Abstract:
A flip chip package structure and a method for manufacturing the same are disclosed. The method for manufacturing a flip chip package structure comprises following steps: (a) providing a semiconductor chip including a plurality of electrode pads and a plurality of first solders, and providing a packaging substrate having a plurality of conductive pads and a plurality of second solders (b) forming a resin adhesive layer on the active surface of the semiconductor chip, and the first solders are exposed from the resin adhesive layer; (c) assembling the packaging substrate and the semiconductor chip with the resin adhesive layer formed thereon to form an assembly unit; and (d) reflow soldering the assembly unit to fuse the first solders of the semiconductor chip with the second solders of the packaging substrate to form fused solders, and the packaging substrate is adhered with the resin adhesive layer.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a flip chip package structure and a method for manufacturing the same and, more particularly to a flip chip package structure with fine pitch and a method for manufacturing the same. 
         [0003]    2. Description of Related Art 
         [0004]    As the capability for semiconductor processing improves, the development of the semiconductor chip tends to have multifunctions, which leads the structure of the semiconductor chip to become more and more complex. Meanwhile, as the information transferred through the semiconductor chip increases, the number of pins of the semiconductor chip has to be increased. 
         [0005]    The conventional wire bonding technique cannot satisfy the demands for the conductivity, due to the development of the semiconductor chip tending to have high frequency and a high number of pins. Comparing to the conventional wire bonding technique, solder bumps are used for the connection between a chip and a substrate in a flip-chip process, wherein the chip faces downward and connects with the substrate through the solder bumps to permit assembly of the flip chip package structure. Additionally, in the semiconductor chip of the flip chip packaging substrate, the I/O pins of the semiconductor chip can be distributed thereon, so that the number of pins can be increased greatly to improve the function of the semiconductor chip, and the pathway for transmitting signals between the semiconductor chip and the substrate can also be shortened. Besides, the interference of noises can be reduced, the ability to diffuse heat can be improved, and the package volume can also be compressed. Hence, the flip-chip technology has become a main trend in the industry. 
         [0006]    A conventional process for manufacturing a flip-chip packaging substrate is shown as  FIG. 3 . A plurality of conductive pads  12  and a solder mask  13  are formed on the packaging substrate  11 , and the solder mask  13  has a plurality of openings to expose the conductive pads  12 . Also, pre-solders  14  are formed on the conductive pads  12 , and the material of the pre-solders  14  is selected from the group consisting of Pb, Sn, Ag, and CU. Furthermore, a plurality of electrode pads  21  and a passivation layer  23  are formed on a chip  20 , and the passivation layer  23  has a plurality of openings to expose the electrode pads  21 . In addition, solder bumps  25  are formed on the electrode pads  21 , as shown in  FIG. 3(   a ). 
         [0007]    With reference to  FIG. 3(   b ), a reflow soldering process is performed on the packaging substrate and the chip to fuse solder bumps  25  on the chip and the pre-solders  14  on the packaging substrate and thus form a fused solder  26 . Herein, the conductive pads  12  are electrically connected to the electrode pads  21  through the fused solder  26 . 
         [0008]    After the chip  20  has been soldered with the packaging substrate  11 , the space between the chip  20  and the packaging substrate  11  is filled with a under-fill a resin  30 , as shown in  FIG. 3(   c ). First, the liquid under-fill resin is deposited in the space between the packaging substrate and the chip. Then, the liquid under-fill resin is cured to fix the positions of the chip and the packaging substrate. Hence, the chip can be secured, and the product reliability can also be improved. 
         [0009]    Although the process of depositing under-fill resin can fix the chip and improve the product reliability, the aforementioned conventional process still has its limitations when the pitches of the conductive pads and the electrode pads in the flip chip package structure are fine. With reference to  FIG. 3 , when the electrode pads  21  and the conductive pads  12  tend to have fine pitches, the volume of the solder bumps  25  has to be reduced. Hence, the gaps between the packaging substrate and the chip have to be reduced. When the gaps between the packaging substrate and the chip are reduced to a certain extent, the process of depositing under-fill resin will become difficult. For example, the under-fill resin cannot fill the space between the packaging substrate and the chip to the full, and voids may be generated between the packaging substrate and the chip. Hence, the phenomenon of popcorn may occur, which will reduce the product reliability. Therefore, the conventional process limits the trend toward manufacturing flip chip package structure with fine pitches. Therefore, it is desirable to provide a flip chip package structure and a method for manufacturing the same to improve the aforementioned problems. 
       SUMMARY OF THE INVENTION 
       [0010]    The object of the present invention is to provide a method for manufacturing a flip chip package structure, which can reduce the pitches of the flip chip package structure, improve the filling quality of a under-fill resin, and improve the reliability of the flip chip package structure. 
         [0011]    Another object of the present invention is to provide a flip chip package structure, which can reduce the pitches of the flip chip package structure. 
         [0012]    A further object of the present invention is to provide a flip chip packaging substrate, which can be applied to the flip chip packaging structure with fine pitches. 
         [0013]    To achieve the aforementioned objects, the method for manufacturing a flip chip package structure of the present invention comprises the following steps: (a) providing a semiconductor chip including a plurality of electrode pads and a plurality of first solders, and providing a packaging substrate having a plurality of conductive pads and a plurality of second solders; wherein the electrode pads are disposed on an active surface of the semiconductor chip, the first solders are disposed on the electrode pads, the conductive pads are disposed on an upper surface of the packaging substrate, and the second solders are disposed on the conductive pads; (b) forming a resin adhesive layer on the active surface of the semiconductor chip, and the first solders are exposed from the resin adhesive layer; (c) assembling the packaging substrate and the semiconductor chip with the resin adhesive layer formed thereon to form an assembly unit, wherein the first solders of the semiconductor chip correspond to the second solders of the packaging substrate; and (d) reflow soldering the assembly unit to fuse the first solders of the semiconductor chip with the second solders of the packaging substrate to form fused solders, and the packaging substrate is adhered with the resin adhesive layer. 
         [0014]    Preferably, according to the method for manufacturing a flip chip package structure, the semiconductor chip in step (a) may further comprise a passivation layer, which comprises a plurality of first openings to expose the electrode pads. 
         [0015]    Preferably, according to the method for manufacturing a flip chip package structure, the packaging substrate in the step (a) may further comprise a solder mask formed on the upper surface, and the solder mask comprises a plurality of second openings to expose the conductive pads. 
         [0016]    Preferably, according to the method for manufacturing a flip chip package structure, in the step (a), the second solders of the packaging substrate may be solder paste. 
         [0017]    Preferably, the method for manufacturing a flip chip package structure may further comprise a step (a1) after step (a): placing a plurality of metal blocks on the second solders of the packaging substrate. According to the aforementioned method, the shapes of the metal blocks are unlimited. Preferably, the metal blocks are ball-shaped metal blocks or ellipse-shaped metal blocks. 
         [0018]    Preferably, the method for manufacturing a flip chip package structure may further comprise a step (a2) after the step (a): forming a plurality of pre-solders on the second solders of the packaging substrate. According to the aforementioned method, the pre-solders may further comprise a flux. 
         [0019]    Preferably, according to the method for manufacturing a flip chip package structure, the first solders in the step (a) have a height of 10-50 μm. 
         [0020]    Preferably, according to the method for manufacturing a flip chip package structure, in step (b), the thickness of the resin adhesive layer is less than the height of the first solders. More preferably, the first solders are exposed from the resin adhesive layer. 
         [0021]    Preferably, the method for manufacturing a flip chip package structure may further comprise a step (b1) after step (b): drying the resin adhesive layer formed on the semiconductor chip. 
         [0022]    According to the method for manufacturing a flip chip package structure, the material of the first solders is selected from the group consisting of Pb, Sn, Zn, Bi, Au, Ag, Cu, and an alloy thereof. 
         [0023]    According to the method for manufacturing a flip chip package structure, the material of the second solders is selected from the group consisting of Pb, Sn, Zn, Bi, Au, Ag, Cu, and an alloy thereof. 
         [0024]    In addition, the flip chip package structure of the present invention comprises: (a) a flip chip packaging chip, which comprises: an active surface, and a plurality of electrode pads formed on the active surface; and a resin adhesive layer disposed on the active surface of the flip chip packaging chip; and (b) a flip chip packaging substrate, which comprises: an upper surface, and a plurality conductive pads formed on the upper surface; and a solder mask formed on the upper surface, and the solder mask comprising a plurality of openings to expose the conductive pads. In the aforementioned flip chip package structure, the resin adhesive layer of the flip chip packaging chip adheres with the solder mask of the flip chip packaging substrate to form a flip chip package structure, and the electrode pads of the flip chip packaging chip are electrically connected to the conductive pads of the flip chip packaging substrate through a fused solder. 
         [0025]    Preferably, the flip chip package structure of the present invention may further comprise a metal block wrapped in the fused solder. According to the aforementioned flip chip package structure, the shape of the metal block is unlimited. Preferably, the metal block is a ball-shaped metal block or an ellipse-shaped metal block. 
         [0026]    Preferably, in the flip chip package structure of the present invention, the conductive pads may be copper pads. 
         [0027]    Preferably, in the flip chip package structure of the present invention, the electrode pads may be aluminum pads or copper pads. 
         [0028]    In the flip chip package structure of the present invention, the material of the fused solder is selected from the group consisting of Pb, Sn, Zn, Bi, Au, Ag, Cu, and an alloy thereof. 
         [0029]    In the flip chip package structure of the present invention, the metal block is a ball-shaped metal block or an ellipse-shaped metal block. 
         [0030]    In the flip chip package structure of the present invention, the second solders are solder paste. 
         [0031]    Furthermore, the flip chip package structure of the present invention comprises: an upper surface, and a plurality of conductive pads formed thereon; a solder mask formed on the upper surface, wherein the solder mask comprising a plurality of openings to expose the conductive pads; a plurality of second solders disposed on the conductive pads; and a plurality of paste-shaped pre-solders disposed on the second solders. 
         [0032]    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 
         [0033]      FIG. 1  is a cross-sectional view for illustrating a process for manufacturing a flip chip package structure according to embodiment 1 of the present invention; 
           [0034]      FIG. 2  is a cross-sectional view for illustrating a process for manufacturing a flip chip package structure according to embodiment 2 of the present invention; and 
           [0035]      FIG. 3  is a cross-sectional view for illustrating a process for manufacturing a conventional flip chip package structure. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0036]    Because of the specific embodiments illustrating the practice of the present invention, a person having ordinary skill in the art can easily understand other advantages and efficiency of the present invention through the content disclosed therein. The present invention can also be practiced or applied by other variant embodiments. Many other possible modifications and variations of any detail in the present specification based on different outlooks and applications can be made without departing from the spirit of the invention. 
         [0037]    The figures in the embodiments of the present invention are simplified perspective views. Only the elements related to the present invention are shown in these figures, and these figures do not illustrate the practical aspects. The numbers and shapes of the elements are designed according to the practical situations. Hence, the arrangement of the elements may be more complex in practice. 
       Embodiment 1 
       [0038]      FIG. 1  shows the process for manufacturing a flip chip package structure of the present embodiment. First, a packaging substrate  100  and a semiconductor chip  200  are provided. A plurality of conductive pads  110  and a solder mask  120  are formed on an upper surface  102  of the packaging substrate  100 , and the solder mask  120  has a plurality of second openings  122  to expose the conductive pads  110 . A plurality of electrode pads  210  and a passivation layer  220  are formed on an active surface  202  of the semiconductor chip  220 , and the passivation layer  220  has a plurality of first openings  222  to expose the electrode pads  210 .  FIG. 1(   a ) and  FIG. 1(   a   1 ) show the cross-sectional views of the packaging substrate and the semiconductor chip. 
         [0039]    Then, as shown in  FIG. 1(   b ) and  FIG. 1(   b   1 ), a plurality of first solders  230  is formed on the semiconductor chip  200 , and the first solders  230  are disposed on the electrode pads  210 . In the present invention, the material of the first solders can be selected from the group consisting of Pb, Sn, Zn, Bi, Au, Ag, Cu, and an alloy thereof. Besides, the first solders can be formed by conventional screen printing or electroplating. In addition, a plurality of second solders  130  is formed on the conductive pads  110  of the packaging substrate  100 . The material of the second solders  130  can be selected from the group consisting of Pb, Sn, Zn, Bi, Au, Ag, Cu, and an alloy thereof. In the present embodiment, the second solders  130  can be solder paste, which can be formed by screen printing or electroplating. 
         [0040]    With reference to  FIG. 1(   c ), a plurality of metal blocks  150  is respectively placed on the second solders  130  of the packaging substrate  100  to form a flip chip packaging substrate, wherein the metal blocks  150  placed on the second solders  130  can provide suitable height that is easily contact with chip. In the present embodiment, each second solder  130  is set with a metal block  150 , and the particle size of the metal block  150  is less than the width of the second solder  130 . Preferably, the metal blocks  150  are ball-shaped metal blocks. Furthermore, in the present embodiment, the second solders  130  are solder paste, so that the metal blocks  150  can adhere on the second solders  130  easily. 
         [0041]    Then, a resin adhesive layer  240  is such as a polymer resin formed on the semiconductor chip  200 . After curing of the resin adhesive layer  240 , the resin adhesive layer  240  is half-dry and viscous, and a flip chip packaging chip  290  is formed. The resin adhesive layer  240  can be formed by spin coating or screen printing. In the present embodiment, the thickness of the resin adhesive layer  240  is less than the height of the first solders  230  formed on the semiconductor chip  220  to expose the top of the first solders  230 , as shown in  FIG. 1(   c   1 ). The process of drying can be performed by vacuum drying or heating to move parts of solvent inside the resin adhesive layer. Besides, the resin adhesive layer  240  can be set on the semiconductor chip  220 . 
         [0042]    With reference to  FIG. 1(   d ), the flip chip packaging chip  290  assembles with and corresponds to the flip chip packaging substrate  190  to form an assembly unit  600 . During the process of assembling the flip chip packaging chip  290  and the flip chip packaging substrate  190 , the active surface  202  of the flip chip packaging chip  290  faces to the upper surface  102  of the flip chip packaging substrate  190 . In addition, the first solders  230  formed on the semiconductor chip correspond to the second solders  230  formed on the substrate respectively. 
         [0043]    With reference to  FIG. 1(   e ), a process of heating and reflow soldering is performed on the assembly unit  600  to fuse the first solders  230  of the flip chip packaging chip with the second solders  130  of the flip chip packaging substrate  190 . During the process of heating and reflow soldering, the first solders  230  and the second solders  130  transfer to a fused state. Hence, the first solders  230  and the second solders  130  can be melted and blended with each other to form a fused solder  330 . Additionally, the metal blocks  150  are wrapped in the fused solder  330 . The fused solder  330 , as a conductive medium, can electrically connect the electrode pads  210  with the conductive pads  110 . 
         [0044]    Meanwhile, during the process of heating and reflow soldering, the resin adhesive layer  240  of the flip chip packaging chip  290  is also under high temperature, so that the resin adhesive layer  240  can adhere with the solder mask  120  of the flip chip packaging substrate  190 . Besides, the resin adhesive layer  240  can fill the space between the flip chip packaging chip  290  and the flip chip packaging substrate  190 . In addition, during the process of heating and reflow soldering, a heavy component may be selectively placed on the semiconductor chip. The heavy component can apply suitable stress on the semiconductor chip to ensure the resin adhesive layer  240  contacts and adheres with flip chip packaging substrate  190  completely. After the process of reflow soldering has been completed, the resin adhesive layer  240  is adhered with the flip chip packaging chip  290  and the flip chip packaging substrate  190 . Finally, the flip chip package structure of the present embodiment is formed. 
         [0045]    In the present embodiment, the resin adhesive layer  240  is formed on the semiconductor chip in advance, and the resin adhesive layer  240  can adhere with the substrate through the process of heating and reflow soldering. Hence, during the process for manufacturing the flip chip package structure of the present embodiment, a step of depositing under-fill resin can be omitted. Therefore, the problem that the under-fill resin cannot fill the space between the semiconductor chip and the substrate to the full when the flip chip package structure has fine pitches, can be diminished. 
         [0046]    In the conventional process of depositing under-fill resin, when the height of the first solders  230  is less than 80 μm, the condition of poor filling may occur easily. In the present embodiment, a process wherein a resin adhesive layer  240  is formed on the semiconductor chip  200  in advance, can replace the conventional process of depositing under-fill resin. Hence, the flip chip package structure of the present invention and the method for manufacturing the same can be applied to the flip chip package structure, in which the height of the first solders  230  of the semiconductor chip  200  is 10˜50 μm. Therefore, the method disclosed in the present embodiment can greatly improve the ability to make the flip chip package structure with fine pitches. Additionally, the method disclosed in the present embodiment can provide products with good reliability at the same time. 
       Embodiment 2 
       [0047]      FIG. 2  shows the process for manufacturing a flip chip package structure of the present embodiment. First, a packaging substrate  100  and a semiconductor chip  200  are provided. A plurality of conductive pads  110  and a solder mask  120  are formed on an upper surface  102  of the packaging substrate  100 , and the solder mask  120  has a plurality of second openings  122  to expose the conductive pads  110 . A plurality of electrode pads  210  and a passivation layer  220  are formed on an active surface  202  of the semiconductor chip  220 , and the passivation layer  220  has a plurality of first openings  222  to expose the electrode pads  210 .  FIG. 2(   a ) and  FIG. 2(   a   1 ) show the cross-sectional views of the packaging substrate and the semiconductor chip. 
         [0048]    Then, as shown in  FIG. 2(   b ) and  FIG. 2(   b   1 ), a plurality of first solders  230  is formed on the semiconductor chip  200 , and the first solders  230  are disposed on the electrode pads and correspond to the electrode pads  210 . In the present invention, the material of the first solders can be selected from the group consisting of Pb, Sn, Zn, Bi, Au, Ag, Cu, and an alloy thereof. Besides, the first solders can be formed by conventional screen printing or electroplating. In addition, a plurality of second solders  130  is formed on the conductive pads  110  of the packaging substrate  100 . In the present embodiment, the material of the second solders  130  can be selected from the group consisting of Pb, Sn, Zn, Bi, Au, Ag, Cu, and an alloy thereof. Besides, the second solders  130  can be formed by screen printing or electroplating. 
         [0049]    With reference to  FIG. 2(   c ), a plurality of pre-solders  160  is respectively formed on the second solders  130  of the packaging substrate  100  to obtain a flip chip packaging substrate  192 , wherein the pre-solders  160  placed on the second solders  130  can provide suitable height that is easily contact with chip. In the present embodiment, the pre-solders  160  are paste-shaped pre-solders which comprise a flux, and the width of the pre-solders  160  is less than the width of the second solders  130 . Besides, the pre-solders  160  can be formed by conventional screen printing or coating. 
         [0050]    Then, a resin adhesive layer  240  is formed on the semiconductor chip  200 . After curing of the resin adhesive layer  240 , the resin adhesive layer  240  is half-dry and viscous, and a flip chip packaging chip  292  is formed. The resin adhesive layer  240  can be formed by spin coating or screen printing. In the present embodiment, the thickness of the resin adhesive layer  240  is less than the height of the first solders  230  formed on the semiconductor chip  220  to expose the top of the first solders  230 , as shown in  FIG. 2(   d ). The process of drying can be performed by vacuum drying or heating to move parts of solvent inside the resin adhesive layer. Besides, the resin adhesive layer  240  can be set on the semiconductor chip  220 . 
         [0051]    With reference to  FIG. 2(   d ), the flip chip packaging chip  292  assembles with and corresponds to the flip chip packaging substrate  192  to form an assembly unit  700 . During the process of assembling the flip chip packaging chip  292  and the flip chip packaging substrate  192 , the active surface  202  of the flip chip packaging chip  292  faces to the upper surface  102  of the flip chip packaging substrate  192 . In addition, the first solders  230  formed on the flip chip packaging chip  292  correspond to the second solders  130  formed on the flip chip packaging substrate  192  respectively. 
         [0052]    With reference to  FIG. 2(   e ), a process of heating and reflow soldering is performed on the assembly unit  700  to fuse the first solders  230  of the flip chip packaging chip  292  with the second solders  130  of the flip chip packaging substrate  192 . In the present embodiment, the pre-solders  160  are paste-shaped solders which comprises a flux. Hence, during the process of heating and reflow soldering, the flux inside the pre-solders  160  can vaporize into gas, so that the first solders  230 , the pre-solders  160  and the second solders  130  can be melted and blended with each other to form fused solders  340 . Herein, the fused solder  340 , as a conductive medium, can electrically connect the electrode pads  210  with the conductive pads  110 . 
         [0053]    Meanwhile, during the process of heating and reflow soldering, the resin adhesive layer  240  of the flip chip packaging chip  292  is also under high temperature, so that the resin adhesive layer  240  can adhere with the solder mask  120  of the flip chip packaging substrate  192 . Besides, the resin adhesive layer  240  can fill the space between the flip chip packaging chip  292  and the flip chip packaging substrate  192 . In addition, during the process of heating and reflow soldering, a heavy component may be selectively placed on the semiconductor chip. The heavy component can apply suitable stress on the semiconductor chip to ensure the resin adhesive layer  240  contacts and adheres with flip chip packaging substrate  192  completely. After the process of reflow soldering has been completed, the resin adhesive layer  240  is adhered with the flip chip packaging chip  292  and the flip chip packaging substrate  192 . Finally, the flip chip package structure of the present embodiment is formed. 
         [0054]    In the present embodiment, the resin adhesive layer  240  is formed on the semiconductor chip in advance, and the resin adhesive layer  240  can adhere with the substrate through the process of heating and reflow soldering. Hence, during the process for manufacturing the flip chip package structure of the present embodiment, a step of depositing under-fill resin can be omitted. Therefore, the problem that under-fill resin cannot fill the space between the semiconductor chip and the substrate to the full when the flip chip package structure has fine pitches can be diminished. 
         [0055]    In the conventional process of depositing under-fill resin, when the height of the first solders  230  is less than 80 μm, the condition of poor filling may occur easily. In the present embodiment, a process wherein a resin adhesive layer is formed on the semiconductor chip in advance can replace the conventional process of depositing under-fill resin. Hence, the flip chip package structure of the present invention and the method for manufacturing the same can be applied to the flip chip package structure, in which the height of the first solders  230  of the semiconductor chip  200  is 10˜50 μm. Therefore, the method disclosed in the present embodiment can greatly improve the ability to make the flip chip package structure with fine pitches. Additionally, the method disclosed in the present embodiment can provide products with good reliability at the same time. 
         [0056]    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 scope of the invention as hereinafter claimed.