Abstract:
A robot is provided which includes a hub plate ( 205 ), and a rotatable hub ( 203 ) which is disposed on the hub plate and which has at least one robotic arm attached thereto. The hub plate includes a first component ( 207 ) which is attached to the hub, and a second component ( 209 ) which is attached to a substrate. The first component of the hub plate is releasably attached to the second component of the hub plate.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of priority from U.S. Provisional Application No. 62/051,843 filed Sep. 17, 2014, having the same inventors, and the same title, and which is incorporated herein in its entirety. 
     
    
     TECHNICAL FIELD OF THE INVENTION 
       [0002]    The present invention pertains generally to robots for use in semiconductor fabrication, and more particularly, to a multi-component robotic hub mounting plate for use with such robots which facilitates hub removal. 
       BACKGROUND OF THE INVENTION 
       [0003]    In a typical semiconductor manufacturing process, a single wafer may be exposed to a number of sequential processing steps including, but not limited to, chemical vapor deposition (CVD), physical vapor deposition (PVD), etching, planarization, and ion implantation. These processing steps are typically performed by robots, due in part to the ability of robots to perform repetitive tasks quickly and accurately and to work in environments that are dangerous to humans. 
         [0004]    Many modern semiconductor processing systems are centered around robotic cluster tools that integrate a number of process chambers. This arrangement allows multiple sequential processing steps to be performed on the wafer within a highly controlled processing environment, and thus minimizes exposure of the wafer to external contaminants. The combination of chambers in a cluster tool, as well as the operating conditions and parameters under which those chambers are utilized, may be selected to fabricate specific structures using a specific process recipe and process flow. Some commonly used process chambers include degas chambers, substrate pre-conditioning chambers, cool down chambers, transfer chambers, chemical vapor deposition chambers, physical vapor deposition chambers and etch chambers. 
         [0005]    One example of a known cluster tool is disclosed in U.S. Pat. No. 6,222,337 (Kroeker et al.), which is reproduced in  FIG. 1  herein. The cluster tool  10  disclosed therein features robots  14 ,  28  having a frog-leg construction. Such robots are adapted to provide  both radial and rotational movement of their associated end effector blades  17  within a fixed plane. These radial and rotational movements may be coordinated or combined to allow wafers  32  to be picked up, transferred and delivered from one processing chamber to another processing chamber within the cluster tool  10 . 
         [0006]    With reference to  FIG. 1 , wafers are introduced into, and withdrawn from, the cluster tool  10  through a cassette loadlock  12 . In the particular cluster tool depicted, a first robot  14  having a wafer plate blade  17  end effector is located within a chamber  18  and is utilized to transfer wafers  32  among a first set of processing chambers. In the particular embodiment depicted, these processing chambers include the aforementioned cassette loadlock  12 , a degas wafer orientation chamber  20 , a preclean chamber  24 , a PVD TiN chamber  22  and a cooldown chamber  26 . The robot  14  is illustrated in the retracted position in which it can rotate freely within transfer chamber  18 . 
         [0007]    A second robot  28  is located in transfer chamber  30  and is adapted to transfer substrates between a second set of process chambers. In the particular embodiment depicted, the second set of process chambers includes a cool down chamber  26  and a pre-clean chamber  24 , and may also include a CVD Al chamber and a PVD AlCu processing chamber. The specific configuration of chambers in the cluster tool  10  is designed to provide an integrated processing system capable of both CVD and PVD processes in a single tool. A microprocessor controller  29  is provided to control the fabricating process sequence, conditions within the cluster tool, and the operation of the robots  14 ,  28 . 
         [0008]      FIG. 2  depicts an example of a robot which may be used in the cluster tool of  FIG. 1 . The particular robot  101  depicted in  FIG. 2  has a double frog-leg design and features first  103  and second  105  pairs of arms which are attached on one end to a wrist assembly  107 , and which are attached on the other end to an elbow joint  109 . Each wrist assembly  107  is in turn attached to an end effector  111  which is used to handle a semiconductor wafer. The robot  101  is further equipped with upper arms  113 ,  115  which are mounted on the upper  117  and lower  119  rotatable rings of a hub  121 . The robot  101  further comprises a monolithic hub plate  123  upon which the hub  121  is mounted, and a motor  125  which drives the upper  117  and lower  119  rotatable rings. The hub  121  and hub plate  123  together constitute a hub assembly  124 . 
         [0009]    As seen in  FIG. 3 , the robot  102  is mounted on the substrate  131  such that the hub plate  123  is attached to a first surface of the substrate  131 . The motor  125  (see  FIG. 2 ) typically extends below the substrate  131  through a hole provided therein.  
       SUMMARY OF THE INVENTION 
       [0010]    In one aspect, a robot is provided which comprises (a) a hub plate, and (b) a rotatable hub disposed on said hub plate and having at least one robotic arm attached thereto. The hub plate includes a first component which is attached to the hub, and a second component which is attached to a substrate. The first component of the hub plate is releasably attached to the second component of the hub plate. 
         [0011]    In another aspect, a robot is provided which comprises (a) a hub plate; and (b) a rotatable hub disposed on said hub plate and having at least one robotic arm attached thereto. The hub plate is equipped with a first generally planar, circumferential surface equipped with a first plurality of holes through which a first set of releasable fasteners extend. The hub plate is further equipped with a second planar, circumferential surface equipped with a second plurality of holes through which a second set of releasable fasteners extend. The hub plate is also equipped with a toroidal surface disposed between said first and second circumferential surfaces which is complimentary in shape to the adjacent surface of said hub. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings in which like reference numerals indicate like features. 
           [0013]      FIG. 1  is an illustration of a prior art cluster tool equipped with a robotic wafer handling system. 
           [0014]      FIG. 2  is an illustration of a prior art robot which may be used in the cluster tool of  FIG. 1 . 
           [0015]      FIG. 3  is an illustration of an embodiment of the robot of  FIG. 2  shown mounted on a substrate. 
           [0016]      FIG. 4  is a perspective view of a particular, non-limiting embodiment of a hub assembly equipped with a two-part hub plate of the type disclosed herein. 
           [0017]      FIG. 5  is a perspective view showing the top of the first element of the hub assembly of  FIG. 4 .  
           [0018]      FIG. 6  is a perspective view showing the top of the second element of the hub assembly of  FIG. 4 . 
           [0019]      FIG. 7  is a top view of the first element of the hub assembly of  FIG. 4 . 
           [0020]      FIG. 8  is a bottom view of the first element of the hub assembly of  FIG. 4 . 
           [0021]      FIG. 9  is a top view of the second element of the hub assembly of  FIG. 4 . 
           [0022]      FIG. 10  is a bottom view of the second element of the hub assembly of  FIG. 4 . 
           [0023]      FIG. 11  is an exploded view of the hub assembly of  FIG. 4 . 
           [0024]      FIG. 12  is a bottom view of the hub assembly of  FIG. 4  showing the attachment of the lower plate to the robotic hub. 
           [0025]      FIG. 13  is a perspective view of the hub assembly of  FIG. 4  depicting the attachment of the lower plate to the robotic hub. 
           [0026]      FIG. 14  is a partially exploded, perspective view of the hub assembly of  FIG. 4  depicting the placement of the upper plate to lower plate fasteners. 
           [0027]      FIG. 15  is a partially exploded, perspective view of the hub assembly of  FIG. 4  depicting the disposition of the O-ring in the assembly. 
           [0028]      FIG. 16  is a cross-sectional illustration of the hub assembly of  FIG. 4  compared to a cross-sectional illustration of a prior art hub assembly and showing the increased material in the former in comparison to the latter. 
           [0029]      FIG. 17  is a magnified view of REGION A of  FIG. 6  showing the alignment marks thereon. 
           [0030]      FIG. 18  is an illustration of a tool which may be utilized to remove the hub from a hub assembly of the type depicted in  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    While robots of the type depicted in  FIGS. 1-3  have some advantages, they also have some significant shortcomings. For example, it is frequently necessary to remove the hub  121  in order to service such robots, which in turn requires removal of the hub plate  123 . However, removal of the hub plate  123  typically requires access to the underside of the tool. In a typical cluster tool, access to the area underneath of the hub  121  is typically restricted, due in part to the tight confinements of the mounting hardware. Consequently, at present, hub removal entails a considerable expenditure of time and effort. Indeed, removal and reinstallation of the hub  121  typically takes at least 1-2 hours. Given the significant cost that is frequently associated with semiconductor line downtime,  the existing hub plate design represents a considerable hidden cost for semiconductor manufacturers. 
         [0032]    The removal or reinstallation of the hub plate  123  also poses significant ergonomic risks for technicians involved in the process. In particular, when coupled with the cramped space underneath the tool, the existing hub plate design causes workers to assume awkward positions and to undertake uncomfortable maneuvers in order to access and remove or reinstall the mounting screws for the hub plate. In such a removal or reinstallation, the worker&#39;s lower body, neck, arms and hands may all be placed in uncomfortable positions and movements for extended periods of time, which may result in strains and injury. 
         [0033]    In addition, the removal or reinstallation of the hub plate  123  frequently results in damage to surrounding hardware in the chambers and tool. Typically, a technician is forced to enter the lower portion of a chamber in order to access the mounting screws. During the removal or reinstallation process, the technician is often forced to lie on gas lines, harnesses, waterlines and high voltage RF and AC cables. Consequently, the likelihood of collateral damage is high each time the removal or reinstallation process is undertaken. 
         [0034]    It has now been found that the foregoing problems may be overcome with the hub plate design disclosed herein. In a preferred embodiment, this hub plate has a 2-component design in which the first (upper) component is attached to the hub, the second (lower) component is attached to the substrate, and the first component is removably attached to the second component. Consequently, removal of the hub only requires detaching the first component from the second component, which may be accomplished by removing a series of screws accessible from above the substrate (e.g., from the inside of the buffer chamber). Since these screws are readily accessible and are not in a space-constrained location, hub removal may be accomplished much faster compared to conventional hub plates, and without the ergonomic issues and risk of collateral damage noted above. 
         [0035]      FIG. 4  depicts a particular, non-limiting embodiment of a hub assembly equipped with a hub plate in accordance with the teachings herein. This hub assembly  201  is designed to be interchangeable with the hub assembly  125  in the robot of  FIGS. 1-3 . The hub assembly  201  comprises a hub  203  and a two-part hub plate  205  having first  207  and second  209  components. The first component  207  of the hub plate  205  is shown  in greater detail in  FIGS. 7 and 8 , and the second component  209  of the hub plate  205  is shown in greater detail in  FIGS. 6 ,  9  and  10 . 
         [0036]    In a preferred embodiment, the dimensions of the hub plate  205  are comparable to the dimensions of the hub plate  123  of  FIG. 4 , thus allowing the former to be substituted for the later in legacy platforms. The hub plate  205  in this particular embodiment is suitable for use in 200 mm and 300 mm legacy and EHubs in Centura, Producer and Endura platforms, although it will be appreciated that similar hub plates may be made in accordance with the teachings herein that may be utilized with other robots and platforms. 
         [0037]      FIG. 11  is a partially exploded view of the hub assembly  201  of  FIG. 4 . As seen therein, the first component  207  of the hub plate  205  is attached to the underside of the hub  203  by way of a first set of fasteners  215  which extend through holes  261  (see  FIGS. 7 and 8 ), the second component  209  of the hub plate  205  is attached to the first component  207  of the hub plate  205  by way of a second set of fasteners  219  which extend through holes  263  (see  FIGS. 6 ,  9  and  10 ), and the second component  209  of the hub plate  205  is attached to a substrate (typically, a chamber bottom) by way of a third set of fasteners  221  (see  FIG. 14 ) which extend through holes  265  (see  FIGS. 7-8 ) and  267  (see  FIGS. 6 ,  9  and  10 ). 
         [0038]    As seen in  FIG. 11 , an O-ring  223  is disposed between the first  207  and second  209  components of the hub plate  201  to allow a vacuum seal to be maintained therein. The O-ring  223  preferably comprises a resilient material such as, for example, nitrile rubber, butyl rubber or PTFE (polytetrafluoroethylene), and is seated in a circumferential, complimentary-shaped groove  271  in the second component  209 .  FIG. 15  depicts the O-ring  223  seated in circumferential groove  271  (see  FIG. 11 ) of the second  209  components of the hub plate  201 . 
         [0039]    It will be appreciated from  FIG. 11  that the design of the hub plate  205  allows the hub  203  to be removed from a substrate by removal of the second set of fasteners  219 . Doing so detaches the first  207  and second  209  components of the hub plate  205  from each other, but leaves the second component  209  of the hub plate  205  attached to the substrate, and the first component  207  of the hub plate attached to the hub  205 . It will further be appreciated that this removal may be accomplished from above the substrate, where accessibility to the third set of fasteners  221  is typically unhindered (although embodiments are also possible in which such removal may be accomplished from below  the substrate, or from both above and below the substrate). Consequently, the two-pat hub plate  205  disclosed herein may be utilized in a platform to overcome the various issues in the art as noted above. 
         [0040]    In the particular embodiment depicted in  FIG. 11 , six fasteners  219  are utilized to attach the second component  209  of the hub plate  205  to the first component  207  of the hub plate  205 , and twelve 8-32 fasteners  215  are utilized to attach first component  207  of the hub plate  205  to the hub  213 . As seen in  FIG. 14 , fifteen 8-32 fasteners  221  are utilized to attach the second component  209  of the hub plate  205  to the substrate. As noted above, the fasteners  219  can be removed from the top of the tool, and hence allow removal of the hub  213  from the top of the tool. Preferably, the first  215 , second  219  and third  221  sets of fasteners are threaded fasteners which rotatingly engage complimentary shaped threaded apertures. Thus, the first set of fasteners  215  preferably rotatingly engage apertures  261 , the second set of fasteners  219  preferably rotatingly engage apertures  265  and  267 , and the third set of fasteners  221  preferably rotatingly engage apertures  263  and/or rotatingly engage threaded apertures provided in the substrate. 
         [0041]      FIGS. 14-15  show the placement of the O-ring  223  on the second component  209  of the hub plate  205 . A complimentary shaped groove  243  (see  FIG. 14 ) is provided in the second component  209  within which the O-ring  223  is seated (see  FIG. 15 ). The hub plate  205  separates the transfer chamber from the atmosphere. The O-ring  223  thus serves to maintain the integrity of this seal across the interface between the first  207  and second  209  components. In addition, three alignment pins (not shown) are provided in the second component  209  of the hub plate  205  to ensure proper alignment between the first  207  and second  209  components of the hub plate  205 . 
         [0042]    As noted above, the hub plates disclosed herein may be frequently utilized to replace hub plates in legacy equipment. In such applications, it is desirable for the two-piece hub plate to have equivalent structural integrity to the Original Equipment Manufacturer (OEM) hub plate. However, fabricating the hub plate as a multicomponent structure may reduce the structural integrity of the hub plate as compared to the monolithic OEM structure. While this problem may be addressed by increasing the overall dimensions of the hub plate (e.g., by increasing the thickness of the hub plate components), such an approach is unacceptable in applications where the hub plate is to be utilized for replacement of an OEM hub plate, since the hub plate design is subject to  constraints in several directions. It will thus be appreciated that strengthening a two-piece hub plate, while preserving its ability to be utilized in legacy platforms, is not trivial. 
         [0043]    In the preferred embodiment of the hub plate  205  depicted in  FIG. 4 , this issue is addressed through the selective addition of material to the hub plate as compared to the OEM hub. The manner in which this is accomplished may be appreciated with respect to  FIG. 16 , which compares the cross-sectional profile of a hub plate  205  in accordance with the teachings herein with that of an OEM hub plate  261 . As seen therein, the first component  207  of the hub plate  205  has a different cross-sectional profile as compared to the OEM hub plate  261 . This difference in profiles results from the addition of a toroid of material  263  to the inner rim of first component  207  of the hub plate  205 , while the corresponding OEM hub plate  261  has an open space in this region. This toroid  263  significantly strengthens the entire hub plate structure, which may thus compensate for any loss in mechanical integrity attendant to the division of the hub plate  205  into multiple components. At the same time, the added toroid of material does not interfere with other components of the hub assembly (that is, in every other respect, the two-part hub plate  205  has the same overall dimensions as the legacy OEM hub plate  261 ), and is thus suitable for OEM hub plate replacement applications. 
         [0044]    The profile of the first component  207  of the hub plate  205  has the additional benefit of helping to contain any particles that may be generated by the lower hub bearing. As seen in  FIG. 7 , this profile includes a first generally planar circumferential surface  291  having apertures  265  therein, a second generally planar circumferential surface  293  having apertures  261  therein, and a toroidal surface  263  disposed between the first  291  and second  293  circumferential surfaces which is complimentary in shape to the adjacent surface of said hub. While this profile is especially advantageous within the context of the two-part hub plate  205  of the type described herein, one skilled in the art will appreciate that this profile may also be utilized in monolithic hub plates, where benefits of improved mechanical strength and containment of particles generated by the lower hub bearing may also be achieved. 
         [0045]      FIG. 17  depicts further details of the second component  209  of the hub plate  205  of  FIG. 5 . As seen therein, the second component  209  of the hub plate  205  is equipped with alignment marks  271 . These alignment marks  271  may be utilized to align the magnetic couplers of the hub  213 .  
         [0046]    In an assembled condition, the first  207  and second  209  components of the hub plate  205  described herein are preferably parallel to each other within a tolerance range that is equal to or greater than that of the OEM hub plate it is replacing. This objective may be achieved by utilizing a stress relieved aluminum alloy as the base material, together with geometric tolerancing of the manufacturing drawings. 
         [0047]      FIG. 18  depicts a hub removal tool which may be utilized in conjunction with the hub plates disclosed herein. As seen therein, the hub removal tool  273  comprises a plurality of legs  275  which are adjoined at one end with a central plate  277 , and which terminate on the other end in feet  279  that engage complimentary-shaped openings  281  provided in the first component  207  of the hub plate  205 . Preferably, the complimentary-shaped openings  281  are sufficiently small that they do not encroach on the areas needed to form a seal with the O-ring  223 . 
         [0048]    In some embodiments, the hub removal tool  273  may be utilized in conjunction with rotary tools (not shown) that attach to the central plate  277  and the hub, and which use a threaded axis to lift the hub from the substrate along an axis which is perpendicular to the substrate. In use, after the requisite fasteners have been removed, the hub removal tool  273  may be attached to the hub  213  by engaging the feet  279  of the tool with the complimentary-shaped openings  281  provided in the first component  203 , after which it may be utilized, alone or with another tool, to remove the hub  213 . 
         [0049]    All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
         [0050]    The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless  otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
         [0051]    Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.