Abstract:
An improved wafer container is provided for use with automated equipment. The container includes a top lid that engages with a bottom base to form a housing having an inner cavity for storing semiconductor wafers. The lid includes a handling member that interfaces with automated equipment for engaging the lid with the base and removing the lid from the base. The container includes latches that can be actuated between a locked position and an unlocked position by automated equipment. The container can hold multiple stacked wafer separator rings, each of which has automation tabs extending outwardly from the ring outer rim. The automation tabs allow for automated equipment to transfer the wafer separators rings between the container and a staging area.

Description:
RELATED APPLICATION DATA 
       [0001]    This application is based on and claims the benefit of U.S. Provisional Patent Application No. 61/702,545 filed on Sep. 18, 2012, the disclosure of which is incorporated herein in its entirety by this reference. 
     
    
     BACKGROUND 
       [0002]    Semiconductor wafers increase in cost and fragility as they move through the fabrication process. During and after the fabrication process wafers are shipped to other fabrication and assembly/test sites that are often located thousands of miles away. Historically semiconductor manufacturer&#39;s reused incoming prime wafer shipper containers to ship finished wafers to other sites because the cost of the shipper container was perceived to be free since it was included in the cost of the incoming silicon. Despite the perception that these incoming wafer shippers were free, the industry now understands that these containers are not designed for finished wafers and suffer yield loss (around 0.5%) plus a significant cost per wafer shipping penalty. 
         [0003]    A superior method of packing and shipping costly, fragile finished wafers is to use a coin stack format horizontal wafer container where wafers are stacked on top of each other with very clean conductive interleaves typically made from polyethylene film or ring separators typically molded from polypropylene separate each wafer. Suspension components—either injection molded forms or clean closed cell polyethylene foam cushions—are placed on each end of the stack to cushion the wafer from external shocks. Coin stack format wafer shippers have virtually eliminated wafer damage through the shipping process and reduced shipping costs by as much as 80%. 
         [0004]    Despite providing outstanding wafer protection and shipping cost reduction, existing coin stack format wafer containers have a significant shortcoming—they are designed primarily for manual handling. The opening and closing latches require manual dexterity of the human hand and are not compatible with automation. Once the operator removes the lid they place the container manually on a process tool. Before starting the process, the operator typically places the wafer suspension components in the container. Upon completion of the packing or unpacking process, the operator manually adds additional suspension components, replaces the lid and removes the container from the process tool. Also, existing ring separators have features that are not compatible with automated handling. In process, the wafer height is not consistent but instead is a function of the wafer thickness. With existing ring separators, the wafer surface sits below the ring edge, which prohibits direct pick and place transfer with vacuum end effectors technology. 
         [0005]    Lead edge wafer fabrication factories, however, are fully automated facilities that in many cases run “lights out” with no operators present. As process technologies continue to shrink the need for increased levels of automation and minimal operator intervention only increases and the next wafer size transition will make operator intervention in the process prohibitive. 
         [0006]    It is an object of the invention, therefore, to provide a new wafer container design and equipment interface that can function properly in a fully automated wafer fabrication environment without the need of operator intervention. 
         [0007]    It is also an object to provide a rugged latching mechanism that is easily opened and closed with automatic actuators. 
         [0008]    Another object of the invention is to provide a ring separator that provides full perimeter protection to the wafer and allows the wafer surface to be accessed by standard vacuum end effectors designs. 
         [0009]    Yet another object of the invention is to provide an improved wafer container lid design with robotic flange to interface with fabrication automation and integrated suspension components that do not require manual placement. 
         [0010]    Still another object of the invention is to provide an equipment interface that can accept the container from standard fabrication automation equipment, open, remove, and replace the container lid, and remove and replace the container contents automatically. 
         [0011]    Additional objects and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations pointed out in this specification. 
       SUMMARY OF THE INVENTION 
       [0012]    To achieve the foregoing objects, and in accordance with the purposes of the invention as embodied and broadly described in this document, there is provided an improved wafer container for use with automated equipment. The container includes a top lid adapted for engagement with a bottom base to form a housing having an inner cavity for storing at least one semiconductor wafer. The lid includes a handling member adapted to interface with automated equipment for placing the lid into engagement with the base and removing the lid from engagement with the base. The base includes a latch member and the lid includes a latch retainer portion adapted for receiving the latch member when the lid is in engagement with the base. When the lid is in engagement with the base and the latch member is received by the lid latch retainer portion, the latch member can be actuated between a locked position and an unlocked position by automated equipment. 
         [0013]    In one advantageous embodiment, the latch member includes a tab adapted to protrude through a latch hole disposed in the lid when the lid is engagement with the base. The tab can be rotated between the locked position and the unlocked position when it protrudes through the latch hole. The tab is disposed within a recess in the lid when the tab is in engagement with the base and the tab protrudes through the latch hole. The lid recess can be sized to allow movement of the latch between the locked position and the unlocked position by hand. The latch member includes a generally cylindrical body that is rotatable between the locked position and the unlocked position. 
         [0014]    According to other features of the invention, the housing inner cavity can be adapted for holding a plurality of wafer separator rings in a stacked configuration. Each of the one or more wafer separator rings can be adapted for placement on the base by automated equipment when the lid is not in engagement with the base. The lid handling member can include a flange adapted to interface with equipment for automatic removal and replacement of the lid. The base can include a latch enclosure and the latch member cylindrical body can be disposed within the latch enclosure with a bottom portion of the cylindrical body and can be accessible at the bottom of the base to automation equipment for rotating the latch between the closed position and the open position. A wafer suspension component can be removably secured to the inside top of the lid. 
         [0015]    In this configuration, the latch can securely hold the base and lid of the container together and can be automatically opened and closed by a keyed actuator or by hand via the tab from the top of the container. The tabs can be slightly recessed from the surface of the lid to prevent damage during shipment or inadvertent operation. The lid interface can include small projections that prevent the tabs from over-rotating and can hold them securely in the closed position. The cylindrical latch body can have flats opposite each other that act as cams to ensure that the latch stays closed during shipment. A latch retainer clip can secure the latch in place, yet allow for removal and replacement of the latch for maintenance or cleaning of the container. The latch retainer clip can include tabs with flat surfaces that fit tight against the latch body to hold it in the closed position and still allow it to rotate. 
         [0016]    The wafer container can include an improved lid with integrated suspension components and a top flange that is compatible with standard semiconductor automated handling equipment. The lid can have a plurality of small bosses or other retention features disposed around the perimeter of wafer containment walls, which can hold a suspension components (such as a molded compression rings or closed cell polyethylene cushions). The top of the lid can include a robotic flange that emulates the flange on the existing industry standard wafer shipping and process carriers and is compatible with existing wafer factory automation. The top flange can either be molded into the lid or replaceable. 
         [0017]    In another embodiment, a wafer container for use with automated equipment according to the invention includes a top lid adapted for engagement with a bottom base to form a housing having an inner cavity for storing at least one semiconductor wafer having a diameter. At least two wafer separator rings are disposed inside the inner cavity. Each of the separator rings includes an outer rim having an outer diameter that is larger than the semiconductor wafer diameter and at least one automation tab extending outwardly from the outer rim. 
         [0018]    According to other features of the invention, at least two of the wafer separator rings are configured so that when they are disposed inside the inner cavity in a stacked arrangement they define a pocket between the wafer separator rings for closely holding a peripheral portion of the semiconductor wafer. The stacked wafer separator rings have interlocking mating surfaces that are chamfered. The wafer separator ring automation tab defines a generally planar top surface that is offset below a top surface of the outer rim. The outer rim includes a recessed slot adjacent the automation tab top surface. The depth of the outer rim recessed slot is below the equator of a semiconductor wafer positioned in the wafer separator ring. The outer rim includes a projection opposing the recessed slot and that has dimensions that correspond with the depth and width of the recessed slot. 
         [0019]    The wafer container includes an improved wafer separator ring that provides complete perimeter protection for the wafer, an automation slot to expose the wafer surface and allow it to be handled using a vacuum end effectors, an automation tab to allow a full container of rings to be transferred from the container to a staging area, and standard wafer spacing regardless of wafer thickness. The outer perimeter of the ring will be greater than the wafer diameter and the wafer will sit in a recess to provide full perimeter protection. 
         [0020]    One embodiment of a wafer separator ring according to the present invention includes an outer rim having an upper portion that has a generally planar top surface and an outer diameter that is greater than the diameter of a semiconductor wafer. The outer rim also has an opposing lower portion having a bottom surface and an outer diameter that is greater than the top portion outer diameter. The ring has a first top inner shoulder disposed inward of the rim upper portion and recessed from the rim top surface, wherein the first top inner shoulder has an outer diameter that is slightly larger than the wafer diameter and has a perimeter shape that corresponds to the shape of the wafer perimeter. A second top inner shoulder is disposed inward of and recessed from the first top inner shoulder. A first bottom inner shoulder is disposed inward of the rim lower portion and recessed from the rim bottom surface, wherein the first bottom inner shoulder has an outer diameter that is slightly larger than the rim upper portion outer diameter. A second bottom inner shoulder is disposed inward of and recessed from the first bottom inward shoulder. The second bottom inner shoulder has a diameter that is slightly larger than the wafer diameter. The rim the lower portion has in inner diameter at the first bottom inner shoulder that corresponds to the perimeter. The second top recessed inner shoulder can define a generally planar vacuum pickup surface having sufficient width for engaging a vacuum cup of automated handling equipment. 
         [0021]    According to another features of the wafer separator ring, the first top inner shoulder can have a recess depth that is greater than half the thickness of the peripheral portion of the wafer. The second bottom inner shoulder has a recess depth that is less than half the thickness of the peripheral portion of the wafer. The sum of the first top inner shoulder recess depth and the second bottom inner shoulder recess depth is greater than the thickness of the peripheral portion of the wafer. 
         [0022]    An equipment interface for the wafer container can provide fully automated operation. The interface can include an automated drawer to accept the wafer carrier from standard factory automated equipment. The drawer can include guide pins to locate the container and keyed actuators to open and close the container latches. The interface can include an overhead cover lifting mechanism to grip the lid flange and remove or replace the lid from the container. The interface also can include an end effectors that can transfer wafer separators rings between the container and a staging area either individually or as a complete stack of a plurality of rings (e.g., twenty five rings). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate the presently preferred embodiments and methods of the invention and, together with the general description given above and the detailed description of the preferred embodiments and methods given below, serve to explain the principles of the invention. 
           [0024]      FIG. 1  shows a perspective exploded view of one embodiment of an automated wafer container according to the present invention, with a plurality of wafer rings disposed between the wafer container lid and base. 
           [0025]      FIG. 2  shows a perspective view of the automated latch in the base of the wafer container of  FIG. 1 , with the automated latch in the open position. 
           [0026]      FIG. 3  shows a top view of the automated latch of  FIG. 2  with the wafer container lid in place and with the automated latch in the locked position. 
           [0027]      FIG. 4  shows a section view of the automated latch of  FIG. 2  in a closed position with locking tabs engaged. 
           [0028]      FIG. 5  is a detailed bottom view of the automated latch of  FIG. 4 , showing the keyed interface of the automated latch at the bottom of base of the wafer container. 
           [0029]      FIG. 6  is a detailed perspective view of one embodiment of an automated latch actuator for use with the automated wafer container of  FIG. 1 , which shows a keyed interface protruding from an equipment wafer carrier interface plate. 
           [0030]      FIG. 7  is a detailed front cross-section view of a portion of the lid of the wafer container of  FIG. 1 , showing an integrated suspension component. 
           [0031]      FIG. 8  is a detailed bottom perspective view of the integrated suspension component retention feature built into the wafer container lid of  FIG. 7 . 
           [0032]      FIG. 9  shows a top perspective view of the automated wafer ring. 
           [0033]      FIG. 10  shows a top perspective detailed view of the ring automation tab with automation slot, recessed wafer pocket, and a second recessed vacuum pick up surface. 
           [0034]      FIG. 11  shows a bottom perspective detailed view of the ring automation tab with locking feature and recessed wafer pocket. 
           [0035]      FIG. 12  shows a section view of a two wafer ring stack with wafers. 
           [0036]      FIG. 13  shows a section view of a two wafer ring stack with wafers at the automation tab. 
           [0037]      FIG. 14  shows a perspective view of two wafer ring automation tabs stacked with the automation slot and bottom locking feature and a wafer in the top ring. 
           [0038]      FIG. 15  shows a perspective view of the equipment interface for the automated wafer carrier system with the automated lid removal system, wafer carrier base on automated sliding shelf and automated wafer ring in the ring handling system. 
           [0039]      FIG. 16  shows a perspective view of the ring handling end effectors with a full set of wafer separator rings. 
           [0040]      FIG. 17  shows a side view of the ring handling end effectors gripper with a full set of twenty five rings held by the ring automation tab. 
           [0041]      FIG. 18  shows a side view of the ring handling end effectors with the vacuum cups holding a single ring and the ring gripper arms retracted. 
       
    
    
     DETAILED DESCRIPTION 
       [0042]    Referring to the drawings, wherein like reference numbers are used herein to designate like elements throughout the various views, preferred embodiments of the present invention are illustrated and described. As will be understood by one of ordinary skill in the art, the figures are not necessarily drawn to scale, and in some instances the drawings have been exaggerated and/or simplified in places for illustrative purposes only. One of ordinary skill in the art will appreciate the many applications and variations of the present invention in light of the following description of the preferred embodiments of the present invention. The preferred embodiments discussed herein are illustrative examples of the present invention and do not limit the scope of the invention to the preferred embodiments described. 
         [0043]    Referring to  FIGS. 1 and 7 , a wafer container  10  according to the present invention includes a wafer container lid  100  and base  200 , which mate in a clam shell arrangement. The wafer container lid  100  and base  200  can house a plurality of semiconductor wafers  21  and ring separators  20 . As shown in  FIG. 1 , a plurality of semiconductor wafers  21  are disposed between the wafer container lid  100  and base  200 . The semiconductor wafers  21  are interleaved between the ring separators  20 . The wafer container base  200  includes a generally planar rectangular bottom section with wall structures  209  that extend perpendicular and in a circular orientation from the bottom section for rigidity. The wafer container lid  100  has a generally planar rectangular top section with an inner wail  106  (see  FIG. 7 ) that extends perpendicularly from the inside surface of the lid  100  in a circular orientation. The base inner walls  209  include an automation slot  204  to allow access to the plurality of wafers, to provide alignment of an automation tab  23  on each ring separator  20  and to prevent damage and shifting of the wafers during shipment and handling. A suspension component  201  can be placed at the bottom of the base inner walls  209  to support the plurality of wafers  21  and ring separators  20 . 
         [0044]    Referring to  FIGS. 1-3 , the base  200  includes a plurality of automated latch enclosures  206 , each of which encloses an automated latch  214  with a latch tab  203  projecting from the top of the latch enclosure  206 . When the lid  100  is placed on the base  200  (see  FIG. 3 ), the latch tab  203  protrudes through a latch slot  101  and into a latch lid recess  103  at the corners of the lid  100 . The latch tab  203  secures the lid  100  to the base  100  when the latch is turned 90 degrees, either by manually accessing the latch tab  203  in the latch lid recess  103  or by automatically turning the latch  214  with a keyed actuator through the base  200 . The lid  100  includes a top robotic flange  102  that provides a standard interface for automated equipment (such as equipment that complies with SEMI M13 or other applicable SEMI Standards) to transport the wafer container  10  through the factory and to automatically remove and replace the lid  100 . The robotic flange  102  can either be molded into the lid  100  or mechanically secured to the lid  100  in a way that can be removed for shipment. 
         [0045]      FIGS. 2 ,  3  and  4  show detailed views of the automated latch enclosure  206  with the automated latch tab  203  in the open position (see FIG. and closed position (see  FIG. 3 ).  FIG. 2  shows a perspective view of the automated latch enclosure  206  molded into the wafer carrier base  200  with the automated latch  214  positioned in the enclosure. The latch  214  includes a cylindrical body  211  with a reduced-diameter upper end  210  that is positioned and rotatable in a corresponding generally cylindrical hole in the top of the enclosure  206 .  FIG. 3  shows a perspective view of the automated latch  214  with the lid  100  in place and the latch tab  203  in a closed position. As the lid  100  is placed on the base  200  with the latch tab  203  in the open position, the latch tab  203  protrudes through the lid slot  101 . To secure the lid  100  in place, the latch  214  is rotated 90 degrees to the closed position shown in  FIG. 3 . The latch  214  can be manually actuated by rotating the latch tab  203  in the lid latch recess  103 . 
         [0046]    Referring to FIG,  4 , the latch  214  is positioned in the latch enclosure  206  with the latch tab  203  protruding from the top of the enclosure  206 . The enclosure  206  has generally cylindrical hole that accepts the latch body upper end  210  and which holds the latch body  211  in place laterally and allows it to rotate. Because the latch body  211  has a diameter that is larger than that of the latch body upper end, the latch  214  is secured from upward vertical movement. A latch retention clip  207  is pressed into the latch enclosure  206  to help secure the lower end of the latch body  211  in place and prevent its movement. The retention clip  207  includes locking centering arms  208  that press against the latch body  211 . The latch body  211  also has flat surfaces  213  on opposing sides that are located so that the latch is secured in the closed position (see  FIG. 3 ) when the arm terminations  208  are tangent to the flat surfaces  213 . The retention clips  207  have a generally cylindrical hole planar to the bottom of a wafer carrier base  300  (see  FIGS. 6 and 15 ), which hole accepts a latch body lower end  212 . The latch body lower end  212  has a reduced diameter portion that closely fits into a hole in the wafer container base  200  (see  FIG. 5 ). The latch  214  includes a keyed slot  204  that can connect to automated equipment actuators positioned below the wafer carrier base  200 . 
         [0047]      FIG. 5  shows a bottom view of the retention clip  207  hole planar to the wafer carrier base  200  with the latch body lower end  212  positioned in the cylindrical hole of the clip  207  and the keyed slot  204  that is access by automated equipment to open and close the latch  214  with a 90 degree rotary motion.  FIG. 6  shows the wafer carrier base plate  300  with an actuator  301  and key  304  that mates with the wafer carrier keyed slot  204  to automatically open and close the wafer carrier latch  214 . 
         [0048]    Referring to  FIGS. 7 and 8 , a suspension component  104  can be mounted inside the top surface of the wafer container lid  100 . A plurality of suspension component retention features  105  can be disbursed around the perimeter of the lid inner wall  106 . The shape and location of the retention component are not critical provided they hold the suspension component in the lid during transportation and processing. 
         [0049]    Referring to  FIGS. 9-13 , the wafer ring separator  20  has an outside diameter is larger than the diameter of a semiconductor wafer and a thickness that is thicker than the semiconductor wafer. A first top recessed portion or first top inner shoulder  26  is formed in the wafer separator  20  with a perimeter shape that corresponds to the shape of the semiconductor wafer. The ring separator  20  has two automation tabs  23  that protrude from the outside diameter and a second recessed portion  22  that forms a flat surface to allow the separator rings to be automatically handled. 
         [0050]      FIGS. 10 ,  11 , and  13  show detailed perspective and section views of the ring separator  20  at the automation tab  23 .  FIG. 12  shows a section view of the perimeter details of the ring separator  20  at a central ring portion adjacent to the automation tab. The ring separator  20  has a maximum diameter that is greater than the wafer diameter. The ring separator  20  includes an outer rim  42  with an upper portion  44  having a top surface  30  and a lower portion  46  having bottom surface  28 . The first top inner shoulder  26  is formed adjacent the rim upper portion  44  and has a perimeter shape that corresponds to the shape of the wafer  21  and is recessed from the rim top surface  30  by a depth that is less than the thickness of the wafer  21 . A second recess portion or second top inner shoulder  22  is formed adjacent the first top inner shoulder  26  at a depth that is greater than the maximum height of the top side wafer topology (i.e., MEMS structures, solder bumps, contact pads, etc.) and provides a planar surface that can be accessed by vacuum robotic handling equipment. The second top inner shoulder  22  terminates at an opening  40  in the center of the ring. A first bottom recessed portion or first bottom inner shoulder  48  is formed adjacent the rim lower portion  46 , and a second bottom recessed portion or second bottom inner shoulder  27  is formed adjacent the first bottom inner shoulder  48 . 
         [0051]    As shown in  FIG. 12 , the outer edge of the rim top surface  30  is sized and shaped to correspond with the inside perimeter of the bottom surface  28  so that when two of the separator rings  20   a,    20   b  are stacked together the rim top surface  30  of the bottom ring  20   b  and the first bottom inner shoulder  48  of the top ring  20   a  form a continuous interlocking mate around the perimeter of two stacked wafer rings  20 . The top outside and bottom inside interlocking surfaces can be chamfered with sufficient clearance to prevent sticking of two stacked rings  20   a ,  20   b.    
         [0052]    Referring to  FIGS. 10 ,  11 ,  13  and  14 , two opposing automation tabs  23  protrude outward from the perimeter of the ring outer rim  42  below the rim top surface  30 . A recessed slot  50  is formed in the rim upper portion  44  adjacent the tab  23 . The tab  23  has a generally planar top surface  24  that is co-planar with the bottom of the recessed slot  50  and is in a plane below the equator of a wafer pocket  29  formed by the first top inner shoulder  26  of the bottom stacked ring  20   b  and the second bottom inner shoulder  27  of the top stacked ring  20   a.  In this configuration, the recessed slot  50  forms an automation slot that allows automated vacuum wafer handling equipment to access the top surface of the wafer  21  even if the wafer&#39;s thickness is significantly reduced. The edge from the top surface to the automated tab can be chamfered or straight. The bottom ring surface  28  has an outside diameter than exceeds the outside diameter of the ring top surface  30 . The first bottom inner shoulder  48  has an outer diameter that corresponds with the outer diameter of the rim top surface  30 . The rim lower portion  44  also includes a downward projection  25  adjacent the automation tab  23  that corresponds with the recessed slot  50 . The second bottom inner shoulder  27  is formed with a perimeter shape that corresponds to the shape of the wafer and is recessed from the first bottom inner shoulder  48  by a depth that is less than the thickness of the wafer  21 . In this configuration, the wafer pocket  29  formed by the first top inner shoulder  26  of the bottom stacked ring  20   b  and the second bottom inner shoulder  27  of the top stacked ring  20   a  provides a continuous enclosure around the wafer perimeter and protection from wafer damage. 
         [0053]      FIG. 14  shows a perspective view of a two ring  20  stack at the automation tab  23 . The top surface of the wafer  21  is elevated above the ring top surface  30  and tab top surface  24  the bottom surface of the automation slot  50  are below the equator of the wafer allowing very thin wafers to be handled from the ring separator with vacuum pick up end effectors. 
         [0054]      FIG. 15  shows an automated equipment interface for handling the wafer container of according to the present invention. A complete wafer container  10  is automatically placed on the wafer carrier mounting plate  300  with automatic sliding drawer  303  extended from the equipment workspace. The drawer  303  and wafer container  10  retract into the equipment workspace, and the actuators  301  in the carrier mounting plate  300  access the carrier base keyed automation slots  204  to open the automated latches  203 . An automated lid removal tool  302  extends until a lid gripper  310  is positioned over the wafer container lid robotic flange  102 . The lid gripper  310  secures the lid flange  102  and retracts to a position above the wafer container base  200 . A ring separator robot secures a plurality of rings  20  from the wafer container base  200  using ring end effectors  305  with the latch arms extended (not shown). The latch arms of the ring end effectors  305  retract allowing the ring robot to individually transfer each ring separator  20  to the wafer container base  200 . A wafer  21  is placed on the wafer ring separator  20  by a wafer robot (not shown) to the right of the wafer carrier base  200 . When the wafer container base  200  is filled with a plurality of rings  20  and wafers  21 , the lid  100  is replaced, the latches  203  are secured and the drawer  303  extends out of the equipment workspace to initiate a new process. 
         [0055]    Referring to  FIGS. 16 and 17 , the ring end effectors  305  with extended pick up arms  307  securely hold a plurality of wafer rings  20  by the ring automation tabs  23  using tab gripper fingers  309 . The distance between the extended pick up arms  307  corresponds to the distance across the ring automation tabs  23 . An axle is firmly pressed into a hinge of the pick-up arm  307  and connects to an actuator, which controls the movement of the arms for opening, closing and gripping the ring automation tabs  23 . In the extended position, the pick up arms  307  are perpendicular to the end effectors body  305 . Narrow gripper fingers  309  are disposed at the tip of the arm  307 , opposite the end effectors frame  305 . The gripper fingers  309  correspond to the width of the automation tab  23  and are roughly with the end effectors body  305  and separator ring automation tabs  23 . In this manner, the end effectors  305  and design of the interlocking separator rings  20  allow a plurality of wafers to be transferred effectively within the equipment workspace. 
         [0056]      FIG. 18  shows a perspective view of the ring end effectors  305  with pick up arms  307  retracted within the end effectors frame. The end effectors  305  is holding a ring separator  20  using vacuum applied to a plurality of vacuum cups  308  disbursed uniformly around the end effectors frame  305  in positions that correspond with the flat vacuum pick up surface  22  of the ring separator  20 . 
         [0057]    Having read this disclosure, it will also be understood by those having skill in the art that modifications may be made to the invention without departing from its spirit and scope. Therefore, the invention in its broader aspects is not limited to the specific details, representative devices, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the general inventive concept.