Patent Publication Number: US-2023139939-A1

Title: Apparatus, system and method for providing self extracting grips for an end effector

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority to International Application No. PCT/US2020/018507, filed Feb. 17, 2020; entitled APPARATUS, SYSTEM AND METHOD FOR PROVIDING SELF EXTRACTING GRIPS FOR AN END EFFECTOR, the entirety of which is incorporated herein by reference as if set forth in its entirety. 
    
    
     BACKGROUND 
     Field of the Disclosure 
     The present disclosure relates to the transfer and processing of articles, such as semiconductor wafers, and more particularly to an apparatus, system and method for providing self extracting grips for an end effector. 
     Description of the Background 
     The use of robotics is well established as a manufacturing expedient, particularly in applications where human handling is inefficient and/or undesirable. One such circumstance is in the semiconductor arts, in which robotics and automated stations are used to handle and hold wafers during various process steps. Such process steps may include, by way of example, chemical mechanical planarization (CMP), etching, deposition, passivation, and various other processes in which a sealed and/or “clean” environment must be maintained, such as to limit the likelihood of contamination and to ensure that various specific processing conditions are met. 
     Current practice in the semiconductor arts to robotically handle these wafers often includes the use of an end effector operably attached to the robotics, such as in order to load semiconductor wafers from a loading stack into the various processing ports that may correspond to the aforementioned exemplary process steps. The robotics are employed to deploy the end effector to retrieve the wafer from a particular port or stack, such as before and/or after processing in an associated process chamber, and/or to associate the wafer with a station, such as may include a station chuck onto which the wafer is placed. 
     The wafer may thus be shuttled by the robotics connectively associated with the end effector between stations for additional processing. When a given wafer process is complete, the robotics may move the processed wafer from its station and return the processed semiconductor wafer to a loading port. It is typical that a stack of several semiconductor wafers is processed in this manner during each process run. 
     The known art also includes robotics to flip and rotate wafers and similar substrates, such as for inspection during or after processing. However, the typical type of end effector in substantial use in the known art is an edge grip wafer handler. In an edge grip wafer handler, the wafer is only minimally handled, with peripheral contact between the end effector and the wafer only at the wafer&#39;s outer circumference. Typically, such edge gripping is provided by mechanical wedges associated at the distal and proximal portions of the end effector (with respect to the corresponding robotic base of the end effector at which robotic movement of the end effector arms and power are provided). 
     However, these wedge guides may exert unwanted friction on the retained wafer, or insufficient friction if a wafer is flipped or rotated sideways, and consequently may provide unpredictable release and/or release positioning of the wafer due to excessive or insufficient wedge-induced friction. Moreover, as wedge clamps typically cover a portion of the outer circumference of the wafer, these edge clamps, or the wafer tooling passing proximate to these edge clamps, may cause snags on the wafer and consequently damage the wafer. For example, if a wafer experiences friction and travels with a wedge clamp beyond the release point rather than timely extracting from the clamp, the wafer and/or structures thereon will be damaged. 
     The foregoing wedge clamp friction often occurs due to the passive self-releasing nature of the wedge clamp. That is, typical edge grip designs compromise the wedge angle to approximately 75°, so that the wedge clamp will not exert undue friction and will be self-releasing. However, this angle for the wedge clamp limits the ability to invert or rotate a wafer associated with the wedge clamp, in part because the angle of the wedge clamp is insufficient to retain an inverted or rotated wafer. This problem is exacerbated for thin, flexible, large wafers, which may require more overlap at the wafer&#39;s circumference to retain the wafer, and a steeper wedge clamp angle in order to positively capture the wafer, due to the wafer&#39;s ability to flex within the clamp, which circumstances may cause self-release of the wafer at an undesired time. 
     In a particular example, some semiconductor processing applications may require the use of a rotating wrist end effector. A rotating wrist end effector may require a steeper angle and deeper wedge base for the wedge clamp, such that the rotation of the end effector will not improperly self-release a wafer from the wedge clamp. However, in such an instance, the deeper wedge base and steeper wedge clamp angle are substantially more likely to cause undue friction at the desired timing of release, and thereby negate the self-release of the wafer, causing the lack of the desired release and/or damage to the wafer, by way of non-limiting example. 
     SUMMARY 
     Certain embodiments are and include an apparatus, system and method for a wedge clamp suitable to provide self extracting grips for an end effector suitable to hold semiconductor wafers. The apparatus, system and method may include two inner jaws at least mechanically associated with a robotic base; two outer arms associated with the inner jaws via at least one arms cam system, such as may comprise a servo motor and a timing belt providing the camming; and a plurality of wedge clamps, wherein two of the plurality of wedge clamps are respectively fastened to each of the two inner jaws proximally to the end effector front end, such as its robotic base, and wherein two of the plurality of wedge clamps are respectively fastened to each of the outer arms distally from the end effector front end. 
     Each of at least one of the distal and the proximal wedge clamps may comprise: a spring; a cam loaded on the spring; and a cam travel path into which the cam is contained and guided, such as slidably. Thereby, a contraction of the inner jaws and a consequent arms camming of the outer arms applies pressure to a circumferential edge of the semiconductor wafer such that the circumferential edge depresses each of the cams along its respective cam travel path and against its respective one of the springs, thus loading the cams to grip the semiconductor wafer within the plurality of edge clamps. 
     Thus, the disclosure provides at least an apparatus, system and method for providing a wedge clamp suitable to provide self extracting grips for an end effector suitable to hold semiconductor wafers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The exemplary compositions, systems, and methods shall be described hereinafter with reference to the attached drawings, which are given as non-limiting examples only, in which: 
         FIG.  1    is an illustration of an end effector for handling semiconductor wafers; 
         FIG.  2    is an illustration of a wafer handling system; 
         FIG.  3    illustrate an end effector and wafer handler; 
         FIG.  4    is an illustration of an end effector with wedge clamps; 
         FIG.  5    is an illustration of an end effector with wedge clamps; 
         FIG.  6    is an illustration of an end effector with wedge clamps; and 
         FIG.  7    is an illustration of an end effector with wedge clamps. 
         FIG.  8    is an illustration of an end effector with wedge clamps. 
     
    
    
     DETAILED DESCRIPTION 
     The figures and descriptions provided herein may have been simplified to illustrate aspects that are relevant for a clear understanding of the herein described apparatuses, systems, and methods, while eliminating, for the purpose of clarity, other aspects that may be found in typical similar devices, systems, and methods. Those of ordinary skill may thus recognize that other elements and/or operations may be desirable and/or necessary to implement the devices, systems, and methods described herein. But because such elements and operations are known in the art, and because they do not facilitate a better understanding of the present disclosure, for the sake of brevity a discussion of such elements and operations may not be provided herein. However, the present disclosure is deemed to nevertheless include all such elements, variations, and modifications to the described aspects that would be known to those of ordinary skill in the art. 
     Embodiments are provided throughout so that this disclosure is sufficiently thorough and fully conveys the scope of the disclosed embodiments to those who are skilled in the art. Numerous specific details are set forth, such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. Nevertheless, it will be apparent to those skilled in the art that certain specific disclosed details need not be employed, and that embodiments may be embodied in different forms. As such, the disclosed embodiments should not be construed to limit the scope of the disclosure. As referenced above, in some embodiments, well-known processes, well-known device structures, and well-known technologies may not be described in detail. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. For example, as used herein, the singular forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The steps, processes, and operations described herein are not to be construed as necessarily requiring their respective performance in the particular order discussed or illustrated, unless specifically identified as a preferred or required order of performance It is also to be understood that additional or alternative steps may be employed, in place of or in conjunction with the disclosed aspects. 
     When an element or layer is referred to as being “on”, “upon”, “connected to” or “coupled to” another element or layer, it may be directly on, upon, connected or coupled to the other element or layer, or intervening elements or layers may be present, unless clearly indicated otherwise. In contrast, when an element or layer is referred to as being “directly on,” “directly upon”, “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). Further, as used herein the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Yet further, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the embodiments. 
     The embodiments provide a self-extracting wedge clamp for association with an end effector, which may be used in semiconductor processes. The disclosed wedge clamp ensures that released components are released when desired, and stay substantially or completely in the desired position when picked up by the end effector, or when released therefrom, such as staying centered on the wedge clamp. Thereby, the semiconductor wafer or processed part is at the position intended for processing, rather than being randomly positioned such that processes carried out thereon are flawed, or such that intended placement within processes or stacks is missed. 
     More particularly, one or more of the disclosed edge clamps may be associated with the two, three, or four “corners” of an end effector&#39;s grip upon a wafer. The wedge clamps disclosed may include a spring-loaded sliding cam, or “puck”, that positively extracts a wafer from the wedge clamp&#39;s grip, such as when the pressure exerted by an opposing “corner” wedge clamp is released. That is, the disclosed wedge clamp extraction cam may be passive, at least in that a wafer may be placed upon the arm or arms of end effector, whereafter the end effector may be robotically contracted such that opposing wedge clamps are exerted upon the circumference of a wafer or part. 
     This exertion of the wedge clamps upon the circumference when the end effector arms are contracted effects a “loading” of the extraction cam into the body of the respective wedge clamp. Thereafter, an increase in the distance between the opposing wedge clamps at opposing “corners” of the end effector, based on robotic expansion of the end effector arms, releases the loading pressure on the spring, thereby allowing the respective extraction cam to be sprung from the wedge clamp housing. This effectuates a release of the wafer or part associated with the end effector. Of course, the skilled artisan will appreciate, in light of the discussion herein, that the extraction cam may not only be passive as disclosed, but may also be active, such as being pneumatically or electrically driven. 
     Thereby, the disclosed extraction cam may allow for spring loading of a wafer or part into an end effector, thus improving inverted handling and thus providing enhanced positioning and targeted release of the wafer or part associated with the end effector. Moreover, the improved positioning provided by the disclosed wedge clamps having embedded extraction cams may drastically improve self-guiding of the wafer upon release from the wedge clamps, such as wherein a wafer may positively guide itself to reach a pallet mask pocket or a wafer chuck, by way of nonlimiting example. 
     Of note, although the discussion herein is provided with respect to a cammed, contractable/expandable end effector suitable to handle multiple sizes of semiconductor wafers, the skilled artisan will appreciate that other end effector technologies may be employed to, for example, provide the spring pressure to load a wafer into the wedge clamps, and/or to release the spring pressure to allow self-releasing of the wafer. Moreover, it will be noted that the disclosed wedge clamps and extraction cams may be used with single wafer-size end effectors, or with the aforementioned end effectors capable of handling multiple wafer sizes. 
       FIG.  1    illustrates a wafer  10  associated with an end effector  12 . The illustrated wafer  10  is maintained upon the end effector  12  by a retainer  60  (shown in dashed), such as a plurality of wedge-shaped clamps. 
       FIG.  2    illustrates an automated handling system  50  suitable to precisely handle semiconductor wafers of varying diameters, compositions and physical attributes. The handling system  50  may be capable of handling the substrates, such as wafer  10 , in a rapid, ordered succession for processing. The substrates  10  supplied may be manipulated or transferred upon end effector  12  among and between stacks  67  and various stationary points  103  for processing, in part, by robotics, such as may be provided in base  110 , to perform the aforementioned manipulation and transfer. The stationary points  103  may comprise one or more chucks, such as may grip the substrates  10  upon placement onto the chuck  103 . This gripping may be performed, by way of example, through the use of one or more vacuums  105 . 
     The illustrated wafer  10  may be maintained upon the end effector  12  by, for example, two pairs of opposing wedge clamps  14   a ,  14   b ,  16   a ,  16   b . In short, each opposing pair  14   a - b ,  16   a - b  comprises a proximal wedge clamp  14   a ,  16   a  and a distal wedge clamp  14   b ,  16   b , thus providing wedge clamps at four “corners” of the gripped wafer  10 . 
       FIG.  3 A  illustrates a front view of an end effector  12  akin to that illustrated in  FIG.  2   . In the illustration of  FIG.  3 A , the end effector  12  comprises a servo driven fork  100  with inner and outer jaws  102 ,  104  that synchronously move to the center in order to grip a wafer  10  placed within the four “corner” wedge clamps  14   a - b ,  16   a - b  shown. 
       FIG.  3 B  is a profile illustration of the end effector  12  of  FIG.  3 A . As shown, the distal most wedge clamps  14   b ,  16   b  (from the end effector base housing  110 , not shown in  FIG.  3 B ) may be cammed  150  distally outward from the housing  110  by jaws  102 ,  104 , thereby lengthening the distance between a respective pair comprised of a distal wedge clamp  14   b ,  16   a  and its corresponding proximal wedge clamp  14   a ,  16   a . More particularly, a decrease in the distance between each respective pair of wedge clamps  14   a - b ,  16   a - b  exerts friction on the wafer  10  (not shown in  FIG.  3 B ) gripped therebetween, and thus causes the circumferential edges of the wafer  10  between each respective pair of wedge clamps  14   a - b ,  16   a - b  to exert loading pressure on, for example, springs associated with each respective distal and proximal wedge clamp pair  14   a - b ,  16   a - b  (springs not shown in  FIG.  3 B ). 
     With reference now additionally to  FIG.  4   , the application of loading pressure caused by the decrease in distance between each pair of wedge clamps  14   a - b ,  16   a - b  may spring load an extraction cam  114  into the respective wedge housing  130 , thereby gripping the wafer&#39;s circumferential edge  10   a  within each respective wedge clamp  14   a, b ,  16   a, b . Of note, this enhanced frictional gripping of the circumferential edge  10   a  of the wafer  10  thus allows for an increase in available wedge angle, and thereby in an improved wafer grip, over the known art. 
     More specifically,  FIG.  4    illustrates a cut-away view of the end effector  12  of  FIGS.  3 A and  3 B , shown gripping a wafer  10  and applying extraction cams  114  within each of the four corner wedge clamps  14   a, b ,  16   a, b . As shown, each wedge clamp  14   a, b ,  16   a, b  may grip the circumferential edge  10   a  of the gripped wafer  10  when the end effector actuation cams  155  cause a decrease in distance between each distal and proximal pair  14   a - b ,  16   a - b  of wedge clamps. 
     With reference now additionally to  FIG.  5   , this gripping upon contraction causes a compression of the springs  120  associated with each extraction cam  114 , and consequently allows for application of each wedge over the circumferential edge  10   a  of the wafer  10 , thus gripping the wafer  10 . Accordingly, an increase in the distance between each pair of wedge clamps  14   a - b ,  16   a - b  causes a decompression of the spring  120  on each extraction cam  114 , thereby causing the extraction cam  114  to spring outwardly from the body of each wedge clamp  14   a, b ,  16   a, b , thus ejecting the edge of the wafer  10  previously gripped. 
     More particularly,  FIG.  5    is an illustration of the proximal wedge clamps  16   a, b  from the illustration of  FIG.  4   . As shown, each of the wedge clamps  14   a ,  16   a  may include a sunk cam  114  within a sunk extraction cam guide  404  that allows the extraction cam  114  to be placed in a compressed and decompressed positions. Furthermore, although the spring  120  of each respective extraction cam  114  may be physically associated with any aspect of the wedge clamp housing to provide a base for application of the spring force, the springs  120  are shown in  FIG.  4    as associated with one or more screws  410  used to screw each wedge clamp onto its respective portion of the edge gripping feature of the end effector  12 . 
       FIG.  6   , in a manner similar to  FIG.  5   , illustrates a close-up of the distal-most ones  14   b ,  16   b  of the pairs of wedge clamps associated with the end effector  12 . As illustrated, movement of the cammed portion  155  of the end effector towards the end effector base  110  has compressed the extraction cams  114  into each respective wedge clamp. 
       FIG.  7    illustrates a top cut away view of a wedge clamp  14   a  forming a portion of an end effector wafer gripping feature. As shown, the extraction cam spring  120  is loaded about a mounting screw  410  for the wedge clamp  14   a , on an innermost portion of the end effector gripping feature. 
     The extraction cam  114  is then pushed inwardly from the flush position of the wafer clamp&#39;s angled portion edge by exertion of pressure from the circumferential portion  10   a  of the wafer. The extraction cam  114  resides within a sunk guide  404  of the wedge clamp portion and the end effector gripping base portion, wherein the sunk guide  404  is sufficient in length so as to allow the extraction cam  114  to be in the fully compressed and fully decompressed position, based on the spring loading compression pressure applied by the wafer&#39;s edge  10   a  to the extraction cam  114 . 
       FIG.  8    is a profile view of a wafer  10  gripped within the wedge clamp  14   a  of  FIG.  7   . As shown, the disclosed wedge clamp  14   a  may have a substantially steeper angle than wedge clamps in the known art, in part because of the affirmative self-releasing pressure applied by the disclosed extraction cam  114  to a gripped wafer&#39;s edge  10   a.    
     The foregoing apparatuses, systems and methods may also include the control of the various robotic and vacuum functionality referenced throughout. Such control may include, by way of non-limiting example, manual control using one or more user interfaces, such as a controller, a keyboard, a mouse, a touch screen, or the like, to allow a user to input instructions for execution by software code associated with the robotics and with the systems discussed herein. Additionally, and as is well known to those skilled in the art, system control may also be fully automated, such as wherein manual user interaction only occurs to “set up” and program the referenced functionality, i.e., a user may only initially program or upload computing code to carry out the predetermined movements and operational sequences discussed throughout. In either a manual or automated embodiment, or in any combination thereof, the control may be programmed, for example, to relate the known positions of substrates, the robotics, the stationary points, and the relative positions there between, for example. 
     It will be appreciated that the herein described systems and methods may operate pursuant to and/or be controlled by any computing environment, and thus the computing environment employed not limit the implementation of the herein described systems and methods to computing environments having differing components and configurations. That is, the concepts described herein may be implemented in any of various computing environments using any of various components and configurations. 
     Further, the descriptions of the disclosure are provided to enable any person skilled in the art to make or use the disclosed embodiments. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein, but rather is to be accorded the widest scope consistent with the principles and novel features disclosed herein.