Hexapod pedestal system for use in semiconductor processing operations.

Abstract

A semiconductor processing tool is disclosed and described that includes a hexapod pedestal system. The hexapod pedestal system may incorporate a hexapod mechanism having a fixed mount connected to a moveable mount via six linear actuators. The moveable mount may support a pedestal disposed within a semiconductor processing chamber. The hexapod mechanism may be controlled to allow the pedestal to shift laterally to center the pedestal relative to a wafer supported by a wafer handling robot, as well as to angularly align a wafer supported by the pedestal with a lower surface of a showerhead, and to allow a wafer supported by the pedestal to undergo any of a variety of motions during wafer processing operations that may facilitate improved wafer uniformity.

Description

Related Applications

[0001] A PCT Requirement Form is being filed contemporaneously herewith as a part of this application. Each application to which this application claims benefit or priority as identified in the contemporaneously filed PCT Requirement Form is hereby incorporated by reference in its entirety for all purposes. [Background technology]

[0002] Semiconductor processing tools typically include one or more pedestals that are used to support a semiconductor wafer within a semiconductor processing chamber. Such pedestals feature a wafer support surface on which a wafer is placed and that is designed to support the wafer during semiconductor processing operations within the semiconductor processing chamber. The pedestal may include any of a variety of auxiliary systems, such as, for example, a vacuum chuck and / or electrostatic chuck (which may provide the wafer support surface of the pedestal), a heating and / or cooling system, an electrode used for radio frequency energy transfer, a purge gas system to protect the underside of the wafer from process gases that are intended to be applied only to the upward facing side of the wafer, a lift pin mechanism that may be used to lift the wafer off of (or lower the wafer onto) the wafer support surface, etc.

[0003] A pedestal is typically configured such that it can be fixed in position relative to the processing chamber in which it resides, or can be actively controlled to move along it with only one or two degrees of freedom. For example, pedestals are commonly mounted on vertical lift mechanisms that allow such pedestals to be actively raised and lowered, e.g., during wafer placement operations, and in some instances, during processing operations. In some instances, the pedestal can additionally or alternatively be configured such that it can be actively rotated about a vertical axis during or before wafer processing operations. Summary of the Invention

[0004] The details of one or more embodiments of the subject matter described herein are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims.

[0005] In some embodiments, an apparatus may be provided that includes a pedestal configured to support a semiconductor wafer during wafer processing operations, a moveable mount supporting the pedestal, a fixed mount, and six independently controllable linear actuators, each linear actuator having a first end pivotally connected to the fixed mount and a second end pivotally connected to the moveable mount. The linear actuators may support the moveable mount relative to the fixed mount, and the moveable mount, the fixed mount, and the six independently controllable linear actuators may be arranged to provide a hexapod mechanism.

[0006] In some embodiments, the linear actuators may be arranged in triplicate symmetrical fashion.

[0007] In some embodiments, the six linear actuators may be grouped into three sets of two linear actuators, and the linear actuators in each pair of linear actuators may be positioned such that they have first ends that connect to the fixed mount closer to each other than the second ends that connect to the movable mount.

[0008] In some embodiments, a first end of each linear actuator may be pivotally connected to a fixed mount by a corresponding spherical joint, universal joint, or biaxial flexure bearing, and a second end of each linear actuator may be pivotally connected to a movable mount by a corresponding spherical joint, universal joint, or biaxial flexure bearing.

[0009] In some embodiments, each first end of each linear actuator may be pivotally connected to the fixed mount by a corresponding first biaxial flexure bearing.

[0010] In some embodiments, each first biaxial flexure bearing may include an inner portion, a middle portion, an outer portion, two first torsion webs spanning between the inner portion and the middle portion, and two second torsion webs spanning between the middle portion and the outer portion. For each first biaxial flexure bearing in such embodiments, the inner portion may be interposed between the two first torsion webs and the middle portion may be interposed between the two second torsion webs.

[0011] In some embodiments, for each first biaxial flexure bearing, the first torsion web can be a thin, substantially flat structure aligned with a first reference surface of that first biaxial flexure bearing, the second torsion web can be a thin, substantially flat structure aligned with a second reference surface of that first biaxial flexure bearing, and the first and second reference surfaces can be orthogonal to one another.

[0012] In some embodiments, the intermediate portion may include two opposing first segments disposed on either side of the inner portion and the first torsion web and spaced apart from the inner portion such that a gap exists between the first segments and the inner portion, the intermediate portion may further include two opposing second segments disposed on either side of the inner portion and spaced apart from the inner portion such that a gap exists between the second segments and the inner portion, each second segment may be connected to the inner portion by a corresponding one of the second torsion webs, and the intermediate portion may further include four bridging segments, each bridging segment extending between a different pair of the first and second segments, and the second segments may be farther from the central axis of the inner portion than the first segments.

[0013] In some embodiments, the first segment can be a curved segment having a convex surface facing toward the inner portion.

[0014] In some embodiments, the first segment can be an arcuate segment concentric with the inner portion.

[0015] In some embodiments, the bridge segment can be a linear segment.

[0016] In some embodiments, the bridge segments may be parallel to one another.

[0017] In some embodiments, the second segment may be located entirely outside of a reference circle that circumscribes the first segment.

[0018] In some embodiments, the distance between the inner portion and the second segment may be at least 1.5 times the distance between the inner portion and the first segment.

[0019] In some embodiments, the distance between the inner portion and the second segment may be at least twice the distance between the inner portion and the first segment.

[0020] In some embodiments, for each first biaxial flexure bearing, a first reference axis defined by the intersection of the first and second reference planes may be parallel to an extension axis of a linear actuator connected to that first biaxial flexure bearing.

[0021] In some embodiments, each second end of each linear actuator may be pivotally connected to the moveable mount by a corresponding second biaxial flexure bearing.

[0022] In some embodiments, each second biaxial flexure bearing may include an inner portion, a middle portion, an outer portion, two first torsion webs spanning between the inner portion and the middle portion, and two second torsion webs spanning between the middle portion and the outer portion. In such embodiments, for each first biaxial flexure bearing, the inner portion may be interposed between the two first torsion webs and the middle portion may be interposed between the two second torsion webs.

[0023] In some embodiments, for each second biaxial flexure bearing, the first torsion web can be a thin, substantially flat structure aligned with a first reference surface of that second biaxial flexure bearing, the second torsion web can be a thin, substantially flat structure aligned with a second reference surface of that second biaxial flexure bearing, and the first and second reference surfaces can be orthogonal to one another.

[0024] In some embodiments, for each second biaxial flexure bearing, the first and second reference planes may intersect along a central axis of the second biaxial flexure bearing, which may be parallel to an extension axis of a linear actuator connected to the second biaxial flexure bearing.

[0025] In some embodiments, the apparatus may further include a semiconductor processing chamber and a showerhead, in some embodiments, the wafer support surface of the pedestal may be disposed within the semiconductor processing chamber, at least a portion of the showerhead may be disposed within the semiconductor processing chamber, and the fixed mount may be fixed relative to the semiconductor processing chamber.

[0026] In some embodiments, the apparatus may further include a controller operatively connected to the six linear actuators to control: a) translation of the movable mount along an axis perpendicular to a wafer support surface of the pedestal; b) rotation of the movable mount about an axis of rotation perpendicular to the wafer support surface and passing through a target position of the pedestal at which the wafer is to be centered; c) translation of the movable mount along a path orbiting an axis perpendicular to a lower surface of the showerhead facing the pedestal and intersecting the target position of the showerhead; d) rotation of the movable mount relative to the fixed mount. or e) tilting the movable mount such that the wafer support surface of the pedestal is oriented at a non-zero acute angle relative to the lower surface of the showerhead, and a maximum acute angle formed between the lower surface of the showerhead and the wafer support surface is defined in a plane that is periodically or continuously varied in azimuth orientation about an axis perpendicular to the lower surface of the showerhead, relative to the pedestal.

[0027] In certain embodiments, the controller may be further configured to control the linear actuator to cause the moveable mount to perform two or more of (a) through (e) at least partially simultaneously while the pedestal supports a wafer disposed thereon.

[0028] In certain embodiments, the controller may be further configured to control the linear actuator to cause the moveable mount to perform two or more of (a) through (e) at least partially continuously while the pedestal supports a wafer disposed thereon.

[0029] In some embodiments, the apparatus may further include a wafer handling robot configured to extend its end effector into the semiconductor processing chamber, and an active wafer centering system configured to determine a location of a center of a wafer carried by the end effector relative to the semiconductor processing chamber. In such embodiments, the controller may further be configured to: i) obtain a location of the center of the wafer determined by the active wafer centering system; ii) control the linear actuator to position a target position of the pedestal in a centered position under the center of the wafer based on the location of the center of the wafer determined by the active wafer centering system; and iii) transfer the wafer to the pedestal after (ii). In some embodiments, the pedestal may include a plurality of lift pins, and the apparatus may include a lift pin actuation mechanism configured to move the lift pins between an extended state in which the lift pins protrude from a wafer support surface of the pedestal and a retracted state in which the lift pins do not protrude from the wafer support surface. In some embodiments, the controller may be configured to perform (iii) by causing the lift pin actuation mechanism to move the lift pins to an extended state into contact with the wafer, causing the wafer handling robot to retract the end effector from a space between the wafer and the wafer support surface, and causing the lift pin actuation mechanism to move the lift pins to a retracted state to position the wafer on the wafer support surface. In some other or further embodiments, the controller may be further configured to, after (iii), control the linear actuator to move the moveable mount in a direction such that the wafer support surface forms a predetermined angle with respect to the underside of the showerhead. In some embodiments, the predetermined angle is 0°. In some embodiments, the predetermined angle may be a non-zero acute angle.

[0030] In addition to the embodiments described above, other embodiments evident from the following discussion and drawings should be understood to be within the scope of the present disclosure. [Brief description of the drawings]

[0031] In the following description, reference will be made to the following drawings, which are not intended to be limiting in scope but are provided solely to facilitate the following description:

[0032] [Figure 1] FIG. 2 illustrates an example of a hexapod pedestal system in a semiconductor processing chamber.

[0033] [Diagram 2] FIG. 2 is an isometric view of the example hexapod pedestal system of FIG. 1.

[0034] [Diagram 3] FIG. 2 is a side view of the example hexapod pedestal system of FIG. 1.

[0035] [Figure 4] FIG. 2 is an isometric exploded view of the example hexapod pedestal system of FIG. 1.

[0036] [Diagram 5] FIG. 1 is a plan view showing an example of a dual-axis flexure bearing.

[0037] [Figure 6] Isometric view showing two example biaxial flexure bearings.

[0038] [Figure 7] 7 is an isometric cross-sectional view of one of the example dual axis flexure bearings of FIG. 6. [Figure 8] 7 is an isometric cross-sectional view of one of the example dual axis flexure bearings of FIG. 6.

[0039] [Figure 9] FIG. 9 is a side view of the dual axis flexure bearing of FIGS. 7 and 8; [Figure 10] FIG. 9 is a side view of the dual axis flexure bearing of FIGS. 7 and 8;

[0040] [Figure 11]FIG. 9 is an isometric view of an example hexapod pedestal system similar to the system of FIG. 1, but utilizing a biaxial flexure bearing similar to that shown in FIGS. 7-8.

[0041] [Figure 12] 12 is an isometric exploded view of the example hexapod pedestal system of FIG. 11 .

[0042] [Figure 13] FIG. 1 shows an example of a four-station module. [Figure 14] FIG. 1 shows an example of a four-station module.

[0043] [Figure 15] 1 is a flow chart of a technique for loading a wafer onto a pedestal of a hexapod pedestal system.

[0044] [Figure 16] 4 is a flow chart of a technique for moving a wafer during a processing operation using a hexapod pedestal system.

[0045] [Figure 17] 1A-1D show top, front, side and isometric views of a hexapod pedestal system with the pedestal in the raised position.

[0046] [Figure 18] 1A-1D show top, front, side and isometric views of a hexapod pedestal system with the pedestal in the lowered position.

[0047] [Figure 19] 1A-1D show top, front, side and isometric views of a hexapod pedestal system with the pedestal in the lift pin extended position.

[0048] [Figure 20] From left to right, top, front, side and isometric views of a hexapod pedestal system with the pedestal in three different rotational positions.

[0049] [Figure 21] 1A-1D show top, front, side and isometric views of a hexapod pedestal system with the pedestal in different orbital positions.

[0050] [Figure 22] 1A-1C show top, front, side and isometric views, from left to right, of a hexapod pedestal system with the pedestal in a first tilted position.

[0051] [Figure 23] 23A-23C are top, front, side and isometric views, from left to right, of the hexapod pedestal system of FIG. 22 with the pedestal in a second tilted position.

[0052] [Figure 24] 1 is a flow chart of a technique for calibrating a semiconductor processing tool having a hexapod pedestal system.

[0053] [Diagram 25] 25A-25C show portions of a semiconductor processing tool at various stages of the technique of FIG. 24. [Figure 26] 25A-25C show portions of a semiconductor processing tool at various stages of the technique of FIG. 24. [Figure 27] 25A-25C show portions of a semiconductor processing tool at various stages of the technique of FIG. 24. [Figure 28] 25A-25C show portions of a semiconductor processing tool at various stages of the technique of FIG. 24. [Figure 29] 25A-25C show portions of a semiconductor processing tool at various stages of the technique of FIG. 24. [Diagram 30] 25A-25C show portions of a semiconductor processing tool at various stages of the technique of FIG. 24. [Diagram 31] 25A-25C show portions of a semiconductor processing tool at various stages of the technique of FIG. 24. [Diagram 32] 25A-25C show portions of a semiconductor processing tool at various stages of the technique of FIG. 24. [Diagram 33] 25A-25C show portions of a semiconductor processing tool at various stages of the technique of FIG. 24. [Diagram 34] 25A-25C show portions of a semiconductor processing tool at various stages of the technique of FIG. 24. [Diagram 35] 25A-25C show portions of a semiconductor processing tool at various stages of the technique of FIG. 24. [Diagram 36] 25A-25C show portions of a semiconductor processing tool at various stages of the technique of FIG. 24.

[0054] The above-mentioned drawings are provided to facilitate understanding of the concepts discussed in the present disclosure and are intended to be illustrative of some embodiments within the scope of the present disclosure, but are not intended to be limiting, and embodiments consistent with the present disclosure that are not shown in the drawings are also deemed to be within the scope of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] Disclosed herein is a new type of semiconductor wafer support and positioning system for use in a semiconductor processing chamber. Such systems are generally characterized by a hexapod mechanism having a fixed mount and a movable mount, with six independently controllable linear actuators connecting the fixed mount to the movable mount in a configuration commonly referred to as a "Stewart platform." The fixed mount of the hexapod mechanism is fixedly attached relative to the semiconductor processing chamber, while the movable mount of the hexapod supports a pedestal that is used to support a semiconductor wafer within the semiconductor processing chamber.

[0056] Stewart platforms are typically utilized in applications where six degrees of freedom are required over a relatively wide range of motion, such as flight simulators, radio telescopes, spacecraft docking systems, etc. Such Stewart platform systems, for example, may often be designed to allow the moveable mount to be tilted by a tilt of 45° to 60° in any direction, and often can translate the moveable mount a significant distance in all directions.

[0057] In semiconductor processing chambers, pedestals used to support semiconductor wafers within the semiconductor processing chamber are typically fixed in position relative to the semiconductor processing chamber or configured to translate vertically and / or rotate about a vertical axis in some rare cases. While some semiconductor processing chambers may have mechanisms (e.g., set screws, alignment shims, etc.) that allow the horizontal position and / or pitch or roll orientation of the pedestal to be fine-tuned prior to use, such mechanisms are passive mechanism systems that are manually adjusted during initial alignment and setup procedures and then fixed in place to secure the pedestal in a desired horizontal position and / or angular orientation. The pedestal will then remain in that horizontal position and / or angular orientation unless such mechanisms are subsequently readjusted or naturally drift, although it may be actively controlled to translate vertically and / or rotate about a vertical axis if equipped with actuators that provide such movement. This approach is typically followed, as it provides only limited degrees of freedom that can be potential sources of positioning error, and typically leads to greater confidence regarding the position of a wafer supported by such pedestal at any given time.

[0058] In contrast, the wafer support / positioning systems discussed herein allow the target location of a pedestal supported by the system (e.g., the center (or a location on the pedestal that is intended to be aligned with the center of a semiconductor wafer supported by the pedestal), as well as the orientation of a pedestal supported by the system, to be actively and controllably repositioned between any number of positions and orientations within a three-dimensional envelope or zone. Thus, whereas existing pedestal systems have no or limited ability to be actively adjusted (e.g., having only one or two degrees of freedom), the wafer support / positioning systems discussed herein, through the utilization of a hexapod mechanism, have at least five degrees of freedom, and in some cases six degrees of freedom, dramatically improving the functionality of the pedestal supported by the system.

[0059] For example, a wafer support / positioning system incorporating a hexapod mechanism as discussed herein may enable dynamic adjustment of the position and orientation of a pedestal supported by the system, e.g., relative to the showerhead of a processing chamber with which it is utilized. For example, it is typically desirable to align the wafer support surface of the pedestal with the underside of the showerhead so that the wafer support surface of the pedestal is parallel to the underside of the showerhead (or to a nominal reference plane defined by a non-planar underside of the showerhead). Such alignment is typically performed manually during initial setup of the apparatus, e.g., using set screws or other fine adjustment mechanisms, and the adjustment mechanism used to perform such alignment is then fixed in place. The hexapod pedestal systems discussed herein may be easily controlled to actively tilt a pedestal supported by the system to align the wafer support surface of the pedestal with the underside of the showerhead.

[0060] Also, the hexapod pedestal systems discussed herein may be controlled to reposition during wafer placement operations. In conventional pedestal systems, wafers placed on a pedestal typically vary slightly in terms of where their wafer centers are located relative to the end effector used to place such wafers on such pedestals. If not corrected, this leads to wafers being sequentially placed at different locations on the receiving pedestal, with each wafer potentially experiencing different degrees of processing non-uniformity. It is therefore common for semiconductor processing chambers to include active wafer centering (AWC) systems. AWC systems use optical sensors to detect at least three points along the wafer edge as the wafer is moved into the semiconductor processing chamber by the wafer handling robot. The locations of such edges / points may then be used to determine the center location of the wafer relative to the end effector of the wafer handling robot. In typical practice, AWC systems are trained using a calibration wafer that is typically centered on the pedestal using an alignment fixture or other device, and then removed from the pedestal using the wafer handling robot. The wafer handling robot is then caused to follow a predetermined path that passes the calibration wafer through the optical sensor of the AWC system, and a determination is made as to the center location of the calibration wafer relative to the end effector of the wafer handling robot. This center location determined by the AWC system can be used as a "reference" location that is used to determine how "off-center" future wafers handled by the wafer handling robot will be from the reference location. Thus, for example, a future wafer to be processed may be placed on the end effector of the wafer handling robot, and the wafer handling robot is then caused to follow the same predetermined path so that the wafer to be processed passes through the AWC system in the same way as the calibration wafer. The center location of the wafer to be processed is determined in the same manner as was used to determine the center location of the calibration wafer.If the center position of the wafer being processed as measured by the AWC system is offset from the center position of the calibration wafer as measured by the AWC system by a distance large enough to require correction, the wafer handling robot can be controlled to adjust its movement within the chamber to offset the placement of the wafer on the pedestal by an amount that offsets the measured offset between the center of the calibration wafer and the center of the wafer being processed. Thus, for example, if the center of the wafer being processed is offset from the center of the calibration wafer by (-1 mm, 0.5 mm) in the XY coordinate system, the wafer handling robot can be controlled to move the end effector to the XY position of the end effector when the calibration wafer was placed on the end effector, but adjusted to offset the offset of (-1 mm, 0.5 mm). For example, the end effector is moved to an X coordinate of +1 mm in the XY position and a Y coordinate of -0.5 mm in the XY position.

[0061] While such an approach works well in some situations, it can be problematic in semiconductor processing tools where there are multiple processing stations, each with its own pedestal, and the wafer may be placed on several of such pedestals using a system that does not allow adjustment of the wafer placement position before placement. For example, in a semiconductor processing tool with four stations, a rotary indexer may be used to move the wafer between the stations, and the wafer handling robot may be able to place the wafer directly on two of the four stations. The indexer may then be used to move the wafer, which has been placed on the pedestal by the wafer handling robot, to one of the pedestals that is inaccessible to the wafer handling robot. However, since indexers are typically only capable of rotational motion, they typically have limited ability to correct for misalignment of the wafer center.

[0062] By using a hexapod pedestal system as described herein, the pedestal can become actively involved in the wafer centering operation. For example, in the techniques described above, the pedestal remains fixed in the XY plane, and all movements required to align the center of the wafer to be processed with the target location on the pedestal are performed by the wafer handling robot (or potentially by a rotary indexer). However, in a hexapod pedestal system, the pedestal can instead be moved to center the target location on the pedestal under the center of the wafer. Thus, for example, the wafer handling robot can simply be controlled to return to the same position it was in when the calibration wafer was placed on its end effector. The hexapod pedestal system is similarly controlled to return to the same position and orientation it was in when the calibration wafer was placed on its end effector, but can be adjusted in the XY direction to compensate for any misalignment between the center of the wafer to be processed and the center of the calibration wafer as determined by the AWC system. After the wafer to be processed is placed on the pedestal, the hexapod pedestal system can be controlled to move the pedestal to a position that orients the wafer support surface of the pedestal, for example, parallel to the underside of the showerhead.

[0063] It will be appreciated that such a hexapod pedestal system may allow wafer centering operations to be performed independently and simultaneously at each station of a multi-station chamber equipped with such a system, even though the wafers disposed on the pedestals are supported by a single common structure (such as an indexer or end effector that supports multiple wafers simultaneously on different pedestals). In some examples, this may allow wafer centering operations to be performed that could not be achieved otherwise. In other or further examples, this may reduce the time required to complete wafer centering operations and increase throughput by allowing wafer centering operations that would otherwise have had to be performed sequentially to be performed simultaneously.

[0064] The hexapod pedestal system also offers a uniquely flexible positioning solution that can be actively controlled during semiconductor processing operations to provide potentially beneficial effects. For example, the hexapod pedestal system may be controlled to cause its pedestal to perform specific motion patterns during wafer processing operations. In one such example, the hexapod pedestal system may increase or decrease the gap between the wafer supported by the pedestal and the showerhead by simply moving the pedestal along the "yaw" axis of the movable mount of the hexapod mechanism that supports the pedestal. Such gap adjustments may be used to affect how the wafer is processed. In another example, the hexapod mechanism may be controlled to introduce a deliberate (but small) angular misalignment between the underside of the showerhead and the wafer support surface of the pedestal. Such angular misalignment may provide beneficial effects in some circumstances. In yet another example, the hexapod mechanism may be controlled to "orbit" the pedestal around a center point (e.g., move the pedestal in XY to follow a circular path). Such orbital motion can help reduce local non-uniformities that may occur across the wafer, for example, by distributing the influences that create the non-uniformity over a larger area, thereby reducing the magnitude of the non-uniformity peaks.

[0065] These and other techniques and advantages provided by utilizing a hexapod pedestal system are discussed in further detail below in conjunction with the drawings.

[0066] Figure 1 illustrates an example semiconductor processing tool having a semiconductor processing chamber with a hexapod pedestal system, while Figures 2-4 show isometric, side, and isometric exploded views of the hexapod pedestal system without the semiconductor processing chamber.

[0067] 1, a semiconductor processing tool 100 is shown with a semiconductor processing chamber 102 that is covered by a lid 104. The lid 104 may be, for example, a recessed showerhead (not shown) with a number of gas distribution ports on its underside that are fluidly connected to one or more gas distribution plenums in the showerhead and that may be used to flow process gases over a wafer 110 supported on a pedestal 106 during semiconductor wafer processing operations. In some embodiments, the semiconductor processing chamber may have a chandelier-style showerhead (not shown) suspended below the lid 104 by a stem that passes through the lid 104.

[0068] The pedestal 106 may have a support 108 that may extend through the floor of the semiconductor processing chamber 102. Although the support 108 is illustrated as a continuous part of the pedestal 106, it is understood that the support 108 may be a separate structure from the pedestal 106 that is later fixedly connected to the pedestal 106 using fasteners or other attachments. Also, while both the pedestal 106 and the support 108 are illustrated as relatively simple monolithic components, it is understood that in practice they may be complex multi-component assemblies. For example, the support 108 may be hollow and / or have one or more passages extending along its length to allow for cables, gas flow lines, cooling flow lines, and the like to potentially be routed therethrough. The pedestal 106 may include internal features, such as thermal breaks, coolant passages, heater elements, electrodes, gas passages, passages for lift pins, and the like, in some embodiments. It will be understood that the hexapod pedestal mechanisms discussed herein may be generally used with any suitable pedestal type, such as pedestal 106 with any one or more of the systems described above (or other systems not explicitly listed above).

[0069] Also shown in Figure 1 is an example of a hexapod mechanism 112 that includes a fixed mount 114 that is bolted or otherwise fixedly connected to the semiconductor processing chamber 102. The hexapod mechanism 112 further includes a movable mount 116 that is connected to the fixed mount 114 by six linear actuators 122. Each linear actuator 122 can be independently driven by a corresponding motor 124. While the illustrated linear actuators are all of similar design, length, diameter, and throw, it will be understood that some embodiments may feature linear actuators where two or more of the linear actuators differ in design or construction (e.g., have different lengths (either maximum or minimum), diameters, throws, etc.). All of the linear actuators are independently controllable (but generally not controlled in a manner that is kinematically incompatible with the kinematics of the overall assembly) such that they can extend or retract to different lengths independent of the extension or retraction of the other linear actuators. The linear actuators may be arranged with radial symmetry (e.g., with tripartite symmetry (e.g., having three-way radial symmetry)) as shown in the figures, although in some other embodiments the linear actuators may be arranged with non-radial symmetry.

[0070] Also, although the illustrated linear actuator 112 has a drive motor 124 that is part of the portion of the linear actuator 112 that is mounted on a fixed mount 114, other embodiments may feature a linear actuator 112 in which the motor 124 is part of the portion of the linear actuator 112 that is mounted on a moveable mount 114 (or a linear actuator that features a mix of such linear actuators (e.g., some linear actuators with motors that are part of the portion of the linear actuator that is mounted on a moveable mount and some linear actuators with motors that are part of the portion of the linear actuator that is mounted on a fixed mount)).

[0071] The hexapod mechanism 112 generally has a configuration in which six linear actuators 122 are divided into three pairs, with the three pairs of linear actuators 122 arranged in a circular array about a common central axis (as shown in more detail in Figures 2-4). Each pair of linear actuators 122 may be arranged such that the linear actuators 122 in that pair of linear actuators 122 are arranged to extend or retract their moveable portion along an axis of movement that is coincident with the common central axis and at an oblique angle to a corresponding reference plane located between the linear actuators 122 in that pair of linear actuators 122, at least when the linear actuators 122 are at similar degrees of extension. Thus, the spacing between the locations where adjacent linear actuators 122 of each pair connect with the fixed mount 114 or the movable mount 116 will be different from the spacing between the locations where adjacent linear actuators 122 of that pair connect with the other of the fixed mount 114 and the movable mount 116.

[0072] In a hexapod system, each linear actuator utilized is configured to have at least five unconstrained degrees of freedom. This may be accomplished by pivotally connecting one end of each linear actuator to one of the fixed or movable mounts using a spherical joint (such as a ball joint) to provide three of the five degrees of freedom, and pivotally connecting the other end of each linear actuator to the other of the fixed or movable mounts using a universal joint to provide the remaining two degrees of freedom (or, alternatively, together with another spherical joint to provide six degrees of freedom). The use of spherical and universal joints allows for large angular displacements of the linear actuators relative to one or both of the fixed and movable mounts in such a hexapod system, providing a wide range of angular motion. For clarity, the term "pivotally connected" as used herein with respect to two components refers to a connection that allows one component to rotate relative to the other component about one or more axes.

[0073] In some contexts of the hexapod mechanism utilized in the hexapod pedestal systems discussed herein, the linear or angular displacement that the hexapod mechanism may need to provide may be much smaller in at least some directions or with respect to some axes than in other directions or axes. For example, the hexapod mechanism used in the hexapod pedestal system may be designed to provide a much larger vertical displacement for the movable mount compared to the range of horizontal displacement (e.g., ±25 mm vertically compared to ±1.5 mm horizontally). This is because the vertical movement of the pedestal using the hexapod mechanism may be used in place of the gross movement of the pedestal used to accommodate wafer placement operations or to move the pedestal closer to the showerhead during processing operations (which may include the need to move the pedestal several centimeters). In contrast, the horizontal movement of the pedestal using the hexapod system may often be used only to simply fine-tune the position of the pedestal relative to the wafer center or relative to a target location (e.g., center) of the showerhead. Such corrective movements are typically quite small, e.g., on the order of less than 1 to 2 millimeters. Of course, if a greater amount of horizontal movement is desired, for example to perform a larger diameter orbital movement as described above, the maximum amount of horizontal displacement required to support such movement may dictate the maximum amount of horizontal displacement that the hexapod mechanism is required to provide.

[0074] Similarly, the angular displacements that a hexapod moveable mount may undergo during normal use in the context of a hexapod pedestal system may be fairly small (e.g., on the order of ±0.2° about the pitch and / or roll axes). Such angular displacements are typically sufficient to allow any non-parallelism between the wafer support surface of the pedestal and the underside of the showerhead to be accommodated and eliminated through tilting of the pedestal. The amount of rotation of the moveable mount about the yaw axis that such a hexapod mechanism must be able to accommodate may in some cases be nonexistent (e.g., when such rotation of the pedestal is not desired). However, in other implementations, the hexapod mechanism employed may be designed to provide such rotational movement of a significant magnitude about the yaw axis (e.g., ±10°, ±20°, or even ±30°).

[0075] At the same time, the hexapod mechanism used in the hexapod pedestal system may be required to provide positional and rotational accuracy in the range of, for example, ±25 μm and ±0.02° for the position and orientation of the pedestal and the moveable mount.

[0076] In view of the above, some embodiments of the hexapod pedestal system may avoid the use of spherical and / or universal joints, as shown in Figures 2 and 4, and instead utilize biaxial flexure bearings 140 used to pivotally connect one or both ends of each linear actuator 122 to the movable mount 116 or fixed mount 114. Each biaxial flexure bearing 140 provides two rotational degrees of freedom, essentially acting like a universal joint with a very limited range of motion. When two biaxial flexure bearings 140 are used with each linear actuator 122, a fifth degree of freedom may be provided through the use of a linear actuator 122 in which a portion of the linear actuator can not only extend or contract along an extension axis relative to other portions of the linear actuator, but also be free to rotate (at least slightly) relative to other portions of the linear actuator about the extension axis.

[0077] FIG. 5 is a detailed view of an example of a biaxial flexure bearing similar to that used in the hexapod pedestal system of FIGS. 1-4. As shown, biaxial flexure bearing 540 is shown as a monolithic component machined or formed from a larger piece of material, and may have a generally constant cross-section through its thickness (into the page). Biaxial flexure bearing 540 includes three distinct portions: inner portion 544 having a mounting hole 558 therethrough, middle portion 546 extending around inner portion 544, and outer portion 548 extending around middle portion 546. Inner portion 544 may be separated from middle portion 546 by a gap extending generally around the entire circumference of inner portion 544, except for two locations where first torsion web 550 spans between inner portion 544 and middle portion 546. The first torsion webs 550 may be thin webs of material located on either side of the inner portion 544 and supporting the inner portion 544 against the intermediate portion 546. The first torsion webs 550 may have a thickness in a direction perpendicular to the cut plane of FIG. 5 that is significantly greater than the thickness of the first torsion web 550 along the vertical axis relative to the orientation of FIG. 5. For example, the thickness of the first torsion web 550 in the direction into the paper may be on the order of 1 centimeter (e.g., 8, 9, 10, 11, or 12 millimeters), while the thickness of the first torsion web 550 in the vertical direction of FIG. 5 may be on the order of 1 millimeter or less (e.g., less than about 0.9 mm, 0.8 mm, 0.7 mm, 0.6 mm, or 0.5 mm). The first torsion webs 550 may have a length, for example, on the order of the thickness into the paper (e.g., 5, 6, 7, 8, or 9 mm).

[0078] 5 and are much more resistant to bending about an axis that is parallel to the cut plane of FIG. 5 and perpendicular to the first reference plane 554 than to twisting about a central axis passing through the center of each first torsion web 550. The first reference plane 554 may generally correspond to a mid-plane of the first torsion web 550 along the thinnest dimension of the first torsion web 550, e.g., the first torsion web 550 may be a substantially flat structure that is aligned with the first reference plane 554. Thus, the first torsion web 550 may generally limit movement of the inner portion 544 relative to the intermediate portion 546, while allowing the inner portion 544 to twist relatively easily (at least for a limited range of rotation) relative to the intermediate portion 546 about an axis that is parallel to the first reference plane 554 and the cut plane of FIG.

[0079] Similarly, the middle portion 546 may be separated from the outer portion 548 by a gap that extends to substantially surround the entire circumference of the middle portion 546, except for two locations where the second torsion web 552 spans between the middle portion 546 and the outer portion 548. The second torsion web 552 may be similar in size and shape to the first torsion web 550 and is disposed on either side of the middle portion 546. The second torsion web 552 supports the middle portion 546 relative to the outer portion 548.

[0080] The second torsion webs 550, like the first torsion webs 550, are parallel to both the second reference plane 556 and the cut plane of FIG. 5 and are much more resistant to bending about an axis that is parallel to the cut plane of FIG. 5 and perpendicular to the second reference plane 556 than to twisting about a central axis passing through the center of each second torsion web 552. The second reference plane 556 may generally correspond to a mid-plane of the second torsion web 552 along its thinnest dimension, e.g., the second torsion web 552 may be a substantially flat structure that is aligned with the second reference plane 556. Thus, the second torsion webs 552 may generally limit movement of the intermediate portion 546 relative to the outer portion 548, while allowing the intermediate portion 546 to twist relatively easily (at least for a limited range of rotation) relative to the outer portion 548 about an axis that is parallel to the second reference plane 556 and the cut plane of FIG. 5.

[0081] A biaxial flexure bearing (such as biaxial flexure bearing 540) allows a component (e.g., an actuator shaft or body) fixedly attached relative to mounting hole 558 and inner portion 544 to undergo a limited range of angular displacement in any direction away from a nominal centerline of mounting hole 558, which may, for example, coincide with both first reference surface 554 and second reference surface 556.

[0082] Such biaxial flexure bearings 140 (or 540) are typically more accurate than spherical bearings or universal joints because they have no sliding or rolling surfaces, and therefore do not require clearances to accommodate such relatively moving components, resulting in zero backlash or slop. Additionally, biaxial flexure bearings 140 may be packaged in a smaller volume or envelope as compared to a comparable spherical bearing or universal joint. Also, biaxial flexure bearings 140 may be machined directly into the moveable mount 116 and fixed mount 114, thus reducing the number of parts that must be assembled, and as such may be less expensive to manufacture than a comparable spherical bearing or universal joint.

[0083] For example, the dual axis flexure bearing configuration shown in FIG. 5 features an intermediate portion 546 having a first segment 545 disposed on either side of the inner portion 544 at a first distance from the central axis of the inner portion 544, and a second segment 549 disposed on either side of the inner portion 544 at a second distance from the central axis of the inner portion 544. The second segment 549 is disposed at a greater distance from the central axis than the first segment 545 and is connected to the inner portion via a first torsion web 550. At the same time, the intermediate portion 546 also has bridging segments 547 that connect each of the different pairs of first and second segments. In the illustrated example, the bridging segments 547 are all linear and parallel to each other (and the bridging segments 547 on either side of the first reference plane 554 are generally collinear with each other). However, it will be appreciated that other configurations may feature non-parallel and / or non-linear bridging segments 547.

[0084] While first segment 545 in the example of Figure 5 is curved or arched, other biaxial flexure bearings may feature first segments of different shapes, however, the general shape of intermediate portion 546 as shown in Figure 5 (e.g., generally elongated in nature (having a dimension in a direction perpendicular to the first datum plane that is smaller or substantially smaller than the dimension in a direction perpendicular to the second datum plane)) allows the illustrated biaxial flexure bearing 540 to be packaged in a much more space-efficient manner than could be achieved with other shapes.

[0085] For example, this allows the first and second flexure webs 550 and 552 to each have a radial length (relative to the central axis of the flexure bearing 540) that is approximately half the distance between the center of the flexure bearing 540 and the outer diameter of the outer portion 548, while allowing the thickness of the structure of the intermediate portion 546 and the structure of the inner portion 544, the radius of the mounting hole 558, and the gap between the inner portion 544 and the intermediate portion 546 to be accommodated.

[0086] It will be appreciated that intermediate portion 546 having an elongated aspect ratio allows (radius of mounting hole 558 + radial length of first flexure web 550 + radial length of second flexure web 552 + radial width of intermediate portion 546) to exceed the radius of outer portion 548 (or, perhaps more accurately, the radius of a circle circumscribing second flexure web 552). This allows the flexure web to be provided with a greater radial length (and thus an increased amount of deflection it can withstand without breaking) than it could otherwise be packaged within outer portion 548 having a given diameter. For example, if the intermediate portion 546 had an aspect ratio that was not elongated (e.g., 1:1), then (the radius of the mounting hole 558 plus the radial length of the first flexure web 550 plus the radial length of the second flexure web 552 plus the radial width of the intermediate portion 546) would have to be equal to the radius of the outer portion 548, thereby limiting the length of the first and second flexure webs 550 and 552 (and thus the amount of deflection that the biaxial flexure bearing 540 can provide). 5 is considered to be drawn to scale, with, for example, second segment 547 located entirely outside of a reference circle circumscribing first segment 545, first and second flexure webs 550 and 552 may be 50% or more longer in radial length (and correspondingly have greater angular deflection capability) than could be achieved for a similarly sized biaxial flexure bearing with a middle portion having a 1:1 aspect ratio. In some embodiments, the distance between the inner portion and the second segment may be at least 1.5 times or at least twice the distance between the inner portion and the first segment.

[0087] The biaxial flexure bearing 540 discussed above utilizes torsion webs that can twist slightly to allow a limited range of biaxial angular motion. Other types of biaxial flexure bearings may be utilized (e.g., biaxial flexure bearings with bending webs). An example of such a biaxial flexure bearing is shown in Figures 6-10.

[0088] FIG. 6 is an isometric view showing biaxial flexure bearing 540 next to biaxial flexure bearing 640. As can be seen, biaxial flexure bearing 540 is designed to be machined directly into a larger structure, such as a plate that serves as a movable or fixed mount in a hexapod system (in the illustrated example, biaxial flexure bearing 540 is shown as part of a small square plate with the understanding that it may simply be part of a larger structure). Biaxial flexure bearing 640 is designed to be connected symmetrically between two components. For example, biaxial flexure bearing 640 may have mounting holes 658a and 658b (not shown, but seen in FIG. 7) that are each threaded (threads not shown) to allow biaxial flexure bearing 640 to be screwed onto a threaded stud or bolt or screw on both ends. In some embodiments, biaxial flexure bearing 640 is designed to be inserted between a linear actuator of a hexapod mechanism and either the fixed or movable mount of the hexapod mechanism, thereby requiring a longer separation distance between the fixed and movable mounts of the hexapod mechanism than would be required with a hexapod mechanism using biaxial flexure bearing 540. However, the overall diameter and size of biaxial flexure bearing 640 is much smaller (e.g., 50% smaller) than the torsion-based biaxial flexure bearing 540 (although the biaxial flexure bearings 540 and 640 shown in FIG. 6 provide comparable angular motion capabilities).

[0089] Figures 7 and 8 are isometric cross-sectional views of biaxial flexure bearing 640. In Figure 7, one quarter of biaxial flexure bearing 640 has been cut away to reveal the interior of biaxial flexure bearing 640. In Figure 8, the top half of biaxial flexure bearing 640 has been cut away to reveal a cross-section of biaxial flexure bearing 640.

[0090] As seen in Figures 7 and 8, a central bore extends through the biaxial flexure bearing 640 along a common axis 643. The ends of the central bore may provide a first mounting hole 658a and a second mounting hole 658b. The first mounting hole 658a and the second mounting hole 658b may be threaded or may include other features that allow the biaxial flexure bearing 640 to be connected with a linear actuator or a fixed or movable mount. The central bore may extend through the entire length of the biaxial flexure bearing 640 in some cases, as shown in Figure 7, while in other cases the central bore may not extend entirely through the biaxial flexure bearing 640.

[0091] Biaxial flexure bearing 640 may include a first portion 644, a second portion 646, and a third portion 648, all of which may be positioned along a common axis 643, such that second portion 646 is between first portion 644 and third portion 648. A first gap 651 may exist between first portion 644 and second portion 646, while a second gap 653 may exist between second portion 646 and third portion 648.

[0092] A pair of first bending webs 650 may span between the first portion 644 and the second portion 646, and a pair of second bending webs 652 may span between the second portion 646 and the third portion 648. The first bending web 650 and the second bending web 652 may each be a relatively thin beam-like structure (similar to the torsion webs discussed above) that is very strong in bending about one axis perpendicular to the common axis 643, and fairly flexible in bending about another axis perpendicular to the common axis 643 but also perpendicular to the other axis. The first bending web 650, which generally defines a first reference plane and may be aligned with the first reference plane, and the second bending web 652, which generally defines a second reference plane and may be aligned with the second reference plane, are positioned such that the first and second reference planes are mutually orthogonal, allowing both the first portion 644 and the third portion 648 to angularly deflect relative to the second portion 646 about orthogonal bending axes perpendicular to the common axis 643. This allows the first portion 644 and the third portion 648 to undergo biaxial bending relative to one another, similar to the motion permitted by the biaxial flexure bearing 540. For example, the first portion 644 and the third portion 648 may bend angularly about a first axis 655 through bending of the first bending web 650, while the first portion 644 and the third portion 648 may bend angularly about a second axis 657 through bending of the second bending web 652.

[0093] The first bending web 650 may be formed, for example, by machining (e.g., milling or wire EDM) two first through holes 659a through the biaxial flexure bearing 640 along a first axis 655. The first through holes 659a may be positioned close to each other such that a small amount of material located between the two first through holes 659a forms the first bending web 650, and may have a substantially flat side where the two first through holes 659a are closest to each other. Similarly, the second bending web 652 may be formed by machining two second through holes 659b through the biaxial flexure bearing 640 along a second axis 657. The second through holes 659b may be similarly positioned close to each other such that a small amount of material located between the two second through holes 659b forms the second bending web 652, and may have a substantially flat side where the two second through holes 659b are closest to each other.

[0094] 9 and 10 are side views of the biaxial flexure bearing 640. As can be seen, both the first bending web 650 and the second bending web 652 extend into the second portion 646 a significant amount, resulting in a significant amount of overlap between the first bending web 650 and the second bending web 652 along a common axis. This allows the first bending web 650 and the second bending web 652 to bend about axes close to each other. In some embodiments, the first bending web 650 and the second bending web 652 may be designed to completely overlap each other along the common axis 643, in which case the bending axes of the first bending web 650 and the second bending web 652 may lie in the same plane perpendicular to the common axis 643. In such an embodiment, the first portion 644 and the third portion 648 may be angularly bendable about a single imaginary point (about the first axis 655 and / or the second axis 657) (e.g., similar to a kinematic connection made via a ball joint).

[0095] Either of the biaxial flexure bearings 640 and 540 may be used to provide a flexible kinematic joint for use in a hexapod mechanism (e.g., between its linear actuator and its movable and / or fixed mounts). The biaxial flexure bearing 640 may provide a greater range of motion within a smaller packaging envelope since the compliant elements (bending webs) flex in bending; in comparison, the compliant elements of the biaxial flexure bearing 540 flex in twisting, requiring the length of the torsion webs to be much longer than the length of the bending webs to provide the same amount of angular deflection. However, the biaxial flexure bearing 640 may be somewhat less stiff than the equivalent biaxial flexure bearing 540. In any event, either type of biaxial flexure bearing may be used with the concepts discussed herein. In some examples, both the biaxial flexure bearings 540 and 640 may be utilized in a single hexapod mechanism. Additionally, it will be appreciated that other types of dual axis flexure bearings may be used as well, and the present disclosure is not limited to only the specific examples discussed herein.

[0096] FIG. 11 is a bi-isometric view of an example hexapod pedestal system similar to the system of FIG. 1, but utilizing biaxial flexure bearings similar to those shown in FIGS. 7-8. FIG. 12 is a bi-isometric exploded view of the example hexapod pedestal system of FIG. 11. Most of the elements shown in FIGS. 11 and 12 are designated by reference numbers having the same last two digits as the reference numbers of the equivalent elements in FIGS. 2 and 4. For the sake of brevity, these elements will not be discussed again here, and reference may be made to the previous discussion of such elements provided with respect to the embodiments of FIGS. 2 and 4.

[0097] As can be seen, the embodiment of Figures 11 and 12 differs in several ways from that of Figures 2 and 4. For example, the linear actuator 1122 is somewhat shorter in length and is coupled at both ends with biaxial flexure bearings 1140 which are similar in design to the biaxial flexure bearings 640 described above.

[0098] The fixed mount 1114 and the movable mount 1116 have fixed mounting locations, as can be seen, where the biaxial flexure bearings 140 are located in the embodiment of Figures 2 and 4. The biaxial flexure bearings 1140 are connected to these mounting locations by screws or other fasteners, as shown.

[0099] It should be understood that the biaxial flexure bearings discussed above are themselves separate elements of the present disclosure and may be implemented (and claimed) separately from the hexapod system discussed herein.

[0100] It will be appreciated that a hexapod pedestal system with a biaxial flexure bearing, such as the biaxial flexure bearing 140 (or other flexure bearings having a different configuration but still providing biaxial rotation) may provide certain advantages in the context of some applications for a hexapod pedestal system, although the present disclosure is not limited to such examples. Additionally, it will be appreciated that the use of a hexapod mechanism featuring precision universal joints in place of the biaxial flexure bearings 140 for each linear actuator 122, or the use of a hexapod mechanism utilizing universal and spherical joints in place of the biaxial flexure bearings 140 for each linear actuator 122, is also considered to be within the scope of the present disclosure.

[0101] Returning to FIGS. 1-4, it can be seen that the movable mount 116 is connected to the post 108 and thus the pedestal 106 by an adapter plate 120 which is connected to the movable mount 116 by a number of standoffs 118. Of course, it will be understood that the adapter plate 120 and the standoffs 118 may be omitted by a direct connection between the post 108 and the movable mount 116 (or the adapter plate 120 and the standoffs 118 may be considered part of the movable mount 116). In either case, the post 108 and the pedestal 106 may be fixed relative to and supported by the movable mount 116. In some embodiments, however, the post 108 may be attached to the movable mount 116 by a rotational interface (not shown) (e.g., a precision bearing system) to enable the pedestal 106 to be rotated about an axis of rotation relative to the movable mount 116. A separate drive motor (not shown) may be provided to provide a rotational input to the post 108 to enable control of such rotation. Such an embodiment may allow the pedestal to be rotated about its central axis regardless of what limitations the hexapod mechanism 112 may have on such movement.

[0102] Another feature shown in Figures 1-4 is bellows 126 and magnetic fluid seal 128. In the illustrated semiconductor processing tool 100, the semiconductor processing chamber is held under vacuum and is therefore sealed from the surrounding environment. Bellows 126 (shown in Figure 1 having rigid ends joined by a flexible pleated structure) is a stainless steel bellows that is resistant to chemical attack from process gases used in the semiconductor processing chamber 102 and is provided to bridge the gap that exists between the semiconductor processing chamber 102 and the post 108. The interface between bellows 126 and post 108 may be provided by a rotary seal (e.g., magnetic fluid seal 128) that allows the post 108 to rotate relative to the bellows 126 and the semiconductor processing chamber 102 in some embodiments. It will be appreciated that the rotating seal may alternatively be disposed at the other end of bellows 126, for example, to rotatably couple the upper end of bellows 126 to semiconductor processing chamber 102 (or to some other component that is fixed relative to semiconductor processing chamber 102, such as fixed mount 114). In such an alternative embodiment, the other end of bellows 126 is fixedly attached to post 108 such that bellows 126 is caused to rotate with rotation of post 108.

[0103] Bellows such as bellows 126 (i.e., bellows formed from stainless steel) are typically designed to support compression or expansion along the bellows' axis, but have little ability to accommodate movement in a direction transverse to their axis of expansion due to the elastic modulus of the steel and the geometry of the bellows. However, the relatively small lateral movements that a hexapod pedestal system might be expected to experience are generally small enough that such bellows can nevertheless accommodate such displacements without compromising the seal.

[0104] If active rotation of the pedestal 106 about the yaw axis is desired, the use of a rotary seal (e.g., magnetic fluid seal 128) allows the pedestal 106 to rotate relative to the bellows 126 (or the bellows 126 to rotate relative to the semiconductor processing chamber). As mentioned above, a bellows (such as bellows 126) is typically free to accommodate axial expansion or contraction and a limited amount of lateral displacement between the ends of the bellows and some degree of angular rotation of the ends of the bellows about an axis that is in a plane perpendicular to the axis of expansion of the bellows. However, such bellows are typically very resistant to twisting about the axis of expansion. As a result, the bellows 126 functions to prevent any rotation of the pedestal 106 relative to the semiconductor processing chamber 102 without the use of a rotary seal (e.g., magnetic fluid seal 128). If such rotation is not desired for a particular semiconductor processing tool 100, the rotary seal shown in the figures may be omitted even if the bellows 126 is present. However, if such rotational movement capability is desired, the rotating seal shown in the figure, or some other similar rotating seal interface, may be used to provide a vacuum-tight rotational interface that allows one end or the other of the bellows 126 to rotate relative to either the support 108 or the semiconductor processing chamber 102.

[0105] The magnetic fluid seal 128 shown is just one example of a rotary seal that may be used to provide a vacuum-tight rotary seal interface that may be used to accommodate rotational motion between the post 108 and the semiconductor processing chamber 102. In a magnetic fluid seal, a first component (e.g., a shaft) is rotatably supported relative to a second component (e.g., a casing or housing) by two or more rotary bearings 130. The casing or housing may include a pair of rings 134 formed of a material that can be magnetized. Each ring 134 may surround a different portion of the first component having a series of multiple circumferential rib portions 136. One or more magnets 132 inserted axially between the rings 134 may generate a magnetic field that passes through one of the rings 134, through the rib portion 136 surrounded by that ring, through the first portion (e.g., of the post 108), to the other rib portion 136, into the other ring 134, and back to the one or more magnets 132. A ferrofluid material 138 introduced into the gaps between the rings 134 and the rib portions 136 that they surround is substantially held in place by the magnetic field. The ferrofluid material 138 spans the radial gaps between the ribs and the surrounding rings, thereby providing a series of annular fluid seals that still allow rotational movement between the first and second portions of the ferrofluid seal.

[0106] As previously mentioned, the hexapod pedestal system may be implemented in the context of a multi-station chamber (e.g., a four-station module or other multi-station chamber). FIGS. 13 and 14 show an example of a four-station module. In FIGS. 13 and 14, a processing chamber 1302 is shown that is large enough to accommodate four pedestals 1306 arranged in a square array. A rotary indexer (not shown) may be included in the semiconductor processing chamber 1302 in some embodiments to facilitate movement of wafers between the pedestals 1306. Two wafer handling robots 1398 are also shown that may be configured to reach into the semiconductor processing chamber 1302 to transfer wafers therein (or retrieve wafers therefrom). As seen in FIG. 14, each pedestal 1306 is supported by a corresponding hexapod mechanism 1312 and is independently controllable according to any of the techniques discussed herein.

[0107] The general kinematics of a hexapod mechanism (e.g., how to extend or contract a linear actuator of a typical hexapod mechanism to move its movable mount to a particular position and / or orientation relative to a fixed mount) are well known and therefore will not be described in this disclosure for the sake of brevity (e.g., the paper "Kinematic and dynamic analysis of Stewart platform-based machine tool structures" by Khalifa Harib and Krishnaswamy Srinivasan, published in September 2003 and incorporated herein by reference in its entirety, provides a detailed discussion of the kinematics of hexapod mechanisms). However, various techniques, some of which have been mentioned above, for controlling and utilizing hexapod pedestal systems in the context of semiconductor processing chambers or tools are discussed in more detail below.

[0108] FIG. 15 is a flow chart illustrating an example of a technique for utilizing / controlling a hexapod pedestal system for wafer centering operations. The technique of FIG. 15 may be performed when various reference positions / orientations for the movable mount of the hexapod mechanism being used have been pre-provided to the control system of the hexapod pedestal system. For example, the control system may be provided with information regarding a "loading" position / orientation of the movable mount as well as a "default processing" position / orientation of the movable mount and a reference wafer center position associated with the loading position. The loading position / orientation corresponds to the position and orientation in which the movable mount was located during a calibration operation performed with a calibration wafer theoretically centered on a desired target position of the pedestal. If the hexapod mechanism is placed in the loading position / orientation and the wafer is placed in the same position and orientation in which the calibration wafer was located immediately before or after a wafer handoff operation between the end effector of the wafer handling robot and the pedestal, the wafer should be similarly centered on the target point when handed off to the pedestal with the hexapod pedestal system in the loading position. The reference wafer center position may correspond, for example, to the position of the center of a calibration wafer measured by the AWC system in connection with such a calibration operation.

[0109] Similarly, the hexapod pedestal system, when in a default processing position / orientation, can position the pedestal such that the wafer support surface of the pedestal is parallel to and a predetermined distance from a bottom surface of a showerhead of a semiconductor processing chamber, and such that an axis passing through a target position on the pedestal and perpendicular to the wafer support surface passes through a target position on the showerhead (e.g., the center of the showerhead).

[0110] The loading position / orientation as well as the default processing position / orientation may be obtained during a calibration operation that may be performed during the initial configuration or setup of the hexapod pedestal system in the semiconductor processing tool, as described above. Some examples of such calibration techniques are discussed later in this specification with reference to later figures.

[0111] References herein to a "target position" with respect to a pedestal and / or showerhead are intended to mean a location at which the center of a wafer is aligned. For example, the target position of a pedestal generally corresponds to a location that is intended to coincide with a point on the underside of a wafer that is at the nominal center of the wafer when the wafer is supported by that wafer support surface. The target position of a pedestal may be considered to be the "center" of the pedestal or its wafer support surface, although such location need not necessarily coincide with the geometric central axis of the pedestal. Rather, the "center" of the pedestal is considered to be a location on the pedestal that generally corresponds to a location at which a wafer is centered when ideally positioned for semiconductor processing operations.

[0112] Similarly, the target position of the showerhead is generally perpendicular to the wafer support surface of the pedestal and coincides with a position intended to intersect an axis passing through the target position of the pedestal when the pedestal is positioned so that the wafer support surface is parallel to the underside of the showerhead.

[0113] At block 1502, a wafer is placed on an end effector of a wafer handling robot (or on a wafer support at the end of a rotating indexer arm). At block 1504, a measurement of the wafer center position is obtained. For example, the wafer handling robot may move its end effector, and thus the wafer supported thereby, through a light beam emitted by a light beam sensor of an AWC system to obtain a measurement that allows the center of the wafer to be determined. For example, the AWC system may have two light beam sensors fixedly mounted relative to a semiconductor processing chamber, each calibrated to emit a light beam in a vertical direction and detect the interruption (uninterruption) of that light beam. The optical sensors may be positioned such that an edge of the wafer intersects the light beam emitted by the optical sensors as the wafer is passed into the semiconductor processing chamber, resulting in four edge / beam crossing events (two events occurring when the wafer intersects and interrupts each light beam, and two events occurring when the wafer passes past and uninterrupts each light beam). By utilizing the position of the wafer handling robot end effector (which may be determined based on the kinematic state of the wafer handling robot) corresponding to each edge / beam crossing event and the diameter of the wafer, the AWC system can determine the center position of the wafer with respect to a coordinate system fixed relative to the semiconductor processing chamber.

[0114] In block 1506, the wafer-handling robot may be further controlled to move its end effector and the wafer disposed thereon to a first position within the semiconductor processing chamber. The first position may be, for example, the same position to which the wafer-handling robot moved the end effector during the calibration process, prior to transferring the calibration wafer between the pedestal and the end effector (or vice versa). Thus, if the AWC-determined center of the wafer supported by the end effector is the same as the AWC-determined center of the calibration wafer from the calibration process (and if the wafer-handling robot is made to accurately replicate the movements of the wafer-handling robot during the calibration process), then the wafer will be in the same position with the end effector in the first position as the calibration wafer was during the calibration process when the end effector was also in the first position.

[0115] In block 1508, the hexapod mechanism may be controlled to move its movable mount to align the pedestal target position to be aligned with the center of the wafer. For example, if the AWC-determined center point of the wafer is identical to the AWC-determined center point of the calibration wafer, the hexapod mechanism may simply be controlled to move its movable mount to the loading position / orientation. In such a scenario, the positions and orientations of the wafer handling robot, wafer, and pedestal will be identical to the positions and orientations of the same components during the calibration operation before or immediately after the transfer of the calibration wafer between the pedestal and the end effector. Thus, as a result of the transfer of the wafer to the pedestal under such conditions, the wafer will be centered on the pedestal target position with the same accuracy as the calibration wafer was centered on the pedestal target position during the calibration process.

[0116] However, if the AWC-determined center of the wafer is not identical to the AWC-determined center of the calibration wafer, the amount and direction of the offset between the AWC-determined center of the calibration wafer and the AWC-determined center of the wafer may be determined. For example, the AWC-determined center of the wafer (in terms of XY coordinates relative to a frame of reference fixed relative to the semiconductor processing chamber) may be determined to be offset 1 mm, -0.5 mm from the AWC-determined center of the calibration wafer, and the hexapod mechanism may be moved to a position and direction offset from the loading position / orientation by the same amount. Thus, when the wafer is subsequently transferred from the end effector to the pedestal, for example, by extending the lift pins to lift the wafer off the end effector, withdrawing the end effector from under the wafer, and lowering the wafer onto the pedestal, the wafer center will be centered over the target location of the pedestal.

[0117] It will be appreciated that a similar end result may be achieved in a variety of ways. For example, the wafer handling robot need not necessarily be moved to the same position that it was in during the calibration process, as long as the wafer handling robot is controlled to position the wafer with its center point at a known location, and the hexapod mechanism may be controlled to move the pedestal such that the target position of the pedestal is aligned with that known position. Alternatively, the hexapod mechanism may be left stationary, and the wafer handling robot may instead have its movements adjusted to correct for any misalignment detected with respect to the wafer using the AWC system (as is typically done in non-hexapod pedestal systems).

[0118] In block 1510, the wafer may be placed on the pedestal. For example, as described above, lift pins may be extended upward from the pedestal to contact the underside of the wafer and lift the wafer off the end effector. The wafer handling robot may then be controlled to withdraw the end effector from the space between the wafer and the pedestal. Once the end effector is clear of the wafer, the lift pins may be retracted to lower the wafer onto the wafer support surface of the pedestal. The wafer is now centered at the target position on the pedestal.

[0119] In block 1512, the hexapod mechanism may be controlled to move the moveable mount to a default processing position / orientation or to a position and orientation offset therefrom by some predetermined and desired amount. Thus, for example, the hexapod mechanism may be controlled to move the moveable mount to a default processing position / orientation to position the pedestal such that the wafer support surface is parallel to and offset a predetermined distance from the lower surface of the showerhead, and an axis passing through the target position of the pedestal and perpendicular to the wafer support surface intersects the target position of the showerhead. Alternatively, the hexapod mechanism may be controlled to simply move the pedestal directly to a desired position without first moving the moveable mount to the default processing position. The hexapod mechanism may then be controlled to move the pedestal along that axis to increase or decrease the gap between the wafer support surface and the lower surface of the showerhead according to the requirements of a particular process. Such adjustments may, in some cases, be performed dynamically during wafer processing operations as part of a process recipe.

[0120] In block 1514, one or more semiconductor processing operations may be performed on the wafer, for example, by flowing one or more process gases from the showerhead, exposing the wafer to a plasma, heating the wafer, etc.

[0121] Once the processing operation is completed, the hexapod mechanism may be controlled to return the moveable mount to the loading position / orientation, and the wafer handling robot may then remove the wafer from the pedestal and move it to a new location (e.g., to another pedestal or chamber) for further processing or handling, or to a load lock for removal from the semiconductor processing tool.

[0122] As mentioned above, the hexapod pedestal systems discussed herein may be used to dynamically adjust the size of the gap between the pedestal wafer support surface and the underside of the showerhead, however, the hexapod pedestal systems may also be used to perform a variety of other wafer position / orientation adjustments dynamically during or prior to wafer processing operations.

[0123] 16 illustrates one example of a technique for utilizing a hexapod pedestal system to perform various types of pedestal motion that may be used to enhance various wafer processing operations. In block 1602, a hexapod mechanism of the hexapod pedestal system may be actuated to move its pedestal, which supports a wafer, to a first position / angular orientation relative to a showerhead of a semiconductor processing chamber coupled to the hexapod pedestal system. The first position / angular orientation may, for example, correspond to a default processing position / orientation of the moveable mount, as previously described.

[0124] Semiconductor processing operations may begin to be performed on the wafer in block 1604. For example, the wafer may be heated and / or cooled via a temperature control system housed in the pedestal, process gases flowed from the showerhead, and / or a plasma that may be formed in the gap between the pedestal and the showerhead.

[0125] Blocks 1606-1612 represent various different types of motions that the hexapod mechanism may be controlled to provide. Depending on the particular requirements of a semiconductor processing operation, one or more of the motions shown in the figures (or none at all) may be performed through control of the hexapod mechanism. It is further understood that in some examples, two or more of the motions shown in the figures may be performed simultaneously (or at least partially simultaneously), or motions shown in two or more different figures may be performed sequentially (such as a repetition of the motions of one or more such figures) or in other orders.

[0126] In block 1606, the hexapod mechanism may be controlled to translate the pedestal along an axis perpendicular to the underside of the showerhead, for example, as described above with respect to FIG. 15. Discussion herein refers to the underside of the showerhead to imply that the underside of the showerhead is flat (e.g., "perpendicular to the underside" or "gap between the wafer support surface and the underside of the showerhead"). However, it should be understood that the underside of the showerhead may be non-flat (e.g., uneven) in some instances. In such cases, the underside of the showerhead defines a reference plane that is understood to be considered herein to represent the underside of the showerhead. Thus, "perpendicular to the underside" is understood to mean, for such showerhead, "perpendicular to a reference plane that represents the underside of the showerhead." Such a reference plane may be, for example, a plane oriented and positioned to have, on average, the shortest spatially distributed distance between itself and all points on the underside of the showerhead. Thus, for example, if the underside of the showerhead is contoured to have a radially sinusoidal cross-sectional profile, the reference plane would be parallel to the X-axis of the sinusoidal profile and located approximately halfway between the top and bottom of the sinusoidal profile.

[0127] Such translational movement of the pedestal can dynamically adjust the gap that exists between the pedestal wafer support surface and the showerhead, which can allow, for example, to increase or decrease the radial flow conductance of gas flowing into the gap between the pedestal wafer support surface and the showerhead, to increase or decrease the volume of gas (and thus the gas flow rate) that must be flowed in the space between the pedestal and the wafer support surface, to adjust or tune the characteristics of the electromagnetic field that exists between the wafer support surface and the showerhead, etc.

[0128] An example of such translational motion is shown in Figures 17-19, which show (from various perspectives, e.g., top, side, front, and isometric) a hexapod pedestal system (with chambers, bellows, and rotating seals omitted from the figures) in various states of operation. The hexapod pedestal system of Figures 17-19 (also shown in Figures 20-23) features a movable mount 1716 connected to a fixed mount 1714 by six linear actuators 1722. The linear actuators 1722 are shown in this example as connected at either end to the movable mount 1716 or the fixed mount 1714 via spherical joints for illustrative purposes, although it will be understood that alternative versions may use flexure bearings or universal joints as described herein above.

[0129] 17 and 18, the linear actuator 1722 may be controlled to raise or lower the pedestal 1706. For example, in FIG. 17, the linear actuator 1722 is retracted, thereby lifting the movable mount 1716 and the pedestal 1706 supported by the linear actuator 1722 to an uppermost position 1776. The uppermost position 1776 may be vertically offset from a plane 1774 that coincides with the underside of a showerhead (not shown), for example. The linear actuator 1722 may similarly be partially extended to lower the movable mount 1716 relative to the fixed mount 1714, thereby lowering the pedestal 1706, as shown in FIG.

[0130] The hexapod pedestal system of FIGS. 17-19 further includes a lift pin mechanism comprising a plurality of lift pins 1768 slidably engaged with the pedestal 1706, which is supported by the movable mount 1716 via the support posts 1708. The lift pins 1768 may protrude from a lower surface of the pedestal 1706 and may be fully retracted below the wafer support surface of the pedestal when in a retracted (stored) state, but may be extended from the wafer support surface (thereby lifting any wafer that may be supported by the wafer support surface) by applying a lifting force to the tips of the lift pins 1768 protruding from the bottom surface of the pedestal 1706. For example, a lift pin actuation mechanism may be provided comprising a lift ring 1770. The lift ring 1770 may surround the support posts 1708 and be supported by a lift actuator 1772 that may be controlled to raise or lower the lift ring 1770. For example, the lift ring 1770 may be raised into contact with the tips of the lift pins 1768 protruding from the underside of the pedestal 1706, thereby causing the lift pins to extend from the wafer support surface of the pedestal to lift a wafer off the pedestal or to lift a wafer supported on an end effector of a wafer handling robot disposed above the pedestal 1706, as shown, for example, in FIG. 19. In FIG. 19, the lift ring 1770 is further raised and the pedestal 1706 is lowered to provide the desired degree of pedestal 1706 / wafer 1710 gap upon actuation of the lift pins 1768. Alternatively, the lift pin actuation mechanism may comprise individually controllable actuators that may be used to actuate each lift pin separately, rather than an actuator that drives the lift pins in unison via the lift ring 1770.

[0131] Returning to FIG. 16, in block 1608, the hexapod mechanism may be controlled to rotate the pedestal about an axis of rotation (e.g., an axis of rotation that passes through the target position of the showerhead and perpendicular to the underside of the showerhead). Such rotation may be performed once, for example, or may be cycled, for example, a +X° rotation followed by a −X° rotation. Depending on the particular configuration of the hexapod mechanism used (e.g., a hexapod mechanism with a universal / spherical joint vs. a hexapod mechanism with a biaxial flexure joint), the amount of such rotation may be relatively large (e.g., up to ±30°) or may be much smaller (e.g., ±3° (or no rotation)). Such rotational motion may be used to reduce or average out azimuthal non-uniformities that may occur during semiconductor processing wafer processing operations.

[0132] FIG. 20 illustrates the hexapod pedestal system of FIG. 17 undergoing a rotational motion as discussed with respect to block 1608 in FIG. 16. The top series of diagrams illustrates the hexapod pedestal system in a default or unrotated state (or a mid-range rotation state, i.e., a state in which the hexapod pedestal system can be rotated an equal amount in either direction). The middle series of diagrams illustrates the hexapod pedestal system actuated to rotate the pedestal by 15° (as viewed from above) in a clockwise direction about an axis of rotation that passes through the center of the pedestal 1706 (see FIG. 17 for the designation). The bottom series of diagrams illustrates the hexapod pedestal system actuated to rotate the pedestal by 15° (as viewed from above) in a counterclockwise direction about the axis of rotation. To facilitate understanding of the rotational motion, the pedestal 1706 includes a triangular reference feature that indicates the rotational orientation of the pedestal 1706 (the same triangular feature is shown in both the displaced and undisplaced states in the ±15° diagrams).

[0133] Returning to FIG. 16, in block 1610, the hexapod pedestal system may be controlled to orbit the pedestal about a position offset from the target position of the showerhead. Thus, for example, the hexapod mechanism may be controlled to move the target position of the pedestal off-center so that it is not centered on the target position of the showerhead. After or during such movement, the hexapod mechanism may be controlled to move the target position of the pedestal to follow a helical, circular, elliptical, or other path that orbits about an axis that is perpendicular to the underside of the showerhead and passes through the target position of the showerhead. Such orbital movement of the pedestal about such an axis may be used to reduce or average out non-uniformities, particularly non-uniformities that are concentrated or clustered in a small area (e.g., an area at least smaller than the maximum dimension of the orbital path used).

[0134] FIG. 21 illustrates the hexapod pedestal system of FIG. 17 undergoing an orbital motion as discussed with respect to block 1610 in FIG. 16. In FIG. 21, the hexapod pedestal system is shown in four different stages of orbital motion. In the leftmost set of figures, the hexapod pedestal system has been actuated to laterally offset the pedestal center 1784 from the orbital central axis 1778 (e.g., the central axis of the pedestal 1706 when the pedestal 1706 is in a default or centered position (see pedestal nominal position 1782), e.g., relative to the showerhead). Thus, the pedestal center 1784 lies along an orbital path 1780 about the orbital central axis 1778, and may be caused to follow the orbital path 1780 as shown in each set of figures proceeding to the right in FIG. 21. Although only a quarter of an orbit is shown in FIG. 21, it will be understood that the illustrated motion may continue for an entire orbit (or multiple orbits). Further, as can be seen, the orbital motion of the pedestal may be performed without any change in rotational orientation with respect to the pedestal (the triangular reference marks indicating the rotational orientation suggest no rotation at all, as is evident from the top view), and of course, the motion of block 1610 combined with the motion of block 1608 results in both orbital and rotational motion of the pedestal 1706.

[0135] 16, in block 1612, the hexapod mechanism may be controlled to purposefully orient the wafer support surface of the pedestal in a non-parallel orientation relative to the lower surface of the showerhead. In some such embodiments, such motion may be controlled to cause the symmetric position of the pedestal to remain centered on an axis that passes through the target position of the showerhead and is perpendicular to the lower surface of the showerhead, while in other embodiments, such motion may be controlled such that the target position of the pedestal is radially offset from such axis.

[0136] For example, the hexapod mechanism may be controlled to move the pedestal in an orientation such that the wafer support surface of the pedestal is at a small, non-zero, acute angle (e.g., ∼0.1° to 2°) with respect to the lower surface of the showerhead. Such non-parallelism between the wafer support surface and the lower surface of the showerhead may lead to a change in the radial flow conductance of process gases flowed into the gap between the wafer support surface and the showerhead (e.g., there may be a higher flow conductance in the radial direction extending toward the edge of the pedestal where the wafer support surface / showerhead lower surface angle creates a larger gap therebetween, as compared to the opposite radial direction (where the above-referenced angle extends toward the edge of the pedestal where the smaller gap exists). Depending on the particular process, such a higher flow conductance may increase or decrease the process rate of that process (e.g., etch or deposition) in the region of the higher flow conductance. Such adjustment of the flow conductance may enable mitigation of certain types of non-uniformities. For example, in a multi-station processing chamber, there may be four pedestals at four stations arranged to form the corners of a square. A rotary indexer that rotates about an axis passing through the center of the square may be used to transfer wafers between the various stations. However, the presence of the rotary indexer may introduce significant asymmetry into the morphology of the processing chamber surrounding each station. For example, if the processing chamber has a cylindrical hole around each pedestal / station, this may provide a relatively uniform radial gap between the pedestal and the portion of the processing chamber closest to the outer edge of the pedestal. However, if the wall of the hole is machined away in some locations to allow the indexer arm to rotate to the area above the pedestal, those locations become discontinuities in the cylindrical surface of the hole that may cause the wafer being processed to have gradient non-uniformities that extend more or less along the diameter of the wafer. By tilting the pedestal slightly to deliberately introduce a similar gradient of non-uniformity in the opposite direction, the magnitude of the non-uniformity may be reduced or eliminated.

[0137] Such tilting may be used, for example, to address potential circumferential gas flow non-uniformities that may exist due to asymmetries in the exhaust system of the semiconductor processing chamber. For example, if the semiconductor processing chamber has an exhaust system that is fluidly connected to the interior volume of the semiconductor processing chamber at a location that is horizontally offset from a vertical axis passing through the target position of the pedestal, this may cause a circumferential pressure gradient to exist around the periphery of the pedestal, thereby causing potential circumferential flow non-uniformities about the periphery of the wafer, even in situations where the semiconductor processing chamber is axially symmetric in the region surrounding the pedestal and the wafer support surface and the lower surface of the showerhead are parallel. By intentionally tilting the wafer support surface relative to the lower surface of the showerhead, potential circumferential gas flow non-uniformities due to such exhaust system asymmetries may potentially be mitigated or negated through the introduction of a countervailing circumferential gas flow non-uniformity caused by tilting the wafer support surface relative to the lower surface of the showerhead. For example, if the exhaust system is in fluid communication with the semiconductor processing chamber at a position that is 0° clockwise with respect to a vertical axis that passes through the target position of the pedestal, the hexapod mechanism may be controlled to tilt the pedestal and its wafer support surface such that a position along the edge of the wafer supported by the pedestal that is ∼180° clockwise with respect to the vertical axis (e.g., a position opposite the position where the exhaust system is in fluid communication with the semiconductor processing chamber) has the widest gap between the wafer edge and the underside of the showerhead, while a position along the edge of the wafer that is ∼0° clockwise with respect to the vertical axis has the narrowest gap between the wafer edge and the underside of the showerhead.

[0138] Figure 22 shows the hexapod pedestal system of Figure 17 with the pedestal 1706 tilted so that it is non-parallel to the horizontal plane 1786 (which for this example represents parallel to the underside of the showerhead). Line 1788 represents a plane that is coplanar with the wafer support surface of the pedestal 1706, and line 1790 represents a plane that is perpendicular to both planes 1786 and 1788. The maximum acute angle that exists between planes 1786 and 1788 is defined by the angle between the line formed by the intersection of those planes with plane 1790. It will be understood that the amount of angular displacement shown in Figure 22 (5°) is significantly exaggerated from angles that may actually be used in a hexapod pedestal system (e.g., ±0.2°), and this is for illustrative purposes only.

[0139] Returning to FIG. 16, in block 1614, the hexapod mechanism may be moved to move the pedestal in a manner similar to that described above with respect to operation 1612, i.e., to create a non-parallel arrangement between the wafer support surface of the pedestal and the lower surface of the showerhead. However, the hexapod mechanism is further controlled to periodically or continuously change its azimuthal direction relative to the wafer support surface to the maximum acute angle that occurs between the wafer support surface and the lower surface of the showerhead. The maximum acute angle is understood to be the maximum acute angle that exists between the wafer support surface and the lower surface of the showerhead in a plane perpendicular to the lower surface of the showerhead. Similarly, the azimuthal direction of the maximum acute angle is the direction vector that is parallel to the lower surface of the showerhead and coincides with the plane in which the maximum acute angle exists.

[0140] Thus, for example, the hexapod mechanism may be controlled to periodically or continuously move diametrically opposed points along the circumference of the wafer supported by the pedestal that are closest to and furthest from the underside of the showerhead along the circumference of the wafer. Such motion may be somewhat similar to that achieved by combining / simultaneously performing the operations of blocks 1608 and 1612 (e.g., tilting the pedestal and wafer support surface relative to the underside of the showerhead, followed by rotating the pedestal and tilted wafer support surface about a vertical axis), except that in the combination of the operations of blocks 1608 and 1612, the diametrically opposed points along the circumference of the wafer supported by the wafer support surface that are closest to and furthest from the underside of the showerhead do not change (and thus the same positions along the wafer circumference remain the furthest / closest points relative to the underside of the showerhead during the rotation of the pedestal by the operation of block 1612). In contrast, the acts of block 1614 advance such position periodically or continuously around the periphery of the wafer.

[0141] Figure 23 shows the hexapod pedestal system of Figure 17 tilted in the same manner as Figure 22, but with the azimuthal direction of the maximum acute angle of the view formed shifted 45° counterclockwise from its orientation in Figure 22, for example, similar to the movement described above with respect to block 1614. Thus, plane 1790 has been shifted by 45° from its orientation in Figure 22. As can be seen, the rotational orientation of the pedestal does not change, except for the rotation required to achieve the tilt of the view.

[0142] The motion described with respect to block 1614 may be used to induce a biased flow conductance between the wafer support surface (or the wafer supported thereby) and the underside of the showerhead that is periodically or continuously rotated relative to the wafer support surface (and the wafer supported thereby). In practice, this may cause circumferentially non-uniform gas flow rates to exist around the circumference of the wafer, but may cause locations of maximum and minimum gas flow rates to traverse around the circumference of the wafer to evenly or more evenly distribute the flowed process gas.

[0143] As discussed above, in some embodiments, only one or a suitable subset of the various operations of blocks 1606 through 1614 may be performed during a particular semiconductor processing operation or set of such semiconductor processing operations. Additionally, any operations of blocks 1606 through 1612 performed during a given set of one or more semiconductor processing operations may be performed separately in some examples or in combination of two or more of such operations in other examples. For example, the orbital motion of block 1610 may be combined with the rotational motion of block 1608 to provide further averaging of any non-uniformities that may be present.

[0144] In some embodiments, the hexapod pedestal system may be calibrated during a calibration process to establish various parameters that may be referenced during subsequent utilization (e.g., when placing a semiconductor wafer on such a pedestal or when positioning such a pedestal in preparation for a wafer processing operation). There may be various techniques that may be used to obtain such information. In some embodiments, the various operations described above may be performed using such information regardless of how accurately such information was obtained. However, to provide a more detailed overview of how the hexapod pedestal system may be utilized, one such technique for obtaining such calibration information is discussed in further detail below with respect to FIG. 24.

[0145] The technique illustrated in FIG. 24 is intended to be performed with an integrated multi-sensor auto-calibration wafer that is nominally the same size and shape as a regular semiconductor wafer, but includes multiple sensor systems that can be utilized during the calibration process to assist in obtaining the calibration information described above. The auto-calibration wafer can function, for example, as the calibration wafer described herein above. An example of an auto-calibration wafer with similar functionality, at least in some respects, is provided in PCT Publication No. WO2021022291, published February 4, 2021, which is incorporated herein by reference in its entirety for all purposes. Such an auto-calibration wafer can include, for example, multiple capacitance-based distance measurement sensors disposed along an upper surface that can be used to obtain capacitance-based measurements indicative of the distance between each distance measurement sensor and the underside of the showerhead (when sufficiently close to the showerhead), and an imaging sensor configured to look both upward toward the showerhead and downward toward the pedestal when such an auto-calibration wafer is positioned between the pedestal and the showerhead.

[0146] 25-36 are schematic diagrams illustrating an example of a semiconductor processing tool and may be referenced in the following discussion. The example semiconductor processing tool features a semiconductor processing chamber 2502 with a showerhead 2560 and connected with a hexapod pedestal system including a pedestal mechanism 2512. For illustrative purposes, the showerhead 2560 is shown with a significant amount of tilt / deviation from horizontal. In practice, the showerhead 2560 may be configured to have a nominally horizontal bottom surface. However, due to assembly tolerances and machining tolerances, the showerhead 2560 may still have a small amount of tilt (e.g., ∼0.2° or less). Although the showerhead is shown floating in space, in practice it may be supported by one or more other structures or may be provided as part of the lid of the semiconductor processing chamber.

[0147] Also shown in FIG. 25 is a pedestal 2506 supported by a movable mount 2516 of a pedestal mechanism 2512, which is coupled to a fixed mount 2514 of the pedestal mechanism 2512 by six linear actuators 2522. The pedestal mechanism 2512 in this example is configured differently than described above with respect to the other embodiments in that the fixed mount 2514 and the movable mount 2516 are swapped in relative positions, but the basic principles of operation are the same. If desired, the hexapod mechanism shown may be replaced with one more similar to the version shown in the previous example (and vice versa). The fixed mount 2514 is fixedly attached to the semiconductor processing chamber 2502.

[0148] 25 also shows an auto-calibration wafer 2564 being supported by an end effector 2566 of a wafer handling robot that may be used to introduce and remove wafers into and from the semiconductor processing chamber 2502. A pair of AWC optical sensors 2562 may be fixedly mounted relative to the semiconductor processing chamber 102, each optical sensor 2562 may emit a light beam as indicated by the dotted line extending from an upper portion to a lower portion of the optical sensor 2562 as shown, as described above, and the other optical sensor 2562 may be positioned on the opposite side of the opening of the semiconductor processing chamber 2502 through which the end effector 2566 passes the wafer, such that an edge of the wafer breaks the light beams of both optical sensors 1662 as the wafer passes through the opening.

[0149] In block 2402, the auto-calibration wafer may be placed on an end effector of a wafer handling robot in much the same manner that a wafer to be processed is placed on the end effector of the robot. In some examples, the auto-calibration wafer may be placed on the end effector with the aid of a fixture that precisely positions the auto-calibration wafer in a particular position and orientation relative to the end effector.

[0150] In block 2404, the wafer handling robot may be controlled to move the auto-calibration wafer on its end effector past an optical sensor of an AWC system of the semiconductor processing chamber, as shown in, for example, FIG. 25. In block 2406, which may be performed during block 2404, the AWC system may determine a center position of the auto-calibration wafer based on the data from the optical sensor, for example, relative to a coordinate system that is fixed (or at least determinable) relative to the semiconductor processing chamber. This center position may be stored, for example, for later reference, for use in determining an amount of misalignment between the center position of the auto-calibration wafer as determined by the AWC and the center position of a wafer to be processed by the AWC.

[0151] In block 2408, the wafer handling robot may be controlled to move the end effector to a first position within the semiconductor processing chamber. The first position may be, for example, a position that is nominally centered over a target position of a pedestal of the hexapod pedestal system when the hexapod pedestal system is in a particular configuration (e.g., a home configuration (e.g., with all actuators of the hexapod mechanism at the same degree of extension)).

[0152] In block 2410, the sensor of the autocalibration wafer may be used to determine the position of the target location of the pedestal relative to the center of the autocalibration wafer, for example, as shown in FIG. 26. For example, a downward-facing image sensor 2592 on the autocalibration wafer may be used to acquire image data of fiducials (e.g., visually detectable patterns, registration marks, etc.) on the pedestal. The fiducials may have a known relationship to the target location of the pedestal, for example, the fiducials may comprise a number of lines that, when extended towards the center of the pedestal, converge to a point that coincides with the target location of the pedestal. Alternatively, there may be fiducials (e.g., two intersecting lines) that are present at the target location itself. In another example, an alignment fixture with such fiducials may be temporarily placed on the pedestal and precisely positioned relative to the pedestal using one or more physical alignment features, and such fixture may be removed from the pedestal after such calibration operation is completed. The acquired image data may enable the horizontal position of the target of interest of the pedestal to be determined relative to the center location of the autocalibration wafer.

[0153] In block 2412, the hexapod mechanism of the hexapod pedestal system may be controlled to move the pedestal an amount that offsets any horizontal offset that exists between the pedestal target position and the center of the autocalibration wafer as indicated by the image data. Thus, at the completion of block 2412, the pedestal target position is generally located directly below and centered relative to the center of the autocalibration wafer, as shown in Figure 27. In Figure 27, the "default" position of the pedestal 2506 is shown in dotted outline, from which the pedestal 2506 is offset, as discussed above.

[0154] At block 2414, information describing the position and orientation of the moveable mount of the hexapod mechanism at the completion of block 2412 may be stored in memory as first position / orientation information for future retrieval. Such information may take any of a variety of forms, but is sufficient to allow the position and orientation of the hexapod mechanism at the completion of block 2412 to be reproduced in the future, as desired. Such information may include, for example, operating status information for each of the actuators of the hexapod mechanism indicating the position of each of the actuators. The information stored at block 2414 may be, for example, information that determines a loading position / orientation for the hexapod pedestal system in a manner similar to that described above.

[0155] In block 2416, the auto-calibration wafer may be placed on a pedestal. For example, the pedestal may include a lift pin mechanism that may be controlled to extend a number of lift pins from the wafer support surface to lift the auto-calibration wafer from the end effector, for example, as shown in FIG. 28. The end effector may then be withdrawn from underneath the auto-calibration wafer (as shown in FIG. 29), and the lift pins are replaced into the pedestal to lower the auto-calibration wafer onto the wafer support surface (as shown in FIG. 30). At the end of this operation, the auto-calibration wafer is supported by the pedestal, and the center of the auto-calibration wafer is centered at the target position.

[0156] In block 2418, the hexapod mechanism may be controlled to reposition the pedestal in proximity to the underside of the showerhead, as shown in Figure 31. The position to which the pedestal is moved may be selected to be close enough to the showerhead that a capacitance-based sensor on the autocalibration wafer can obtain capacitance measurements related to the gap between the autocalibration wafer and the underside of the showerhead. The position of the pedestal resulting from the information stored as a result of block 2414 is indicated by the dashed outline of the pedestal in Figure 31 and subsequent figures.

[0157] In block 2420, the capacitance-based distance sensors of the autocalibration wafer may be used to obtain information indicative of the angular orientation of the wafer support surface of the pedestal relative to the underside of the showerhead. For example, if there are three capacitance-based sensors (such as capacitance-based distance sensor 2594 in FIG. 32) positioned along the periphery of the autocalibration wafer, the capacitance measured by each such sensor may depend on the size of the gap between that sensor and the underside of the showerhead. Thus, for example, if each such sensor is identically configured, the capacitance measured by such sensors will be the same if the gap between the sensor and the underside of the showerhead is the same (and thus the wafer support surface is parallel to the underside of the showerhead). Even if the sensors are not identical in size and performance, such sensors may be calibrated using an external fixture to determine the relationship between the capacitance measured by each sensor and the gap that exists between the sensor and the surfaces forming other parts of the capacitive circuit. Such calibration information may then be applied to capacitance measurements obtained with respect to the underside of the showerhead to determine the actual relative distance between the sensor and the underside of the showerhead.

[0158] In block 2422, the hexapod mechanism may be controlled to adjust the orientation of the pedestal wafer support surface relative to the underside of the showerhead. For example, the hexapod mechanism may be controlled to tilt the pedestal such that the wafer support surface and the auto-calibration wafer supported thereby are tilted to equalize the distance measured by the capacitance-based sensor, for example, as shown in FIG.

[0159] At block 2424, information indicative of the orientation state of the moveable mount of the hexapod mechanism may be stored in memory for later reference as a second orientation state. The second orientation state may be, for example, an orientation state that serves as the default process orientation described herein above.

[0160] In block 2426, the up-looking image sensor of the auto-calibration wafer may be used to determine the location of the showerhead target location relative to the center of the auto-calibration wafer, as shown in FIG. 34. For example, the up-looking image sensor on the auto-calibration wafer may be used to acquire image data of fiducials on the underside of the showerhead. The fiducials may have a known relationship to the showerhead target location, such as a pedestal fiducial, and may comprise a number of lines that, when extended toward the center of the showerhead, converge to a point that coincides with the showerhead target location. Alternatively, there may be fiducials (e.g., two intersecting lines) that reside at the target location itself. In another example, an alignment fixture with such fiducials may be temporarily placed on the showerhead and precisely positioned relative to the showerhead using one or more physical alignment features, and such fixture may be removed from the showerhead after such calibration operation is completed. The acquired image data may enable the location of the showerhead target to be determined relative to the center location of the auto-calibration wafer.

[0161] In block 2428, the hexapod mechanism may be controlled to move the pedestal based on the information collected in block 2426 such that an axis passing through the pedestal target position and perpendicular to the wafer support surface passes through the showerhead target position. In FIG. 34, the showerhead target position is shown by a dashed-dotted centerline through the showerhead 2560. The showerhead target position in this example coincides with the position where the center axis intersects with the underside of the showerhead. Similarly, the pedestal target position in this example coincides with the intersection between the pedestal's center axis (shown as a dashed-dotted centerline through the support posts 2508 and the pedestal 2506) and the wafer support surface of the pedestal 2506. In FIG. 35, the pedestal 2506 has been shifted such that the two axes are aligned (e.g., an axis passing through the pedestal target position and perpendicular to the wafer support surface passes through the showerhead target position).

[0162] In block 2430, information indicative of the position of the movable mount after completion of block 2428 may be stored in memory as second position state information (e.g., information that may correspond to the default processing position described herein above). The pedestal may then be returned to the default position, for example, as shown in Figure 36, after removal of the auto-calibration wafer. The upper dashed outline of the pedestal 2506 in Figure 36 represents the position of the pedestal 2506 defined by the second position / orientation state information, while the lower dashed outline of the pedestal 2506 in Figure 36 represents the position of the pedestal 2506 defined by the first position / orientation state information.

[0163] Thus, at the completion of the operations described above with respect to blocks 2402 through 2430, there is obtained state information for the hexapod pedestal system indicating the positional state of the movable mount of the hexapod mechanism for a wafer loading operation including a "centered" wafer, as well as state information for a default processing state in which the wafer support surface is parallel to and a predetermined distance from the lower surface of the showerhead, and the target positions of the showerhead and pedestal are both along a common axis perpendicular to the wafer support surface. Additionally, the wafer center position information of the autocalibration wafer determined by the AWC system may be stored to allow a misalignment between the center of future wafers determined by the AWC and the wafer center position of the autocalibration wafer to be determined to guide alignment of the pedestal in future wafer placement operations.

[0164] Control of the hexapod pedestal system and potentially other equipment discussed above (such as wafer handling robots, indexers, active wafer centering systems, etc.) may be facilitated through the use of a controller that may be included as part of a semiconductor processing tool, such as the examples of semiconductor processing tools and / or chambers discussed above. The above-described systems may be integrated with electronics for controlling operation of the system before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as a "controller" and may control various components or sub-components of the system. Depending on the processing requirements and / or type of system, the controller may be programmed to control any of the processes disclosed herein, such as supply of process gases, temperature settings (e.g., heating and / or cooling), valve operation, light source control for radiant heating, pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow settings, fluid supply settings, position and motion settings, and wafer movement in and out of tools or chambers and other transfer tools and / or load locks connected or coupled to a particular system. More specifically, such a controller may be configured to control, among other things, a linear actuator of the hexapod pedestal system. In some such embodiments, the controller may be further configured to receive data from an autocalibration wafer or other calibration system that enables the controller to obtain information from a sensor system of the autocalibration wafer or other calibration system to facilitate calibration of the hexapod pedestal system.

[0165] In general, a controller may be defined as electronic equipment having various integrated circuits, logic, memory, and / or software that receive instructions, issue instructions, control operations, enable cleaning operations, enable endpoint measurements, etc. Integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and / or one or more microprocessors or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions that are communicated to the controller in the form of various individual settings (or program files) that define operational parameters for performing a particular process on or for a semiconductor wafer, or for a system. The operational parameters may, in some embodiments, be part of a recipe defined by a process engineer to accomplish one or more process steps during processing of one or more layers, materials, metals, oxides, silicon, silicon oxides, surfaces, circuits, and / or dies of a wafer.

[0166] The controller may be part of or connected to a computer that is integrated with, connected to, or otherwise networked with the system, or a combination thereof, in some embodiments. For example, the controller may be in the "cloud" or may be all or part of a fab host computer system that may enable remote access of wafer processing. The computer may enable remote access to the system to monitor the current progress of a manufacturing operation, look at the history of past manufacturing operations, or look at trends or performance indicators from multiple manufacturing operations, to change parameters of a current process, set up a process step according to a current process, or start a new process. In some examples, a remote computer (e.g., a server) may provide a process recipe to the system over a network (which may include a local network or the Internet). The remote computer may include a user interface that allows for entry or programming of parameters and / or settings, which are communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, where the instructions specify parameters for each of the process steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process being performed as well as the type of tool the controller is configured to interface with or control. Thus, as described above, the controller may be distributed, such as by having one or more separate controllers that are networked and operate toward a common purpose (such as the process and control described herein). One example of a distributed controller for such purposes is one or more integrated circuits on the chamber that communicate with one or more remotely located integrated circuits (e.g., located remotely at the platform level or as part of a remote computer) that cooperate to control the process in the chamber.

[0167] Without being limited thereto, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin rinse chamber or module, a metal plating chamber or module, a cleaning chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing system that may be associated with or utilized in the fabrication and / or manufacturing of semiconductor wafers.

[0168] As described above, depending on the processing step or steps being performed by the tool, the controller may communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, nearby tools, tools located throughout the factory, a main computer, another controller, or tools used in material transport to carry containers of wafers to or from tool locations and / or load ports within a semiconductor manufacturing factory.

[0169] The use of ordinal numbers (e.g., (a), (b), (c),..., or (1), (2), (3),..., etc.) in this disclosure and claims should not be understood to imply any particular order or sequence unless such order or sequence is explicitly stated. For example, where there are three steps labeled (i), (ii), and (iii), these steps may be performed in any order (or simultaneously, if not otherwise inconsistent) unless otherwise indicated. For example, if step (ii) involves manipulation of an element produced in step (i), then step (ii) may be considered to be performed at some time after step (i). Similarly, if step (i) involves manipulation of an element produced in step (ii), then it should be understood that the opposite is true. It should be understood that the use of the ordinal marker "first" herein (e.g., "first item") should not be read as implying, either implicitly or inherently, that a "second" instance (e.g., "second item") necessarily exists.

[0170] It should be understood that phrases such as "for each <item> of one or more <items>," "for each <item> of one or more <items>," when used herein, include both single-item groups and multiple-item groups; that is, the phrase "for each" is used in the sense that it is used in programming languages ​​to refer to each item of any collection of items. For example, if the collection of items referred to is a single item, then "each" refers only to that single item and does not imply that there must be at least two of those items (even though dictionary definitions of "each" often define the term as referring to "every one of two or more"). Similarly, the terms "set" or "subset" should not, in and of themselves, be considered to necessarily encompass a plurality of items, and it is understood that a set or subset may encompass only one member or multiple members (unless the context suggests otherwise).

[0171] In this disclosure, the term "fluidically connected" is used in reference to spaces, plenums, holes, etc. that may be connected to one another, either directly or through one or more intervening components or volumes, to form a fluid connection, similar to the use of the term "electrically connected" in reference to components that are connected to one another to form an electrical connection. The term "fluidically inserted" is used in reference to a component, space, plenum, or hole that is fluidly connected to at least two other components, spaces, plenums, or holes, such that fluid flowing from one of the other components, spaces, plenums, or holes to the other or another of the other components, spaces, plenums, or holes first passes through the "fluidically inserted" component before reaching the other or another of the components, spaces, plenums, or holes. For example, if a pump is fluidly inserted between a reservoir and an outlet, fluid flowing from the reservoir to the outlet will first pass through the pump before reaching the outlet. The term "fluidically adjacent," as used herein, refers to the placement of a fluid element relative to another fluid element such that there is no potential structure fluidically interposed between the two elements that could potentially impede fluid flow between the two fluid elements. For example, in a flow path having a first valve, a second valve, and a third valve arranged in sequence along the flow path, the first valve would be fluidly adjacent to the second valve, the second valve would be fluidly adjacent to both the first and third valves, and the third valve would be fluidly adjacent to the second valve.

[0172] As used herein, the term "between," when used in conjunction with a range of values, should be understood to include the first and last values ​​in the range, unless otherwise stated. For example, between 1 and 5 should be understood to include 1, 2, 3, 4, and 5, not just 2, 3, and 4.

[0173] The term "operably connected" should be understood to refer to a state in which two components and / or systems are connected, either directly or indirectly, such that, for example, at least one component or system can control the other. For example, a controller may be described as operably connected with a resistive heating unit, including being connected with a sub-controller of the resistive heating unit that is electrically connected with a relay configured to controllably connect or disconnect the resistive heating unit from a power source capable of providing an amount of power that can be supplied to the resistive heating unit to produce a desired degree of heating. The controller itself may not be able to provide such power to the resistive heating unit due to the currents involved, but the controller is still understood to be operably connected with the resistive heating unit.

[0174] It is understood that the examples and embodiments described herein are merely for illustrative purposes, and in light of them, various modifications or alterations will occur to those skilled in the art. Various details have been omitted for simplicity, but various design changes may be implemented. Therefore, the above examples are considered to be illustrative and not limiting, and the present disclosure is not limited to the details shown herein, but may be modified within the scope of the present disclosure.

[0175] While the above disclosure focuses on one or more particular embodiments, it should be understood that the disclosure is not limited to only the above-mentioned examples, but is also applicable to similar modifications and mechanisms, and such similar modifications and mechanisms are also considered to be within the scope of the present disclosure. In particular, the present disclosure is directed to at least the following numbered embodiments, but may also include additional embodiments that are apparent from the above discussion but are not listed herein:

[0176] Example 1: An apparatus comprising: a pedestal configured to support a semiconductor wafer during wafer processing operations; 1. A hexapod mechanism, comprising: a movable mount supporting the pedestal; A fixed mount and a hexapod mechanism comprising six independently controllable linear actuators, each having a first end pivotally connected to a fixed mount and a second end pivotally connected to a moveable mount, the linear actuators supporting the moveable mounts relative to the fixed mounts; An apparatus comprising:

[0177] Example 2: The apparatus as described in Example 1, wherein the linear actuators are arranged symmetrically in three directions.

[0178] Example 3: A device according to any of the preceding claims, further comprising: The six linear actuators are grouped into three sets containing two linear actuators each. The apparatus, wherein the linear actuators in each pair of linear actuators are arranged to have first ends that connect to the fixed mount at positions closer to each other than the positions at which the second ends connect to the movable mount.

[0179] Example 4: A device according to any one of Examples 1 to 3, each first end of each linear actuator is pivotally connected to a fixed mount by a corresponding spherical joint, universal joint, or biaxial flexure bearing; The apparatus, wherein each second end of each linear actuator is pivotally connected to a moveable mount by a corresponding spherical joint, universal joint, or biaxial flexure bearing.

[0180] Example 5: The apparatus of any of Examples 1 to 3, wherein each first end of each linear actuator is pivotally connected to the fixed mount by a corresponding first biaxial flexure bearing.

[0181] Example 6. The apparatus of example 5, wherein each first biaxial flexure bearing comprises: The inner part and The middle part, The outer part and two first torsion webs extending between the inner portion and the intermediate portion; two second torsion webs extending between the intermediate portion and the outer portion; Equipped with For each first biaxial flexure bearing, The inner portion is interposed between the two first torsion webs, The intermediate portion is inserted between two second torsion webs, the device.

[0182] Example 7. The apparatus of example 6, further comprising: the first torsion web is a thin, substantially flat structure aligned with a first reference surface of the first dual axis flexure bearing; the second torsion web is a thin substantially flat structure aligned with the second reference surface of the first dual axis flexure bearing; The first and second reference planes are orthogonal to each other.

[0183] Example 8: The device according to example 6 or example 7, the intermediate portion includes two opposing first segments disposed on either side of the inner portion and the first torsion web and spaced apart from the inner portion such that a gap exists between the first segments and the inner portion; the intermediate portion further comprises two opposing second segments disposed on either side of the inner portion and spaced apart from the inner portion such that a gap exists between the second segments and the inner portions; Each second segment is connected to the inner portion by a corresponding one of the second torsion webs; the intermediate portion further comprises four bridging segments, each bridging segment extending between a different pair of the first and second segments; The second segment is further from the central axis of the inner portion than the first segment.

[0184] Example 9: The device of example 8, wherein the first segment is a curved segment having a convex surface facing towards the inner portion.

[0185] Example 10: The device of Example 9, wherein the first segment is an arcuate segment concentric with the inner portion.

[0186] Example 11: The device according to any of Examples 8 to 10, wherein the bridging segment is a linear segment.

[0187] Example 12: The device of Example 11, wherein the bridge segments are parallel to each other.

[0188] Example 13: The device of any of Examples 8 to 12, wherein the second segment is positioned entirely outside a reference circle that circumscribes the first segment.

[0189] Example 14: The device according to any of Examples 8 to 13, wherein the distance between the inner portion and the second segment is at least 1.5 times the distance between the inner portion and the first segment.

[0190] Example 15: The device according to any of Examples 8 to 13, wherein the distance between the inner portion and the second segment is at least twice the distance between the inner portion and the first segment.

[0191] Example 16: The apparatus of any of Examples 7 to 15, wherein, for each first biaxial flexure bearing, a first reference axis defined by the intersection of the first and second reference planes is parallel to an extension axis of a linear actuator connected to that first biaxial flexure bearing.

[0192] Example 17. The apparatus of example 5, wherein each first biaxial flexure bearing comprises: A first part; A second part; A third part; Two first bending webs extending between the first portion and the second portion; two second bending webs extending between the second portion and the third portion; Equipped with For each first biaxial flexure bearing, The second part is interposed between the first part and the third part; the first portion, the second portion, and the third portion lie along a common axis; a first gap exists between the first portion and the second portion; A second gap exists between the second portion and the third portion.

[0193] Example 18. The apparatus of example 17, further comprising: the first flexure web is a thin substantially flat structure aligned with a first reference surface of the first biaxial flexure bearing; the second flexure web is a thin substantially flat structure aligned with the second reference surface of the first biaxial flexure bearing; The first and second reference planes are orthogonal to each other.

[0194] Example 19: The apparatus of example 17 or example 18, wherein each first biaxial flexure bearing comprises a central bore extending through the first portion, the second portion, and the third portion along a common axis of the first biaxial flexure bearing.

[0195] Example 20. The apparatus of any of Examples 17 to 19, further comprising: The first biaxial flexure bearing has two first through holes and two second through holes; The first bending web is disposed between the first through holes, The second bending web is disposed between the second through holes, the first through hole extends completely through the first biaxial flexure bearing; The second through hole extends completely through the first biaxial flexure bearing of the device.

[0196] Example 21: The apparatus of any of Examples 17-20, wherein the first flexure web and the second flexure web of each first biaxial flexure bearing extend into the second portion.

[0197] Example 22: The apparatus of any of Examples 1 to 16, wherein each second end of each linear actuator is pivotally connected to the movable mount by a corresponding second biaxial flexure bearing.

[0198] Example 23. The apparatus of example 22, wherein each second biaxial flexure bearing comprises: The inner part and The middle part, The outer part and two first torsion webs extending between the inner portion and the intermediate portion; two second torsion webs extending between the intermediate portion and the outer portion; Equipped with For each first biaxial flexure bearing, The inner portion is interposed between the two first torsion webs, The intermediate portion is inserted between two second torsion webs, the device.

[0199] Example 24. The apparatus of example 23, further comprising: the first torsion web is a thin, substantially flat structure aligned with the first reference surface of the second biaxial flexure bearing; the second torsion web is a thin substantially flat structure aligned with the second reference surface of the second biaxial flexure bearing; The first and second reference planes are orthogonal to each other.

[0200] Example 25. The apparatus of example 24, further comprising: the first and second reference planes intersect along a central axis of the second biaxial flexure bearing; The central axis is parallel to an extension axis of a linear actuator that is connected to a second biaxial flexure bearing.

[0201] Example 26: The apparatus of any of Examples 1 to 25, further comprising a semiconductor processing chamber and a showerhead; The wafer support surface of the pedestal is disposed within a semiconductor processing chamber; At least a portion of the showerhead is disposed within the semiconductor processing chamber; The stationary mount is fixed relative to a semiconductor processing chamber.

[0202] Example 27. The apparatus of Example 26, further comprising a controller, the controller operatively connected to the six linear actuators for: a) translating the movable mount along an axis perpendicular to a wafer support surface of the pedestal; b) rotating the movable mount about an axis of rotation perpendicular to the wafer support surface, passing through a target position of the pedestal at which the wafer is to be centered; c) translating the movable mount along a path orbiting an axis perpendicular to a lower surface of the showerhead facing the pedestal and intersecting the target position of the showerhead; d) rotating the wafer support surface of the pedestal relative to the showerhead; or e) tilting the movable mount relative to the fixed mount such that the wafer support surface of the pedestal is oriented at a non-zero acute angle relative to the lower surface of the showerhead, and a maximum acute angle formed between the lower surface of the showerhead and the wafer support surface is defined in a plane that is periodically or continuously varied in azimuth orientation about an axis perpendicular to the lower surface of the showerhead, relative to the pedestal.

[0203] Example 28: The apparatus of Example 27, wherein the controller is further configured to control the linear actuator to cause the movable mount to perform two or more of (a) to (e) at least partially simultaneously while the pedestal supports a wafer disposed thereon.

[0204] Example 29: An apparatus described in either Example 27 or Example 28, wherein the controller is further configured to control the linear actuator to cause the movable mount to perform two or more of (a) to (e) at least partially continuously while the pedestal supports a wafer disposed thereon.

[0205] Example 30: The device of any of Examples 27 to 29, further comprising: a wafer handling robot configured to extend its end effector into a semiconductor processing chamber; an active wafer centering system configured to determine a location of a center of a wafer being carried by the end effector relative to a semiconductor processing chamber; Equipped with The controller further comprises: i) obtaining the location of the center of the wafer as determined by an active wafer centering system; ii) controlling the linear actuator to position the target position of the pedestal at a position centered under the center of the wafer based on the location of the center of the wafer determined by the active wafer centering system; iii) after (ii), the apparatus is configured to transfer the wafer to the pedestal.

[0206] Example 31: The device according to example 30, the pedestal includes a plurality of lift pins, the apparatus including a lift pin actuation mechanism configured to move the lift pins between an extended state in which the lift pins extend beyond the wafer support surface of the pedestal and a retracted state in which the lift pins do not extend beyond the wafer support surface; The controller is configured to perform (iii) by causing the lift pin actuation mechanism to move the lift pins to an extended state into contact with the wafer, causing the wafer handling robot to retract the end effector from a space between the wafer and the wafer support surface, and causing the lift pin actuation mechanism to move the lift pins to a retracted state to position the wafer on the wafer support surface.

[0207] Example 32: The apparatus of any of Example 30 or Example 31, wherein the controller is further configured to control the linear actuator to move the movable mount in a direction such that the wafer support surface forms a predetermined angle with respect to the underside of the showerhead after (iii).

[0208] Example 33: The apparatus of Example 32, wherein the predetermined angle is 0°.

[0209] Example 34: The apparatus of example 32, wherein the predetermined angle is a non-zero acute angle.

Claims

1. 1. An apparatus comprising: a pedestal configured to support a semiconductor wafer during wafer processing operations; 1. A hexapod mechanism comprising: a movable mount supporting the pedestal; Fixed mount and and a hexapod mechanism having six independently controllable linear actuators, each linear actuator having a first end pivotally connected to the fixed mount and a second end pivotally connected to the movable mount, the linear actuators supporting the movable mount relative to the fixed mount.

2. 10. The apparatus of claim 1, wherein the linear actuators are arranged in a tripartite symmetrical fashion.

3. 10. The apparatus of claim 1, the six linear actuators are grouped into three sets of two linear actuators; wherein the linear actuators in each set of two linear actuators are arranged to have first ends that connect to the fixed mount at positions closer to each other than the positions at which the second ends connect to the movable mount.

4. 10. The apparatus of claim 1, each first end of each linear actuator pivotally connected to the fixed mount by a corresponding spherical joint, universal joint, or biaxial flexure bearing; The apparatus, wherein each second end of each linear actuator is pivotally connected to the movable mount by a corresponding spherical joint, universal joint, or biaxial flexure bearing.

5. 2. The apparatus of claim 1, wherein each first end of each linear actuator is pivotally connected to the fixed mount by a corresponding first biaxial flexure bearing.

6. 6. The apparatus of claim 5, wherein each first biaxial flexure bearing comprises: A first part; and A second part; and A third part; and two first bending webs extending between the first portion and the second portion; two second bending webs extending between the second portion and the third portion; Equipped with For each first biaxial flexure bearing: the second portion is interposed between the first portion and the third portion; the first portion, the second portion, and the third portion lie along a common axis; a first gap exists between the first portion and the second portion; A second gap exists between the second portion and the third portion.

7. 7. The apparatus of claim 6, wherein for each first biaxial flexure bearing: the first flexure web is a thin, substantially flat structure aligned with a first reference surface of the first biaxial flexure bearing; the second flexure web is a thin, substantially flat structure aligned with the second reference surface of the first biaxial flexure bearing; The first and second reference planes are orthogonal to each other.

8. 7. The apparatus of claim 6, wherein each first biaxial flexure bearing comprises a central bore extending through the first portion, the second portion, and the third portion along the common axis of the first biaxial flexure bearing.

9. 7. The apparatus of claim 6, wherein for each first biaxial flexure bearing: the first biaxial flexure bearing includes two first through holes and two second through holes; the first bending webs are disposed between the first through holes; the second bending web is disposed between the second through holes; the first through hole extends completely through the first biaxial flexure bearing; The apparatus, wherein the second through hole extends completely through the first biaxial flexure bearing.

10. 7. The apparatus of claim 6, wherein the first flexure web and the second flexure web of each first biaxial flexure bearing extend into the second portion.

11. 11. The apparatus of any one of claims 1 to 10, further comprising a semiconductor processing chamber and a showerhead; the wafer support surface of the pedestal is positioned within the semiconductor processing chamber; at least a portion of the showerhead is disposed within the semiconductor processing chamber; The stationary mount is fixed relative to the semiconductor processing chamber.

12. 12. The apparatus of claim 11, further comprising a controller operatively connected to the six linear actuators and configured to control, relative to the fixed mount: a) translation of the movable mount along an axis perpendicular to the wafer support surface of the pedestal; b) rotation of the movable mount about an axis of rotation perpendicular to the wafer support surface and passing through a target position on the pedestal at which a wafer is centered; c) translation of the movable mount along a path orbiting an axis perpendicular to a lower surface of the showerhead facing the pedestal and intersecting the target position on the showerhead; d) rotation of the movable mount relative to the wafer support surface of the pedestal. or e) tilting the movable mount so that the wafer support surface of the pedestal is oriented at a non-zero acute angle relative to the lower surface of the showerhead and a maximum acute angle formed between the lower surface of the showerhead and the wafer support surface is defined in a plane that is periodically or continuously varied in azimuth about an axis perpendicular to the lower surface of the showerhead.

13. 13. The apparatus of claim 12, wherein the controller is further configured to control the linear actuator to cause the movable mount to perform two or more of (a) through (e) at least partially simultaneously while the pedestal supports a wafer disposed thereon.

14. 13. The apparatus of claim 12, wherein the controller is further configured to control the linear actuator to cause the movable mount to perform two or more of (a) through (e) at least partially continuously while the pedestal supports a wafer disposed thereon.

15. 13. The apparatus of claim 12, further comprising: a wafer handling robot configured to extend its end effector into the semiconductor processing chamber; an active wafer centering system configured to determine the location of a center of a wafer carried by the end effector relative to the semiconductor processing chamber; Equipped with The controller further comprises: i) obtaining the location of the center of the wafer as determined by the active wafer centering system; ii) controlling the linear actuator to position the target position of the pedestal in a position centered under the center of the wafer based on the position of the center of the wafer determined by the active wafer centering system; iii) after (ii), an apparatus configured to transfer the wafer to the pedestal.

16. 16. The apparatus of claim 15, the pedestal includes a plurality of lift pins, the apparatus including a lift pin actuation mechanism configured to move the lift pins between an extended state in which the lift pins protrude from the wafer support surface of the pedestal and a retracted state in which the lift pins do not protrude from the wafer support surface; the controller is configured to perform (iii) by causing the lift pin actuation mechanism to move the lift pins to the extended state into contact with the wafer, causing the wafer handling robot to retract the end effector from a space between the wafer and the wafer support surface, and causing the lift pin actuation mechanism to move the lift pins to the retracted state, thereby positioning the wafer on the wafer support surface.

17. 16. The apparatus of claim 15, wherein the controller is further configured, after (iii), to control the linear actuator to move the movable mount in a direction such that the wafer support surface forms a predetermined angle with respect to the lower surface of the showerhead.

18. 18. The apparatus of claim 17, wherein the predetermined angle is 0 degrees.

19. 18. The apparatus of claim 17, wherein the predetermined angle is a non-zero acute angle.

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