Abstract:
A wafer handler for semiconductors or like substrates for significantly reduces alignment problems by reducing or eliminating sagging in large diameter wafers such as 300 mm wafers.

Description:
REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of, and incorporates herein by reference an entirety of, U.S. Provisional Application No. 60/397,356, filed Jul. 18, 2002. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Technical Field  
           [0003]    The present invention relates to handling of wafers.  
           [0004]    2. Background Information  
           [0005]    Over the past several decades, the microelectronics and semiconductor has exponentially grown in use and popularity. Microelectronics and semiconductors have in effect revolutionized society by introducing computers, electronic advances, and generally revolutionizing many previously difficult, expensive and/or time consuming mechanical processes into simplistic and quick electronic processes. This boom has been fueled by an insatiable desire by business and individuals for computers and electronics, and more particularly, faster, more advanced computers and electronics whether it be on an assembly line, on test equipment in a lab, on the personal computer at one&#39;s desk, or in the home via electronics and toys.  
           [0006]    The manufacturers of microelectronics and semiconductors have made vast improvements in end product quality, speed and performance as well as in manufacturing process quality, speed and performance. However, there continues to be demand for faster, more reliable and higher performing semiconductors.  
           [0007]    One process that has evolved over the past decade plus is the microelectronic and semiconductor inspection process. The merit in inspecting microelectronics and semiconductors throughout the manufacturing process is obvious in that bad wafers may be removed at the various steps rather than processed to completion only to find out a defect exists either by end inspection or by failure during use. In the beginning, wafers and like substrates were manually inspected such as by humans using microscopes. As the process has evolved, many different systems, devices, apparatus, and methods have been developed to automate this process such as the method developed by August. Technology Inc. of Bloomington, MN and disclosed in U.S. Pat. No. 6,324,298, the teachings of which are incorporated by reference. Many of these automated inspection systems, devices, apparatus, and methods focus on two dimensional inspection, that is inspection of wafers or substrates that are substantially or mostly planar in nature. Alternatively or in addition, automated wafer or substrate inspection systems provide three dimensional inspection, such as inspection of bumps or other three dimensional features.  
           [0008]    Regardless, to perform such inspection, it is necessary to handle the wafers to be inspected. To this end, accepted wafer processing techniques entail formation thereof on a film that is otherwise supported about it periphery by a circular ring (or “film frame”). A number of these film frames are loaded within a “cassette” for transport between processing and inspection stations. The cassettes themselves are uniquely designed for receiving film frames, forming a series of spaced slots that are otherwise sized to receive individual ones of the film frames. The number of slots (and thus the number of loaded film frames) may vary for a particular cassette design. Further, the slots oftentimes extend at a slight downward angle (or pitch) relative to a front opening of the cassette so as to prevent unexpected forward movement of a loaded film frame from the cassette slot. A conventional cassette slot pitch is on the order of 0.39 inch. In any event, cassette loading normally occurs at a handling station having an end effector configured to grip individual film frames at an edge thereof, normally in a cantilevered fashion in an attempt to account for the pitch of the cassette slot. Once engaged, the end effector maneuvers the film frame to an available cassette slot, and inserts the film frame within the slot. This process is reversed to remove a loaded film frame from a cassette.  
           [0009]    The above-described technique for loading/unloading film frame cassettes has been shown to be quite viable in the handling of many available film frames. By way of reference, conventional film frame (and thus wafer) diameters are 150 mm and 200 mm. More recently, however, wafers (and thus their associated film frames) have grown in diameter, such as up to the current standard of 300 mm, while remaining very thin in thickness. Handling of these larger diameter film frames, such as with the loading and/or unloading of cassettes, may be problematic with the known equipment described above. For example, the heavy wafer will often sag or bow in the middle when lifted at the edge of the film frame. Such sagging is undesirable and may lead to cassette loading/unloading problems and even wafer breakage. Further alignment complications, regardless of film frame diameter, may also arise due to the inconsistencies in cassette slot pitch, number of slots per cassette, etc.  
         SUMMARY OF INVENTION  
         [0010]    The handling of semiconductors or like substrates by the present invention significantly reduces alignment problems by reducing or eliminating sagging in large diameter wafers such as 300 mm wafers. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    Preferred embodiment of the invention, illustrative of the best mode in which applicant has contemplated applying the principles, are set forth in the following description and are shown in the drawings and are particularly and distinctly pointed out and set forth in the appended claims.  
         [0012]    [0012]FIG. 1 is a view of the present invention; and  
         [0013]    [0013]FIG. 2 is an enlarged view of a portion of the present invention. Similar numerals refer to similar parts throughout the drawings.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0014]    A handling system  10  in accordance with the present invention is best shown in FIG. 1. In accordance with one of the features of the invention, the handling system  10  includes a novel and unique Y-shaped frame support  12 .  
         [0015]    The handling system  10 , and in particular the frame support  12 , is adapted to handle and load/unload film frames  14  (one of which is shown in FIG. 1, it being noted that the film frame  14  does not include a formed wafer) to and from a cassette  16 . The cassette  16  is maintained by a load port  18  of the handling system  10  at a fixed position relative to the frame support  12 . To this end, the cassette  16  forms a plurality of slots  20  (referenced generally in FIG. 1) each sized to receive one cassette  16 . With this in mind, the handling system  10  is adapted to handle a variety of differently sized film frames, such as 150 mm, 200 mm and 300 mm film frames. As a point of reference, when a 300 mm film frame is gripped from its edge, the size and mass of the frame causes a slight sag in the film stretched in between the ring-shaped frame. Due to a variety of factors, it is difficult to anticipate the actual amount of sag from film frame to film frame, although it is known that the typical pitch of a film frame cassette is 0.39″.  
         [0016]    To help ensure proper placement of the film frames  14  into and out of the cassette  16 , the frame support  12  in accordance with one of the features of the present invention is used in conjunction with a robotic end effector  22  and elevator mechanism  24 . The end effector  22  can be of any type known in the art, and is adapted to grip the film frame  14  at an edge thereof, as provided with conventional film frame handling equipment. Preferably, the end effector  22  is mounted to the frame support  12 , but alternatively can positioned to engage the film frame  14  apart from the frame support  12 . Similarly, the elevator mechanism  24  can assume a variety of forms, and facilitates vertical movement of the frame support  12  and/or the end effector.  
         [0017]    To overcome the deficiencies of prior handling systems, including eliminating possible sagging of the film frame  14  (or the wafer (not shown) maintained thereon) and facilitating proper alignment of the film frame  14  relative to the cassette  16 , the Y-shaped frame support  12  is provided. The frame support  12  includes a substantially vertical base arm  30  and at least two support arms  32 ,  34  extending therefrom. As described in greater detail below, each of the support arms  32 ,  34  include adjustable feet  36  (referenced generally for the support arm  32  in FIG. 1) adapted to receive and support the film frame  14  and are adjustable to properly align with the film frame  14 .  
         [0018]    In one embodiment, the Y-shaped frame support  12  is linearly positioned using the elevator mechanism  24 , which can include a servo motor. As best shown in FIG. 2, each of the feet  36  includes at least one, preferably a series, of contact elements  40 . Where two or more contact elements  40  are provided for each of the support arms  32 ,  34 , the contact elements  40  are slightly spaced from one another and are positioned to support the film frame  14  and compensate for any horizontal misalignment of the film frame  14  when gripped by a gripper in the robot end effector  22 .  
         [0019]    The contact elements  40  are mounted to the respective support arm  32  or  34  so as to be horizontally moveable (relative to the orientation of FIGS. 1 and 2). For example, the contact elements  40  are secured to or about a shaft that is otherwise extendably connected to the respective support arm  32  or  34 . Alternatively, the contact elements  40  can be mounted to a support plate that is pivotally secured to the respective support arm  32  or  34 . Regardless of the exact mounting technique, a programmable drive mechanism (unnumbered in the Figures) is connected to the component otherwise supporting the contact elements  40  and dictates a desired horizontal position of the rollers  40  relative to the base arm  30  and/or the support arms  32 ,  34 . For example, a servo actuator can be provided that, upon activation, horizontally extends/retracts the contact elements  40  to the desired location that is otherwise dictated by a diameter of the film frame  14  being handled.  
         [0020]    With the above in mind, the frame support  12  can be programmed to accommodate different cassette pitches and frame counts. In effect, the contact elements  40  are horizontally adjustable to accommodate film frame width, while the entire assembly  12  is vertically adjustable to assure that the contact elements  40  properly align and provide a smooth transition as the film frame  14  is pulled from or pushed back into a slot  20  in the cassette  16 . Basically, the contact elements  40  provide a planar surface for the film frame  14  to roll out on to when the end effector  22  pulls the film frame  14  out of the cassette  16 . This eliminates sag as the film frame  14  is not solely gripped in a cantilever fashion as in the prior art and instead is both gripped by the end effector  22  at the front edge of the film frame  14  (cantilever fashion) as well as supported along its outer underneath by the contact elements  40 . This assures proper alignment during insertion of a film frame  14  into a slot  20  in the cassette  16 , thus reducing the risks of mis-feed into the wrong slot, cross feed where opposite sides of the film frame  14  are not in planar slots, or the worst result where a wafer is broken because of resistance.  
         [0021]    During use, a diameter of the film frame  14  is determined, and the handling system  10  is arranged to handle the film frame  14 . For example, where it is determined that the film frame  14  has a diameter of 300 mm, the handling system  10  is arranged such that the contact elements  40  are properly positioned to contact the outer, bottom edge of a 300 mm diameter film frame  14 . Arrangement of the contact elements  40  is preferably accomplished electronically, such as by programming of the actuator mechanism that otherwise dictates a horizontal position of the contact elements  40 . Alternatively or in addition, the handling system  10  can be configured such that the contact elements  40  are manually positioned. Regardless, when a differently sized film frame  14  (e.g., a 200 mm diameter film frame) is subsequently processed (in connection with a differently-sized cassette), the contact elements  40  are readily horizontally re-positioned to accommodate the diameter of the new film frame.  
         [0022]    In the embodiment shown in FIGS. 1 and 2, the contact elements  40  are rollers that are rotatably mounted to the respective support arms  32 ,  34 . Though not readily seen in the Figures, the rollers  40  are preferably spring-loaded, so as to facilitate compliance of the rollers  40  relative to slight constructional variations in different film fames  14 . Alternatively, the contact elements  40  can assume other forms that provide a relatively planar surface for support an underside of the film frame  14  at an outer periphery thereof. For example, the contact elements can be sliders, compliant material bodies, etc.  
         [0023]    Accordingly, the invention as described above and understood by one of skill in the art is simplified, provides an effective, safe, inexpensive, and efficient device, system and process which achieves all the enumerated objectives, provides for eliminating difficulties encountered with prior devices, systems and processes, and solves problems and obtains new results in the art.  
         [0024]    In the foregoing description, certain terms have been used for brevity, clearness and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirement of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed.  
         [0025]    Moreover, the invention&#39;s description and illustration is by way of example, and the invention&#39;s scope is not limited to the exact details shown or described.  
         [0026]    Having now described the features, discoveries and principles of the invention, the manner in which it is constructed and used, the characteristics of the construction, and the advantageous, new and useful results obtained; the new and useful structures, devices, elements, arrangements, parts and combinations, are set forth in the appended claims.