Patent Publication Number: US-11640948-B2

Title: Microelectronic devices and apparatuses having a patterned surface structure

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/414,440, filed May 16, 2019, now U.S. Pat. No. 10,950,564, issued Mar. 16, 2021, which is a continuation of U.S. patent application Ser. No. 15/966,447, filed Apr. 30, 2018, now U.S. Pat. No. 10,354,966, issued Jul. 16, 2019, which is a divisional of U.S. patent application Ser. No. 14/731,426, filed Jun. 5, 2015, now U.S. Pat. No. 10,008,461, issued Jun. 26, 2018, the disclosure of each of which is hereby incorporated herein in its entirety by this reference. 
    
    
     BACKGROUND 
     A bump is an important component in a flip-chip package structure for connecting a substrate and chip. The flip-chip package structure often applies the bump as an agent to mechanically or electrically connect the substrate and the chip. The bump is crucial for the connection between the substrate and the chip, as the reliability of the bump affects the operation of the whole flip-chip package structure. The purpose of packaging is to protect the chip during various processes and attach a packaged chip onto a printed circuit board. However, any damage during packaging to the chip is not acceptable. 
     Reflow process is the most common method of attaching surface mount components to a circuit board and/or a metal pad. For better reliability and attachment to the metal pad, the bump is processed through the reflow process. In the reflow process, the entire assembly of the circuit board and bump is under a thermal treatment, such as by annealing. The thermal treatment may be accomplished by passing the assembly through a reflow oven or under an infrared lamp. Accordingly, it is essential to improve the reliability of the bump in the packaging process. 
     BRIEF SUMMARY 
     The present disclosure provides a connector structure. The connector structure includes a semiconductor substrate, a metal layer, a passivation layer, and a conductive structure. The metal layer is over the semiconductor substrate. The passivation layer is over the metal layer and includes an opening. The conductive structure is contacted with the metal layer in a patterned surface structure of the conductive structure through the opening of the passivation layer. 
     In various embodiments of the present disclosure, the conductive structure includes a bump or a soldering ball. 
     In various embodiments of the present disclosure, the patterned surface structure of the conductive structure includes a metal portion and a supporting portion. 
     In various embodiments of the present disclosure, the connector structure further includes an under-bump metallurgy (UBM) layer. The UBM layer is disposed between the metal layer and the conductive structure. 
     In various embodiments of the present disclosure, the supporting portion of the patterned surface structure is a mesh, regularly aligned pillars, or a concentric cylinder. 
     In various embodiments of the present disclosure, the pillars have a cross section comprising a polygon, a circle or an oval. 
     In various embodiments of the present disclosure, the supporting portion of the patterned surface structure is made of at least one inorganic material such as silicon dioxide, silicon nitride, titanium dioxide, aluminum oxide, or at least one organic material such as polyimide, polybenzoxazole (PBO), or a combination thereof. 
     In various embodiments of the present disclosure, the metal portion of the patterned surface structure is made of Sn, Ag, Cu, Au, alloy or a combination thereof. 
     In various embodiments of the present disclosure, the UBM layer is made of TiN, Ti, WN, Sn, Ag, Cu, Au, Ni, alloy or a combination thereof. 
     In various embodiments of the present disclosure, the opening of the passivation layer has a shape comprising a polygon, a circle or an oval. 
     The present disclosure provides a method of manufacturing a connector structure, and the method includes the following steps. A metal layer is formed over a semiconductor substrate. A passivation layer is formed over the metal layer. The passivation layer is recessed to form an opening. The conductive structure is formed. The conductive structure has a patterned surface structure, and the patterned surface structure is in contact with the metal layer through the opening of the passivation layer. 
     In various embodiments of the present disclosure, the process of recessing the passivation layer to form the opening includes the following steps. A photoresist is applied onto the passivation layer. The passivation layer is subjected to lithography and etching to form the opening with a remaining portion of the passivation layer as a supporting portion therein. 
     In various embodiments of the present disclosure, the process of forming the conductive structure includes the following steps. Metal is applied into the opening of the passivation layer. The metal is reflowed to form the conductive structure. 
     In various embodiments of the present disclosure, after recessing the passivation layer and before forming the conductive structure, the method further includes forming a supporting portion in the opening of the passivation layer. 
     In various embodiments of the present disclosure, the process of forming the conductive structure includes the following steps. Metal is applied into the opening of the passivation layer. The metal is reflowed to form the conductive structure. 
     In various embodiments of the present disclosure, the process of forming the conductive structure includes the following steps. The conductive structure is formed, and the conductive structure has the patterned surface structure with a metal portion and a supporting portion. The patterned surface structure of the conductive structure is connected to the metal layer through the opening of the passivation layer. 
     In various embodiments of the present disclosure, after recessing the passivation layer and before forming the conductive structure, the method further includes forming an under-bump metallurgy (UBM) layer between the metal layer and the conductive structure. 
     In various embodiments of the present disclosure, the supporting portion is made of at least one inorganic material such as silicon dioxide, silicon nitride, titanium dioxide, aluminum oxide, or at least one organic material such as polyimide, polybenzoxazole (PBO), or a combination thereof. 
     In various embodiments of the present disclosure, the metal portion of the patterned surface structure is made of Sn, Ag, Cu, Au, alloy or a combination thereof. 
     In various embodiments of the present disclosure, the UBM layer is made of TiN, Ti, WN, Sn, Ag, Cu, Au, Ni, alloy or a combination thereof. 
     These and other features, aspects, and advantages of the present disclosure will become better understood with reference to the following description and appended claims. 
     It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure may be more fully understood by reading the following detailed description of the embodiments, with reference made to the accompanying drawings as follows: 
         FIG.  1    is a cross-sectional view of a connector structure according to various embodiments of the present disclosure; 
         FIGS.  2 A- 2 C  are bottom views along line A-A′ in  FIG.  1    according to various embodiments of the present disclosure; 
         FIG.  3    is a cross-sectional view of a connector structure according to various embodiments of the present disclosure; 
         FIGS.  4 A- 4 C  are cross-sectional views of intermediate stages during the fabricating of a connector structure according to various embodiments of the present disclosure; 
         FIGS.  5 A- 5 D  are cross-sectional views of intermediate stages during the fabricating of a connector structure according to various embodiments of the present disclosure; 
         FIGS.  6 A- 6 D  are cross-sectional views of intermediate stages during the fabricating of a connector structure according to various embodiments of the present disclosure; and 
         FIGS.  7 A- 7 D  are cross-sectional views of intermediate stages during the fabricating of a connector structure according to various embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
     The following embodiments are disclosed with accompanying diagrams for detailed description. For illustration clarity, many details of practice are explained in the following descriptions. However, it should be understood that these details of practice do not intend to limit the present invention. That is, these details of practice are not necessary in parts of embodiments of the present invention. Furthermore, for simplifying the drawings, some of the conventional structures and elements are shown with schematic illustrations. 
     As mentioned above, the bump is crucial for the connection between the substrate and chip, as the reliability of the bump affects the operation of the whole flip-chip package structure. For better reliability and attachment to the metal pad, the bump is processed through the reflow process. However, the bump often causes chip warpage during reflowing. Accordingly, an improved connector structure and a manufacturing method thereof are required. 
     The present disclosure provides a connector structure and a method of fabrication thereof. The connector structure has a patterned surface structure, which can improve chip warpage during reflowing. Therefore, the connector structure provided by the present disclosure can avoid chip crack, enhance reliability, and further lower the overall warpage level. 
       FIG.  1    is a cross-sectional view of a connector structure according to various embodiments of the present disclosure. As shown in  FIG.  1   , a connector structure  100  includes a semiconductor substrate  110 , a metal layer  120 , a passivation layer  130 , and a conductive structure  140 . The semiconductor substrate  110  has a top metal layer  120  thereon. The passivation layer  130  with an opening is over the metal layer  120 , and the conductive structure  140  is in contact with the metal layer  120  in a patterned surface structure  142  of the conductive structure  140  through the opening of the passivation layer  130 . The patterned surface structure  142  of the conductive structure  140  includes a metal portion  142   a  and a supporting portion  142   b . In some embodiments, it should be noted that the supporting portion  142   b  of the patterned surface structure  142  may be obtained from a remaining portion of the passivation layer  130 , from newly added materials in the opening of the passivation layer  130 , or by directly forming the supporting portion  142   b  in the conductive structure  140 . The abovementioned options for obtaining the supporting portions will be discussed in greater detail hereafter (in  FIGS.  4 A- 6 D ). 
     In some embodiments, the conductive structure  140  includes a bump or a soldering ball. According to some embodiments, the opening of the passivation layer  130  has a shape comprising a polygon, a circle or an oval. When the shape of the opening is a polygon, examples of the polygon include, but are not limited to, triangle, rectangle, trapezoid, parallelogram, rhombus, pentagon, or hexagon. In some embodiments, the material of the supporting portion  142   b  of the conductive structure  140  includes, but is not limited to, at least one inorganic material such as silicon dioxide, silicon nitride, titanium dioxide, aluminum oxide, or at least one organic material such as polyimide, polybenzoxazole (PBO), or a combination thereof. In some embodiments, the material of the metal portion  142   a  of the patterned surface structure  142  is Sn, Ag, Cu, Au, alloy or a combination thereof. In some embodiments, the material of the passivation layer  130  is at least one inorganic material such as silicon dioxide, silicon nitride, titanium dioxide, aluminum oxide, or at least one organic material such as polyimide, polybenzoxazole (PBO), or a combination thereof. 
     The present disclosure provides a connector structure  100 , which has the conductive structure  140  in contact with the metal layer  120  through the patterned surface structure  142 . Further, the supporting portion  142   b  of the patterned surface structure  142  can reduce stress during a reflow process to improve chip warpage. Therefore, the patterned surface structure  142  of conductive structure  140  in the connector structure  100  can avoid chip crack, enhance reliability, and further lower the overall warpage level. 
       FIGS.  2 A- 2 C  are the bottom views along line A-A′ in  FIG.  1    according to various embodiments of the present disclosure. Referring to  FIG.  2 A , the supporting portion  142   b  of the patterned surface structure  142  is a mesh in an embodiment. According to another embodiment,  FIG.  2 B  illustrates the supporting portion  142   b  of the patterned surface structure  142  as regularly aligned pillars. For example, the pillars have a cross section including a polygon, a circle or an oval. In addition, examples of the polygon include, but are not limited to, triangle, rectangle, trapezoid, parallelogram, rhombus, pentagon, or hexagon.  FIG.  2 B  illustrates the pillars with a circular cross section. In some embodiments, the supporting portion  142   b  of the patterned surface structure  142  is one or more concentric cylinder.  FIG.  2 C  illustrates that the supporting portion  142   b  of the patterned surface structure  142  is two concentric cylinders. 
       FIG.  3    is a cross-sectional view of a connector structure according to various embodiments of the present disclosure. As shown in  FIG.  3   , a connector structure  200  includes a semiconductor substrate  210 , a metal layer  220 , a passivation layer  230 , a conductive structure  240  and an under-bump metallurgy (UBM) layer  250 . The semiconductor substrate  210  has a top metal layer  220  thereon. The passivation layer  230  with an opening is over the metal layer  220 , and the conductive structure  240  is contacted with the metal layer  220  in a patterned surface structure  242  of the conductive structure  240  through the opening of the passivation layer  230 . The patterned surface structure  242  of the conductive structure  240  includes a metal portion  242   a  and a supporting portion  242   b . The UBM layer  250  is disposed between the metal layer  220  and the conductive structure  240 , and examples of the material of the UBM layer  250  include, but are not limited to, TiN, Ti, WN, Sn, Ag, Cu, Au, Ni, alloy or a combination thereof. However,  FIG.  3    illustrates the embodiments corresponding to the embodiments shown in  FIG.  1   , and hence the details are not repeated herein. Therefore, similar materials and any details, such as those discussed above with reference to  FIG.  1    may be utilized according to some embodiments. 
       FIGS.  4 A- 4 C  are cross-sectional views of intermediate stages during the fabricating of a connector structure according to various embodiments of the present disclosure. 
     In some embodiments, the present disclosure provides a method of manufacturing a connector structure, such as connector structure  300  (see  FIG.  4 C ). Referring first to  FIG.  4 A , a metal layer  320  is formed over a semiconductor substrate  310 , and then a passivation layer  330  is formed over the metal layer  320 . Next, as illustrated in  FIG.  4 B , the passivation layer  330  is recessed to form an opening  332 . As discussed below in greater detail, a photoresist (not shown) is applied onto the passivation layer  330 . The passivation layer  330  is subjected to lithography and etching to form the opening  332  with a remaining portion of passivation layer  330  as a supporting portion  334  therein. Continuing in  FIG.  4 C , metal is applied into the opening  332  (see  FIG.  4 B ), and then the metal is reflowed to form a conductive structure  340  with a patterned surface structure  342 . The patterned surface structure  342  includes a metal portion  342   a  and a supporting portion  334 , and is in contact with the metal layer  320  through the opening  332  (see  FIG.  4 B ) of the passivation layer  330 . As discussed below in greater detail, examples of the means of applying metal into the opening  332  ( FIG.  4 B ) include, but are not limited to, plating, thermal evaporation or sputtering. In some embodiments, the metal is reflowed by annealing through a reflow oven or under an infrared lamp. 
     With continued reference to  FIGS.  4 A- 4 C , in some embodiments, the material of the supporting portion  334 , which is the same as the passivation layer  330 , is at least one inorganic material such as silicon dioxide, silicon nitride, titanium dioxide, aluminum oxide, or at least one organic material such as polyimide, polybenzoxazole (PBO), or a combination thereof. The metal portion  342   a  of the patterned surface structure  342  includes, but is not limited to, Sn, Ag, Cu, Au, alloy or a combination thereof according to some embodiments. 
       FIGS.  5 A- 5 D  are cross-sectional views of intermediate stages during the fabricating of a connector structure according to various embodiments of the present disclosure. 
     In some embodiments, the present disclosure provides a method of manufacturing a connector structure, such as connector structure  400  (see  FIG.  5 D ). Referring first to  FIG.  5 A , a metal layer  420  is formed over a semiconductor substrate  410 , and then a passivation layer  430  is formed over the metal layer  420 . Next, as illustrated in  FIG.  5 B , the passivation layer  430  is recessed to form an opening  432 . As discussed below in greater detail, a photoresist (not shown) is applied onto the passivation layer  430 . The passivation layer  430  is subjected to lithography and etching to form the opening  432 . Referring now to  FIG.  5 C , a supporting portion  440  is formed in the opening  432  (see  FIG.  5 B ). According to some embodiments, the supporting portion  440  is made of dielectric material, such as silicon dioxide, silicon nitride, titanium dioxide, or a combination thereof. Continuing in  FIG.  5 D , metal is applied into the opening  432  ( FIG.  5 B ), and then the metal is reflowed to form the conductive structure  450  with a patterned surface structure  452 . The patterned surface structure  452  includes a metal portion  452   a  and a supporting portion  440 , and is in contact with the metal layer  420  through the opening  432  ( FIG.  5 B ) of the passivation layer  430 . As discussed below in greater detail, examples of the means of applying metal into the opening  432  ( FIG.  5 B ) include, but are not limited to, plating, thermal evaporation or sputtering. In some embodiments, the metal is reflowed by annealing through a reflow oven or under an infrared lamp. In addition, similar materials such as those discussed above with reference to  FIGS.  4 A- 4 C  may be utilized according to some embodiments. 
       FIGS.  6 A- 6 D  are cross-sectional views of intermediate stages during the fabricating of a connector structure according to various embodiments of the present disclosure. 
     In some embodiments, the present disclosure provides a method of manufacturing a connector structure, such as connector structure  500  (see  FIG.  6 D ). Referring first to  FIG.  6 A , a metal layer  520  is formed over a semiconductor substrate  510 , and then a passivation layer  530  is formed over the metal layer  520 . Next, as illustrated in  FIG.  6 B , the passivation layer  530  is recessed to form an opening  532 . As discussed below in greater detail, a photoresist (not shown) is applied onto the passivation layer  530 . The passivation layer  530  is subjected to lithography and etching to form the opening  532 . Referring to  FIG.  6 C , a conductive structure  540  is formed independently, and has a patterned surface structure  542  with a metal portion  542   a  and a supporting portion  542   b . Continuing in  FIG.  6 D , the patterned surface structure  542  of the conductive structure  540  is connected to the metal layer  520  through the opening  532  (see  FIG.  6 B ) of the passivation layer  530 . In addition, the similar materials such as those discussed above with reference to  FIGS.  4 A- 4 C  may be utilized according to some embodiments. 
     According to some embodiments, after recessing the passivation layer and before forming the conductive structure, the method further includes forming an under-bump metallurgy (UBM) layer between the metal layer and the conductive structure. Examples of the method of forming the UBM layer include, but are not limited to, the process as shown in  FIGS.  7 A- 7 D . 
       FIGS.  7 A- 7 D  are cross-sectional views of intermediate stages during the fabricating of a connector structure according to various embodiments of the present disclosure. 
     In some embodiments of the present disclosure provide a method of manufacturing a connector structure  600  (see  FIG.  7 D ). Referring first to  FIG.  7 A , a metal layer  620  is formed over a semiconductor substrate  610 , and then a passivation layer  630  is formed over the metal layer  620 . Next, as illustrated in  FIG.  7 B , the passivation layer  630  is recessed to form an opening  632 . As discussed below in greater detail, a photoresist (not shown) is applied onto the passivation layer  630 . The passivation layer  630  is subjected to lithography and etching to form the opening  632  with a remaining portion of passivation layer  630  as a supporting portion  634  therein. The opening  632  with the supporting portion  634  has an upper surface. Continuing in  FIG.  7 C , a UBM layer  640  is formed conformally on the upper surface of the opening  632 . Subsequently, referring to  FIG.  7 D , metal is applied into the opening  632  (see  FIG.  7 B ), and then the metal is reflowed to form the conductive structure  650  with a patterned surface structure  652 . The patterned surface structure  652  includes a metal portion  652   a  and a supporting portion  634 , and is in contact with the metal layer  620  through the opening  632  ( FIG.  7 B ) of the passivation layer  630 . As discussed below in greater detail, examples of the means of applying metal into the opening  632  ( FIG.  7 B ) include, but are not limited to, plating, thermal evaporation or sputtering. In some embodiments, the metal is reflowed by annealing through a reflow oven or under an infrared lamp. In addition, similar materials such as those discussed above with reference to  FIGS.  4 A- 4 C  may be utilized according to some embodiments. 
     The embodiments of the present disclosure discussed above have advantages over existing connector structures and processes, and the advantages are summarized below. The bump often causes chip warpage during reflowing. Instead, the present disclosure provides an improved connector structure and a manufacturing method thereof. The conductive structure of the connector structure can contact with the metal layer through the patterned surface structure. Furthermore, the patterned surface structure includes a metal portion and a supporting portion. The supporting portion can reduce stress during reflowing, so as to improve the issue of chip warpage. To summarize the above points, the patterned surface structure of the conductive structure in the connector structure can improve chip warpage during reflowing to avoid chip crack, enhance reliability, and further lower the overall warpage level. 
     Although the present invention has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein. 
     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 appended claims.