Abstract:
A loadport for handling film frames is disclosed. The loadport is modular and substantially compatible with applicable standards regarding modular equipment. In particular, the load port is substantially interchangeable with loadports not adapted for handling film frames. The loadport has a compact shuttle for moving film frames and flexible alignment mechanisms for aligning film frames and cassettes of different configurations.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation in part of application Ser. No. 11/742,355, filed Apr. 30, 2007, which is a continuation of application Ser. No. 10/891,278 filed on Jul. 14, 2004 now U.S. Pat. No. 7,316,938 and claims priority to the provisional application Ser. No. 60/487,151 filed Jul. 14, 2003 and provisional application Ser. No. 61/567,634 filed on Dec. 7, 2011. 
     
    
     TECHNICAL FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to methods of and mechanisms for handling substrates and in particular to the handling of semiconductor substrates of various kinds. 
       BACKGROUND OF THE INVENTION 
       [0003]    Manufacturers and users of semiconductor equipment rely upon standardized equipment specifications to ease system integration and factory design. An example of one such standard that is often relied upon is referred to as the BOLTS-M standard (SEMI E15, E63). This standard specifies a mechanical interface for mechanisms called loadports, among others, that are often coupled to equipment front-end modules (EFEM&#39;s) for handling semiconductor substrates. Loadports that are adapted to accommodate standard front opening unified pods (FOUP&#39;s) or cassettes can easily be made to meet the BOLTS-M standard as the robot in the EFEM is capable of reaching into the FOUP or cassette in the loadport to extract or replace wafers. Not so with wafers mounted on film frames. 
         [0004]    Wafers on film frames tend to sag and pose a difficult handling proposition. Rather than using a spatulate end effector with a robot to pick up a film frame with a wafer or singlulated chips mounted thereon, a film frame handler extracts each film frame by sliding it from its cassette onto a platform. A specialized overhead end effector equipped system then picks up the film frame by applying vacuum against the upper surface of the film frame&#39;s frame and moves the film frame onto a top plate for processing, inspection, metrology, etc. 
         [0005]    The footprint of mechanisms for reliably extracting and replacing film frames in a cassette is typically too large for incorporation into a BOLTS-M compatible loadport. Accordingly, film frame handlers tend to be specialized affairs that are typically single purpose, i.e. film frame only. Where provisions are made to handle wafers or substrates other than film frames, the flexibility and capability of such systems is necessarily limited to accommodate the film frame handling capability. 
         [0006]    There is, therefore, a need for a modular loadport for handling substrates such as film frames or hoops that at least approximates the flexibility exhibited by substrate loadports that comply with industry standards such as the BOLTS-M standard. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  illustrates one embodiment of a film frame loadport. 
           [0008]      FIG. 2  shows one embodiment of a frame support coupled to a stiffener that is used to secure the frame support to the frame and to ensure that the frame support remains rigid and flat and in the desired plane. 
           [0009]      FIG. 3  shows the upper jaw of the gripper is adjustable with respect to the lower jaw to the extent necessary to accommodate film frames or hoops of differing thicknesses. 
           [0010]      FIGS. 4 and 5  show an elevator, a cassette plate, and cassettes. 
           [0011]      FIG. 6  illustrates an exemplary film frame of a type that may be handled by the present invention. 
           [0012]      FIGS. 7A-7E  show examples of end effectors and gripping devices that may be used to grip, grasp or otherwise secure for transport a film frame. 
           [0013]      FIG. 8  shows one embodiment of a cassette plate provided with an automatic cassette alignment mechanism. 
           [0014]      FIG. 9  illustrates how a generic end effector having vacuum devices may be addressed to a film frame from above. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    In the following detailed description of the invention, reference is made to the accompanying drawings that form a part hereof, and in which is shown, by way of illustration, specific embodiments in which the invention may be practiced. In the drawings, like numerals describe substantially similar components throughout the several views. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims and equivalents thereof. 
         [0016]      FIG. 1  illustrates one embodiment of a film frame loadport  10  according to the principles of the present invention. In this FIGURE one can see a generally rectangular frame  12  having a port  14  formed therethrough. This port  14  aligns with a pass-through or aperture of an EFEM or other system or mechanism (not shown). The loadport  10  is attached to an EFEM by means of the frame  12 . In one embodiment the loadport  10  may be secured to an EFEM or other mechanism by means of a number of fasteners such as bolts or quick release fasteners such as Cleco fasteners (not shown) that pass through a number of apertures  16  formed through the frame  12 . Any useful number or arrangement of apertures  16  may be provided and in some embodiments hanging mechanisms such as a hook or lip may be provided in addition to or in lieu of such fasteners. 
         [0017]    The loadport  10  shown in  FIG. 1  includes shrouds  18  that cover at least some portion of the working components of the load port  10  to reduce the airflow around the covered components. Shrouds may also be used for safety purposes. The use of shrouds  18  minimizes contamination of substrates due to particles, grease, and other contaminants from the loadport components or from the environment in general. These shrouds  18  may have any useful configuration or may be omitted where the application does not require them. 
         [0018]    Extending through the port  14  in the frame  12  is a film frame support  20 . When film frames such as exemplary film frame  22  are extracted from a cassette (not shown), they are pulled onto the frame support. Film frames such as film frame  22  are well known to those skilled in the art as being a ring of fairly rigid material that forms a central aperture. Across this aperture is stretched an adhesive film to which is adhered a substrate such as a semiconductor substrate. As the ring of a film frame is not typically sufficiently rigid to support the film frame in a desired attitude when gripped solely at one edge, the film frame will be slide out of a cassette in which it is stored onto the film frame support  20 . When a film frame  22  is slid onto a film frame support  20 , a pair of slots that supports the film frame  22  in a cassette (not shown) is aligned with an upper surface of the film frame support  20  as described hereinbelow. 
         [0019]    The film frame support  20  acts as a platform for an appropriate end effector to pick up and put down film frames  22 . The film frame support  20  needn&#39;t extend far into the interior of an EFEM provided that an appropriate end effector is used. In one embodiment the film frame support  20  extends beyond the port  14  approximately the same depth as a diameter of a film frame  22  that will be handled. In some embodiments the frame support  20  may be longer than a film frame diameter, particularly where a large end effector on a robot or overhead transport device is utilized move film frames about in an EFEM. Where an overhead transport device is used to move film frames, the frame support  20  should extend approximately the same distance into the EFEM as the film frame&#39;s diameter. While it is not strictly necessary to constrain the length or projection of the film frame support  20  in this one embodiment to the diameter of a film frame, constraints on the lateral movement of an overhead transport device must be accommodated. Where such lateral movement constraints are satisfied, the film frame support&#39;s projection may vary. In other embodiments, such as where an end effector of a 3 or 4 axis robot of a type commonly used in the field is used, the film frame support may extend less than a diameter of a film frame  22  through the port  14 . 
         [0020]      FIG. 6  illustrates an exemplary film frame  22  of a type that may be handled by the present invention. Note that the loadport  10  may be adapted to handle substrates other than film frames such as hoops or the like. Solid substrates such as silicon wafers or other discs (metallic or otherwise) may in some instances be handled by the load port  10 , but care must be taken to prevent scratch these substrates as they slide on the film frame support  20 . The film frame  22  is formed by a substantially rigid ring  22   a . Stretched across this ring  22   a  is an adhesive film  22   b . A wafer or other substrate “S” is adhered to the film in approximately the center of the ring  22   b . The ring  22   a  has a pair of alignment notches  22   c  and one or more straight edges  22   d  that may be used to locate or guide a film frame  22 . Those skilled in in the art will recognize the generic nature of the film frame  22  of  FIG. 6  and will appreciate that the many variations on this basis arrangement are or could in the future be in use. The loadport  10  of the present invention is flexible enough to accommodate many different variations in film frames  22  including different sizes such as for example 200 m, 300 mm or 450 mm film frames or hoops. Other sizes and configurations are also contemplated. 
         [0021]    Referring next to  FIGS. 7A-7E , one can see examples of end effectors and gripping devices that may be used to grip, grasp or otherwise secure for transport a film frame  22 . Because film frames  22  are often not sufficiently rigid to support their own weight without deflecting, a simple pincer type frame gripper  30  affixed to a robot arm  31  such as that shown in  FIG. 7E  may not be sufficient, though for very small film frames or substrates this may not be the case. Larger pincer type grippers  32  such as those illustrated in  FIG. 7D  may be used for larger film frames. The larger, arcuate gripper  32  grips a larger portion of the periphery of the film frame  22  and hence reduces deformation of the film frame  22  when it is supported as compared to the gripper  30  shown in  FIG. 7E . 
         [0022]    A more secure way of handling a film frame  22 , a hoop, or any other substrate to which the loadport  10  may be addressed is to use and end effector having vacuum devices to secure a film frame thereto. By way of explanation, an end effector is a mechanism that is either attached to or formed as part of a transport mechanism such as a robot arm or overhead transport system that is adapted to address and secure a substrate for movement or adjustment. A transport mechanism may be an overhead transport system or may be an arm or arms of a 3 or 4 axis robot of an EFEM.  FIG. 9  illustrates how a generic end effector  40  having vacuum devices  42  may be addressed to a film frame  22  from above. In the context of the loadport  10 , the film frame  22 , supported on the film frame support is addressed by the end effector  40  from above. Note that an end effector utilizing a gripper such as grippers  30  or  32  may address the film frame  22  edge-on. Vacuum devices  42 , which are essentially suction cups connected to at least a source of vacuum pressure, contact the non-substrate portion of a film frame  22  and are then activated by connecting the vacuum devices to the source of vacuum pressure. The activated vacuum devices  42  couple the film frame  22  to the end effector  40  which is then actuated to move the film frame  22  to a desired location, i.e. to remove the film frame  22  from the film frame support  20 . Similarly, a film frame  22  may be returned to the film frame support  20  by the end effector  40 . 
         [0023]      FIG. 7A  schematically shows an embodiment of an end effector having four vacuum devices  42  that may be addressed to a film frame  22  (shown as dashed lines).  FIG. 7B  illustrates an embodiment having three vacuum devices  42 . In a similar vein,  FIG. 7C  illustrates an embodiment in which two vacuum devices  42  are addressed to a film frame  22 . It is noted that in  FIG. 7C  the vacuum devices are shown in solid line as being oriented horizontally and in dashed line as being oriented vertically. It is to be understood that for each embodiment shown in  FIGS. 7A-7E , the end effector  40 , the grippers  30  and  32 , and the number, placement and orientation of the vacuum devices  42  may be modified to suit a given application. In some embodiments, the vacuum devices may be affixed to a spatulate end effector that is integral to a robot arm of a robot in an EFEM. In other embodiments, the end effector may be a separate portion removably attached to a distal end of a robot arm, the vacuum devices  42  being affixed to the end effector. End effectors may be spatulate, fork shaped, curvilinear, arcuate, or may approximate the size and shape of the film frame  22  or other substrate or holder that is being handled. 
         [0024]      FIG. 2  shows one embodiment of a frame support  20  coupled to a stiffener  50  that is used to secure the frame support  20  to the frame  12  and to ensure that the frame support  20  remains rigid and flat and in the desired plane. A retractable gripper is shown in a first position in which the retractable gripper may be addressed to the edge of a film frame (not shown) that is stored in a cassette (not shown). The retractable gripper in its first position denoted as  54 ′.  FIG. 2  also includes a representation of the retractable gripper in a second position in which the gripper is positioned to address an edge of a film frame (not shown) that rests on the film frame support  20 . The film frame addressed by the retractable gripper  54 ″ may have been extracted from a cassette (not shown) or may have been newly placed on the film frame support  20  as having been returned from a processing, inspection or metrology step or process. Note that the gripper shown in the second position is denoted as  54 ″ and is exemplary only. Only a single gripper  54  is provided. When the gripper  54  is in its second position it may be retracted downward below the upper surface of the frame support  20 . In this way, a film frame  22  may be freely moved upon the surface of the frame support for alignment. Further, retracting the gripper  54  allows film frames  22  to be securely set down on the frame support  20  without worry of the gripper  54 . 
         [0025]    The gripper  54  is reciprocated between its first and second positions by a compact shuttle  56  that is positioned beneath the frame support  20 . The shuttle  56  facilitates the fitment of the film frame loadport to a BOLTS-M standard EFEM by doing away with the large reciprocating mechanisms that previously took up so much space. 
         [0026]    In one embodiment the shuttle  56  has a body  58  that travels on a linear bearing  60 . The position of the body  58  may be determined using a linear encoder (not shown) coupled between the body  58  and the frame support  22 . In other embodiments a rotary encoder (not shown) may be coupled to an actuating mechanism  62  to determine a position of the gripper  54 . The body  58  may be moved in a number of different types of actuating mechanism  62  ways including the use of a toothed belt  64  or a ball screw (not shown). These and other embodiments for moving the body  58  may be selected as needed for a particular application. 
         [0027]    The retractable gripper  54  is coupled to the body  58  for vertical or near vertical travel in a straight or curvilinear line with respect to the upper surface of the film frame support  20 . A small actuator  66  moves, i.e. extends and retracts, the gripper  54  up and down as the operation of the system requires. The gripper  54  may also rotate in a plane defined by the first and second positions of the gripper  54  to some degree to prevent or at least minimize the rotation of a film frame when it is grasped by the gripper  54 . The idea here is to grip the film frame and then actuate the movement of the body  58  from the first to the second position whilst retaining the film frame in a substantially planar orientation with respect to the frame support  20 . 
         [0028]    The lower jaw  55   a  of the gripper  54  may in some embodiments be reciprocal but is in other embodiments stationary. The upper jaw  55   b  of the gripper  54  is adjustable with respect to the lower jaw  55   a  to the extent necessary to accommodate film frames or hoops of differing thicknesses as seen in  FIG. 3 . 
         [0029]    Film frames are preferably coarse aligned by the film frame loadport  10  as the film frame may not easily be placed on a standard pre-aligner. As with U.S. Pat. No. 7,316,938, a continuation of which is co-pending herewith and from which this application claims priority as a continuation in part, pusher pins  70  are used to push the film frame into a first alignment position. As can be seen in  FIG. 2 , an adjustable set of pusher pins  70  provided for pushing a film frame  22  into contact with a selected set of alignment pins  72 . Each of the pins  70  is mounted on an adjustment mechanism  73  that moves the pins toward and away from one another in a generally symmetrical manner in a direction that is generally perpendicular to the travel of the gripper  54  in the plane of the frame support  20 . The pins  70  are adjustable to accommodate film frames of different sizes. 
         [0030]    The adjustment mechanism  73  is in one embodiment rotatably mounted to the frame  12  (not shown in  FIG. 2 ) such that the pins  70  mounted there on can move and reciprocate in the same direction as the motion of the gripper  54 . Note that in other embodiments the adjustment mechanism may move linearly instead of rotatably. The adjustment mechanism  73  is in one embodiment an actuator that moves the pins  70  laterally with respect to the direction of travel of the gripper  54 . The adjustment mechanism  73  is caused to rotate or reciprocate by an actuator (not shown) coupled between the frame  12  and the adjustment mechanism  73 . 
         [0031]    Typically film frames have alignment notches  22   c  formed into their sides that have the same spacing as selected alignment pins  72 . The pins  70  are adjusted to contact a curvilinear portion of the edge of a film frame to reliably guide the alignment notches  22   c  of film frame  22  into contact with the alignment pins  72 . The pusher pins  70  reciprocate toward one of a number of sets of alignment pins that may be extended above the surface of the frame support as needed and retracted below the surface when not. During alignment, the set of alignment pins appropriate for the size and/or configuration of the film frame or hoop are extended above the surface of the frame support  20  and the pusher pins  70  that push the film frame or hoop into contact with the stop pins to achieve a first alignment. The adjustability of the alignment pins is not strictly required as a first alignment may be performed using manually adjustable or non-adjustable alignment pins  72 . However, the automatic adjustability of the alignment pins  72  and of the pusher pins  70  does allow for rapid implementation of new product recipes or set ups. For example, a recipe or product set up may include information regarding the size of a film frame contained in a cassette such that when the cassette is loaded, the appropriate pusher or alignment pins are selected and used automatically without user input. In other instances, a cassette may be loaded with film frames having various form factors and/or or alignment notch  22   c  spacing. The automatic adjustment of the pins  70 ,  72  allows for the continuous inspection or processing of film frames or hoops even where different form factor frames or hoops are included in a single cassette. 
         [0032]    Alignment pins  72  may be reciprocated between an extended position in which they extend above the surface of the film frame support  20  and a retracted position in which the pins  72  are positioned below the surface of the film frame support by any useful means. In one embodiment pneumatic actuators move the alignment pins between their extended and retracted positions as needed. These pneumatic actuators may be plumbed for control as respective pair of alignment pins  72  or controlled individually to be extended or retracted as needed alone or in pairs. 
         [0033]      FIGS. 4 and 5  show an elevator  80 , a cassette plate  82 , and cassettes  84 . The film frame loadport  10  has on its outboard side an elevator  80  that supports a cassette plate  82 . Cassettes  84  secured to the cassette plate  82  are moved vertically with respect to the port  14  through the frame  12  and to the frame support  50 . Generally the cassette  84  is moved so that a pair of slots (not shown) in the cassette that house and support a film frame  22  or similar type of frame or hoop is aligned with the frame support  20 . To remove a film frame from the cassette  84 , the gripper  54  is moved to its first position in which the upper jaw  55   b  and lower jaw  55   a  of the gripper  54  have and edge of the film frame positioned therebetween. At least the upper jaw  55   b  of the gripper  54  is extended above the surface of the frame support  20  and the lower jaw  55   a  of the gripper is preferably planar parallel to the upper surface of the film frame support  20 , though in some embodiments the elevator will position the film frame  22  such that the lower jaw  55   a  which is positioned slightly above the film frame support  20  may address the edge of the film frame  22 . The jaws of the gripper  54  are then actuated to grasp the film frame  22 . In this embodiment the lower jaw  55   a  remains stationary and the upper  55   b  moves, but it is to be understood that the case may be reversed or both jaws may move. 
         [0034]    The elevator  80  has associated therewith a linear or rotary encoder (not shown) to accurately identify the position of the cassette with respect to the frame support  20 . Further, the elevator  80  is provided with a sensor that can optically or capacitatively determine whether a film frame, hoop or wafer is present in the cassette  84 , in which slot, and whether there are any cross-slotting issues. Generally when a cassette  84  is first placed on the cassette plate  82 , the elevator  84  will be vertically cycled to allow the sensor (which is often but not always coupled to the frame  12  (directly or indirectly) so as to remain stationary as the elevator  80  is cycled) to map the position of all film frames  22  in the cassette  84 . Note that in some embodiments the sensor may move for the mapping procedure while the elevator and cassette remain stationary. 
         [0035]    It is important to ensure that a cassette  84  placed on the cassette plate  82  remains in an aligned position. To do this, one embodiment of the cassette plate  82  is provided with an automatic cassette alignment mechanism  90  as seen in  FIG. 8 . In one embodiment, the forward stops  92  at the front edge of the cassette plate  82  create a positive alignment at the front edge of the cassette  84  with respect to the cassette plate  82 . The actuation of the actuating mechanism causes the appropriate corner grippers  96  to clamp the cassette  84  into the desired position. Note that the foregoing actuating mechanism  94  and stops  92  are typically used in the 200 mm cassette operations but other size cassettes  84  may be accommodated. 
         [0036]    The retractable cassette alignment pins  98  may be extended above the cassette plate where appropriate to act as a standard three pin kinematic mount for a 300 mm FOUP or cassette  84 . 
         [0037]    Operation of the whole is coordinated by a controller (not shown) that may take the form of a personal computer connected for local control, a computing device or computer that is located remotely from the load port  10  and connected via any useful networking protocol (wireless or wired), or a distributed computing device having multiple elements coupled to the loadport  10 . For example, in one embodiment an industrial computer located within an EFEM to which a loadport  10  is coupled controls the operation of the loadport  10 . In addition to local or remote control of the loadport and its mechanisms, databases or stores of data or information may be maintained remotely and served up as needed to allow for the automatic operation and adjustment of the loadport  10  and its elements. The loadport  10  may then operation in conjunction with the EFEM and whatever inspection, metrology or process tool or tools that are coupled to the EFEM. Control and information such as recipes may be handled locally or remotely through a fab-wide host system as is well understood by those skilled in the art. 
       CONCLUSION 
       [0038]    Although specific embodiments of the present invention have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement that is calculated to achieve the same purpose may be substituted for the specific embodiments shown. Many adaptations of the invention will be apparent to those of ordinary skill in the art. Accordingly, this application is intended to cover any adaptations or variations of the invention. It is manifestly intended that this invention be limited only by the following claims and equivalents thereof.