Patent Publication Number: US-2005139848-A1

Title: Image sensor package and method for manufacturing the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      This application claims the priority benefit of Taiwan application serial no. 92137701, filed on Dec. 31, 2003.  
     BACKGROUND OF THE INVENTION  
      1. Field of Invention  
      The present invention relates to structure of image sensor package. More particularly, the present invention relates to structure of image sensor package having a reduced height in whole structure.  
      2. Description of Related Art  
      The image sensor semiconductor is a semiconductor chip, in which the optical signals are converted into electric signals. The image sensor semiconductor includes an optical sensing device, such as a complementary metal-oxide semiconductor (CMOS) device or a charge coupled device (CCD).  
      Taking the U.S. Pat. No. 5,636,104 as a reference of the invention, it discloses a structure of image sensor package  10 , as shown in  FIG. 1 . The structure of image sensor package  10  includes a chip  30 , a housing  14 , a lens  16 , a glass  18 , and a substrate  20 . The chip  30  is electrically coupled on the substrate  20 , using the technology of bonding connection. The chip  30  has an optical sensing device  32 , located within the housing  14 . The housing  14  adheres to the substrate  20 , and supports the lens  16  and the glass  18 . The housing  14 , the glass  18 , the substrate  20  form a close space  12 , so as to adapt the chip  30 . When the light passes the lens  16  and the glass  18  and reaches to the optical sensing device  32 , the optical sensing device  32  reacts with the light and converts the light into electric signals. The substrate  20  is disposed with multiple metal circuit lines  22 , multiple bonding pads  24 , and multiple solder balls  26 . The solder balls  26  are electrically coupled to the chip  30  through the metal circuit lines  22  and the bonding pads  24 , and further electrically coupled to an external circuit (not shown), so as to transmit the signals from the optical sensing device  32 .  
      The conventional structure of image sensor package  10  is restricted to the manner of using the bonding technology for mounting the chip  30  to the substrate  20 . Since the total height, which is a distance between the lens and the substrate, is too large, it restricts the adjustment on the focal distance. Moreover, when the conventional structure of image sensor package  10  is disposed on an electronic apparatus, the volume of the electronic apparatus becomes large due to the total height of the structure of image sensor package  10  being over long.  
      Referring to  FIG. 2 , another conventional structure of image sensor package mainly includes a chip  80 , a housing  64 , a lens  66 , a glass  68 , and a resin layer  70 . The chip  80  is electrically coupled to the resin layer  70  by a flip-chip technology. The chip  80  has an optical sensing device  82  and multiple bumps  84 . The housing  64  adheres to the resin layer  70  and supports the lens  66 . The glass  68  is disposed between the housing  64  and the resin layer  70 . The resin layer  70  has multiple metal circuit lines  72  and multiple connection ends  76 . The metal circuit lines  72  are used to electrically connect the connection ends  76  to the bumps  84  of the chip  80 . The connection ends  76  is electrically coupled to an external circuit  90 , so as to transmit the signals of the optical sensing device  82 . Even though the total height of the foregoing structure of the image sensor package, which is the distance from the lens  66  to the chip  80 , has been reduced, the total height of the structure of the image sensor package  60  is still over long, with respect to a small electronic products.  
      Therefore, it is necessary to provide a structure of image sensor package at a wafer level, so as to solve the foregoing disadvantages.  
     SUMMARY OF THE INVENTION  
      The invention provides a structure of image sensor package, having a reduced package height.  
      For achieving the foregoing objective, the invention provides a structure of image sensor package, including a substrate, a chip, a transparent cover, and a lens module. The substrate has an upper surface and a lower surface, multiple connection pads disposed on the lower surface, and a through hole. The chip has an active surface, an optical sensing device disposed on the active surface, and multiple bumps disposed on the active surface at the peripheral regions with electrical coupling to the connection pads. The transparent cover is disposed in the through hole of the substrate and covers over the optical sensing device. The lens module is disposed on the upper surface of the substrate.  
      According to the structure of the image sensor package in the invention, the chip is coupled to the substrate by a flip-chip type, so that the structure height of the image sensor package can be reduced. Moreover, the transparent cover directly covers over the chip, so that the structure height of the image sensor package can also be reduced. As a result, in comparing with the conventional structure of image sensor package, the novel structure of image sensor package has the smaller structure height. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.  
       FIG. 1  is a cross-sectional view, schematically illustrating a conventional structure of an image sensor package.  
       FIG. 2  is a cross-sectional view, schematically illustrating another conventional structure of an image sensor package.  
       FIG. 3  is a cross-sectional view, schematically illustrating a structure of an image sensor package, according to embodiment of the invention.  
       FIGS. 4-14  are drawings, schematically illustrating the fabrication processes for the image sensor package, according to embodiment of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring to  FIG. 3 , it is a cross-sectional view, schematically illustrating a structure of an image sensor package  100 , according to embodiment of the invention. The structure of an image sensor package  100  includes a chip  130 , a transparent cover  118 , a substrate  120 , and a lens module  116 . The chip  130  has an active surface  136 , a back surface  137 , an optical sensing device  132 , and multiple bumps  134  disposed on the active surface  136 . The bumps  134  are located at the peripheral region of the active surface on the chip  130 . In detail, the bumps  134  can be disposed on one side, two sides, three sides, or four sides of the active surface  136 . The optical sensing device  132  can be a Complementary Metal-Oxide Semiconductor (CMOS) device or a charge coupled device (CCD). The bumps  134  can be a gold bump or a solder bump.  
      The transparent cover  118  is adhered to the chip  130  by a sealant  146  and covers the optical sensing device  132 . The sealant  146  can be an UV adhesive, and preferably, several spacing particles  144  are mixed therein. The sealant  146  is disposed between the transparent cover  118  and the chip  130 , and a distance between them is determined by the size of the spacing particles  144 . The transparent cover  118  can be an optical filter, such as an infrared low pass filter, or is formed from transparent material, such as glass. The spacing particles  144  can be formed by, for example, borosilicate glasses.  
      The substrate  120  has an upper surface  128  and a lower surface  129  against to each other, and a through hole  121  penetrating through the substrate  120  and corresponding to the optical sensing device  132  of the chip  130 . The bumps  134  of the chip  130  are connected to the connection pads  123  on the lower surface  129  of the substrate  120  by the flip-chip technology, and the transparent cover  118  is located within the through hole  121 . An underfill  148  is disposed between the chip  130  and the lower surface  129  of the substrate  120 , and encapsulating the bumps  134 . The connection pads  126  are disposed on the lower surface  129  of the substrate  120 , and are electrically connected to the bumps  134  of the chip  130  via multiple first metal circuit lines  122  and connections pads  123 . The connection pad  126  can be electrically connected to an external circuit  140 , such as a flexible printed circuit, by multiple solder balls  127 , which are processed by thermal pressing process. The ordinary skilled artisans can know that the substrate  120  can also have a solder mask layer (not shown), disposed on the lower surface  129 , so as to define the connection pad  123  and connection pad  126 . The substrate  120  is formed by material of Fiber Glass Reinforced Epoxy Resin, such as FR4 Fiber Glass Reinforced Epoxy Resin substrate or Fiber Glass Reinforced Bismalemide Triazine (BT) resin substrate.  
      The substrate  120  is a multi-layer substrate. In addition, multiple second circuit lines  156  are disposed on the upper surface  128  of the substrate  120 , and multiple electrical vias  152  for electrically connecting the first circuit lines  122  and the second circuit lines  156 . Multiple electronic devices  158 , such as passive devices, are disposed on the upper surface  128  of the substrate  120 , and are electrically connected to the second metal circuit lines  156 . The electrical via  152  can be a laser via.  
      The lens module  116  has a lens  117 , which is supported on the upper surface  128  of the substrate  120  by a housing  114 , so as to focus the light onto the optical sensing device  132 . The housing  114  is adhered to the upper surface  128  of the substrate  120 . The lens module  116  additionally includes an adjusting device  115 , used to adjust a distance between the lens  117  and the optical sensing device  132 .  
      Referring to  FIGS. 4-14 , they are the drawings, schematically illustrating the method for fabricating the structure of image sensor package  100 , according to the present invention.  
      In  FIGS. 4 and 5 , a wafer  160  has multiple chips  130 , and the chips  130  are separated by the cutting line  164 . The wafer  160  or the chips  130  has an active surface  136  and a back surface  137 . Each the chip  130  has an optical sensing device  132 , disposed on the active surface  136 . The cutting line  164  is located on the active surface  136  of the wafer  160  or the chip  130 .  
      At first, a set of alignment mark, such as two cutting openings  163 , is formed on the wafer  160  by cutting, so as to define a two-dimensional coordinate  162 . By this two-dimensional coordinate  162 , and also referencing to the length and the width of the chip  130 , the cutting line can be defined on the back surface  137  of the wafer  160 , and the wafer  160  can be precisely cut. It should be noted that, in the subsequent fabrication processes of the method of the invention, the wafer  160  is cut along the cutting line  164  for cutting-out the singulated chip  130 . However, in preferred situation, the wafer  160  is cut on the back surface  137  of the wafer  160 , but the back surface  137  has no cutting line. In this situation, the wafer  160  should provide an alignment mark, so as to be able to cut the wafer  160  from the back surface  137 . The alignment mark can be any type of opening, such as a cutting hole, through hole, or groove, which are used to define the cutting coordinate or cutting line on the back surface  137  of the wafer  160 .  
      Referring to  FIG. 6  and  FIG. 7 , multiple bumps  134  are formed on the active surface  136  of the chip  130 , and are disposed at the periphery of the active surface  136 .  
      Referring to  FIGS. 8 and 9 , a transparent cover substrate  170  is first provided. A plurality of grooves  172  in longitudinal and transversal directions are formed a surface  142  of the transparent cover substrate  170 . Both sides  174  of each groove  172  respectively define the two cutting lines  176 , and also define multiple cover  118  by this way.  
      Referring to  FIG. 10 , it preferably includes multiple sealant  146 . Each sealant is mixed with multiple spacers  144 , and is disposed on the active surface  136  of the chips  130  in surrounding manner, and respectively surrounding the optical sensing device  132 . The one ordinary skill in the art can understand that the sealant  146 , mixed with the spacers  144 , can be disposed the surface  142  of the transparent cover substrate  170 .  
      Referring to  FIG. 11 , the transparent cover substrate  170  is aligned and covers over the wafer  160 . The grooves  172  are respectively corresponding to the cutting lines  164  and the grooves  172  adapt the bumps  134 . After then, the sealant  146  is cured, so that the transparent cover substrate  170  is adhered to the wafer  160 . In this situation, the optical sensing device  132  is encapsulated in the sealant  146  and the transparent cover substrate  170 .  
      Referring to  FIG. 12 , by the 2-dimensional reference coordinate and referencing to the length and width of the chip  130 , a cutting tool  183  cuts the wafer  160  from the back surface  137  of the wafer  160 . Another cutting tool  182  is cutting the transparent cover substrate along the cutting line  176 . In practical operation, the cutting tool  183  and  182  can be not completely cutting through the wafer  160  and the transparent substrate  170 . And then, a braking process is subsequently performed, so as to form the singulated structure of optical device package  190 , as shown in  FIG. 13 .  
      Referring to  FIG. 14 , a substrate  120  with an upper surface and a lower surface  129  has a through opening  121 , multiple first metal circuit lines  122  disposed on the lower surface  129 , multiple second metal circuit lines  156  disposed on the upper surface  128 , and multiple conductive vias  152  for electrically connecting the second circuit lines  165  to the first circuit lines  122 . The substrate  120  can additionally provide multiple electronic devices  158 . For example, the electronic device  158  is disposed on the upper surface  128  and is connected to the second metal circuit lines  156 .  
      The substrate  120  further has multiple connection pads  123  and  126 , disposed on the lower surface  129 , electrically connected to the first metal circuit line  122 . The structure of optical device package  190  is affixed to the lower surface  129  of the substrate  120  by a flip-chip technology, in which the transparent cover  118  is located within the through opening  121 . The bumps  134  of the chip  130  can be connected to the connection pads  123  by a reflow process. Then, an underfill  148  is dispensed with capillary effect, so as to fill between the chip  130  and the  120 . The connection pads  126  can be electrically connected to an external circuit  140 , such as the flexible printed circuit, by the solder balls  127  with a thermal pressing process. The ordinary skilled artisans can understand that the external circuit  140  can be any type of circuit board, and substrate  120  can be affixed to the external circuit board  140  by various methods.  
      After then, the lens module  116  with the housing  114  and the adjusting device  115  is adhered to the upper surface  128  of the substrate  120 , so that the structure of image sensor package  100  can be formed, as shown in  FIG. 3 .  
      According to the embodiment of the invention, the4 chip  130  of the structure of image sensor package  100  is connected to the substrate  120  by the flip-chip type, so that a height of the structure of image sensor package  100  can be reduced, in which the height is a distance from the lens  117  to the chip  130 . Moreover, the transparent cover  118  is directly covering over the chip  130 , and can further reduce the height of the structure of image sensor package  100 . As a result, comparing with the conventional structure of image sensor package, the structure of image sensor package  100  has a smaller total height.  
      It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing descriptions, it is intended that the present invention covers modifications and variations of this invention if they fall within the scope of the following claims and their equivalents.