Abstract:
A semiconductor device including a circuit structure and a protective layer is provided. The circuit structure has multiple contacts. The protective layer is located on the circuit structure and has multiple openings and multiple protrusions, wherein the contacts are exposed by the openings and the protrusions are located on the contacts.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the priority benefit of Taiwan application serial no. 95106753, filed on Mar. 1, 2006. All disclosure of the Taiwan application is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a semiconductor device and a manufacturing process thereof. More particularly, the present invention relates to a semiconductor device in which the reliability of the electrical connection between the device and other electronic devices is enhanced and a manufacturing process of the semiconductor device. 
         [0004]    2. Description of Related Art 
         [0005]    Flip chip interconnect technology is a type of packing technology that provides a connection of a die to a printed circuit board, wherein a plurality of bumps is formed on a plurality of contacts on the die. The die is then flipped over, and the bumps are connected to the terminals on the printed circuit board to electrically connect the die to the printed circuit board via the bumps. 
         [0006]      FIGS. 1A to 1C  are schematic, cross-sectional views showing the steps for fabricating a bump on a contact of a die according to the prior art. As shown in  FIG. 1A , a die  110  is first provided, wherein the die has an active surface  112 . The die  110  also has a plurality of contacts  114 , disposed on the active surface  112 . A protective layer  120  is further formed on the active surface  112 . 
         [0007]    Continuing to  FIG. 1B , subsequent to a photolithography/etching process, a plurality of openings  122  is formed in the protective layer  120 , wherein these openings expose the contacts  114 . It is worthy to note that the size of the openings  122  is smaller than the contacts  114 . Accordingly, the protective layer  120  at the vicinity of each opening  122  has a protrusion P. A layer of under bump metallurgy (UBM) material  150  is formed on the protective layer  120  and the contacts  114 . A photoresist layer  130  is then formed on the UBM material  150 . Subsequent to a photograph/etching process, a plurality of openings  132  is formed in the photoresist layer  130 , wherein these openings  132  expose the UBM material  150  at where the contacts  114  are disposed. Subsequent to electroplating gold in these openings, a plurality of gold bumps  140  is formed on the die  110 , wherein these gold bumps  140  are electrically connected to the contacts  114  through the UBM material  150 . 
         [0008]    Continuing to  FIG. 1C , the photoresist layer  130  is removed. Further using these bumps  140  as a mask, the UBM material  150  not covered by the gold bumps  140  is removed to form a die structure  100  having a plurality of gold bumps  140 . It is also worthy to note that the region covered by the gold bump  140  also includes a ring of protrusion P on the protective layer  120 . Accordingly, the gold bump  140  also includes a ring of protrusion Q, corresponding to the ring of protrusion P on the protective layer. 
         [0009]    Referring to  FIG. 2 ,  FIG. 2  is schematic, cross-sectional view showing the convention fabrication method of a bump on a die that is electrically connected to a printed circuit board. Accordingly to the conventional technique, the printed circuit board  200 is electrically connected to the die  110  through an anisotropic conductive film (adhesive)  250  and a gold bump  140 , wherein the anisotropic conductive film  250  has a plurality of granules  252  having a conductive interior and an insulating exterior. The printed circuit board  200  has a plurality of terminals  210 . 
         [0010]    When the printed circuit board  200  is electrically connected to the die  110  through the anisotropic conductive film  250  and the gold bumps  140 , some of the granules  252  are pressured by the protrusion Q on each gold bump  140  and the terminals  210 . The insulating exterior of the granules  252  at where pressure is being applied is fractured by the protrusions Q on the gold bumps  140  and the terminals  210  for the die  110  exposing the conductive interior. As a result, the conductive interior of the granules  252  can electrically connect to the protrusion Q and the terminals  210  through the fracture site of the insulating exterior in order for the die to electrically connect to the printed circuit board  200 . 
         [0011]    It is also important to note that the surface area of the protruded region Q of the gold bump  140  is very small. Using the conventional technique to electrically connect the gold bump  140  to the contact pad  210  via the anisotropic conductive film  250 , the reliability of the electrical connection between the gold bumps  140  and the terminals  210  is lower. 
       SUMMARY OF THE INVENTION 
       [0012]    Accordingly, the present invention provides a semiconductor device and a fabrication method thereof, wherein the effective area of electrical connection at the top of the gold bump disposed on the semiconductor device is increased. 
         [0013]    The present invention provides a semiconductor device which includes a circuit structure and a protective layer. The circuit structure has a plurality of contacts. The protective layer is disposed on the circuit structure. The protective layer includes a plurality of openings and a plurality of protrusions, wherein the openings expose these protrusions and these protrusions are disposed over these contacts. 
         [0014]    According to an embodiment of the present invention, the semiconductor device further includes a plurality of UBM pads and a plurality of bumps, wherein these UBM pads are disposed on the contacts and the protrusions, and the gold bumps are disposed on the UBM pads. 
         [0015]    According to the semiconductor device of an embodiment of the present invention, the material of the bumps is gold, for example. 
         [0016]    According to the semiconductor device of an embodiment of the present invention, each contact has one protrusion disposed thereon. 
         [0017]    According to the semiconductor device of an embodiment of the present invention, the protrusion can be ring shape, strip shape, or block shape, for example. 
         [0018]    According to the semiconductor device of an embodiment of the present invention, each contact has a plurality of protrusions disposed thereon. 
         [0019]    According to the semiconductor device of an embodiment of the present invention, the protrusions can be ring shape, strip shape, block shape or a combination of the above, for example. 
         [0020]    The present invention provides a fabrication method for a semiconductor device, wherein an circuit structure is first provided. The circuit structure includes a plurality of contacts. A layer of protective material is further formed to cover the circuit structure. The layer of protective material is then patterned to form a protective layer. The protective layer has a plurality of openings and a plurality of protrusions, wherein the openings expose the contacts and the protrusions are disposed on these contacts. 
         [0021]    According to the fabrication method of a semiconductor device of an embodiment of the present invention, a layer of UBM material is formed over the contacts and the protrusions. A plurality of bulges is formed on the UBM material, wherein the positions of these bulges correspond to those of the protrusions. The UBM material not covered by the bulges is then removed. 
         [0022]    According to the present invention, the contacts on the circuit structure has a plurality of protrusions, each bump disposed on each contact has a plurality of bulges corresponding to the protrusions. Further, the thickness of the bulges is substantially the same. Consequently, the electrical connection between the bumps a semiconductor device and the terminals of a printed circuit board has a higher reliability. 
         [0023]    Several exemplary embodiments of the invention will now be described in detail with reference to the accompanying drawings. It is to be understood that the foregoing general description and the following detailed description of preferred purposes, features, and merits are exemplary and explanatory towards the principles of the invention only and are not restrictive of the invention, as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    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. 
           [0025]      FIGS. 1A to 1C  are schematic, cross-sectional views showing the steps for fabricating a bump on a contact of a die according to the prior art. 
           [0026]      FIG. 2  is schematic, cross-sectional view showing the convention fabrication method of a bump on a die that is electrically connected to a printed circuit board. 
           [0027]      FIGS. 3A-3C  are schematic, cross-sectional views showing the steps for fabricating a semiconductor device according to one embodiment of the present invention. 
           [0028]      FIG. 4  is a schematic diagram illustrating the electrical connection between the semiconductor device in  FIG. 3C  and a substrate. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]      FIGS. 3A-3C  are schematic, cross-sectional views showing the steps for fabricating a semiconductor device according to one embodiment of the present invention. As shown in  FIG. 3A , an circuit structure  310  is provided, wherein the circuit structure  310  has an active surface  312 . The circuit structure  310  has a plurality of contacts  314 , disposed on the active surface  312 . A layer of protective material  320   a  is then formed on the active surface  312  and the contacts  314 . The protective layer  320   a  is formed by, for example, screen printing, coating or a direct adhesion of a dry film of the protective material  320   a  on the active surface  312 . 
         [0030]    Continuing to  FIG. 3B , a protective layer  320   b  is formed by patterning the protective material  320   a  via the photolithography and etching processes. The protective layer  320   b  has a plurality of openings  322  and a plurality of protrusions  324 , wherein the openings  322  expose the contacts  314  and the protrusions  324  are configured on the contacts  314 . The protrusions  324  on each contact  314  can be ring shape, strip shape, block shape or a combination of the above, for example. 
         [0031]    It is important to note that although the disposition of the plurality of the protrusions  324  on a single contact  314  is used in the aforementioned embodiment, the number of the protrusions  324  being configured on a single contact  314  according to this invention is not limited as such. In other embodiments of the present invention, one protrusion  324  is configured on a single contact  314  using an appropriate patterning process. Further, when one protrusion  324  is disposed on a single contact  314 , the protrusion  324  can be ring shape, strip shape or block shape, for example. 
         [0032]    Thereafter, a layer of under bump metallurgy (UBM) material  360   a  is formed on the protective layer  320   b  and the contacts  314 . A photoresist layer  330  is then formed over the layer of under bump metallurgy (UBM) material. The photoresist layer  330  is formed by coating, electro deposition, or a direct adhesion of a dry-film photoresist on the protective layer  320   b . A plurality of openings  332  is then formed in the photoresist layer  330  via the photolithography and etching processes, wherein the openings  332  expose the UBM material at where the contact  314  are disposed. A bump  340  is then formed in each opening  332  via electroplating, wherein the bump  340  is mechanically and electrically connected to the UBM material  360   a . The material of the bump  340  includes, but not limited, to gold. 
         [0033]    Continuing to  FIG. 3C , the photoresist layer  330  is removed. Further using the bump  340  as a mask, the UBM material  360   a  that is not covered by the bump  340  is removed to form a plurality of UBM pads  360   b . The fabrication of a semiconductor device  300  is thus completed. It is important to note that the thickness of the protective layer  320   b  is fixed, the height of the bulge S on the protective layer  320   b  near the opening  322  is substantially the same as the height of the protrusions  324 . Accordingly, the top of the bump  340  which is disposed on the contact  314 , the protrusions  324  and the bulge S of the protective layer  320   b  also has a plurality of corresponding bulges X, wherein the height of each bulge X is basically the same. 
         [0034]      FIG. 4  is a schematic diagram illustrating an electrical connection between a semiconductor device and a substrate. Referring to  FIG. 4 , a printed circuit board  200  is electrically connected to the circuit structure  310  via the bump  340  and an anisotropic conductive film (adhesive)  250 . The anisotropic conductive film (adhesive)  250  has a plural of granules  252  having a conductive interior and insulating exterior. The printed circuit board  200  further includes a plurality of terminals  210 . 
         [0035]    When the printed circuit board  200  is electrically connected to the circuit structure  310  via the anisotropic conductive film (adhesive)  250  and the bump  340 , some of the granules  252  are pressured by the plurality of the bulges X on the surface of the bump  340  and the terminals  210 . The insulating exterior of the granules  252  will fracture at where pressure is being applied by the bulges X and the terminals  210  to expose the conductive interior. As a result, the conductive interior of the granules makes an electrical contact with the bump  340  and the terminal  210  at the fracture site. The electrical connection between the circuit structure  310  and the printed circuit board  200  is thereby completed. 
         [0036]    Accordingly, the contact of the circuit structure of the present invention has a plurality of protrusions thereon. The bump that covers the contacts also has a plurality of bulges on its top surface, wherein the positions of the bulges correspond to the positions of the protrusions. Further, the thickness of the bulges is substantially the same. As the electric circuit structure is electrically connected to a substrate through these bumps of the present invention, the electrical connection between the bumps of the semiconductor device and the terminals has a higher reliability. This is due to the fact that, in the present invention, the plurality of bulges at the top of the bump can be used to pressure the granules of the anisotropic conductive film (adhesive), whereas, in the prior art, only a single bulge on the gold bump is being relied on to pressure the granules of the anisotropic conductive film. 
         [0037]    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, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.