Abstract:
A cutting device for breaking fragile materials is constructed to include a lifting mechanism adapted to move the cutter vertically, a rotary table adapted to control the cutting angle of the cutter on the workpiece, a feed mechanism adapted to control the federate of the cutter, and a rotary mechanism adapted to rotate the cutter for enabling the cutter to cut the workpiece with one of multiple cutting points thereof selectively.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a cutting device for breaking fragile materials such as semiconductor wafers or the like and, more particularly, to such a cutting device, which uses lifting, rotary, and feed mechanisms to adjust the position and angle of the diamond cutter, enabling the diamond cutter to scribe and break the workpiece precisely. 
     2. Description of Related Art 
     In semiconductor foundries, wafer scribing and breaking apparatus are used to scribe and break 8″ or 12″ semiconductor wafers into individual dies. The cutting tips of cutters for use in wafer scribing and breaking apparatus are commonly made from diamond for the advantage of high hardness. Conventional wafer scribing and breaking apparatus commonly use a rotary mechanism and a feed mechanism to control the cutting position of the diamond cutter relative to the workpiece. This design can simply achieve a coarse manipulation, i.e., the distance between the cutter and the workpiece cannot be precisely controlled, affecting the precision of the scribing of the cutter on the workpiece. 
     Further, during cutting working of the diamond cutter according to conventional methods, one specific crystal phase position of the diamond cutter is used as the cutting point. This cutting point wears quickly with use. When the cutting point worn out, the diamond cutter becomes useless and must be replaced. When a new diamond cutter installed, the alignment of the newly installed diamond cutter must be calibrated again. It takes time to calibrate the alignment of the loaded diamond cutter. Additionally, it is very hard to manually adjust the angle of the specific crystal phase point of the newly installed diamond cutter to a precise position corresponding to the workpiece. 
     Therefore, it is desirable to provide a cutting device for breaking fragile materials that eliminates the aforesaid drawbacks. 
     SUMMARY OF THE INVENTION 
     It is one object of the present invention to provide a cutting device for breaking fragile materials, which uses lifting, rotary, and feed mechanisms to adjust the position and angle of the diamond cutter, enabling the diamond cutter to scribe the workpiece precisely. 
     It is another object of the present invention to provide a cutting device for breaking fragile materials, which uses a feed mechanism to control the federate of the diamond cutter relative to the fragile workpiece. 
     It is still another object of the present invention to provide a cutting device for breaking fragile materials, which uses a rotary mechanism to adjust the angle of the diamond cutter, enabling the diamond cutter to scribe the fragile workpiece with one of multiple cutting points thereof. 
     To achieve these and other objects of the present invention, the cutting device for breaking fragile materials is comprised of a base frame, a lifting mechanism, a rotary table, a cutter holder, and a cutter module. The base frame is installed in a worktable of a wafer scribing and breaking apparatus, having a front mounting face. The lifting mechanism comprises a base block fixedly mounted on the mounting face of the base frame, and a lifting block coupled to the base block for vertical movement on the base block. The rotary table comprises a fixed member fixedly mounted on the lifting block of the lifting mechanism, and a rotary member supported on the fixed member for rotation relative to the fixed member. The rotary member has a front face. The cutter holder is installed in the front face of the rotary member, having a through hole. The through hole has a center axis in parallel to the front face of the rotary member. The cutter module is installed in the through hole of the cutter holder and holding a diamond cutter, comprising a rotary mechanism adapted to rotate the diamond cutter around the center axis of the through hole and a feed mechanism adapted to move the diamond cutter axially along the center axis of the through hole. 
     By means of the linear or rotary motion of the lifting mechanism, the rotary table and the feed mechanism of the cutter module, the position of the diamond cutter can be precisely adjusted, i.e., the diamond cutter can be shifted vertically through a coarse manipulation of the lifting mechanism, and then rotated to the desired cutting angle on the workpiece, for example, a semiconductor wafer, and then linearly adjusted through a fine micromanipulation of the feed mechanism of the cutter module. Therefore, the relative angle and distance between the diamond cutter and the semiconductor wafer can be adjusted, causing the diamond cutter to scribe the semiconductor wafer precisely. 
     Furthermore, when the diamond cutter started to wear after long uses, the rotary mechanism is controlled to rotate the diamond cutter through an angle (for example, 90°), enabling the diamond cutter to cut the workpiece with another crystal phase cutting point. Therefore, the diamond cutter can be rotated to different angular positions to cut the workpiece with different crystal phase cutting points, preventing the occurrence of a precision problem due to a replacement of the diamond cutter. 
     Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a cutting device installed in a wafer scribing and breaking apparatus according to the present invention. 
     FIG. 2 is an exploded view of the cutting device according to the present invention. 
     FIG. 3 is an exploded view of the lifting mechanism for the cutting device according to the present invention. 
     FIG. 4 is an assembly view of the cutter module for the cutting device according to the present invention. 
     FIG. 5 is a sectional view of the cutter module for the cutting device according to the present invention. 
     FIG. 6 is a schematic drawing showing the cutter module rotated relative to the semiconductor wafer according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to FIG. 1, a cutting device  1  is installed in the worktable  91  of a wafer scribing and breaking apparatus  9 , and controlled to scribe a semiconductor wafer  92 . 
     With reference to FIG. 2, the aforesaid fragile material cutting mechanism is comprised of a base frame  2 , a lifting mechanism  3 , a rotary table  4 , a cutter holder  5 , and a cutter module  6 . The base frame  2  is installed in the worktable  91  of the wafer scribing and breaking apparatus  9  (see FIG.  1 ), having a front mounting face  21  at the front side. The lifting mechanism  3  is comprised of a base block  32  located on the mounting face  21  of the base frame  2 , and a lifting block  31  coupled to the base block  32  for vertical movement on the base block  32 . 
     Referring to FIG. 3, the lifting mechanism  3  further comprises a screw rod  35  fastened pivotally with the base block  32 , a nut  36  threaded onto the screw rod  35 , a connecting block  360  connected between the lifting block  31  and the nut  36 , and a power drive  37  adapted to drive the screw rod  35  in the base block  32 . When driving the screw rod  35 , the lifting block  31  is driven to move with the nut  36  upwards or downwards along the screw rod  35 . The screw rod  35  preferably has a relatively greater screw pitch to provide a relatively greater vertical moving distance during lifting/lowering of the lifting mechanism  3 . 
     According to this embodiment, the power drive  37  of the lifting mechanism  3  is a motor  371 . Alternatively, a hydraulic cylinder or air cylinder may be used for the power drive  37 . Further, a pair of first sliding rails  34  are vertically arranged in parallel on the base block  32 , and a pair of second sliding rails  33  are vertically arranged in parallel on the lifting block  31  and respectively coupled to the first sliding rails  34  to guide vertical movement of the lifting block  31  along the first sliding rails  34 . 
     Referring to FIG. 2 again, a coupling plate  8  is fastened to the lifting block  31  to hold the rotary table  4  on the lifting block  31 . The rotary table  4  is comprised of a fixed member  42  and a rotary member  41 . The rotary member  41  can be rotated on the fixed member  42  by a motor. The coupling plate  8  is connected between the lifting block  31  and the fixed member  42 , for enabling the rotary table  4  to be moved vertically up and down with the lifting block  31 . The coupling plate  8  has optics sensors  81 ,  82 ,  83  for detection of angle of rotation of the rotary member  41 . The coupling plate  8  is not requisite, i.e., the fixed member  42  can directly be fastened to the lifting block  31 . 
     The rotary member  41  has a front face  410 , and a raised alignment portion  411  for supporting the bottom edge  53  of the cutter holder  5  during installation of the cutter holder  5 . 
     Referring to FIGS. 4 and 5, the cutter holders has a through hole  51 . The central axis  510  of the through hole  51  is disposed in parallel to the front face  410  of the rotary member  41 . The cutter module  6  is mounted in the through hole  51  of the cutter holder  5  to hold a diamond cutter  7 , comprising a rotary mechanism  61  and a feed mechanism  62 . The feed mechanism  62  comprises a hollow column  63 , a coil  621 , and a permanent magnet  622 . The hollow column  63  is axially movably mounted in the through hole  51  of the cutter holder  5 . The cutter holder  5  has an axially endless groove  511  concentrically extended around the through hole  51 . The permanent magnet  622  is mounted within the endless groove  511 . The hollow column  63  has an axially concentric flange  630  holding the coil  621  and insertable with the coil  621  into the endless groove  511  and relative to the permanent magnet  622 . Further, the cutter holder  5  has an extension  52  extended in axial direction at one side of the through hole  51 , and a sliding track  521  located on the extension  52  in parallel to the center axis  510  of the through hole  51 . The cutter module  6  comprises a sliding block  631  fixedly fastened to the hollow column  63  and coupled to the sliding track  521 , and a return spring  623  connected between the sliding block  631  and the extension  52  of the cutter holder  5 . When the coil  621  is electrically connected, controlling the amount of current controls the movement of the feed mechanism  62  along the sliding track  521 , and therefore the diamond cutter  7  can be moved axially along the center axis  510  of the through hole  51 . When the coil  621  is electrically disconnected, the return spring  623  imparts an upward recover force to the cutter module  6 , preventing damage to the diamond cutter  7 . 
     By means of the linear or rotary motion of the lifting mechanism  3 , the rotary table  4  and the feed mechanism  62  of the cutter module  6 , the position of the diamond cutter  7  can be precisely adjusted, i.e., the diamond cutter  7  can be shifted vertically through a coarse manipulation of the lifting mechanism  3 , and then rotated to the desired cutting angle θ 2  on the workpiece, for example, a semiconductor wafer  92  (see FIG. 6) by using the rotary table  4  and then linearly adjusted through a fine micromanipulation of the feed mechanism  62  of the cutter module  6 . Therefore, the relative angle and distance between the diamond cutter  7  and the semiconductor wafer  92  can be adjusted, causing the diamond cutter  7  to scribe the semiconductor wafer  92  precisely. According to the present preferred embodiment, regulating the amount of electric current to the coil  621  controls the feedrate of the feed mechanism  62 . Therefore, the feed mechanism  62  can be used to control the amount of force applied to the semiconductor wafer  92  when operating the diamond cutter  7  to scribe the semiconductor wafer  92 . 
     Furthermore, the rotary mechanism  61  of the aforesaid cutter module  6  is mounted in the inside space of the hollow column  63 . The rotary mechanism  61  comprises a rotary chuck  612  holding the diamond cutter  7 , a motor  611 , a coupling  613  coupled between the rotary chuck  612  and the motor  611  for enabling the motor  611  to rotate the rotary chuck  612  and the diamond cutter  7  around the center axis  510  of the through hole  51 , and an encoder  614  adapted to detect the angle of rotation of the motor  611 . The motor  611  is carried on a mount  64 , which is installed in the hollow column  63 . Therefore, the diamond cutter  7  can be rotated with the rotary chuck  612 , and moved axially up and down with the motor  611  and the hollow column  63 . 
     When the diamond cutter  7  begins to wear after long uses use for example, when the cutting point B is worn out (see FIG.  6 ), the DC servo motor  611  of the rotary mechanism  61  is numerically controlled with the monitoring of a CCD device  901  electrically connected to a monitor  902  (see FIG. 1) to rotate the diamond cutter  7  through an angle θ 1  (for example, 90°) or other predetermined angle precisely, enabling the diamond cutter  7  rotated to a precise angle to cut the workpiece with different crystal phase cutting points (for example, cutting point C, D, or A). Therefore, the diamond cutter  7  can be used repeatedly, preventing the occurrence of a precision problem due to a replacement of the diamond cutter. Further, the diamond cutter  7  can have its angle easily adjusted to a precise position with numeric control, preventing the precision problem caused by conventional manual adjustment. 
     When the diamond cutter  7  begins to wear after long uses use for example, when the cutting point B is worn out (see FIG.  6 ), the DC servo motor  611  of the rotary mechanism  61  is numerically controlled with the monitoring of a CCD device  901  electrically connected to a monitor  902  (see FIG. 1) to rotate the diamond cutter  7  through an angle θ 1  (for example, 90°) or other predetermined angle precisely, enabling the diamond cutter  7  rotated to a precise angle to cut the workpiece with different crystal phase cutting points (for example, cutting point C, D, or A). Therefore, the diamond cutter  7  can be used repeatedly, preventing the occurrence of a precision problem due to a replacement of the diamond cutter. Further, the diamond cutter  7  can have its angle easily adjusted to a precise position with numeric control, preventing the precision problem caused by conventional manual adjustment. 
     Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.