Circular wafer lateral positioning device

Abstract

A wafer positioning device includes: at least one fixed stop positioned at a periphery of a clamping location on a chuck surface; and an extendable finger. A finger extension mechanism extends the finger outward toward a center of the chuck surface and retracts the finger away from the center of the chuck surface. When a wafer is placed on the chuck surface and the finger extension mechanism is operated to extend the finger outward, the finger is configured to push the wafer laterally toward the fixed stop until an edge of the wafer contacts the fixed stop when a distal end of the finger is at the periphery of the clamping location.

Description

Technical Field

[0001] The present invention relates to wafer processing. More particularly, the present invention relates to an apparatus for lateral positioning of circular wafers. Background Art

[0002] Many processes in semiconductor wafer manufacturing require accurate positioning of continuously processed wafers at repeatable locations. Typically, semiconductor wafers have a round shape, for example, as a result of cutting the wafer from a typical crystalline material grown in the form of a cylindrical boule. This precise positioning enables repeated processing to produce different types of products. When accurately positioned, various processing steps can be applied to the exposed surface of the wafer, for example, to produce reliable semiconductor-based electronic components.

[0003] Many devices capable of precise positioning have been described that can position a wafer with high repeatability in a direction perpendicular to its surface. Such devices include various types of chucks as well as non-contact support surfaces. For example, a non-contact support surface, such as one that includes interspersed ports for outflow of pressurized air (or another fluid) and application of suction, can exhibit a fluidic spring effect that maintains the wafer at a desired height. Summary of the invention

[0004] Therefore, according to an embodiment of the present invention, a wafer positioning device is provided, comprising: at least one fixed stop positioned at the periphery of a clamping position on a chuck surface; an extendable finger; and a finger extension mechanism for extending the finger outward toward the center of the chuck surface and retracting the finger away from the center of the chuck surface, wherein, when a wafer is placed on the chuck surface and the finger extension mechanism is operated to extend the finger outward, the finger is configured to push the wafer laterally toward the at least one fixed stop until an edge of the wafer contacts the at least one fixed stop when the distal end of the finger is at the periphery of the clamping position.

[0005] Furthermore, according to an embodiment of the present invention, the perimeter of the clamping location is circular.

[0006] Furthermore, in accordance with an embodiment of the present invention, at least one fixed stop comprises a pin extending outwardly from a plane of the chuck surface.

[0007] Furthermore, according to an embodiment of the invention, the pins extend substantially perpendicular to the chuck surface.

[0008] Furthermore, according to an embodiment of the invention, the at least one fixed stop comprises two pins at different azimuthal positions on the periphery of the clamping location.

[0009] Furthermore, according to an embodiment of the invention, at least one pin comprises polyetheretherketone (PEEK).

[0010] In addition, according to an embodiment of the present invention, the finger extension mechanism includes a rotatable arm and a rotating mechanism for rotating the arm, and the finger is attached to the arm so that the operation of the rotating mechanism rotating the arm in one direction extends the finger outward toward the center of the chuck surface, and the operation of the rotating mechanism rotating the arm in the opposite direction retracts the finger away from the center of the chuck surface.

[0011] Furthermore, according to an embodiment of the invention, the arm is coupled to the rotatable column.

[0012] Furthermore, according to an embodiment of the present invention, the proximal end of the arm is coupled to the rotatable post.

[0013] Furthermore, according to an embodiment of the present invention, the rotating mechanism is pneumatically operated.

[0014] Furthermore, according to an embodiment of the present invention, the rotating mechanism is connected to two pneumatic inlets, wherein applying compressed gas to one of the pneumatic inlets causes the rotating mechanism to rotate the arm in one direction, and applying compressed gas to the other pneumatic inlet causes the rotating mechanism to rotate the arm in the opposite direction.

[0015] Furthermore, in accordance with an embodiment of the present invention, the rotation mechanism and arm are configured such that when the arm is rotated so that the fingers are fully extended without a wafer placed on the chuck surface, the distal ends of the fingers are within the perimeter of the clamping position.

[0016] Furthermore, according to an embodiment of the present invention, the arms are flexible and resilient.

[0017] Furthermore, according to an embodiment of the invention, the arm comprises a U-shaped bend.

[0018] Furthermore, according to an embodiment of the present invention, the arm comprises a spiral arm or two substantially parallel finger-like arms.

[0019] Furthermore, according to an embodiment of the present invention, the rotation mechanism and the arm are configured such that when the arm is rotated such that the fingers are fully retracted, the distal ends of the fingers are outside the perimeter of the clamping position.

[0020] Furthermore, in accordance with an embodiment of the present invention, the housing of the arm includes a distal protrusion to limit lateral movement of the wafer on the chuck surface when the fingers are fully retracted.

[0021] Furthermore, according to an embodiment of the present invention, the device comprises a chuck.

[0022] Furthermore, according to an embodiment of the present invention, the finger extension mechanism comprises an arm capable of longitudinal translation, the finger being attached to the arm by an elastic element.

[0023] Furthermore, according to an embodiment of the present invention, the finger extension mechanism includes an arm with two legs, a foot at a proximal end of one of the legs is fixed, and a foot at a proximal end of the other leg is linearly translatable. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to better understand the present invention and to appreciate the practical application of the present invention, the accompanying drawings are provided and referenced below. It should be noted that the accompanying drawings are given as examples only and in no way limit the scope of the present invention. The same parts are represented by the same reference numerals.

[0025] Figure 1A A circular wafer lateral positioning device according to an embodiment of the present invention is schematically shown.

[0026] Figure 1B yes Figure 1A Schematic top view of a circular wafer lateral positioning device shown in .

[0027] Figure 1C yes Figure 1A Schematic side view of a circular wafer lateral positioning device shown in .

[0028] Figure 2 Schematically shows Figure 1A The fixed stop of the circular wafer lateral positioning device shown in .

[0029] Figure 3 Schematically shows Figure 1A The finger assembly of the circular wafer lateral positioning device shown in FIG.

[0030] Figure 4 Schematically shows Figure 3 The finger assembly is shown with its cover removed.

[0031] Figure 5A Schematically shows the Figure 4 An example of a straight finger arm of a finger assembly is shown in FIG.

[0032] Figure 5B An example of a finger arm with two straight arms is schematically shown.

[0033] Figure 5C An example of a finger arm having two flat arms at different heights relative to the plane of the chuck surface is schematically shown.

[0034] Figure 5D An example of a finger arm having two arms at different heights relative to the plane of the chuck surface is schematically shown.

[0035] Figure 5EAn example of a finger arm with a rigid arm and a resilient connection to the fingers is schematically shown.

[0036] Fig. 5F Examples of helical finger arms are shown schematically.

[0037] Figure 5G An example of a composite finger arm is schematically shown, where the two sections of the double arm are in different orientations.

[0038] Fig. 6A A finger with a V-shaped notch is schematically shown.

[0039] Figure 6B A finger with a U-shaped notch is schematically shown.

[0040] Fig. 7A A linearly translatable finger arm having a linear spring connection to the finger is schematically shown.

[0041] Figure 7B A linearly translatable finger arm with a leaf spring connection to the finger is schematically shown.

[0042] Figure 8 The composite finger arms are shown schematically. DETAILED DESCRIPTION

[0043] In the following detailed description, many specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be appreciated by those of ordinary skill in the art that the present invention can be practiced without these specific details. In other cases, well-known methods, processes, components, modules, units and / or circuits are not described in detail in order not to obscure the present invention.

[0044] Although embodiments of the present invention are not limited in this regard, discussions using terms such as "processing," "computing," "calculating," "determining," "establishing," "analyzing," "checking," and the like may relate to operations and / or processes of computers, computing platforms, computing systems, or other electronic computing devices that manipulate and / or convert data represented as physical (e.g., electronic) quantities within registers and / or memories of a computer to other data similarly represented as physical quantities within registers and / or memories of a computer or other information non-transitory storage media (e.g., memory) that may store instructions for performing operations and / or processes. Although embodiments of the present invention are not limited in this regard, the terms "multiple" or "multiple" as used herein may include, for example, "many" or "two or more." The terms "multiple" or "multiple" may be used throughout this specification to describe two or more components, devices, elements, units, parameters, and the like. Unless explicitly stated, the method embodiments described herein are not limited to a particular order or sequence. In addition, some of the described method embodiments or elements thereof may occur or be performed simultaneously, at the same point in time, or simultaneously. Unless otherwise indicated, the conjunction "or" as used herein should be construed as inclusive (any or all of the stated options).

[0045] According to an embodiment of the present invention, the device is configured to laterally position a circular wafer with high repeatability without applying excessive compressive force to the wafer. Typically, the surface of the wafer to be processed can be supported at a precise height (e.g., in a dimension perpendicular to the plane of the surface of the wafer to be processed) by a chuck, for example, the chuck includes a non-contact support surface or at least other surfaces capable of limiting the lateral sliding of the wafer on the chuck surface. For example, when positioning the wafer, fluid pressure (e.g., air pressure) can be applied via the face of the chuck on which the wafer rests, so as to reduce friction between the wafer and the chuck surface. After the wafer has been laterally positioned, suction can be applied via the chuck surface to hold the wafer to the chuck surface. In other examples, applying pressure and suction simultaneously via pressure and vacuum ports interspersed on the chuck surface can form a fluid spring that holds the wafer above the chuck surface at a precise height.

[0046] As used herein, the lateral movement or positioning of a wafer refers to the movement or positioning dimension of a plane generally parallel to the surface of the wafer, which is exposed or to be treated. The lateral position of a wafer configured to hold the wafer in the lateral positioning device refers to the clamping position of the wafer in this article. As used herein, a chuck refers to any surface that can support a wafer when the wafer is positioned by a lateral positioning device as described herein. Although reference to the lateral positioning of a wafer is made herein, the device as described herein can be used to laterally position any circular object having a flat surface supported by a chuck. Therefore, any reference to a wafer herein should be understood to refer to any such object (and not necessarily a semiconductor wafer). Although the lateral positioning of a circular wafer is described, it may be possible to use a device as described herein to laterally position a wafer or object having a polygonal, elliptical or other non-circular shape with some restrictions (e.g., a specific orientation of a wafer or object).

[0047] The wafer lateral positioning device comprises one or more static components in the form of fixed stops located or extending to two or more different azimuthal positions on the circular periphery of the clamping position of the wafer. Thus, the fixed stops are located tangentially to the edge of the wafer held in the clamping position.

[0048] For example, each fixed stop may include a pin that extends outwardly from the plane of a surface of the chuck (eg, perpendicular to the chuck surface or at another angle to the chuck surface).

[0049] Alternatively or in addition, a single azimuthally elongated (e.g., arcuate) fixed stop may extend around the periphery of the clamping location to at least two azimuthally separated positions around the periphery of the clamping location, for example so as to be tangential to at least two different points on the edge of a wafer held in the clamping location.

[0050] The movable member can move radially inward or outward on the surface of the chuck. Typically, the movable member is in the form of a finger that is positioned near the periphery of the clamping location and can extend inward toward the center of the chuck surface and can be retracted away from the center of the chuck surface. In some cases, more than one movable member can be provided. For example, two or more fingers can be positioned at azimuthally separated positions along the periphery of the chuck surface. In some cases, the device can include three or more fingers without any fixed stops.

[0051] Alternatively or in addition, the movable member may be elongated azimuthally around the periphery of the clamping position. As the elongated movable member moves inwardly, the movable member may contact the edge of the wafer at two or more different locations. In this case, the fixed stop may include a single fixed stop that is positioned generally diametrically opposite the movable member. In some cases, the device may include two or more elongated movable members and no fixed stop.

[0052] The adjustable finger assembly includes extendable fingers positioned at another different (different from the fixed stop) azimuth position on the perimeter of the clamping location. The fingers are movable between an open position, in which the fingers are maximally retracted away from the clamping location, and a closed position, in which the fingers are maximally extended. When the fingers are maximally extended and no wafer is present on the chuck, the fingers extend proximally into the perimeter of the clamping location.

[0053] The fingers are mounted on flexible arms so that when a wafer is present on the chuck and the finger assembly is in the closed state, the fingers push against the lateral edges of the wafer. This push pushes the wafer against the fixed stops. When the wafer is pushed against the fixed stops, the wafer is in a clamped position. Thus, when the finger assembly is in the closed state, the periphery of the wafer abuts the fixed stops and fingers at the periphery of the clamped position, and the fixed stops and fingers are tangential to the wafer in the clamped position.

[0054] Typically, at least a portion of each of the fixed stop and the fingers configured to contact the wafer can be made of a material that does not interfere with the processing of the wafer. For example, the material used for the fixed stop and the fingers can be a material that does not degrade at the temperature of wafer processing and has antistatic properties. Examples of suitable materials include polyetheretherketone (PEEK), another thermoplastic material, or another material.

[0055] The lateral force applied by the fingers and fixed stops to the circular edge of the wafer is directed laterally inward at the tangent point. The lateral force is configured to be sufficient to hold the wafer in a clamped position during processing of the wafer. In addition, the friction force applied tangentially can resist rotation of the wafer. The flexibility of the arm can ensure that the force applied by the fingers on the edge of the wafer does not exceed a predetermined maximum force. For example, the predetermined maximum force can be selected to ensure that the wafer remains in place without risking bending or warping the wafer.

[0056] For example, the finger assembly can include a rotatable column to which the proximal end of the flexible arm is attached. The finger is mounted on the distal portion of the arm and extends laterally outward from the arm (toward the center of the chuck surface). The column can be rotated by a motorized mechanism or other mechanism. In one example, the column can be rotated in one direction by applying pneumatic pressure to one end of a rotatable blade connected to the column (e.g., via a port). The direction of rotation can be reversed by applying pneumatic pressure to the other end of the blade (e.g., via a different port). Other mechanical, electromagnetic, pneumatic, hydraulic or other mechanisms can be used to rotate the column.

[0057] Rotation of the post in one direction can rotate the arm so that the distal end of the arm with the fingers extends toward the clamping position. Rotation of the post in the opposite direction can rotate the arm so that the fingers at the distal end rotate outward, thereby retracting the fingers away from the clamping position.

[0058] The post can be provided with a plurality of stops that prevent the arm from rotating beyond a predetermined range of rotation angles. For example, the stops can include a plurality of tabs extending outwardly from the post. When these tabs contact a protrusion in the housing of the finger assembly, the force applied can resist further rotation of the post in that direction. The connection of the post to a motor or other mechanism that provides torque for rotating the post can include a clutch mechanism to release the connection when further rotation is prevented. Alternatively or in addition, an electrical or electronic circuit can prevent further rotation of the post beyond the allowed range of rotation angles. For example, rotation to the end of the range of rotation can operate a mechanical switch or an optical, electronic, electromagnetic or other mechanism to stop the operation of the motor, disconnect the transmission mechanism, or otherwise stop the rotation of the post.

[0059] Figure 1A A circular wafer lateral positioning device according to an embodiment of the present invention is schematically shown. Figure 1B yes Figure 1A Schematic top view of a circular wafer lateral positioning device shown in . Figure 1C yes Figure 1A Schematic side view of a circular wafer lateral positioning device shown in .

[0060] The circular wafer positioning device 10 is configured to hold the circular wafer 12 in a clamped position on the chuck surface 28 of the chuck head 11. For example, the circular wafer positioning device 10 and the chuck head 11 can be mounted to a support fixture using one or more mounting tabs 27, bolts 22, or other components.

[0061] For example, the chuck surface 28 may include a non-contact platform that exhibits a fluidic spring effect that maintains a fixed distance (typically a fixed height) between the circular wafer 12 and the chuck surface 28. In this case, the wafer support surface 28 may include an arrangement of interspersed pressure ports and vacuum ports that are connected to one or more fluid pressure and suction sources. In another example, pressure may be applied via an opening in the chuck surface 28 to reduce friction during lateral positioning of the circular wafer 12 on the chuck surface 28, followed by suction being applied to hold the circular wafer 12 to the chuck surface 28. In other examples, the chuck surface 28 may include another suitable type of surface (e.g., a surface coated with a non-stick material).

[0062] In the example shown, the circular wafer positioning device 10 includes two fixed stops 14 at different azimuthal positions about the chuck surface 28. The finger assembly 16 is located at a third azimuthal position that is different from the azimuthal position of the fixed stops 14. In the example shown, the finger assembly 16 and the two fixed stops 14 are approximately equally spaced about the perimeter of the chuck surface 28 at intervals of approximately 120°. In other examples, the device may include more than two fixed stops 14, and the azimuthal separation may be greater or less than 120° (e.g., but less than 180°). The fingers 20 may extend from the finger assembly 16 to hold the circular wafer 12 in a clamping position in which the circular wafer 12 is held tangentially to the distal ends of the fingers 20 and at least two fixed stops 14. Before the fingers 20 are extended, movement of the circular wafer 12 may be limited by the distal protrusions 24 on the finger assembly 16.

[0063] Figure 2 Schematically shows Figure 1A The fixed stop of the circular wafer lateral positioning device shown in .

[0064] In the example shown, the fixed stops 14 are in the form of pins mounted on a stop base 26 which in turn is mounted to one side of the chuck head 11. Each fixed stop 14 extends perpendicularly to the plane of the chuck surface 28.

[0065] Each fixed stop 14 is sufficiently rigid to prevent the circular wafer 12 adjacent to the fixed stop 14 from moving outwardly. Each fixed stop 14 can be constructed of or coated with a material that does not risk damaging or destroying the circular wafer 12 (e.g., by preventing scratches, cracks, or other types of damage) or interfering with the processing of the circular wafer 12 (e.g., by preventing the accumulation of static charge, by preventing undesirable heat conduction, or other interference with processing). For example, the fixed stop 14 can include or be coated with PEEK or other suitable material. Similarly, at least the distal ends of the fingers 20 can be made of or coated with a similar material, such as PEEK.

[0066] Figure 3 Schematically shows Figure 1A The finger assembly of the circular wafer lateral positioning device shown in FIG.

[0067] In the illustrated example, the components of the mechanism for extending and retracting the fingers 20 of the finger assembly 16 are enclosed within an assembly cover 30. The post rotation mechanism 18 is operated to rotate a rotatable post 40 (in Figure 4 ) to achieve extension or retraction of the finger 20.

[0068] In the illustrated example, the column rotation mechanism 18 can be pneumatically operated, for example, by applying gas pressure to any of the pneumatic inlets 17. For example, an elongated blade can be connected to the rotatable column 40 within the column rotation mechanism 18. Pneumatic pressure provided through one pneumatic inlet 17 can apply force to one end of the blade, thereby providing torque to rotate the column in one direction. Pneumatic pressure provided through another pneumatic inlet 17 can apply force to the opposite end of the blade, thereby providing torque to rotate the column in the opposite direction. A valve 19 (e.g., in the form of a needle valve or other type of valve) can be operated to regulate the pneumatic inflow through each pneumatic inlet 17. Regulating the inflow can enable efficient operation of the pneumatically operated column rotation mechanism 18.

[0069] Alternatively or in addition, the column rotation mechanism 18 may include another mechanism for rotating the column connected to the finger 20. For example, the column rotation mechanism 18 may include an electric motor or another rotation mechanism. In this case, an electrical connection or other control or power supply component may replace the pneumatic inlet 17 and valve 19.

[0070] In the illustrated example, the assembly cover 30 includes the distal protrusion 24. The distal protrusion 24 can be configured to limit lateral movement of the circular wafer 12 on the chuck surface 28 when the fingers 20 are retracted or not fully extended. The limitation of lateral movement can facilitate lateral positioning of the circular wafer 12 by the circular wafer positioning device 10 when the fingers 20 are extended.

[0071] Figure 4 Schematically shows Figure 3 The finger assembly is shown with its cover removed.

[0072] In the illustrated example, the rotatable column 40 can be rotated by operation of the column rotation mechanism 18. For example, the rotatable column 40 can represent one end of a drive column that is rotated by a blade, motor, or other torque generating mechanism of the column rotation mechanism 18. In another example, the rotatable column 40 can be coupled to a separate drive column by a transmission mechanism. The drive column can be directly driven to rotate by the torque generating mechanism of the column rotation mechanism 18. The transmission mechanism may include one or more gears, belts, or other mechanisms for transmitting torque from the drive column to the rotatable column 40.

[0073] The column rotation mechanism 18 typically includes a mechanism for limiting the rotation of the rotatable column 40 or the rotation of the drive column to which the rotatable column 40 is coupled. For example, the typical rotation range in which the rotatable column 40 can rotate can be less than 90°. The rotation limiting mechanism may include a tab, a stopper, or other protrusion on the rotatable column 40 (or on the drive column or on a component of the transmission mechanism), and the rotation limiting mechanism is configured to engage with a corresponding structure within the column rotation mechanism 18 to limit the rotation of the rotatable column 40 beyond the end point of the allowed rotation range. The corresponding structure may include a mechanical protrusion that physically prevents further rotation of the protrusion beyond the limited rotation angle. In another example, when the protrusion rotates to the limited angle, the protrusion can operate a switch to turn off the motor or disconnect the transmission mechanism. In another example, the limiting mechanism may include an optical, electromagnetic, electronic, or other mechanism for detecting that the rotatable column 40 rotates to the limited rotation angle or rotates beyond the limited rotation angle. In some cases, such as where column rotation mechanism 18 includes an electric motor, the transmission mechanism may include a clutch mechanism capable of disconnecting the drive column from the rotatable column 40 when further rotation of the rotatable column 40 is mechanically prevented.

[0074] In the example shown, the proximal ends of the finger arms 42 are clamped to the rotatable column 40 by arm clamps 44. Alternatively or in addition, the finger arms 42 may be connected to the rotatable column 40 by other means. For example, the finger arms 42 may be connected to the rotatable column 40 by one or more screws or clips, by insertion into grooves or openings in the rotatable column 40, by welding or adhesive, or in other ways. In other examples, the finger arms 42 may be rotated directly by a rotation mechanism.

[0075] The fingers 20 are mounted at the distal ends of the finger arms 42. The finger arms 42 extend laterally outward from the finger assembly 16 in a direction that is generally perpendicular to the direction in which the finger arms 42 extend from the rotatable post 40. Thus, rotation of the finger arms 42 in one direction (counterclockwise in the example shown) causes the fingers 20 to extend outward toward the center of the chuck surface 28. Rotation of the finger arms 42 in the opposite direction causes the fingers 20 to retract away from the center of the chuck surface 28.

[0076] In another example, the finger 20 can be connected to the finger arm 42 in other ways. For example, the finger 20 can extend longitudinally from one end of the finger arm 42, or at an oblique angle to the finger arm 42. The finger arm 42 can be connected to the rotatable column 40 in other ways or to another type of finger extension mechanism (e.g., a longitudinal translation mechanism or another mechanism operable to extend or retract the finger 20). The finger 20 can extend from a point on the finger arm 42 that is distal to the arm clamp 44 but adjacent to the distal end of the finger arm 42.

[0077] The post rotation mechanism 18 can be configured such that when the fingers 20 are maximally extended (e.g., in the example shown, when the rotatable post 40 is rotated to a maximum counterclockwise rotation angle), and when no circular wafer 12 is placed on the chuck surface 28, the distal ends of the fingers 20 extend within the perimeter of the gripping location of the circular wafer 12 on the chuck surface 28. Similarly, when the fingers 20 are maximally retracted (e.g., in the example shown, when the rotatable post 40 is rotated to a maximum clockwise rotation angle), the distal ends of the fingers 20 are retracted to a position outside the perimeter of the circular wafer 12 on the chuck surface 28. For example, the distal ends of the fingers 20 can be retracted from the center of the chuck surface 28 by a radial distance that is greater than the radial distance to the distal end protrusion 24 on the assembly cover 30 of the finger assembly 16.

[0078] The finger arms 42 can be configured to be flexible and resilient. For example, the finger arms 42 can be constructed of a material that can withstand multiple bends without breaking. For example, the finger arms 42 can be constructed of a flat and possibly bendable strip of metal, plastic, or another suitable material that is flexible enough to bend when flexed, but has sufficient stiffness and resiliency to return to its original shape when the flexing force is removed. In the example shown, the finger arms 42 are provided with features that facilitate resilient bending without mechanically fatigue the finger arms 42. In the example shown, the finger arms 42 include a U-shaped bend 41 such that the proximal end segment of the finger arms 42 is substantially parallel to the distal end segment of the finger arms 42. The distal segment of the finger arms 42 includes a longitudinal slot 43 that is generally parallel to the elongated dimension of the distal segment of the finger arms 42.

[0079] Therefore, when the finger arms 42 are rotated to maximally extend the fingers 20, the outer edge of the circular wafer 12 may contact the distal ends of the fingers 20 to prevent full extension of the fingers 20. Therefore, the distal ends of the finger arms 42 near the fingers 20 may bend outward from the center of the chuck surface 28. Therefore, the elasticity of the finger arms 42 may apply a force to the fingers 20 to maintain the pressing force of the fingers 20 on the circular wafer 12. Therefore, the force may keep the outer edge of the circular wafer 12 pressed against the two or more fixed stops 14. The force applied to the circular wafer 12 by the fingers 20 and the fixed stops 14 may be sufficient to keep the circular wafer 12 in a clamped position on the chuck surface 28.

[0080] In some cases, the finger arms 42 or other structures on which the fingers 20 are mounted may be rigid. In such cases, the fingers 20 themselves may be made of a flexible and resilient material so that when the fingers 20 are extended they can exert a compressive force on the outer edge of the circular wafer 12, thereby holding the circular wafer 12 in a clamped position on the chuck surface 28.

[0081] In some cases, once operation of the finger assembly 16 and fixed stop 14 has positioned the circular wafer 12 in a clamping position on the chuck surface 28, suction may be applied through an opening in the chuck surface 28. The suction may hold the circular wafer 12 to the chuck surface 28. The friction created between the chuck surface 28 and a face of the circular wafer 12 that faces the chuck surface 28 may be sufficient to hold the circular wafer 12 in place. In this case, after the suction is applied, the finger assembly 16 may be operated to retract the fingers 20.

[0082] Thus, when the fingers 20 are fully retracted, the circular wafer 12 may be placed between the fixed stops 14 and the finger assemblies 16 on the chuck surface 28. The fixed stops 14 and fingers 20 (or other types of fixed and movable components) may be positioned around the perimeter of the chuck surface 28 such that there is no space between adjacent fixed stops 14 or between fingers 20 and adjacent fixed stops 14 that is greater than the diameter of the circular wafer 12. Thus, if the size of the circular wafer 12 is approximately the size of the chuck surface 28, the azimuthal spacing between adjacent positioning components (e.g., fixed stops 14 and fingers 20) cannot be greater than about 180° (or less, depending on the relative sizes of the circular wafer 12 and the chuck surface 28).

[0083] When the circular wafer 12 is first placed on the chuck surface 28, the circular wafer 12 can slide freely on the chuck surface 28. For example, air or other gas or fluid can be exhausted through the openings on the chuck surface 28 to reduce the friction between the circular wafer 12 and the chuck surface 28. Alternatively, the chuck surface 28 can include interspersed openings for applying pressure and suction simultaneously to form a fluid cushion that exhibits a fluid spring effect. Alternatively or in addition, the chuck surface 28 can be made of or coated with a non-stick surface material.

[0084] The post rotation mechanism 18 is operable to extend the fingers 20 of the finger assembly 16. For example, air pressure from a pressure source may be provided to one of the pneumatic inlets 17 to rotate the rotatable post 40 and the attached finger arms 42 to extend the fingers 20 outward. When the distal ends of the fingers 20 contact the edge of the circular wafer 12, continued extension of the fingers 20 may push the circular wafer 12 toward the fixed stop 14. When the circular wafer 12 is pushed to the fixed stop 14, lateral movement of the circular wafer 12 may be stopped, and further extension of the fingers 20 may bend the finger arms 42 to apply a lateral force to hold the circular wafer 12 in a clamped position, and the circular wafer is tangential to the fixed stop 14 and the fingers 20 in this position.

[0085] Once the circular wafer 12 has been laterally positioned in a clamping position (where the chuck surface 28 is configured to do so), the friction between the circular wafer 12 and the chuck surface 28 may be increased. For example, suction may be applied to the circular wafer 12 through an opening in the chuck surface 28 to hold the circular wafer 12 against the chuck surface 28.

[0086] Then, processing (e.g., modification or inspection) of the circular wafer 12 can be performed. When processing is completed, the circular wafer 12 can be released from the chuck surface 28. For example, the fingers 20 can be fully retracted away from the circular wafer 12. The suction applied via the chuck surface 28 can be stopped. The circular wafer 12 can then be removed from the chuck surface 28.

[0087] Typically, the operation of the circular wafer positioning device 10 can be controlled by a controller. The controller may include one or more units configured to operate according to programmed instructions. For example, the controller may operate the column rotation mechanism 18 to extend or retract the finger 20. In some cases, the controller may also operate, or may communicate with one or more controllers that operate other functions. Therefore, the operation of the column rotation mechanism 18 and the circular wafer positioning device 10 can be coordinated with other functions. These other functions may include one or more of the following: applying fluid pressure, suction force, or both to the opening on the chuck surface 28, processing the circular wafer 12, transporting the circular wafer 12 to the chuck surface 28 and transporting the circular wafer from the chuck surface, or other functions related to processing one or more circular wafers 12.

[0088] Alternatively or in addition, the wafer positioning device may include other configurations of fingers and finger extension mechanisms. In some configurations, the fingers may be enabled to move in a direction generally perpendicular to the chuck surface 28, for example to laterally position the circular wafer 12 in a clamping position until the circular wafer 12 is secured to the chuck surface 28, for example, by suction.

[0089] In some configurations, the fingers may be enabled to move in a direction generally parallel to the chuck surface.

[0090] Figure 5A Schematically shows the Figure 4 An example of a straight finger arm of a finger assembly is shown in FIG.

[0091] In the example shown, the fingers 20 extend laterally from the distal end of a straight finger arm 50, the proximal end of which is attached to the rotatable post 40. The straight finger arm 50 may include a single elongated arm of flat or other cross-section that may be flexible and resilient, for example, so as to be able to bend at least laterally.

[0092] Figure 5B An example of a finger arm with two straight arms is schematically shown.

[0093] In the example shown, the fingers 20 extend laterally from the distal ends of two parallel and laterally displaced straight finger arms 52, the proximal ends of which are attached to the rotatable post 40. Each finger arm 52 can have a flat (e.g., substantially perpendicular to the plane of the chuck surface 28) or other cross-section, and can be flexible and resilient, e.g., so as to be capable of at least lateral bending.

[0094] Figure 5C An example of a finger arm having two flat arms at different heights relative to the plane of the chuck surface is schematically shown.

[0095] In the example shown, the fingers 20 extend transversely from the distal ends of two parallel straight finger arms 54, the proximal ends of which are attached to the rotatable post 40. In the example shown, each finger arm 54 has a flat cross-section that is generally parallel to the plane of the chuck surface 28. The finger arms 54 are displaced from each other along an axis that is perpendicular to the plane of the chuck surface 28. Each finger arm 54 can be flexible and resilient, for example, to be able to bend at least in a direction perpendicular to the plane of the chuck surface 28.

[0096] Figure 5D An example of a finger arm having two arms at different heights relative to the plane of the chuck surface is schematically shown.

[0097] In the example shown, the fingers 20 extend laterally from the distal ends of two parallel straight finger arms 56, the proximal ends of which are attached to the rotatable post 40. In the example shown, each finger arm 56 has a circular or other non-flat cross-section. The finger arms 56 are displaced from each other along an axis perpendicular to the plane of the chuck surface 28. Each finger arm 56 can be flexible and resilient, for example, to be able to bend laterally and in a direction perpendicular to the plane of the chuck surface 28.

[0098] Figure 5E An example of a finger arm with a rigid arm and a resilient connection to the fingers is schematically shown.

[0099] In the example shown, the finger 20 is connected by a resilient (e.g., flexible and resilient) element in the form of a spring 60 to extend laterally from a distal end of a rigid arm 58, the proximal end of which is attached to the rotatable post 40. The resilient connection to the rigid arm 58 enables the finger 20 to move relative to the rigid arm 58 both laterally and in a direction perpendicular to the plane of the chuck surface 28.

[0100] Fig. 5F Examples of helical finger arms are shown schematically.

[0101] In the example shown, the fingers 20 extend longitudinally from the distal end of a spiral arm 62, the proximal end of which is attached to the rotatable post 40. The spiral arm 62 may be flexible and resilient, for example, so as to be able to bend in a transverse direction and in a direction perpendicular to the plane of the chuck surface 28.

[0102] Figure 5G An example of a composite finger arm is schematically shown, where the two sections of the double arm are in different orientations.

[0103] In the example shown, the fingers 20 extend laterally from the distal end of a compound finger arm 66, the proximal end of which is attached to the rotatable post 40. In the example shown, the proximal section of the compound finger arm 66 includes two finger arms 54 that are displaced from each other along an axis perpendicular to the plane of the chuck surface 28. The distal section of the compound finger arm 66 includes two parallel and laterally displaced straight finger arms 52. The proximal section and the distal section are connected at a connection 64. Each of the finger arms 52 and 54 can be flexible and resilient, for example, to be able to bend in a lateral direction and in a direction perpendicular to the plane of the chuck surface 28.

[0104] The fingers 20 may be configured to hold the circular disk 12 at a predetermined distance from the chuck surface 28. For example, the fingers 20 may include grooves or notches configured to guide the edge of the circular disk 12 to a specific portion along the distal end of the fingers 20.

[0105] Fig. 6A A finger with a V-shaped notch is schematically shown.

[0106] The edge of the circular disk 12 supported on the chuck surface 28 can be guided into the V-shaped recess 70 on the distal end of the finger 20. Therefore, when the finger 20 extends to move the circular disk 12 to the clamping position on the chuck surface 28, the edge can be retained in the V-shaped recess 70.

[0107] Figure 6B A finger with a U-shaped notch is schematically shown.

[0108] The edge of the circular disk 12 supported on the chuck surface 28 can be guided into the U-shaped recess 72 on the distal end of the finger 20. Therefore, when the finger 20 extends to move the circular disk 12 to the clamping position on the chuck surface 28, the edge can be retained in the U-shaped recess 72.

[0109] Fig. 7A A linearly translatable finger arm having a linear spring connection to the finger is schematically shown.

[0110] The extension mechanism 80 is configured to extend and retract the finger arms 82 via a longitudinal motion 88. For example, the extension mechanism 80 may include an electric motor (e.g., with a transmission that transfers rotary motion to linear motion), an electric or electromagnetic linear actuator, or another hydraulic, pneumatic, electromagnetic, or otherwise powered mechanism. The longitudinal motion 88 may represent linear movement of a physical finger arm 82, or lengthening and shortening of a variable length finger arm 82 (e.g., by telescoping, unfolding and folding of telescopic joints, expansion and contraction, or other means).

[0111] The finger 20 may be connected to the finger arm 82 by a resilient element. The resilient element may facilitate maintaining contact between the finger 20 and the circular disk 12 without the risk of damaging the circular disk 12.

[0112] In the example shown, the resilient element connecting the finger 20 to the distal end of the finger arm 82 comprises a linear spring 84 .

[0113] Figure 7B A linearly translatable finger arm with a leaf spring connection to the finger is schematically shown.

[0114] In the example shown, the resilient element connecting the finger 20 to the distal end of the finger arm 82 comprises a leaf spring 86. In the example shown, the leaf spring 86 is closed. In other examples, the leaf spring 86 can be open (e.g., having a U-shaped profile).

[0115] Figure 8 The composite finger arms are shown schematically.

[0116] At the proximal end of the leg 90a of the composite finger arm 90 is a fixed foot 92, which can be attached to a fixed point on or near the finger extension mechanism. At the proximal end of the leg 90b is a movable foot 94, which can be linearly translated by the finger extension mechanism to move outward and inward, as shown by arrow 96. For example, the movable foot 94 can be moved by a linear actuator or other mechanism for producing linear bidirectional movement of the movable foot 94. The outward and inward movement of the movable foot 94 can cause a rocking motion of the composite finger arm 90 about the fixed foot 92, which can correspondingly extend or retract the finger 20 generally in the direction shown by the arrow 98.

[0117] Different embodiments are disclosed herein. Features of certain embodiments may be combined with features of other embodiments; therefore, certain embodiments may be a combination of features of multiple embodiments. The above description of embodiments of the present invention has been presented for the purpose of illustration and description. This is not intended to be exhaustive or to limit the invention to the precise form disclosed. It will be appreciated by those skilled in the art that many modifications, variations, substitutions, changes, and equivalents are possible in light of the above teachings. Therefore, it will be appreciated that the appended claims are intended to cover all such modifications and variations that fall within the true spirit of the invention.

[0118] Although certain features of the present invention have been shown and described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It should be understood, therefore, that the appended claims are intended to cover all such modifications and changes that fall within the true spirit of the invention.

Claims

1. A wafer positioning device, comprising: at least one fixed stop positioned at a periphery of the clamping location on the chuck surface; Extendable fingers; as well as a finger extension mechanism for extending the fingers outwardly toward the center of the chuck surface and retracting the fingers away from the center of the chuck surface, wherein, when a wafer is placed on the chuck surface and the finger extension mechanism is operated to extend the fingers outwardly, the fingers are configured to push the wafer laterally toward the at least one fixed stop until an edge of the wafer contacts the at least one fixed stop when the distal ends of the fingers are at the periphery of the clamping position, wherein the finger extension mechanism comprises a rotatable arm and a rotation mechanism for rotating the arm, the finger being attached to the arm so that operation of the rotation mechanism rotating the arm in one direction extends the finger outwardly toward the center of the chuck surface, and operation of the rotation mechanism rotating the arm in an opposite direction retracts the finger away from the center of the chuck surface, wherein the rotating mechanism is pneumatically operated, and wherein the rotating mechanism is connected to two pneumatic inlets, wherein applying compressed gas to one of the pneumatic inlets causes the rotating mechanism to rotate the arm in one direction, and applying compressed gas to the other pneumatic inlet causes the rotating mechanism to rotate the arm in an opposite direction.

2. A wafer positioning device, comprising: at least one fixed stop positioned at a periphery of the clamping location on the chuck surface; Extendable fingers; as well as a finger extension mechanism for extending the fingers outwardly toward the center of the chuck surface and retracting the fingers away from the center of the chuck surface, wherein, when a wafer is placed on the chuck surface and the finger extension mechanism is operated to extend the fingers outwardly, the fingers are configured to push the wafer laterally toward the at least one fixed stop until an edge of the wafer contacts the at least one fixed stop when the distal ends of the fingers are at the periphery of the clamping position, wherein the finger extension mechanism comprises a rotatable arm and a rotation mechanism for rotating the arm, the finger being attached to the arm so that operation of the rotation mechanism rotating the arm in one direction extends the finger outwardly toward the center of the chuck surface, and operation of the rotation mechanism rotating the arm in an opposite direction retracts the finger away from the center of the chuck surface, wherein the rotation mechanism and the arm are configured such that when the arm is rotated to fully extend the fingers without a wafer placed on the chuck surface, the distal ends of the fingers are within the perimeter of the gripping location, and Wherein, the arm is flexible and resilient.

3. The device according to claim 2, wherein: The arm includes a U-shaped bend.

4. The device according to claim 2, wherein: The arms may comprise a spiral arm or two parallel finger-like arms.

5. A wafer positioning device, comprising: at least one fixed stop positioned at a periphery of the clamping location on the chuck surface; Extendable fingers; as well as a finger extension mechanism for extending the fingers outwardly toward the center of the chuck surface and retracting the fingers away from the center of the chuck surface, wherein, when a wafer is placed on the chuck surface and the finger extension mechanism is operated to extend the fingers outwardly, the fingers are configured to push the wafer laterally toward the at least one fixed stop until an edge of the wafer contacts the at least one fixed stop when the distal ends of the fingers are at the periphery of the clamping position, Wherein, the finger-like extension mechanism includes an arm with two legs, a foot located at the proximal end of one of the legs is fixed, and a foot located at the proximal end of the other leg is capable of linear translation.

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