other implementations where the actuator 332 and the grounding feature 330 are designed to make inductive connection (i.e., contact electrical connection) between the upper and the lower chamber body (102a, 102b), the pocket may be purged using an inert gas prior to engaging the actuator to make the inductive connection. In some implementations, an inert gas inlet (not shown) may be positioned relative to an opening in the pocket 350. The inert gas inlet is coupled to an inert gas source (not shown) and is configured to direct a flow of the inert gas so as to spray the inside surfaces of the pocket 350 to purge the particle residues deposited on the inside surfaces of the pocket 350 350, so as to prevent contamination of the surface of the grounding feature 330. In some implementations, the flow of the inert gas is automatically activated upon detecting the deactivation of the actuator rod - i.e., when the grounding feature 330 is in the retracted position, and is automatically deactivated upon conclusion of the cleaning cycle. After the inert gas purge, the grounding feature 330 is extended out of the housing to the raised position so as to establish inductive connection with the inside surface of the pocket 350.

[0050] Although various implementations have been described with the grounding features being defined along the chamber ribs 322 of the lower chamber body 102b of the multi-station process chamber 300, the implementations are not restricted to only such implementations. Additional grounding features can be defined along the chamber ribs 322 and / or along an outer perimeter of a center portion of the bottom plate 103b, in some implementations. In the case where the additional grounding features are disposed along the outer perimeter of the center portion, each of the additional grounding features are disposed in corresponding housings defined along the outer perimeter of the center portion of the lower chamber body 102b. Each additional grounding feature is offset from the adjacent grounding feature 330 by a predefined offset angle. In some implementations, the predefined offset angle isdefined to be about 90 deg. In alternate implementations, the predefined offset angle can be greater than or less than 90 deg.

[0051] In some implementations, each of the additional grounding features are operated using a distinct actuator that is disposed with each additional grounding feature in the respective housing defined in the center portion of the lower chamber body 102b. In some implementations, the location and the offset of the additional grounding features are defined so that each grounding feature and each additional grounding feature are equidistant from one another and from the lateral sidewall of the lower chamber body 102b so as to provide symmetric return paths to ground. In the case where the additional grounding features are disposed in the center portion of the lower chamber body 102b, the number of additional grounding features can be equal to number of chamber ribs extending from each lateral sidewall of the lower chamber body 102b. In some implementations, the number of additional grounding features and of the housing to store the additional grounding feature is four. In some implementations, each additional grounding feature is equidistant from the other grounding features and from other additional grounding features. In the case where additional grounding features are defined along the chamber ribs, the additional grounding features are disposed so as to be equidistant from one another. The grounding features and the additional grounding features are defined to improve the symmetric return path to ground via the chamber ribs for the electric current flowing through the upper and lower chamber bodies.

[0052] In the implementations where each grounding feature 330 disposed along each chamber rib 322 is coupled to a distinct actuator 332, each actuator 332 is individually coupled to the controller and configured to receive signals from the controller for moving the corresponding grounding feature 330 into and out of the housing 323. In alternate implementations, two or more grounding features 330 can be coupled to a single actuator 332 and each actuator 332 is coupled to a controller to receive the activation and deactivation signals. In the example lower chamber body 102b of Figure 4 where a grounding feature 330 is defined in each of the four chamber ribs 322 defined between each pair of adjacent wafer processing stations, the grounding features 330 disposed along opposite chamber ribs may be coupled to a single actuator 332. Alternately, all the grounding features 330 disposed between adjoining pair of wafer processing stations (4 in the case of quad station module, 2 in the case of dual station module, etc.) may be coupled to and operated by a singleactuator 332. The controller can provide a single signal to operate all the actuators or send individual signals to operate each of the actuators. In the case where individual signals are sent, the signals are sent simultaneously.

[0053] Broadly speaking, the process chamber used for processing a plurality of wafers includes a plurality of grounding features distributed within to provide multiple return paths to ground for electrical connection established between an upper chamber portion and a lower chamber portion of the process chamber. The various implementations have been described in detail with reference to the plurality of grounding features disposed in a lower chamber body, and, more particularly, along chamber ribs that extend inward from a center of each lateral sidewall of the lower chamber portion. However, the distribution of the grounding features is not restricted to such implementations and additional implementations of the grounding features distributed along upper chamber body or anywhere within the process chamber, can also be envisioned.

[0054] In some implementations, instead of defining the housing 323 in the chamber rib 322 to store the grounding feature 330, the housing 323 for the grounding feature 330 can be defined in a recess (not shown) defined in each lateral sidewall 325 of the chamber wall defining the outer boundary of the bottom plate 103b. In such implementations, the recess is defined in the center of each lateral sidewall so as to align with a groove (not shown) defined in the corresponding chamber rib 322. The chamber rib 322 is defined to extend inward from a center of each lateral sidewall 325 for a first length, and the groove is defined to extend from the recess for a second length along the chamber rib 322, wherein the second length is less than the first length. In some implementations, the housing in the recess and the groove are defined for a depth so as to be able to fully accommodate the grounding feature 330, when retracted. In such implementations, when the grounding feature 330 is extended, the grounding feature 330 is slid out of the recess and along the groove to a predefined location defined along the chamber rib 322, and then extended out of the groove. The predefined location defined along the groove, in some implementations, corresponds with the installed position for the grounding feature 330. In some implementations, the predefined location (i.e., the installed position) is equal to the second length. In alternate implementations, the predefined location is less than the second length of the groove. The groove, in these implementations, acts as an extension of the recess and the chamfer edge 331 limits how far the groundingfeature 330 can extend out of the groove. The predefined location on the chamber rib 322 is defined to provide symmetrical return path to ground via the chamber rib 322 for the electrical current.

[0055] The actuator 332 coupled to each grounding feature 330, when activated, is configured to slide the grounding feature 330 radially out of the housing defined in the recess in the lateral sidewall 325 and along the groove to the predefined location along the chamber rib 322. The grounding feature 330 is extended out of the groove to make electrical contact (either capacitive or inductive connection) with a surface of the upper chamber body 102a, in response to a signal generated from the controller when the process chamber 100 is being prepared for processing of the wafer(s). When the grounding feature 330 is to be retracted (i.e., moved to a retracted state), the actuator 332 is deactivated and the reverse process occurs by first retracting the grounding feature into the groove and sliding the grounding feature radially along the groove and into the recess in the lateral sidewall.

[0056] In alternate implementations, the recess in each lateral sidewall is defined to have sufficient depth to fully accommodate the grounding feature 330 when retracted into the housing 323 but the groove has sufficient depth to slide the grounding feature 330 into and out of the recess. In this case, when the grounding feature 330 is to be extended to establish the electrical connection, the grounding feature is slid out of the housing defined in the recess and along the groove to the predefined location in the chamber rib 322. There is no need to extend the grounding feature 330 out of the groove as the grounding feature 330 is already in a raised position coming out of the recess.

[0057] In some implementations, the groove is defined to extend a depth that is equal to a height of the lower chamber body 102b. In some implementations where the groove is defined to extend the height of the lower chamber body 102b, a portion of the actuator (e.g., an actuator rod) 332 is defined to extend for a portion of the height of the lower chamber body 102b, and the remaining portion, such as the linear guide (not shown) is defined to extend below the groove (i.e., below the lower chamber body 102b). In these implementations, the linear guide is configured to slide radially out of the housing in the recess of the lateral sidewall 325 and move the grounding feature 330 vertically so as to extend the grounding feature 330 out of the groove.

[0058] The housing 323 for the grounding feature 330 is not restricted to the chamber rib 322 or the lateral sidewall 325 of the chamber wall but can be defined in any other surface of the chamber 102 or can be housed outside of the chamber 102 and extended into the chamber 102 when additional return paths to ground has to be established during processing of the wafers in the chamber 102. In some implementations, more than one grounding feature may be defined in each chamber rib 322. In such implementations, the grounding features may be spaced apart from one another and the distance of separation of the grounding features from one another and from the corresponding lateral sidewall 325 can be defined to ensure symmetry in the return paths to ground.

[0059] The grounding features, in the various implementations discussed above, are defined along lower chamber ribs extending inward from or align to a center of the lower lateral sidewalls 325 of the lower chamber body 102b. In such implementations, the return paths to ground are established along the chamber ribs 322 disposed between adjacent pair of wafer holding surfaces 321 defined in the lower chamber body 102b. In alternate implementations, the grounding features 330 can be disposed along upper chamber ribs 352 extending from a center of the upper lateral sidewalls 326 of the upper chamber body 102a. In this implementation, the grounding features 330 are stored in housing defined in the upper chamber ribs 352 and are extended downward and out of the housing using an actuator 332 coupled to each grounding feature 330 defined in the housing to establish electrical connection between the upper chamber body 102a and the lower chamber body 102b. The return paths to ground for the electrical current, in such implementations, are along each upper chamber rib 352, the corresponding lower chamber rib 322 disposed between an adjacent pair of wafer processing stations of the plurality of wafer processing stations defined in the lower chamber body 102b. It is to be noted that the return paths to ground provided by the grounding features along the chamber rib disposed between adjacent pair of wafer processing stations is in addition to the return paths that are defined via the upper and the lower chamber walls, which are electrically grounded. The additional return paths improve the electrical field uniformity across the surfaces of the wafers.

[0060] As previously noted, the grounding features distributed in the process chamber provide a tighter boundary condition around each wafer process station thereby resulting in a more uniform distribution of the electrical field (alsoreferred to as “e-field”) on the surface of the wafers received in the wafer processing stations. Consequently, the features formed on the wafer surfaces do not lean toward the center or the outer boundary of the lower chamber body 102b and the power loss variation is minimal across each wafer.

[0061] This is a marked improvement from conventional multi-station process modules (e.g., quad station modules (QSMs)) where the grounding features (e.g., ground rod / post) providing the return path to ground were disposed over the wafer indexer in the center of the bottom plate. Thus, in the conventional multistation modules, the wafer surface exhibited non-uniform electrical field due to wider or expanded boundary conditions and the limited RF return paths. This caused a noticeable tilt to the layers formed over the surfaces of the wafers, as the tendency was to lean towards the return paths.

[0062] The advantages of having additional grounding features in a process chamber used for processing a plurality of wafers is the increase in the number of return paths to ground, establishment of tighter boundary conditions for each wafer processing station within a multi-station processing tool so as to improve electrical field uniformity over the wafer surface, which leads to uniformity in the layers formed on the wafer surface to define the devices, improved device reliability and consistent device performance and repeatability of the device structures, to name a few.

[0063] In some implementations, the grounding feature is made of same material as the chamber wall. In alternate implementations, the grounding feature is made of a different material than the chamber wall, wherein the different material is selected to withstand the chamber conditions during processing. In some implementations, the material used for defining the grounding feature can include any one or a combination of Aluminum or Stainless Steel.

[0064] In some implementations, the grounding feature has a distinct profile due to presence of a chamfer edge defined in the bottom portion of the RF fin. The chamfer edge, as earlier noted, is used to limit the extension of the grounding feature out of the housing and to ensure that reliable electrical connection is established between the top and the bottom plates of the process chamber. The chamfer edge causes an increase in the amount of surface contact area for the grounding feature. The grounding feature extends for a first width (wl of Figure 3 A) in the top or upper portion that is over the chamfer edge and for a second width (w2 ofFigure 3 A) in the bottom portion that is below the chamfer edge, wherein the first width wl is smaller than the second width w2. In some implementations, the first width wl is defined to be between about 2.75” and about 3.00”, and the second width w2 is defined to be between about 3.0” and about 3.25”. The height (hl of Figure 3 A) at which the chamfer edge is defined from a top surface of the grounding feature 330 can depend on the type of electrical connection (e.g., capacitive or inductive) that is being established between the upper chamber body 102aand the lower chamber body 102b, a height of a bottom surface of the upper chamber body 102aor an inner surface of the pocket 350 defined in the upper chamber body 102afrom the top surface of the housing 323 and any other component that is defined on the top surface of the lower chamber body 102b. In some implementations, the height hl is defined is between about 1.875” and about 2.125”, and the height (h2 of Figure 3 A) of the bottom portion from a top of the chamfer edge to the bottom surface of the grounding feature is defined to be between about 0.40” and about 0.60”. In some other implementations, the height h2 can range between about 0.10” and about 0.75” or beyond, wherein the height h2 is defined based on the height of the grounding feature, the height of the housing defined in the lower chamber body 102b, the height hl to which the grounding feature needs to be extended out of the housing to make reliable inductive or capacitive coupling with the upper chamber body 102a. In some implementations, the thickness of the grounding feature is defined to be between about 0.25” and about 0.50”. The first and the second heights of the grounding feature is defined to ensure that the grounding feature 330 extends sufficiently out of the housing 323 to make reliable electrical contact between upper and the lower chamber bodies (102a, 102b) and to ensure that the grounding feature 330 is not overextended out of the housing 323 by the actuator 332.

[0065] In some implementations, a length and width of the lateral sidewall of the lower chamber body 102b, the length of the chamber rib defined to extend from or align with the center of each lateral sidewall, and the offset of the housing defined in the chamber rib from each lateral sidewall depends on the size of the process chamber. In some implementations, a height of the opening in the housing is defined to be between about 2.4” and 2.6”, a length of the opening in the housing is defined to be between about 3.15” and 3.25” and the width of the opening in the housing is defined to be between about 0.55” and about 0.70”. It should be understood the aforementioned dimension ranges can vary by about + 15%. Of course, theaforementioned dimensions are provided as mere examples and should not be considered restrictive and that other dimensions can also be envisioned. Ultimately, the various dimensions of the RF fin will depend on the dimensions of the various features of the process chamber, such as the thickness of the chamber rib, the height of the lower chamber body 102b, the distance between the lateral sidewall, the opening of the housing, etc.

[0066] While the design of the process chamber with the additional grounding features has been described in detail with reference to specific implementations, it will be apparent to those skilled in the art that various changes and modifications can be made, and equivalents employed, without departing from the scope of the appended claims.

[0067] The present embodiments are to be considered as illustrative and not restrictive, and the embodiments are not to be limited to the details given herein, but may be modified within their scope and equivalents of the claims.What is claimed is:

Claims

CLAIMS1. A process chamber used for processing a plurality of wafers, comprising: an upper chamber body defined in an upper portion of the process chamber, the upper chamber body having a showerhead configured to supply deposition gases to top surfaces of the plurality of wafers received within the process chamber; a lower chamber body defined in a lower portion of the process chamber, the lower chamber body having a plurality of wafer processing stations, wherein each wafer processing station of the plurality of wafer processing stations includes a wafer holding surface for receiving a wafer of the plurality of wafers for processing, the lower chamber body comprising, a chamber wall defined by a plurality of lateral sidewalls, the chamber wall forming an outer boundary; a chamber rib located centrally and extend inwardly between a pair of adjacent wafer processing stations of the plurality of wafer processing stations; and a grounding feature defined in a housing disposed in the chamber rib and configured to move between a raised position and a retracted position, the grounding feature providing an electrical current return path, along the chamber rib, for an electrical connection established between the upper chamber body and the lower chamber body, when the grounding feature is moved to the raised position.

2. The process chamber of claim 1, wherein the chamber rib extends inward from a center of each lateral sidewall of the plurality of lateral sidewalls.

3. The process chamber of claim 1, wherein the chamber rib extends to align to a center of each lateral sidewall of the plurality of lateral sidewalls and is separated from each lateral sidewall of the plurality of lateral sidewalls by a gap of a predefined length.

4. The process chamber of claim 1, wherein the process chamber is defined to be a quad station module with four wafer processing stations, wherein the chamber rib is defined between each adjacent pair of wafer processing stations of the quad station module, such that each wafer processing station is encompassed by portions of a pair of adjacent lateral sidewalls and the chamber ribs extending from each of said pair of adjacent lateral sidewalls.

5. The process chamber of claim 1, wherein the process chamber is defined to be a dual station module with a pair of wafer processing stations, wherein the chamber rib is defined between the pair of the wafer processing stations, such that each wafer processing station is encompassed by portions of three adjacent lateral sidewalls and the chamber rib.

6. The process chamber of claim 1, wherein the grounding feature is coupled to and operated by an actuator used to control movement of the grounding feature between the raised position and the retracted position, such that when the actuator is activated, the grounding feature is extended out of the housing to the raised position, and when the actuator is deactivated, the grounding feature is withdrawn into the housing to the retracted position.

7. The process chamber of claim 6, wherein the actuator is defined by, a linear guide defined in a bottom portion, an actuator rod is disposed over the linear guide, such that movement of the actuator rod is guided by the linear guide, and the grounding feature is coupled to a top of the actuator rod, so that movement of the grounding feature is coordinated with the movement of the actuator rod.

8. The process chamber of claim 7, wherein the actuator rod is automatically activated upon detecting the upper chamber body being engaged with the lower chamber body to allow processing of the plurality of wafers, and automatically deactivated upon detecting the conclusion of the processing of the plurality of wafers to allow movement of the wafers from a first wafer processing station to a second wafer processing station of the plurality of wafer processing stations.

9. The process chamber of claim 6, wherein the upper chamber body includes a plurality of top lateral sidewalls, each top lateral sidewall of the plurality of top lateral sidewalls includes a rib defined along a bottom surface facing the lower chamber body and extending inward so as to align to a center of said each top lateral sidewall and to a corresponding chamber rib defined in the lower chamber body, said rib includes a pocket that aligns with and is sized to correspond with an opening of the housing defined in the chamber rib of the lower chamber body, and wherein the pocket is configured to receive the grounding feature extending out of the housing, when the actuator rod is activated and the grounding feature is moved to the raised position.

10. The process chamber of claim 9, wherein the actuator is configured to extend the grounding feature into the pocket in the upper chamber body so as to generate one of a capacitive connection and an inductive connection between the upper chamber body and the lower chamber body.

11. The process chamber of claim 9, further includes a top strike plate defined to line an inside bottom surface of the pocket, the top strike plate providing a reliable electrical connection when the grounding feature is moved to the raised position and is extended into the pocket.

12. The process chamber of claim 9, further includes an inert gas inlet coupled to an inert gas source and positioned relative to an opening of the pocket, the inert gas inlet configured to direct flow of an inert gas to inside surfaces of the pocket, so as to purge off any particle residues deposited on inside surfaces of the pocket, wherein the flow of the inert gas is automatically activated upon detecting deactivation of the actuator rod, and is automatically deactivated upon conclusion of a cleaning cycle.

13. The process chamber of claim 6, wherein said actuator is one of a pneumatic cylinder actuator, an air cylinder actuator and leadscrew actuator, and wherein said each grounding feature is defined to be one of a fin, a series of posts, and a series of pins disposed along a length of corresponding chamber rib.

14. The process chamber of claim 1, wherein the grounding feature is a radio frequency (RF) fin having a distinct profile, the distinct profile characterized by a chamfer edge in a bottom portion, such that a top portion above the chamfer edge extends for a first width and a bottom portion below the chamfer edge extends for a second width, and wherein the first width is smaller than the second width.

15. The process chamber of claim 14, wherein the chamber rib includes a strike plate disposed on a top surface of the housing, the strike plate having a plate opening that aligns with an opening of the housing, so as to allow the grounding feature to extend out of the housing and through the plate opening of the strike plate, when the grounding feature is moved to the raised position, the strike plate and the chamfer edge defining an extent to which the grounding feature can extend out of the housing.

16. The process chamber of claim 1, wherein the upper chamber body includes, an upper chamber wall having a plurality of top lateral sidewalls,a rib is defined to extend inward from a center of each top lateral sidewall of the plurality of top lateral sidewalls and along a bottom surface of the upper chamber body , so as to align with the corresponding chamber rib defined in the lower chamber body, a strike plate disposed on said rib so as to align with the housing in the lower chamber body, the strike plate assisting in establishing electrical connection with the grounding feature, when the grounding feature is moved to the raised position and is extended out of the housing.

17. The process chamber of claim 1, further includes a first strike plate disposed on a top surface of the housing defined along the chamber rib of the lower chamber body, a first opening of the first strike plate aligning with an opening in the housing; and a second strike plate disposed along the bottom surface of a pocket defined in a rib extending inward from a center of each top lateral sidewall of a plurality of top lateral sidewalls defining an outer boundary of the upper chamber body, the pocket having a second opening and the second strike plate having a third opening that each aligns with the first opening of the first strike plate disposed in the lower chamber body, wherein the first strike plate and the second strike plate are defined to guide and limit extension of the grounding feature from the housing and into the opening in the upper chamber body to establish reliable electrical connection between the upper chamber body and the lower chamber body.

18. The process chamber of claim 1, wherein a radio frequency (RF) liner is defined on a top surface of the lower chamber body so as to cover top surfaces of the lateral sidewalls, top surface of the chamber rib extending inward and a center portion of the lower chamber body, the RF liner having a liner opening that aligns with an opening of the housing defined in the chamber rib, and a strike plate is defined to extend for a length along the chamber rib and is disposed between the RF liner and a top surface of the housing, the strike plate defined to include a plate opening that aligns with an opening of the housing defined in said chamber rib and with the liner opening defined in the RF liner.

19. The process chamber of claim 1, wherein the lower chamber body further includes a second set of housing defined along an outer perimeter of a center portion of the lower chamber body for storing a second set of grounding features, eachhousing in the second set of housing is offset from an adjacent housing by a predefined offset angle, wherein the upper chamber body further includes a second set of pockets defined in a center portion of the upper chamber body so as to align with openings defined in the corresponding second set of housing defined in the lower chamber body, and wherein each grounding feature of the second set of grounding features is coupled to and is operated using a distinct second actuator, so as to control movement of said grounding feature between raised position and retracted position, the distinct second actuator stored in the corresponding housing with said each grounding feature of the second set.

20. The process chamber of claim 1, wherein each lateral sidewall of the plurality of lateral sidewalls extends for a first length and the chamber rib extends inward centrally for a second length, and wherein the second length is less than half the first length.

21. The process chamber of claim 1, wherein the electrical current return path is defined by an inductive coupling established between the upper chamber body and the lower chamber body, the inductive coupling established when the grounding feature is extended out of the housing and into a corresponding pocket defined in the upper chamber body, so as to contact an inner side of the pocket, wherein a pocket opening of the pocket defined in the upper chamber body aligns with an opening of the housing defined in the lower chamber body.

22. The process chamber of claim 1, wherein the electrical current return path is defined by capacitive coupling established between the upper chamber body and the lower chamber body, the capacitive coupling established when the grounding feature is extended out of the housing and into a corresponding pocket defined in the upper chamber body so as to define a gap between the grounding feature and a top surface of the pocket, the gap defined to enable a non-contact electrical connection.

23. The process chamber of claim 1, wherein the electrical current return path established along the chamber rib is in addition to electrical current return path established along the chamber wall that is electrically grounded.

24. A process chamber used for processing a plurality of wafers, comprising:an upper chamber body defined in an upper portion of the process chamber, the upper chamber body having a showerhead configured to supply deposition gases to top surfaces of the plurality of wafers received within the process chamber; a lower chamber body defined in a lower portion of the process chamber, the lower chamber body having a plurality of wafer processing stations, wherein each wafer processing station of the plurality of wafer processing stations includes a wafer holding surface for receiving a wafer of the plurality of wafers for processing, the lower chamber body comprising, a chamber wall having a plurality of lateral sidewalls, the chamber wall forming an outer boundary; a chamber rib extending inward for a first length from a center of each lateral sidewall of the plurality of lateral sidewalls, the chamber rib having a groove that extends for a second length of the chamber rib; and a recess defined in the center of each lateral sidewall of the plurality of lateral sidewalls and aligned with the groove of the chamber rib, the recess providing a housing for storing a grounding feature, the grounding feature configured to move between an installed position and a retracted position and is used for providing a return path, along the chamber rib, for an electrical connection established between the upper chamber body and the lower chamber body, when the grounding feature is moved to the installed position; and an actuator coupled to the grounding feature, the actuator, when activated, is configured to move the grounding feature to the installed position by sliding the grounding feature out of the housing in the recess and along the groove of the chamber rib and extending out of the groove, and, when deactivated, is configured to move to the retracted position by retracting the grounding feature into the groove and sliding along the groove back into the housing in the recess within the lateral sidewall of the plurality of lateral sidewalls.

25. The process chamber of claim 24, wherein the groove is defined to extend for a height of the lower chamber body.

26. The process chamber of claim 24, wherein the actuator is defined by, a linear guide disposed in a bottom portion,an actuator rod is disposed over the linear guide, such that movement of the actuator rod is controlled using the linear guide, the grounding feature is coupled to a top of the actuator rod, such that the movement of the actuator rod controls a corresponding movement of the grounding feature, and wherein the linear guide extends below the groove defined along the chamber rib and the actuator rod extends for a portion of a height of the lower chamber body.

27. The process chamber of claim 26, wherein the linear guide is configured to move the actuator rod radially so as to extend the grounding feature out of the housing in the recess in the lateral sidewall and along the second length of the groove, and vertically upward to extend the grounding feature out of the groove to the installed position, when the actuator is activated.

28. The process chamber of claim 24, wherein the first length of the chamber rib is less than half a length of the lateral sidewall, and wherein the first length of the chamber rib is greater than the second length of the groove.

29. The process chamber of claim 24, further includes a spindle disposed in a center of the lower chamber body and configured to provide rotational movement, the spindle coupled to a plurality of paddles, wherein each paddle of the plurality of paddles supports an end-effector used to hold and support a wafer, when the spindle is engaged to transport the wafer to a wafer processing station of the plurality of wafer processing stations defined in the lower chamber body.

30. The process chamber of claim 29, wherein each wafer processing station of the plurality of wafer processing stations further includes a plurality of lift pins operated using a lift pin control, the lift pin activated to support the wafer of the plurality of wafers, when the wafer is moved into the wafer processing station, and wherein the paddle is configured to slide below the wafer and the end-effector is configured to hold and support the wafer during movement, the spindle and the paddles are coupled to an index control used for indexing movement of the spindle and the wafer supported on the paddle to the wafer processing station.

31. The process chamber of claim 29, further includes additional grounding features defined proximal to an outer periphery of the center of the lower chamber body, such that the additional grounding features are disposed between the spindle and the outer periphery of the center of the lower chamber body, each additionalgrounding feature is received in a corresponding additional housing defined in the center of the lower chamber body and is coupled to an additional actuator, and wherein the additional actuator is configured to control vertical movement of the additional grounding feature into and out of the corresponding additional housing.

32. The process chamber of claim 31, wherein the additional grounding features are uniformly distributed, a number and orientation of the additional grounding features defined in the center of the lower chamber body based on a number of wafer processing stations of the plurality of wafer processing stations defined in the lower chamber body.

33. The process chamber of claim 24, wherein the return path for the electrical connection is defined by an inductive coupling established between the upper chamber body and the lower chamber body when the grounding feature is moved to the installed position and contacts with a bottom surface of the upper chamber body.

34. The process chamber of claim 24, wherein the return path for the electrical connection is defined by a capacitive coupling established between the upper chamber body and the lower chamber body when the grounding feature is moved to the installed position and is brought proximal to a bottom surface of the upper chamber body to define a gap between the grounding feature and the bottom surface of the upper chamber body, a size of the gap defined to establish a non-contact electrical connection.

35. The process chamber of claim 24, wherein the groove is defined to extend for a height of the lower chamber body.

36. The process chamber of claim 24, wherein the process chamber is defined to be a quad station module with four wafer processing stations defined within, with each wafer processing station providing a wafer holding surface of the plurality of wafer holding surfaces for receiving a wafer of the plurality of wafers for processing, and wherein the chamber rib is defined between each adjacent pair of wafer processing stations of the quad station module, such that each wafer processing station is encompassed by portions of a pair of adjacent lateral sidewalls and the chamber ribs extending from each of said pair of adjacent lateral sidewalls.

37. A process chamber used for processing a plurality of wafers, comprising: an upper chamber body having a showerhead configured to supply deposition gases to top surfaces of the plurality of wafers received within the process chamber,the upper chamber body having an upper chamber wall defining an upper outer boundary, the upper chamber wall defined by a plurality of upper lateral sidewalls; a lower chamber body having a plurality of wafer processing stations, each wafer processing station having a wafer holding surface for receiving a wafer of the plurality of wafers for processing, the lower chamber body having a lower chamber wall defining a lower outer boundary, the lower chamber wall defined by a plurality of lower lateral sidewalls; a plurality of grounding features distributed within the process chamber, each grounding feature of the plurality of grounding features is configured to move between a raised position and a retracted position, the grounding feature providing a return path for an electrical connection established between the upper chamber body and the lower chamber body, when the grounding feature is moved to the raised position.

38. The process chamber of claim 37, wherein the return path provided by the plurality of grounding features is in addition to a return path defined between the upper chamber wall and the lower chamber wall, when the upper chamber wall is engaged with the lower chamber wall.

39. The process chamber of claim 37, wherein said each grounding feature is defined in a housing disposed in the lower chamber body and is coupled to an actuator, the actuator is configured to extend the grounding feature out of the housing in the lower chamber body to the raised position, when activated, to establish the electrical connection between the upper chamber body and the lower chamber body.

40. The process chamber of claim 39, wherein a lower chamber rib extends inward to align to a center of each lower lateral sidewall of the plurality of lower lateral sidewalls and the housing is defined in the lower chamber rib for storing the grounding feature, the return path for the electrical connection established along the lower chamber rib disposed between an adjacent pair of wafer processing stations of the plurality of wafer processing stations defined in the lower chamber body.

41. The process chamber of claim 37, wherein said each grounding feature is defined in a housing disposed in the upper chamber body and is coupled to an actuator, the actuator is configured to extend the grounding feature out of the housing in the upper chamber body to the raised position, when activated, to establish the electrical connection between the upper chamber body and the lower chamber body.

42. The process chamber of claim 41, wherein an upper chamber rib extends inward to align to a center of each upper lateral sidewall of the plurality of upper lateral sidewalls and the housing is defined in the upper chamber rib for storing the grounding feature, the return path for the electrical connection established along the upper chamber rib that is defined over an area defined between an adjacent pair of wafer processing stations of the plurality of wafer processing stations defined in the lower chamber body.

43. A process chamber used for processing a plurality of wafers comprising: an upper chamber body defining an upper portion of the process chamber; and a lower chamber body defining a lower portion of the process chamber and having a pair of wafer processing stations, the lower chamber body having a rib extending between the pair of wafer processing stations and a grounding feature housed within the rib, the grounding feature configured to move between a retracted state and an extended state relative to the rib, wherein the grounding feature establishes an electrical current return path between the upper chamber body and the lower chamber body and along the rib when the grounding feature is in the extended state.

44. The process chamber of claim 43, wherein the lower chamber body has a chamber wall defined by plurality lateral sidewalls, the rib extends inward and aligns with a center of a pair of parallel lateral sidewalls that extend proximal to opposite ends of the rib defined between the pair of wafer processing stations.

45. The process chamber of claim 43, wherein the grounding feature is coupled to and operated by an actuator used to control movement of the grounding feature between the retracted state and the extended state.

46. The process chamber of claim 45, wherein the housing is sized to accommodate at least a portion of the actuator with the grounding feature.

47. The process chamber of claim 45, wherein the actuator is configured to move the grounding feature to the extended state so as to establish one of a capacitive connection and an inductive connection between the upper chamber body and the lower chamber body and along the chamber rib.

48. A grounding feature for use in a process chamber used for processing a plurality of wafers, comprising: an upper portion extending for a first width; a lower portion extending for a second width; anda chamfer edge disposed between the upper portion and the lower portion, wherein the grounding feature is disposed in a first portion of the process chamber and is configured to move between an extended state and a retracted state, the grounding feature establishes an electrical current return path between the first portion and a second portion of the process chamber, when moved to the extended state.

49. The grounding feature of claim 48, wherein the chamfer edge defines a feature profile used to reliably establish a connection between the first portion and the second portion and to limit an extent to which the grounding feature can move to establish the electrical current return path, when in the extended state.

50. The grounding feature of claim 48, wherein the grounding feature is stored in a housing defined in the first portion of the process chamber and is extended out of the housing when the grounding feature is moved to the extended state and retracts into the housing when the grounding feature is moved to the retracted state.

51. The grounding feature of claim 48, wherein the grounding feature is stored in a housing defined in the second portion of the process chamber.

52. The grounding feature of claim 48, wherein the grounding feature is coupled to and operated by an actuator used to control movement of the grounding feature between the extended state and the retracted state.

53. The grounding feature of claim 48, wherein the first portion is a chamber rib defined in a lower chamber body of the process chamber and the second portion is a surface defined on an upper chamber body of the process chamber.

54. The grounding feature of claim 53, wherein the lower chamber body includes a chamber wall with a plurality of lateral sidewalls and the chamber rib extends inward from a center of each lateral sidewall of the plurality of lateral sidewalls in the lower chamber body.

55. The grounding feature of claim 53, wherein the lower chamber body includes a chamber wall with a plurality of lateral sidewalls and the chamber rib extends inward to align to a center of each lateral sidewall of the plurality of lateral sidewalls in the lower chamber body and is separated from each lateral sidewall of the plurality of lateral sidewalls by a gap of a predefined length.

56. The grounding feature of claim 53, wherein the lower chamber body includes a chamber wall with a plurality of lateral sidewalls, the grounding feature is stored in a housing defined in a center of each lateral sidewall and is configured to extend outof the housing and slide along the chamber rib to an installed position, when moved to the extended state, and slide back along the chamber rib into the housing to a resting position, when moved to the retracted state.

57. The grounding feature of claim 48, wherein the grounding feature establishes one of a capacitive coupling and an inductive coupling defined between the first portion and the second portion, when moved to the extended state, by a contactless connection and an inducive coupling defined by a contact connection, and wherein the capacitive coupling is established by moving the grounding feature to define a contactless connection and the inductive coupling is established by moving the grounding feature to define a contact connection between the grounding feature and a surface defined in the second portion.

58. The grounding feature of claim 48, wherein the process chamber includes a plurality of grounding features distributed uniformly to establish multiple electrical current return paths between the first portion and the second portion.

59. The grounding feature of claim 48, wherein the first portion is a lower chamber body of the process chamber, the process chamber is a quad station module with four wafer processing stations defined in the lower chamber body and the grounding feature is disposed between each pair of adjacent wafer processing stations.

60. The grounding feature of claim 48, wherein the first portion is a lower chamber body of the process chamber, the process chamber is a dual station module with two wafer processing stations defined in the lower chamber body and the grounding feature is disposed between the pair of adjacent wafer processing stations.

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