Patent Publication Number: US-2004052631-A1

Title: Mechanical arm device for carrying and detecting wafer

Description:
FIELD OF THE INVENTION  
       [0001] The present invention relates to mechanical arm device and more particularly to such a mechanical arm device carrying wafer for feeding into a wafer container for measuring a horizontal level and a height of wafer in a detection operation. After the detection operation, wafer is fetched out of the wafer container by the mechanical arm device.  
       BACKGROUND OF THE INVENTION  
       [0002] Electronic technologies have known a rapid and a spectacular development recently. Further, there is a trend of developing slim, compact electronic products for tailoring the needs of consumers. As such, manufacturing processes of integrated circuits (ICs) are critical to the quality of ICs. Conventionally, there are almost 100 processes such as diffusion, printing, etching, masking, and reading marker in manufacturing ICs from wafers. Typically, wafer container such as cassette, boat, POD, or FOUP capable of storing a plurality of wafers is used to transport wafers among wafer cassette stations (or sorters) of various interbays during the processes.  
       [0003] Conventionally, a rack is provided on walls in wafer container. A wafer is placed on one of a plurality of levels of rack. Horizontal level and height of plurality of wafers placed on the levels of rack must be highly correct for preventing a mechanical arm device from contacting, thus damaging wafer when an arm mechanism is extending into wafer container. Hence, operator must measure horizontal level of rack before using the wafer container in order to ensure that stored wafers have correct horizontal level.  
       [0004] Laser is typically used in measuring horizontal level and height of wafers in wafer container. In operation, laser head is extended into wafer container for measuring a horizontal level of several internal pivots which are responsible for supporting wafers. However, the prior art aims at a measuring of wafer container rather than wafers stored in wafer container. This means that a correct measuring of horizontal level of wafer container does not represent a correct measuring of horizontal level of wafer in wafer container. Thus improvement exists.  
       SUMMARY OF THE INVENTION  
       [0005] It is therefore an object of the present invention to provide a mechanical arm device for carrying and detecting wafer. In operation, the mechanical arm device carries wafer for feeding into a wafer container for measuring wafer by a sensor in a non-contact manner. The invention ensures a highly correct horizontal level and height measuring of wafer.  
       [0006] It is another object of the present invention to provide a mechanical arm device for carrying and detecting wafer. The invention aims at a measuring of horizontal level and height of wafer stored in wafer container. Hence, the measuring result is more correct and substantially represents the actual state of wafer stored in wafer container.  
       [0007] The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0008]FIG. 1 is an exploded perspective view of a mechanical arm device according to the invention;  
     [0009]FIG. 2 is a perspective view of a portion of the assembled mechanical arm device;  
     [0010]FIG. 3 is a schematic perspective view showing an operation of feeding a wafer into wafer container; and  
     [0011]FIG. 4 is view similar to FIG. 3 wherein a detection operation of wafer is made possible after wafer has been placed in wafer container.  
     [0012]FIG. 5 is the illustrative view of a plurality of forearm applied by this invention; and  
     [0013]FIG. 6 is the illustrative view of operation in application with another detection according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0014] Referring to FIGS. 1 and 2, there is shown a mechanical arm device constructed in accordance with the invention comprising a seat  10  and an arm mechanism  20  coupled to the seat  10  and including an elbow  21 , a forearm  22 , and a sensor  23 . Elbow  21  comprises several short elements  211  pivotably connected together. The operation of elbow  21  is controlled by signals transmitted from seat  10 . Forearm  22  is threadedly secured to one end of elbow  21 . Forearm  22  comprises a front fork  221  and a recess  222  in the front fork  221 . Sensor  23  is threadedly secured to a bottom of forearm  22  at a free end. Sensor  23  comprises a lever  231  extended from the recess  221  and a digital displacement sensor  232  (or laser sensor in the other embodiment) threadedly secured to a front bottom end of lever  231 . The digital displacement sensor  232  is electrically coupled to seat  10  through a cord  233  for signal transmission.  
     [0015] Referring to FIG. 3, the mechanical arm device of the invention is operative to carry a wafer  30  to feed into a wafer container  100 . Wafer  30  to be detected has a layer of metal film  31  plated or coated thereon. In the other embodiment, a layer of metal film  31  is adhered on the wafer  30  to be detected at a detection station. Such layer of metal film  31  is responsive to digital displacement sensor  232  in the detection operation. Eventually, wafer  30  is placed on a level of rack  101  in both walls of wafer container  100 .  
     [0016] Referring to FIG. 4, the detection operation (i.e., horizontal level and height measuring) of wafer  30  will now be described in detail. First, seat  10  is reset with respect to digital displacement sensor  232 . Then forearm  22  of arm mechanism  20  is operative to carry wafer  30 . A detection on wafer  30  is performed by arm mechanism  20  after wafer  30  has been placed on a level of rack  101  in wafer container  100 . It is possible of measuring several points of wafer  30  by the digital displacement sensor  232  in a non-contact manner since the digital displacement sensor  232  is located below the front fork  221 . This also ensures that digital displacement sensor  232  will not be damaged by scraping in carrying wafer  30  for detection. The advantage is that the mechanical arm device of the invention aims at a measuring of horizontal level and height of wafer stored in wafer container rather than that of wafer container. In comparison with prior art, the measuring result of the invention is more correct and substantially represents the actual state of wafer stored in wafer container.  
     [0017] Referring to FIG. 5, which is the illustrative view of a plurality of forearm applied by this invention, wherein the end of said elbow  21  is connecting a plurality of forearm  22  and the sensor  23  which could precede the operation of measure toward a plurality of water trays to elevate the integrated operation performance. Besides, as shown in FIG. 6, which is the apparatus that said sensor  23  is matching with the metallic-made wafer  30  (or there electroplates a layer of metal on the surface of wafer) and to adjust the level of the arm mechanism  20  and the gate seat  32  of the platform of the wafer loading/dislodging.  
     [0018] While the invention has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the invention set forth in the claims.