Abstract:
A carrier structure for a semiconductor chip and a method for manufacturing the same are disclosed. The method includes the following steps: providing a carrier board having at least one through cavity, wherein a removable film is formed on the surface of the carrier board, and a semiconductor chip is temporarily fixed in the through cavity by the removable film; filling the gap between the through cavity of the carrier board and the semiconductor chip with an adhesive material in order to fix the semiconductor chip; and removing the removable film. The disclosed method can reduce the alignment error resulted from the tiny shift of the semiconductor chip caused by jitters before the semiconductor is fixed in the cavity, thereby to increase the accuracy of the alignment, to facilitate fine wiring, and to meet the trend toward compact size of semiconductor packages.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a carrier structure for a semiconductor chip and a method for manufacturing the same, and especially, to a method for manufacturing a carrier structure having a cavity in which a semiconductor chip is disposed. 
         [0003]    2. Description of Related Art 
         [0004]    Customer demands of the electronics industry continue to evolve rapidly and the main trends are high integration and miniaturization. In order to satisfy those requirements, especially in the packaging of semiconductor devices, development of packaging substrates sufficing active and passive components and conductive wires has progressed from single layer to multiple layers. This means that a greater usable area is available due to interlayer connection technology. 
         [0005]    In the conventional semiconductor device, semiconductor chips are mounted on the front side surface of a substrate by its inactive surface, and then are processed by wire bonding, or semiconductor chips are directly conducted by its active surface with the front side surface of a substrate by flip-chip technology. After that, solder balls are implanted on the back side surface of the substrate to provide electrical connections for a printed circuit board. Although an objective of high quantity pin counts is achieved, it is limited that electric characteristics are unable to be improved in higher-frequency and higher-speed operation due to long pathways of conductive wires. 
         [0006]    In many studies, semiconductor chips directly electrically connecting to external electronic devices are embedded into a packaging substrate to shorten conductive pathways, to decrease signal loss and distortion, and to increase abilities of high-speed operation. 
         [0007]    In a carrier structure having a chip embedded therein, as shown in  FIG. 1 , metal layers are added on electrode pads of an active surface of the chip for preventing destruction by laser ablation of the chip in a carrier. The carrier structure having a chip embedded therein includes: a carrier board  11  having a through cavity  110  formed therein; a chip  12  placed in the cavity  110 , wherein the active surface of the chip  12  has a plurality of electrode pads  13  thereon; a protective layer  14 , having a plurality of openings  140  exposing the electrode pads  13 , formed on the active surface of the chip  12 ; a plurality of metal layers  15  formed on surfaces of the electrode pads  13 ; and a built-up structure  16  formed on the active surface of the chip  12  and on one surface of the carrier board  11  on the same side with the active surface of the chip  12 . The built-up structure  16  has a plurality of conductive vias  161  to electrically connect the electrode pads  13  of the chip  12 . 
         [0008]    Currently, in a carrier structure embedded with chips, the cavity of the carrier board is used for disposing the chip. However, a gap exists between the chip and the carrier board. Prior to fixing the chip, tiny shifts occur inevitably. Therefore, alignment errors caused by the shifts of the chip are already greater than those resulted from formation of via holes by laser ablation. In order to benefit circuit layers to electrically connect the electrode pads, those pads of the chip have to be formed in a size about 200˜250 μm. Accordingly, alignment by laser ablation will be more available during the formation of built-up structures, and failure of alignment will not occur, thus avoiding destruction of the chip. Nevertheless, the greater electrode pads of the semiconductor can not satisfy the demand of circuit miniaturization nowadays. On the other hand, due to aforementioned alignment errors, panels used during manufacturing circuit layer have to be exposed many times in part to control alignment errors being smaller, hence manufacturing processes are difficult to be simplified. Conclusively, prior arts do not satisfy the requirements of circuit miniaturization, and are not capable of following the trends of compact semiconductor packages. 
         [0009]    Furthermore, an adhesive material is required to fill in the gap between the chip and the cavity of the carrier board so that the problem of excess adhesive material spilling out of the gap prior to solidification can occur. In order to avoid the problem illustrated above, complexity of the manufacturing processes will be unavoidably increased. Finally, problems of stress between different materials still occur in prior arts to cause warpage, delamination, or popcorn of the carrier board. Therefore, those problems have become imperative issues to be solved by the industry. 
       SUMMARY OF THE INVENTION 
       [0010]    In view of the foregoing shortcomings, an object of the present invention is to provide a method for manufacturing a carrier structure for a semiconductor chip. This method can avoid alignment errors resulting from tiny shifts of the unfixed semiconductor chip located in the cavity of the carrier board. Therefore, the method benefits to advance the alignment accuracy, to simplify manufacturing processes, and to achieve the goal of fine circuits. 
         [0011]    Another object of the present invention is to provide a method for manufacturing a carrier structure for a semiconductor chip so that the problem of excess adhesive material spilling out of a gap prior to solidification can be avoided to reduce the complexity of manufacturing processes. 
         [0012]    Further another object of the present invention is to provide a carrier structure for a semiconductor chip. The carrier structure has a property of dispersing stress between different materials in order to reduce occurrence of delamination. 
         [0013]    In order to achieve the above-mentioned objects, the present invention provides a method for manufacturing a carrier structure for semiconductor chips. The method comprises the steps: providing a carrier board having a first surface and an opposite second surface, wherein the carrier board has at least one through cavity in which a semiconductor chip, having an active surface with a plurality of electrode pads thereon and an opposite inactive surface, is disposed, and a first removable film is formed on the first surface of the carrier board and on one surface of the semiconductor chip on the same side with the first surface of the carrier board so as to temporarily fix the semiconductor chip; filling the gap between the through cavity of the carrier board and the semiconductor chip with an adhesive material in order to fix the semiconductor chip, wherein the first removable film is dented into the gap between the cavity of the carrier board and the semiconductor chip so that the adhesive material does not spill out of the gap; and removing the first removable film, wherein the revealed surface of the adhesive material is a concave surface resulted from the dented first removable film. 
         [0014]    In the present invention, the carrier board comprises a first core layer, a second core layer, and an inner adhesive layer. The inner adhesive layer is located between the first and second core layers to form a sandwich structure. Then, the sandwich structure is combined by thermal pressing to obtain the carrier structure. Part of the inner adhesive layer is squeezed into the gap between the through cavity of the carrier board and the semiconductor chip so as to fix the semiconductor chip. 
         [0015]    The method illustrated above further comprises forming a second removable film on the second surface of the carrier board and on the other surface of the semiconductor chip on the same side with the second surface of the carrier board before filling the gap so that the adhesive material does not spill out of the gap and the semiconductor chip is protected. Then, the second removable film is removed after the first removable film is removed. 
         [0016]    In the present invention, the first and second core layers independently can be metal materials, ceramics materials, circuit boards, or other dielectric materials. Besides, the metal materials can be one selected from the group consisting of Cu, Al, Ni, Fe, Ti, and Mg, or the alloy of the group. The dielectric materials can be photosensitive or non-photosensitive organic resins such as ABF (Ajinomoto Build-up Film), PPE (poly(phenylene ether)), PTFE (poly(tetra-fluoroethylene)), FR4, FR5, BT (bismaleimide triazine), LCP (liquid crystal polymer), BCB (benzocyclo-buthene), PI (poly-imide), and aramide. Preferably, the first and second core layers independently can be circuit boards having circuit structures. 
         [0017]    Besides, the inner adhesive layer located between the first and second core layers, and the adhesive material filling in the gap between the through cavity of the carrier board and the semiconductor chip can be made of one selected from the group consisting of organic dielectric materials, liquid organic resin materials, and pre-preg materials, but preferably are made of pre-preg. 
         [0018]    The semiconductor chip in the present invention can be temporarily fixed in the through cavity of the carrier board by the active or inactive surface of the semiconductor chip attached on the first removable film. 
         [0019]    In the present invention, the first removable film is used to temporarily fix the semiconductor chip. The first removable film can be made of heat-resistant and removable adhesive film materials, but preferably is a release film or an adhesive tape. 
         [0020]    The method of the present invention further comprises forming a built-up structure on the active surface of the semiconductor chip and on one surface of the carrier board on the same side with the active surface of the semiconductor chip. The built-up structure comprises at least one dielectric layer, one circuit layer stacked on every dielectric layer, a plurality of conductive vias, and a plurality of conductive pads, and parts of the conductive vias electrically connect to the electrode pads of the semiconductor chip. 
         [0021]    The present invention also provides a carrier structure for semiconductor chips. The carrier structure comprises a carrier board having at least one through cavity in which a semiconductor chip, having an active surface with a plurality of electrode pads thereon and an opposite inactive surface, is disposed; an adhesive material filling the gap between the through cavity of the carrier board and the semiconductor chip in order to fix the semiconductor chip, wherein the revealed surface of the adhesive material is a concave surface; and a built-up structure having at least one dielectric layer, wherein the dielectric layer is formed on the active surface of the semiconductor chip, on one surface of the carrier board on the same side with the active surface of the semiconductor chip, and on the concave surface of the adhesive material so that the combination of the dielectric layer and the concave surfaces of the adhesive material is advantageous to disperse the stress between different materials. 
         [0022]    In the structure described above, the carrier board comprises a first core layer, a second core layer, and an inner adhesive layer. The inner adhesive layer is located between the first and second core layers to form a sandwich structure. The first and second core layers independently can be metal materials, ceramics materials, circuit boards, or other dielectric materials. The inner adhesive layer and the adhesive material can be made of one selected from the group consisting of organic dielectric materials, liquid organic resin materials, and pre-preg materials. 
         [0023]    In the foregoing structure, the active surface of the semiconductor chip can has a height the same as, higher than, or lower than that of the surface of the carrier board on the same side with the active surface. 
         [0024]    In the foregoing structure, the built-up structure further comprises one circuit layer stacked on every dielectric layer, a plurality of conductive vias, and a plurality of conductive pads, and parts of the conductive vias electrically connect to the conductive pads of the semiconductor chip. 
         [0025]    Hence, in the present invention, the semiconductor chip is fixed temporarily in the through cavity of the carrier board by the first removable film. Then, the semiconductor chip is fixed thoroughly by filling by the adhesive material. Therefore, the problem of alignment errors caused by tiny shifts of the semiconductor chip prior to being fixed in the through cavity of the carrier board can be solved so that the alignment accuracy will be promoted to benefit circuit miniaturization. Moreover, in the present invention, only one exposure is needed for panels during manufacturing for one circuit layer. Hence, possible alignment errors can be controlled to a smaller range so as to simplify the manufacturing processes. Furthermore, the problem of an adhesive material spilling out of a gap prior to solidification can be solved to reduce the complexity of manufacturing processes. The carrier structure of the present invention has a property of dispersing stress between different materials in order to reduce occurrence of delamination. 
         [0026]    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 
         [0027]      FIG. 1  is a cross-sectional view of a conventional carrier structure embedded with chips; 
           [0028]      FIGS. 2A to 2D  show a manufacturing flow chart in cross-sectional views in the embodiment of the present invention; 
           [0029]      FIGS. 3A and 3B  show part of a flow chart in cross-sectional views for manufacturing a carrier structure for a semiconductor chip in the embodiment of the present invention; and 
           [0030]      FIGS. 4A-D  to  8 A-D show manufacturing flow charts in cross-sectional views in other embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0031]    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. 
       Embodiment 1 
       [0032]    With reference to  FIGS. 2A to 2D , there is shown a flow chart in cross-sectional views for manufacturing a carrier structure for a semiconductor chip in the present invention. As shown in  FIG. 2A , a carrier board  20  having a first surface  20   a  and an opposite second surface  20   b  is provided. The carrier board  20  has at least one through cavity  201 . A semiconductor chip  40  having an active surface  40   a  and an opposite inactive surface  40   b  is disposed in the through cavity  201 . A first removable film  30  is formed on the first surface  20   a  of the carrier board  20  so that the semiconductor chip  40  is fixed temporarily by the active surface  40   a  thereof in the through cavity  201  of the carrier board  20 . The carrier board  20  consists of a first core layer  21 , a second core layer  22 , and an inner adhesive layer  23 . The inner adhesive layer  23  is located between the first core layer  21  and the second core layer  22  to form a sandwich structure  20 ′. The sandwich structure  20 ′ is manufactured by stacking the inner adhesive layer  23  on the surface of the first core layer  21 , and subsequently stacking the second core layer  22  on the surface of the inner adhesive layer  23 . Then, at least one through cavity  201  is formed by drilling the sandwich structure  20 ′. 
         [0033]    Herein, the first core layer  21  and the second core layer  22  independently can be metal materials, ceramics materials, circuit boards, or other dielectric materials. Besides, the metal materials can be one selected from the group consisting of Cu, Al, Fe, Ti, and Mg or the alloy of the group. The dielectric materials can be photosensitive or non-photosensitive organic resins such as ABF (Ajinomoto Build-up Film), PPE (poly(phenylene ether)), PTFE (poly(tetra-fluoroethylene)), FR4, FR5, BT (bismaleimide triazine), LCP (liquid crystal polymer), BCB (benzocyclo-buthene), PI (poly-imide), and aramide. In the present embodiment, the first core layer  21  is a circuit board  211  having circuit  212 , and the second core layer  22  is a circuit board  221  having circuit  222 . The inner adhesive layer  23  can be made of one selected from the group consisting of organic dielectric materials, liquid organic resin materials, and pre-preg materials. In the present embodiment, the inner adhesive layer  23  is pre-preg. 
         [0034]    The semiconductor chip  40  illustrated above can be an active component or a passive component. 
         [0035]    Moreover, the first removable film  30  in the present embodiment is used to temporarily fix the semiconductor chip  40 . The first removable film  30  can be made of heat-resistant and removable adhesive film materials. In the present embodiment, a release film is used. 
         [0036]    In  FIG. 2B , the gap between the through cavity  201  of the carrier board  20  and the semiconductor chip  40  is filled with an adhesive material  50  in order to fix the semiconductor chip  40 . The first removable film  30  is dented into the gap between the cavity  201  so that the adhesive material  50  does not spill from the gap. The adhesive material  50  can be made of the same material as the inner adhesive layer  23 . When the carrier board  20  is formed by thermal pressing the sandwich structure  20 ′ consisting of the first core layer  21 , the second core layer  22 , and the inner adhesive layer  23  disposed therebetween, part of the inner adhesive layer  23  is squeezed into the gap between the through cavity  201  of the carrier board  20  and the semiconductor chip  40 , and serves as the adhesive material  50  to fix the semiconductor chip  40 . 
         [0037]    Then, the first removable film  30  in the structure described above is removed. The structure as shown in  FIG. 2C  is obtained. Otherwise, as shown in  FIG. 2B-1 , before the gap is filled by the adhesive material  50 , a second removable film  30 ′ can be formed on the second surface  20   b  of the carrier board  20  and on the inactive surface  40   b  of the semiconductor chip  40  so that the adhesive material  50  does not spill from the gap and the semiconductor chip  40  can be protected. After the first adhesive film  30  is removed, the second adhesive film  30 ′ is also removed to obtain the structure as shown in  FIG. 2C . 
         [0038]    With reference to  FIG. 2D , a built-up structure  60  is formed by the build-up technology on the first surface  20   a  of the carrier board  20  and on the active surface  40   a  of the semiconductor chip  40 . Besides, the built-up structure  60  can be disposed on one side or on both sides (not shown in the figures) of the carrier board  20 . The built-up structure  60  comprises at least one dielectric layer  61 , one circuit layer  62  stacked on every dielectric layer  61 , and a plurality of conductive vias  63 . Parts of the conductive vias  63  electrically connect to electrode pads  401  of the semiconductor chip  40 . Furthermore, a plurality of conductive pads  64  are formed on the surface of the built-up structure  60 . A solder mask  65 , which has a plurality of openings  651  exposing the conductive pads  64  of the built-up structure  60 , is formed on the surface of the built-up structure  60 . Likewise, the solder mask  65  can be formed on the second surface  20   b  of the carrier board  20  to protect the circuit  222  of the second core layer  22 . Moreover, the solder mask  65  has a cavity  650  to expose the inactive surface  40   b  of the semiconductor chip  40  for heat dissipation. 
       Embodiment 2 
       [0039]    The present embodiment is approximately similar to Embodiment 1 except for the manufacturing processes of the carrier board  20 . With reference to  FIGS. 3A and 3B , there is a flow chart in a cross-sectional view. As shown in  FIG. 3A , a core layer  21  adhered with a first removable film  30  is provided first. The core layer  21  has a cavity  21   a.    
         [0040]    Subsequently, as shown in  FIG. 3B , the semiconductor chip  40  is temporarily fixed by the active surface  40   a  thereof adhered on the first removable film  30  in the cavity  21   a  of the first core layer  21 . Finally, the inner adhesive layer  23  and the second core layer  22  are stacked in sequence on the other surface of the first core layer  21  so as to obtain the structure shown in  FIG. 2A . Other steps followed are the same as those of Embodiment 1 hence not to be illustrated again. 
       Embodiment 3 
       [0041]    With reference to  FIGS. 4A to 4D , the present embodiment is approximately similar to Embodiment 1 except the inactive surface  40   b  of the semiconductor chip  40  is higher than the second surface  20   b  of the carrier board  20  ( FIG. 4C ). However, in  FIG. 2C  of Embodiment 1, the inactive surface  40   b  of the semiconductor chip  40  is flush with the second surface  20   b  of the carrier board  20 . Subsequently, other steps are the same as those of Embodiment 1 hence not to be illustrated again. Likewise, the structure of the present embodiment can be manufactured by the processes disclosed in Embodiment 2. 
       Embodiment 4 
       [0042]    With reference to  FIGS. 5A to 5D , the present embodiment is approximately similar to Embodiment 1 except the inactive surface  40   b  of the semiconductor chip  40  is lower than the second surface  20   b  of the carrier board  20  ( FIG. 5 ). Subsequently, other steps are the same as those of Embodiment 1 hence not to be illustrated again. Likewise, the structure of the present embodiment can be manufactured by the processes disclosed in Embodiment 2. 
       Embodiment 5 
       [0043]    With reference to  FIGS. 6A to 6D , the present embodiment is approximately similar to Embodiment 1 except the semiconductor chip  40  is temporarily fixed by the inactive surface  40   b  thereof adhered on the first removable film  30  in the through cavity  201  of the carrier board  20  ( FIG. 6C ), and the active surface  40   a  of the semiconductor chip  40  is flush with the second surface  20   b  of the carrier board  20 . Subsequently, other steps are the same as those of Embodiment 1 hence not to be illustrated again. Likewise, the structure of the present embodiment can be manufactured by the processes disclosed in Embodiment 2. 
       Embodiment 6 
       [0044]    With reference to  FIGS. 7A to 7D , the present embodiment is approximately similar to Embodiment 5 except the active surface  40   a  of the semiconductor chip  40  is higher than the second surface  20   b  of the carrier board  20  ( FIG. 7C ). Subsequently, other steps are the same as those of Embodiment 1 hence not to be illustrated again. Likewise, the structure of the present embodiment can be manufactured by the processes disclosed in Embodiment 2. 
       Embodiment 7 
       [0045]    With reference to  FIGS. 8A to 8D , the present embodiment is approximately similar to Embodiment 5 except the active surface  40   a  of the semiconductor chip  40  is lower than the second surface  20   b  of the carrier board  20  ( FIG. 8C ). Subsequently, other steps are the same as those of Embodiment 1 hence not to be illustrated again. Likewise, the structure of the present embodiment can be manufactured by the processes disclosed in Embodiment 2. 
         [0046]    Conclusively, besides the methods disclosed in Embodiments 1 and 2, another method for disposing the semiconductor chip in the carrier board is mentioned as follows. A first core layer of which an inner adhesive layer is laminated on one surface is provided first. A cavity is formed in a structure of the first core layer laminated with the inner adhesive layer. Then, a first removable film is formed on the other surface of the first core layer. A semiconductor chip is temporarily fixed by the first removable film in the cavity. Finally, a second core layer with a cavity is laminated on the surface of the inner adhesive layer. Therefore, the structure as shown in  FIG. 2A  can be obtained by various methods. 
         [0047]    The present invention also provides a carrier structure for semiconductor chips as shown in  FIGS. 2D ,  4 D,  5 D,  6 D,  7 D, and  8 D. The carrier structure comprises a carrier board  20  having at least one through cavity  201  in which a semiconductor chip  40 , having an active surface  40   a  with a plurality of electrode pads  401  thereon and an opposite inactive surface  40   b , is disposed; an adhesive material  50  filling the gap between the through cavity  201  of the carrier board  20  and the semiconductor chip  40  in order to fix the semiconductor chip  40 , wherein the revealed surface of the adhesive material  50  is a concave surface  500 ; and a built-up structure  60  having at least one dielectric layer  61 , wherein the dielectric layer  61  is formed on the active surface  40   a  of the semiconductor chip  40 , on one surface of the carrier board  20  on the same side with the active surface  40   a  of the semiconductor chip  40 , and on the concave surface  500  of the adhesive material  50  so that the combination of the dielectric layer  61  and the concave surfaces  500  of the adhesive material  50  is advantageous to disperse the stress between different materials. 
         [0048]    In the structure described above, the carrier board  20  comprises a first core layer  21 , a second core layer  22 , and an inner adhesive layer  23 . The inner adhesive layer  23  is located between the first core layer  21  and the second core layer  22 . The first core layer  21  and the second core layer  22  independently can be metal materials, ceramics materials, circuit boards, or other dielectric materials. Besides, the inner adhesive layer  23  and the adhesive material  50  can be made of one selected from the group consisting of organic dielectric materials, liquid organic resin materials, and pre-preg materials. 
         [0049]    In the foregoing structure, the active surface  40   a  of the semiconductor chip  50  can be higher ( FIG. 7D ) than, lower ( FIG. 8D ) than, or flush ( FIGS. 2D and 6D ) with the surface of the carrier board  20  on the same side. 
         [0050]    In the foregoing structure, the built-up structure  60  further comprises one circuit layer  62  stacked on every dielectric layer  61 , a plurality of conductive vias  63 , and a plurality of conductive pads  64 , and parts of the conductive vias  63  electrically connect to the conductive pads  401  of the semiconductor chip  40 . 
         [0051]    Moreover, a solder mask  65  can be formed on the surface of the built-up structure. The solder mask  65  has a plurality of openings  651  so as to expose the conductive pads  64  of the built-up structure  60 . Likewise, the solder mask layer  65  can be made on the other surface of the carrier board  20 . 
         [0052]    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.