Abstract:
A sawing method for a Micro Electro-Mechanical Systems (MEMS) semiconductor device, wherein a gum material is disposed between a wafer having at least one MEMS and a carrier, and the gum material is disposed around the MEMS. The wafer is sawed according to the position correspondingly above the gum material. Finally, the carrier and the gum material are removed. By disposing the gum material between the carrier and the wafer, the MEMS are protected, and the wafer and the MEMS can avoid the pollution of water and foreign material, so that the yield can be improved. Furthermore, the wafer is sawed from the backside till the gum material without sawing through the gum material, so that the carrier is not sawed. Therefore, the carrier can be reused, such that the cost is reduced.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a sawing method for a semiconductor device. More particularly, the present invention relates to a sawing method for a MEMS semiconductor device. 
   2. Description of the Related Art 
   Referring to  FIGS. 1A to 1B , schematic views of a conventional sawing method for a MEMS semiconductor device are shown. Referring to  FIG. 1A , firstly, a wafer  11  having at least one MEMS structure  12  is provided. Referring to  FIG. 1B , the wafer  11  is sawed on a periphery of the MEMS  12  according to a plurality of sawing lines (as shown by dashed lines) on the wafer  11 , so as to form a MEMS semiconductor device  1 . 
   In the conventional sawing method for the MEMS semiconductor device, the wafer  11  is sawed directly according to the sawing lines on the wafer  11 . Therefore, during the sawing process, it is impossible to protect the MEMS structure  12  from being damaged, and the wafer  11  and the MEMS structure  12  may be polluted by water or foreign material, thereby reducing the yield of the process. 
   Consequently, there is an existing need for providing a sawing method for the MEMS semiconductor device to solve the above-mentioned problems. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a sawing method for a MEMS semiconductor device, which includes: (a) providing a first carrier; (b) providing a wafer having a plurality of MEMS structures; (c) disposing a gum material between the first carrier and the wafer, in which the gum material is disposed around the MEMS structures and corresponding to a plurality of predetermined sawing lines; (d) sawing the wafer according to the predetermined sawing lines; and (e) removing the first carrier and the gum material. 
   In the sawing method for the MEMS semiconductor device of the present invention, the gum material is disposed between the first carrier and the wafer, so as to protect the MEMS structure from being damaged during the sawing process, and to protect the wafer and MEMS structure from being polluted by the water or the foreign material, thereby improving the yield of the process. Further, in the present invention, the wafer is sawed from a backside till the gum material without sawing through the gum material, so the first carrier can be reused, such that the production cost is reduced. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is a schematic view of a conventional MEMS semiconductor wafer; 
       FIG. 1B  is a schematic view of conventionally sawing the MEMS semiconductor wafer; 
       FIG. 2  is a schematic view of disposing a gum material on a first carrier according to a first embodiment of the present invention; 
       FIG. 3A  is a schematic view of disposing a MEMS semiconductor wafer on the gum material according to the first embodiment of the present invention; 
       FIG. 3B  is a schematic view of disposing the gum material in slot channels of the first carrier according to the first embodiment of the present invention; 
       FIG. 3C  is a schematic view of disposing the gum material on protruding portions of the first carrier according to the first embodiment of the present invention; 
       FIG. 3D  is a schematic view of disposing the gum material in recesses of the wafer according to the first embodiment of the present invention; 
       FIG. 3E  is a schematic view of firstly disposing the gum material on the protruding portions of the first carrier and then combining the wafer and the first carrier according to the first embodiment of the present invention; 
       FIG. 3F  is a schematic view of firstly disposing the gum material in the recesses of the wafer and then combining the wafer and the first carrier according to the first embodiment of the present invention; 
       FIG. 4A  is a schematic view of sawing the wafer according to the first embodiment of the present invention; 
       FIG. 4B  is a schematic view of another aspect of sawing the wafer according to the first embodiment of the present invention; 
       FIG. 5  is a schematic view of the wafer finishing sawing according to the first embodiment of the present invention; 
       FIG. 6  is a schematic view of disposing the gum material on a first carrier according to a second embodiment of the present invention; 
       FIG. 7A  is a schematic view of disposing a MEMS semiconductor wafer on the gum material according to the second embodiment of the present invention; 
       FIG. 7B  is a schematic view of disposing the gum material in the slot channels of the first carrier according to the second embodiment of the present invention; 
       FIG. 7C  is a schematic view of disposing the gum material on the protruding portions of the first carrier according to the second embodiment of the present invention; 
       FIG. 7D  is a schematic view of disposing the gum material in the recesses of the wafer according to the second embodiment of the present invention; 
       FIG. 7E  is a schematic view of firstly disposing the gum material on the protruding portions of the first carrier and then combining the wafer and the first carrier according to the second embodiment of the present invention; 
       FIG. 7F  is a schematic view of firstly disposing the gum material in the recesses of the wafer and then combining the wafer and the first carrier according to the second embodiment of the present invention; 
       FIG. 8  is a schematic view of disposing a protection thin film on the MEMS semiconductor wafer according to the second embodiment of the present invention; 
       FIG. 9A  is a schematic view of sawing the wafer according to the second embodiment of the present invention; 
       FIG. 9B  is a schematic view of another aspect of sawing the wafer according to the second embodiment of the present invention; 
       FIG. 10  is a schematic view of disposing a second carrier on the protection thin film according to the second embodiment of the present invention; and 
       FIG. 11  is a schematic view of removing the first carrier and the gum material according to the second embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 2 to 5  are schematic views of a sawing method for a MEMS semiconductor device according to a first embodiment of the present invention. Referring to  FIG. 2 , firstly, a first carrier  21  is provided. Preferably, the first carrier  21  is of silicon, glass, or sapphire material. Next, a gum material  22  is disposed on a surface  211  of the first carrier  21 . In this embodiment, the gum material  22  is an adhesive material. It should be noted that the gum material  22  could also be a light sensitive material (capable of being removed after being irradiated by a light source) or a heat sensitive material (capable of being removed after being heated by a heat source). 
   Referring to  FIG. 3A , a wafer  23  is disposed on the gum material  22 , and the wafer  23  has a plurality of MEMS structures  231  (only one MEMS structure  231  is used as a representative of illustration). The gum material  22  is disposed between the first carrier  21  and the wafer  23 , and the gum material  22  is disposed around the MEMS structure  231  and corresponding to a plurality of predetermined sawing lines (as shown by dashed lines). It should be noted that in the present invention, the gum material  22  may be firstly disposed on the surface of the wafer  23 , and then the first carrier  21  is further disposed on the gum material  22 . In this embodiment, the MEMS structure  231  is an optical device. In other applications, the MEMS structure  231  can be a micro-motion structure, or the MEMS structure  231  may be a light sensor region. 
   Referring to  FIG. 3B , in other applications, the surface  211  of the first carrier  21  has a plurality of slot channels  212 , and each slot channel  212  is defined by two protruding portions  213  on the surface  211 . Preferably, the gum material  22  is disposed in the slot channels  212 . In addition, the gum material  22  may also be disposed on the protruding portions  213  (as shown in  FIG. 3C ). Alternatively, the wafer  23  may have a plurality of recesses  232 , and the recesses  232  are disposed corresponding to the protruding portions  213  (as shown in  FIG. 3D ). It should be noted that the gum material  22  may be firstly disposed on the protruding portions  213 , and the recesses  232  of the wafer  23  are engaged with the protruding portions  213  (as shown in  FIG. 3E ). Alternatively, the gum material  22  may be firstly disposed in the recesses  232  of the wafer  23 , and then the protruding portions  213  are engaged with the recesses  232  (as shown in  FIG. 3F ). 
   Referring to  FIG. 4A , the wafer  23  is sawed according to the predetermined sawing lines  24 . In this embodiment, the wafer  23  is sawed by water-cutting till a part of the gum material  22 , so as form a notch on the gum material  22 . In other applications, the wafer  23  may also be sawed till a contact surface of the gum material  22  and the wafer  23 , as shown in  FIG. 4B . 
   Referring to  FIG. 5 , finally, the first carrier  21  and the gum material  22  are removed, so as to finish the sawing method for the MEMS semiconductor device of the present invention. 
   In the sawing method for the MEMS semiconductor device according to the first embodiment of the present invention, the gum material  22  is disposed between the first carrier  21  and the wafer  23 , so as to protect the MEMS structure  231  from being damaged during the sawing process, and to protect the wafer  23  and the MEMS structure  231  from being polluted by water or foreign material, thereby improving the yield of the process. Further, in the present invention, the wafer  23  is sawed from the backside till the gum material  22  without sawing through the gum material  22 , such that the first carrier  21  can be reused, so as to reduce the production cost. 
     FIGS. 6 to 10  are schematic views of the sawing method for the MEMS semiconductor device of a second embodiment of the present invention. Referring to  FIG. 6 , firstly, a first carrier  31  is provided. Preferably, the first carrier  31  is of silicon, glass, or sapphire material. Next, a gum material  32  is disposed on a surface  311  of the first carrier  31 . The gum material  32  is an adhesive material. It should be noted that the gum material  32  may also be a light sensitive material (capable of being removed after being irradiated by a light source) or a heat sensitive material (capable of being removed after being heated by a heat source). 
   Referring to  FIG. 7A , a wafer  33  is disposed on the gum material  32 , the wafer  33  has a plurality of MEMS microphone units  331  (only one MEMS microphone unit  331  is used as a representative of illustration), a first surface  332 , and a second surface  333 , in which the second surface  333  corresponds to the first surface  332 . The MEMS microphone unit  331  has a vibrating thin film  334  and a depressed portion  335 , in which the depressed portion  335  is correspondingly located above the vibrating thin film  334 , the vibrating thin film  334  is disposed on the first surface  332 , and the depressed portion  335  is formed on the second surface  333 . The gum material  32  is disposed between the first carrier  31  and the first surface  332  of the wafer  33 , and the gum material  32  is disposed around the vibrating thin film  334  and corresponding to a plurality of predetermined sawing lines (as shown by dashed lines). It should be noted that in the present invention, the gum material  32  may be firstly disposed on the surface of the wafer  33 , and then the first carrier  31  is disposed on the gum material  32 . 
   Referring to  FIG. 7B , in other applications, the surface  311  of the first carrier  31  has a plurality of slot channels  312 , and each slot channel  312  is defined by two protruding portions  313  on the surface  311 . Preferably, the gum material  32  is disposed in the slot channels  312 . In addition, the gum material  32  may also be disposed on the protruding portions  313  (as shown in  FIG. 7C ). Alternatively, the wafer  33  can have a plurality of recesses  336 , and the recesses  336  are located corresponding to the protruding portions  313  (as shown in  FIG. 7D ). It should be noted that the gum material  32  may be firstly disposed on the protruding portions  313 , and the recesses  336  of the wafer  33  are engaged with the protruding portions  313  (as shown in  FIG. 7E ). Alternatively, the gum material  22  may be firstly disposed in the recesses  336  of the wafer  33 , and then the protruding portions  313  are engaged with the recesses  336  (as shown in  FIG. 7F ). 
   Referring to  FIG. 8 , a protection thin film  34  is formed on the second surface  333  of the wafer  33  and covers the depressed portion  335 . It should be noted that the step of forming protection thin film  34  may be selectively finished before the step of disposing the wafer  33  on the gum material  32 . In this embodiment, the protection thin film  34  is formed by adhering. Preferably, the protection thin film  34  is epoxy. 
   Referring to  FIG. 9A , the protection thin film  34  and the wafer  33  are sawed according to the predetermined sawing lines  37 . In this embodiment, the wafer  33  is sawed by water-cutting till a part of the gum material  32 , so as to form a notch on the gum material  32 . In other applications, the wafer  33  may also be sawed till a contact surface of the gum material  32  and the wafer  33 , as shown in  FIG. 9B . 
   Referring to  FIG. 10 , a second carrier  35  is disposed on the protection thin film  34 . Preferably, the second carrier  35  and the protection thin film  34  are combined by using an adhesive material  36 . Referring to  FIG. 11 , finally, the first carrier  31  and the gum material  32  are removed, so as to finish the flow of sawing the MEMS semiconductor device of the present invention. 
   In the sawing method for the MEMS semiconductor device according to the second embodiment of the present invention, the gum material  32  is disposed between the first carrier  31  and the wafer  33 , and the protection thin film  34  covers the depressed portion  335 , so as to protect the vibrating thin film  334  from being damaged during the sawing process, and to protect the wafer  33  and the vibrating thin film  334  from being polluted by water or foreign material, thereby improving the yield of the process. Further, in the present invention, the wafer  33  is sawed from the backside till the gum material  32  without sawing through the gum material  32 , such that the first carrier  35  can be reused, so as to reduce the production cost. 
   While the embodiments of the present invention have been illustrated and described, various modifications and improvements can be made by those skilled in the art. The embodiments of the present invention are therefore described in an illustrative but not restrictive sense. It is intended that the present invention may not be limited to the particular forms as illustrated, and that all modifications that maintain the spirit and scope of the present invention are within the scope as defined in the appended claims.