Abstract:
An interconnect structure of an integrated circuit and manufacturing method therefor are provided, relating to an interconnect structure of flexible packaging. The interconnect structure includes a first and a second conductive pads. A plurality of tiny and conductive first pillars is respectively formed on the first and second pads. With different densities and thicknesses of the first and second pillars, a contact strength can be generated when the pillars interconnecting with each other, such that the pillars are connected closely. Furthermore, the interconnect structure can also be used to connect with fibers made of conductive materials. Moreover, the higher the density of the pillars, the stronger the contact strength. And, electronic substrates and active or passive electronic elements can be stuck on the other side of each pad. Therefore, the interconnect structure can maintain flexibility and have high reliability without being enhanced by any thermosetting polymer.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No(s). 094142678 filed in Taiwan, R.O.C. on Dec. 2, 2005, the entire contents of which are hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of Invention  
         [0003]     The present invention relates to an interconnect structure and manufacturing method therefor, and more particularly relates to an interconnect structure of an integrated circuit and manufacturing method therefor.  
         [0004]     2. Related Art  
         [0005]     Recently, with the rapid development of technology, people enjoy a better life due to the active research and hard work of scientists. It is the most urgent subject in the future for scientists to research, develop, and manufacture compact and light in weight devices which are safe, environment friendly, portable, and wearable along with the development of multifunctional electronic products. Therefore, it becomes one of the main development directions to develop flexible semiconductor packaging. However, in recent research of flexible electronic packaging, there is no solution that meets the requirement of flexibility directed to the interconnection between individual devices.  
         [0006]     The current interconnect structures presented employ a surface mount process, wherein a solder between the electronic substrates must be employed to accomplish the connection. The process is rather bothersome and cannot provide flexibility, and the contacts cannot bear the thermal stress caused by heat. If the connected substrates need to separate, the solder should be heated to about 220° C. and melted, and then the connected substrates can be separated; Therefore, solder residue may remain on the substrates, affecting the performance. So, it will be a great benefit for the public to develop a flexible interconnect structure that can be interconnected or disconnected easily.  
       SUMMARY OF THE INVENTION  
       [0007]     The object of the present invention is to provide an interconnect structure of the integrated circuit and manufacturing method therefor. With the concept of, for example, fastening tape, a plurality of pillars having different sizes, shapes, and densities is formed on different pads, such that the two pads are closely engaged with each other after they interconnect. Since the pillars are tiny and flexible, users can separate the two pads just by tearing along the edge, thereby solving the problem in the prior art.  
         [0008]     Therefore, to achieve the above object, an interconnect structure of the integrated circuit and manufacturing method therefor disclosed in the present invention are used for interconnecting a first substrate and a second substrate. A first pad is attached on the first substrate, and a second pad is attached on the second substrate. Then, a plurality of first pillars is formed on the first pad, and a plurality of second pillars is formed on the second pad. The distribution densities, shapes, thicknesses, and sizes of the first pillars and the second pillars can be different. By cross-connecting the plurality of first pillars and the plurality of second pillars, the first substrate and the second substrate can be interconnected, the concept of which is similar to cross-connecting two combs with different thicknesses and densities, such that a tight engagement can be achieved.  
         [0009]     The first and second pads and the first and second pillars formed thereon are made of a conductive material, for transmitting the electrical signals sent by the first substrate and the second substrate.  
         [0010]     Moreover, with the interconnect structure of the integrated circuit of the present invention, in addition to interconnecting electronic substrates, the electronic substrate can be interconnected with an object having fibers, for example, clothes having conductive fibers. The electronic substrate is adhered to a pad, in which a plurality of pillars is formed. The pad and the pillars are made of conductive materials. Each pillar is cross-connected with the fibers, thus the electronic substrate or the electronic device constituted of electronic substrate can be attached to the object having conductive fibers.  
         [0011]     In addition to achieving the property of flexibility, the special contact design can absorb the stress resulting from thermal or flexible deformation. In the structure, a plurality of tiny pillars made of conductive materials is formed on the both sides of the contact surface. With the different densities and thicknesses of the pillars on both sides, a tight connecting can be achieved due to the contact strength generated when both sides interconnecting with each other. And the other corresponding side of the contact surface can be of a same structure, and also can be fibers made of conductive materials, such that the conductive hooks can be connected closely. The higher the density of the hooks is, the stronger the contact strength is. And the conductive pillars on both sides of the contact surface are interconnected by using different distribution densities and thicknesses.  
         [0012]     The detailed features and advantages of the present invention will be described in detail in the following embodiments, the content thereof is sufficient to make any skilled in the art to understand the technical content of the present invention and implement accordingly. And any skilled in the art can easily understand the related objects and advantages of the present invention according to the disclosure, claims and drawings of the present specification.  
         [0013]     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     The present invention will become more fully understood from the detailed description given herein below for illustration only for, and which thus is not limitative of the present invention, and wherein:  
         [0015]      FIG. 1A  and  FIG. 1B  are schematic views of an interconnect structure of an integrated circuit according to a first embodiment of the present invention;  
         [0016]      FIG. 2A  and  FIG. 2B  are schematic views of an interconnect structure of an integrated circuit according to a second embodiment of the present invention;  
         [0017]      FIG. 3  is a schematic view of an interconnect structure of an integrated circuit according to a third embodiment of the present invention;  
         [0018]      FIG. 4 a  schematic view of an interconnect structure of an integrated circuit according to a fourth embodiment of the present invention;  
         [0019]      FIG. 5A  is a schematic view of a structure interconnected with an object having fibers according to a fifth embodiment of the present invention;  
         [0020]      FIG. 5B  is a schematic view of a structure interconnected with an object having fibers according to a sixth embodiment of the present invention;  
         [0021]      FIG. 5C  is a schematic view of a structure interconnected with an object having fibers according to a seventh embodiment of the present invention; and  
         [0022]      FIGS. 6A  to  6 N are flow charts of manufacturing the interconnect structure of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]     In order to further illustrate the objects, structures, features, and functions of the present invention, it is described in detail with embodiments. The illustration related to the content of the present invention described above and the following detailed description of the present invention are used for illustrating and explaining the principle of the present invention, and for providing a further explanation of the claims of the present invention.  
         [0024]     Referring to  FIG. 1A , it shows a schematic view of an interconnect structure of an integrated circuit according to a first embodiment of the present invention for interconnecting a first substrate  140  and a second substrate  150 . The interconnect structure comprises a first pad  110 , a plurality of first pillars  130 , a second pad  120 , and a plurality of second pillars  132 , which are all made of conductive materials.  
         [0025]     The first substrate  140  is attached on one side of the first pad  110 , and a plurality of first pillars  130  is formed on the other side of the first pad  110 . The second substrate  150  is attached on one side of the second pad  120 , and a plurality of second pillars  132  is formed on the other side of the second pad  120 . The distribution density of the first pillars  130  is different from that of the second pillars  132 . The shapes, sizes, and thicknesses of the first pillars  130  and the second pillars  132  are different as well. The pillar may be column-shaped, taper-shaped, or hook-shaped. And the arrangement of the first pillars  130  and the second pillars  132  on the pad may be an area array, a peripheral arrangement, or an individual contact arrangement. Similar to the conception of the fastening tape, the plurality of first pillars  130  and the plurality of second pillars  132  are cross-connected because of the different distribution densities of the pillars, so the first substrate  140  and second substrate  150  can be interconnected closely.  
         [0026]     Moreover, a first conductive layer  160  can be further provided between the first pad  110  and the first substrate  140 , and a second conductive layer  170  can be further provided between the second pad  120  and the second substrate  150 . The conductive layers are used for transmitting the electrical signals sent by the first substrate  140  and the second substrate  150 . The attaching method between the first pad  110 , the first substrate  140 , and the first conductive layer  160  can be implemented by one of direct interconnect, alloy reflow interconnection, adhesion, and lamination. The attaching method of the second pad  120 , the second substrate  150 , and the second conductive layer  170  is the same as the above.  
         [0027]     Referring to  FIGS. 1B , it shows a schematic view of the interconnect structure of the integrated circuit of  FIG. 1A  after interconnection, which is similar to cross-connecting two combs having different density and thickness to accomplish an interconnection. In addition, a protective layer  180  is used for protecting the first substrate  140 , the second substrate  150 , the first conductive layer  160 , and the second conductive layer  170  made of conductive materials, and to provide an effect of isolating them from foreign objects.  
         [0028]     Referring to  FIG. 2A , it shows a schematic view of an interconnect structure of the integrated circuit according to a second embodiment of the present invention. It can be seen from the drawing that the shape of the first pillars  210  and the second pillars  212  is the same, and the structure of pillars is constituted of a relatively thin pillar and a relatively thick pillar.  FIG. 2B  is a schematic view of the interconnect structure of  FIG. 2A  after interconnection. The interconnect structure can provide a superior interconnection effect. Since each pillar is tiny, the structure is flexible, such that the structure can be easily disconnected just by tearing along the edge.  
         [0029]      FIG. 3  is a schematic view of an interconnect structure according to a third embodiment of the present invention. The first pillars  312  and second pillars  310  are hook-shaped. And the same structures at two sides can be engaged closely after interconnection. Also,  FIG. 4  is a schematic view of an interconnect structure according to a fourth embodiment of the present invention, wherein the first pillars  410  are column-shaped, and the second pillars  420  are taper shaped, for cross-connecting to accomplish the interconnection.  
         [0030]     In the present invention, the interconnect structures can be connected with each other, and further, the interconnect structure can be interconnected with an object  560  having fibers. Referring to  FIG. 5A , a conductive pad  530  is attached on one side of a substrate  540  with electronic elements, and a plurality of conductive pillars  520  is formed on the pad  530 . The pillars in  FIG. 5A  are hook-shaped, and the arrangement of the pillars  520  on the pad  530  can be an area array, a peripheral arrangement, or an individual contact arrangement. The hooks are cross-connected with the fibers  510 , so as to accomplish the interconnection with the substrate  540 .  
         [0031]     The material of fibers  510  is a conductive material, and the fibers can be weaved in clothes, thus the electronic substrate can stick to the cloths and be wearable. Moreover, a conductive layer  550  is further provided between the substrate  540  and the pad  530 , for transmitting electrical signals sent by the substrate  540 . And the process for attaching between the substrate  540 , the pad  530 , and the conductive layer  550  can be implemented by one of direct interconnection, alloy reflow interconnection, adhesion, or lamination.  
         [0032]     In  FIG. 5B , the shape of pillars  522  is constituted of a thin pillar and a thick pillar. And in  FIG. 5C , the pillars  524  are taper-shaped, and the pillars  522 ,  524  can be inserted in the object  560  having fibers  510 , such as clothes having fibers  510 .  
         [0033]     Finally, referring to  FIGS. 6A  to  6 N, they are flow charts of process of manufacturing the interconnect structure of a shape as in  FIG. 2A . First, a pad  610  is provided. Then, a first photoresist layer  620  is coated on the pad  610 . A first mask  630  is placed on the first photoresist layer  620 , wherein the first mask  630  is provided with a plurality of holes  632 , for exposing the first photoresist layer  620  to an exposure light  634  through the first mask  630 . Thereafter, the first photoresist layer  620  is developed. Then, all exposed portions of the first photoresist layer  620  are removed. The each exposed portion is corresponding to the position of each hole of the first mask  630 , thus a plurality of first column-shaped holes  636  is formed. Subsequently, a conductive material  640  is filled in each of the first column-shaped holes  636 . Then, the first mask  630  is removed, thus the first parts of pillars are completed.  
         [0034]     A second photoresist layer  650  is coated on the first photoresist layer  620 , and a second mask  652  is placed on the second photoresist layer  650 , wherein the second mask  652  is provided with a plurality of holes  654 , and the position of each hole  654  corresponds to the position of each of the first column-shaped holes  636 . The hole  654  is slightly wider than the first column-shaped hole  636 . Thereafter, the second photoresist layer  650  is exposed to the exposure light  634  through the second mask  652 . Then, the second photoresist layer  650  is developed. Next, all exposed portions of the second photoresist layer  650  are removed, and the each exposed portion is corresponding to the position of each hole of the second mask  652 , thus a plurality of second column-shaped holes  656  is formed. Then, the conductive material  640  is filled in each of the second column-shaped holes  656 , and the second mask  652  is removed. Finally, a part of the first photoresist layer  620  and a part of the second photoresist layer  650  without being filled with the conductive material  640  are removed together by etching, thus the interconnect structure of the integrated circuit of the present invention is completed. This interconnect structure can provide a superior interconnection effect.  
         [0035]     The present invention relates to an interconnect structure of flexible packaging, which provides a special interconnect structure design to allow the packaging to maintain flexibility. The contact surface is also capable of bearing the flexible deformation, and absorbing the thermal stress generated by heat. Therefore, the present invention not only has the property of flexibility, but also has a relatively high reliability.  
         [0036]     With the concept of fastening tape, the connecting is flexible and capable of absorbing thermal stress caused by mismatch of the coefficient of thermal expansion, and in conjunction with flexibility of the thin chips and the flexible substrate, a flexible packaging can be obtained. A plurality of small hooks or various clip structures is manufactured on the pad. And the same structures at two sides can be engaged closely after interconnection. Though the binding force generated is small, if the number increases, a relatively strong binding force will be generated. And such a design allows a structure to be separated easily just by tearing along the edge, thus the advantages of convenient displacement and reuse can be achieved. In addition, the other side of the contact surface can have tightly woven metal fibers in addition to the same structure. The present invention can maintain flexibility without thermosetting polymer for enhancing flexibility, and the interconnect structure itself has the property of flexibility such that it can bear deformation when flexed, thus having high reliability.  
         [0037]     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.