Abstract:
A wet bench system comprising a plurality of sequentially aligned containers. A first rail positioned generally horizontally adjacent a first side of the container and a first arm having a first end moveable on the first rail. A second rail positioned generally horizontally and adjacent a second side of the container and having a second arm having a first end moveable on the second rail. The arms being capable of moving articles to be treated by chemicals in containers by movement in a back and forth leap frog fashion.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority from U.S. Provisional Application No. 61/319,824 filed Mar. 31, 2010, which is hereby incorporated by reference. 
     
    
     FIELD 
       [0002]    This application relates to a wet bench apparatus and method for treating articles by immersion in various tanks containing liquids. In particular, this application relates to a wet bench for treating articles such as silicon wafers and gravel. 
       BACKGROUND 
       [0003]    A wet bench apparatus is used to treat articles typically placing the articles into a series or sequence of tanks containing different chemical compositions. In particular, the wet bench assembly may consist of multiple tanks. In a chemical etching procedure, an article may be dipped in the first tank containing an acidic chemical, and then moved to a subsequent tank containing water to rinse the acidic chemical, in may then be moved to an area for air drying and/or vacuum drying. To move the articles, an over-head crane or gantry is used which has hooks to pick up cassettes or mesh cages containing the articles being treated, for example wafers and/or silicon gravel. In particular, the wafers may be silicon wafers for, for example photovoltaic (PV) applications. 
         [0004]    Known wet bench systems are typically only well suited for operation in a sequential fashion where articles advance along consecutive baths in order. For example, a single over-head crane can move cassettes or mesh cages containing the articles sequentially from a first tank to a second tank and then to a drying station. However, where spatial constraints are imposed and/or the articles have to be moved for example from the first bath to the second bath, and then back to the first bath, known wet bench systems are not advantageous. 
         [0005]    Other methods in the past use either a return route external to the bench, or require the main gantry to be used for the return. 
         [0006]    As such, there is need for an improved system and apparatus for and method of operating a wet bench. 
       SUMMARY 
       [0007]    This application is directed to a wet bench apparatus which can provide for continuous rack and pinion motion with multiple robots mounted on a single linear axis to work in a wet bench with overlapping work areas. 
         [0008]    This application also provides for leap frog motion whereby the platform uses two linear motion rails along the length of the wet bench on opposite sides of the tanks from each other. This arrangement can allow robots to move past one another within the wet bench and can reduce cycle time and can also prevent a potentially acid-contaminated part from being removed from the safety of a fume and drip containment of the wet bench for return to the beginning. 
         [0009]    In one aspect, a wet bench apparatus is provided, comprising: a first arm movable in a horizontal direction of a container; and a second arm movable in the horizontal direction. 
         [0010]    In a preferred case, the first and second arms are positioned on a same side of the container. 
         [0011]    In a preferred case, the first arm and the second arm are positioned on opposite sides of the container. 
         [0012]    In a preferred case, the first arm and second arms are movable in a vertical direction. 
         [0013]    In a preferred case, the first arm is adapted to move at least one first item, and the second arm is adapted to move at least one second item, the first item and the second item being movable into and out of a plurality of treatment containers and the first arm and the at least one first item are positionable in a user specified orientation to move without contacting the second arm and the at least one second item. 
         [0014]    In a preferred case, the first arm is connected to a first robot and the second arm is connected to a second robot, the first robot being movable on a first track, the second robot being movable on a second track. 
         [0015]    In a preferred case, the first robot has a first cam follower system comprising at least one cam roller positioned between a first guide bar and a second guide bar, and the second robot has a second cam follower system comprising at least one cam roller positioned between a first guide bar and a second guide bar. 
         [0016]    In a preferred case, the first robot has a first cam follower system comprising a first cam roller positioned on one side of a guide bar and a second cam roller positioned on an opposite side of the guide bar, and the second robot has a second cam follower system comprising a first cam roller positioned on one side of a guide bar and a second cam roller positioned on an opposite side of the guide bar. 
         [0017]    In a preferred case, the first and second robots, the first and second arms, and the first and second tracks are made of corrosion resistant material. 
         [0018]    In another aspect, a wet bench system is provided, comprising: a first container; a first rail positioned generally horizontally adjacent a first side of the container, a first arm having a first robot moveable on the first rail; and a second rail positioned generally horizontally adjacent a second side of the container, a second arm having a second robot moveable on the second rail. 
         [0019]    In a preferred case, the first and second arms are also movable in a vertical direction. 
         [0020]    In a preferred case, the first arm has a first end effector connected to a second end of the first arm opposite to the first end, and the second arm has a second end effector connected to a second end of the second arm opposite to the first end. 
         [0021]    In a preferred case, a second container is positioned proximate to the first container in the horizontal direction and wherein the first arm is operable to move at least one first item and the second arm is operable to move at least one second item from the first container to the second container, the first arm and the at least one first item are positionable in a user specified orientation to move without contacting the second arm and at least one second item. 
         [0022]    In a preferred case, the first robot has a first cam follower system comprising at least one cam roller positioned between a first guide bar and a second guide bar, and the second robot has a second cam follower system comprising at least one cam roller positioned between a first guide bar and a second guide bars. 
         [0023]    In a preferred case, the first robot has a first cam follower system comprising a first cam roller positioned on one side of a guide bar and a second cam roller positioned on an opposite side of the guide bar, and the second robot has a second cam follower system comprising a first cam roller positioned on one side of a guide bar and a second cam roller positioned on an opposite side of the guide bar. 
         [0024]    In a preferred case, the first and second robots, the first and second arms, and the first and second tracks are made of corrosion resistant material. 
         [0025]    Other aspects and features will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments in conjunction with the accompanying figures. 
     
    
     
       BRIEF DESCRIPTION OF FIGURES 
         [0026]    For a better understanding of the embodiments described herein and to show more clearly how they may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings which show the exemplary embodiments and in which: 
           [0027]      FIG. 1  shows an end view of a “leap frog” robot arm system with one arm shown raised to clear second arm; 
           [0028]      FIG. 2  shows a cam follower system having a double guide bar arrangement; 
           [0029]      FIG. 3  shows a cam follower system having a single guide bar arrangement; 
           [0030]      FIG. 4  shows a system with multiple robots on the same linear axis; and 
           [0031]      FIG. 5  shows multiple cable tracks for other robots. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    It will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements or steps. In addition, numerous specific details are set forth in order to provide a thorough understanding of the exemplary embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. Furthermore, this description is not to be considered as limiting the scope of the embodiments described herein in any way, but rather as merely describing the implementation of the various embodiments described herein. 
         [0033]      FIG. 1  shows an end view of a “leap frog” robot arm system  2  with a first arm  4  vertically raised to clear second arm  6 . As shown, the system  2  uses a first robot  8  positioned on one side of the process tank, and a second robot  10  positioned on an opposite side of the process tank, to move respective arms  4  and  6 . As shown, the first arm  4  has a first end effector  12  positioned thereon. The second arm  6  has a second end effector  14  positioned thereon. 
         [0034]    The first end effector  12  is shown lifting a first product  16 . The second end effector is shown lifting a second product  18 . Preferably, the first product  16  and the second product  18  are silicon wafers or gravel. As shown, the first arm  4  and product  16  are lifted vertically so as to clear the second arm  6 , when the respective first and second arms  4 ,  6  are moved in a horizontal direction in or out of the page. 
         [0035]    Also shown in  FIG. 1  is a process tank  20  which can contain chemicals into which the first product  16  and/or second product  18  can be placed for processing the product. 
         [0036]    Each of the first and second robots,  8  and  10 , preferably has two servo-controlled axis: (a) a Z-axis that is long enough to place the product in the process tanks and to pass over the second robot while carrying product; and (b) an X-axis that runs a length of the wet bench system. 
         [0037]    The first and second robot arms,  4  and  6 , can be made of coated stainless steel, such as Teflon™ coated stainless steel. The linear motion rails and the rack and pinion system can be coated with a black chrome coating impregnated with Teflon™, such as Raydent™. These components may then be coated with a Teflon™ based grease such as DuPont Krytox™ to increase corrosion protection. Preferably, the motors on the robots are chemical duty motors with air purge. 
         [0038]    The system  2  having the first robot arm  4  and second robot arm  6  which can be vertically off-set from each other is advantageous in enabling moving items from bath tank to bath tank without requiring handing off from one robot arm to another. Further, the vertically off-set robot arms,  4  and  6 , advantageously increase throughput of the process and avoid time consuming steps such as handing off or the need for a staging area to set one cage down and pick another up. 
         [0039]      FIG. 2  shows a cam follower system having a single rack as the motion backbone for multiple robots. The cam follower system of  FIG. 2  has a double guide bar arrangement whereby a set of cam rollers  30  run between a first guide bar  32  and a second guide bar  34 . Preferably, the guide bar arrangement is made of corrosion resistant or coated material. An upper rail (not shown) supports the robot, and the cam rollers  30  are provided to resist moment. Preferably, at least three rollers are provided in the set of cam rollers  30 . The double guide bar arrangement protects the rollers  30  from drips. 
         [0040]      FIG. 3  shows a cam follower system having a single bar arrangement. As shown, a single bar  38  is provided with a first roller set  40  on one side of the bar  38 , and a second roller set  42  on an opposite side of the bar  38 . A robot  44  is attached to an upper rail (not shown) and the first roller set  40  and the second roller set  42  are provided to resist moment. Preferably, the linear guide system for the lower portion of the linear axis is low-cost and easily replaceable. 
         [0041]    To resist corrosion, the components of the cam follower system shown in  FIGS. 2 and 3  can be coated with a corrosion resistant coating. For example, the corrosion resistant coating may be Raydent™, Armalloy™, or NiCoTef™. Preferably, the robots  36  and  44  carry their own pinion and drive motor. Each robot  36  and  44  can pull a cable chain to supply it with compressed air, communications, and electricity, as desired. 
         [0042]    In the arrangements shown in  FIGS. 2 and 3 , a moment from the long arm of the robot is resisted by the cam follower system. Preferably, the cam follower systems are a simple linear track mounted near the base of the wall. As these parts are generally positioned closer to a treatment bath tank, they may be deteriorated by fumes from the bath, and therefore are preferably made inexpensive and easy to replace. 
         [0043]    Also, the segmented rack and rail design allows for very long travel. The system shown can have a rail length of approximately 22,000 mm, or just over 72 feet. 
         [0044]      FIG. 4  shows a system  50  with multiple robots on the same linear axis. The robot system  50  has a first robot  52 , a second robot  54 , and a third robot  56 . A respective cable track  58 ,  60 , and  62  is run for each of the respective first robot  52 , second robot  54 , and third robot  56  in the system  50 . 
         [0045]      FIG. 5  shows the middle robot  54  of  FIG. 4 , as well as multiple cable tracks for other robots. 
         [0046]    Although this disclosure has described and illustrated certain embodiments, it is also to be understood that the system, apparatus and method described is not restricted to these particular embodiments. Rather, it is understood that all embodiments which are functional or mechanical equivalents of the specific embodiments and features that have been described and illustrated herein are included. 
         [0047]    It will be understood that, although various features have been described with respect to one or another of the embodiments, the various features and embodiments may be combined or used in conjunction with other features and embodiments as described and illustrated herein.