Patent Publication Number: US-2006011711-A1

Title: Method of fabricating a semiconductor device and mounting equipment

Description:
CROSS REFERENCE TO RELATED APPLICATION  
      This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2004-205427, filed Jul. 13, 2004, the entire contents of which are incorporated herein by reference.  
     FIELD OF THE INVENTION  
      The present invention relates to a method of fabricating a semiconductor device and a mounting equipment, and in particular, relates to a mounting method and a mounting equipment to mount a semiconductor component including a solder bump on a substrate.  
     DESCRIPTION OF THE BACKGROUND  
      In conventional technique of mounting a semiconductor component including a solder bump, such as a flip chip, on a substrate, an oxidized film formed on a lower end portion of the solder bump is removed so as to form a newly exposed surface while a height of lower surface of the solder bump is uniformed by flattening technique. The semiconductor component is electrically connected to the newly exposed surface on the substrate.  
      Japanese Patent Publication (Kokai) No. 2003-23036 discloses a mounting method with connecting the semiconductor component including the solder bump to the substrate.  FIGS. 5A-5F  are cross-sectional views showing a conventional method of mounting a semiconductor component including a solder bump on a substrate in order steps.  
      As shown in  FIG. 5A , a semiconductor component  103  including a solder bump  103   a  is picked up from a tray  102  by a transfer head  101 .  
      As shown in  FIG. 5B , the transfer head  101  retaining the semiconductor component  103  including the solder bump  103   a  is moved above a flux supply portion  104 , subsequently the transfer head  101  is descending so as to descend the semiconductor component  103  including the solder bump  103   a  to a flat plane  105   a  of the flux supply portion  104 . A coated flux film  106   a  having a prescribed film thickness is formed on the surface of the flat plane  105   a.    
      As shown in  FIG. 5C , the solder bump  103   a  of the semiconductor component  103  contacts with the surface of the flat plane  105   a.  The transfer head  101  presses the semiconductor component  103  including the solder bump  103   a  to the flat plane  105   a  by a prescribed pressing weight while horizontally reciprocating with a prescribed amplitude so as to polish a lower end portion of the solder bump  103   a  by sliding on the flat plane  105   a.    
      As shown in  FIG. 5D , the transfer head  101  is again ascended from the flux supply portion  104  so that a flux  106  is coated on a lower end portion of the solder bump  103   a  by transfer technique. In the process steps mentioned above, the oxidized film at the surface of the lower end portion of the solder bump  103   a  is removed by polishing so that a newly exposed surface is formed on the solder alloy. The flux  106  prevents a newly exposed surface from oxidation.  
      As shown in  FIG. 5E , the transfer head  101  is moved again above a substrate support portion  107 . The solder bump  103   a  is positioned to an electrode  108   a  formed on a substrate  108 . Descending the transfer head  101  provides to dispose the semiconductor component  103  including the solder bump  103   a  on the substrate  108 .  
      As shown in  FIG. 5F , the substrate  108  on which disposed the semiconductor component  103  including the solder bump  103   a  is transferred to reflow process steps. The solder bump  103   a  is heating in the reflow process steps so as to be melt and to be connected with the electrode  108   a.    
      In the mounting method of the semiconductor component including the solder bump mentioned above, polished surface of the solder bump is flattened, as a result, forming the newly exposed surface cannot provide a sufficient area of the surface.  
      Therefore, a mounting method of a semiconductor component including a many solder bumps, each of which has narrow interval for the adjusting bumps, may not provide sufficiently reliable connections.  
     SUMMARY OF THE INVENTION  
      According to an aspect of the invention, there is provided a method of fabricating a semiconductor device including, heating a semiconductor component including a first solder bump, pressing the first solder bump onto a stage having asperity, coating a flux on the first solder bump, heating a substrate including a second solder bump, pressing the second solder bump on the stage having asperity, coating the flux on the second solder bump, contacting the first solder bump on the second solder bump by disposing the semiconductor component on the substrate, and coupling the first solder bump and the second solder bump by heating the semiconductor component and the substrate.  
      According to another aspect of the invention, there is provided a method of fabricating a semiconductor device including, heating a semiconductor component including a first solder bump, pressing the first the solder bump onto a stage having asperity, coating a flux on the first solder bump, heating a substrate including a second solder bump, pressing the second solder bump on the stage having asperity, coating a resin on the second solder bump, contacting the first solder bump on the second solder bump by disposing the semiconductor component on the substrate, and coupling the first solder bump and the second solder bump by heating the semiconductor component and the substrate.  
      According to another aspect of the invention, there is provided mounting equipment mounting a semiconductor component including a first solder bump on a substrate including a second solder bump including, a base, a semiconductor component supply portion disposed on the base, the semiconductor component supply portion supplying a semiconductor component and a substrate, a bump pressing portion disposed on the base, the bump pressing portion including a transfer head and a first stage, the bump pressing portion descending the transfer head, the transfer head including a vacuum chuck and a heater, the transfer head retaining the semiconductor component and the substrate, the transfer head moving above the base, the transfer head descending at prescribed portions, the vacuum chuck picking up the semiconductor component and the substrate from the semiconductor component supply portion, the vacuum chuck retaining the semiconductor component and the substrate, the heater heating the semiconductor component and the substrate, the first stage arranged in opposed to the transfer head, the first stage having asperity, the first stage including a vacuum chuck and a heater, the vacuum chuck retaining the substrate, the heater heating the substrate, the bump pressing portion pressing the semiconductor component and the substrate onto the first stage so as to form a newly exposed surface on the first solder bump and the second solder bump, respectively, and a semiconductor component disposing portion disposed on the base, the semiconductor component including the second stage, the second stage being disposed the substrate on, wherein the second solder bump on the substrate contact with the first solder bump on the semiconductor component retained by the transfer head. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a block diagram showing a mounting equipment fabricating a semiconductor component having a solder bump according to a first embodiment of a present invention;  
       FIG. 2  is a cross-sectional view showing a bump pressing portion in the mounting equipment according to the first embodiment of the present invention;  
       FIGS. 3A-3I  are cross-sectional views showing a method of mounting the semiconductor component having a solder bump according to the first embodiment of the present invention;  
       FIGS. 4A-4B  are cross-sectional views showing a method of mounting a semiconductor component having a solder bump according to a second embodiment of the present invention;  
       FIGS. 5A-5F  are cross-sectional views showing a method of mounting a semiconductor component having a solder bump according to a conventional method. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Embodiments of the present invention will be described hereinafter in detail with reference to the drawings mentioned above.  
      First, according to a first embodiment of the present invention, a mounting equipment for mounting a semiconductor component on a substrate and a method of fabricating a semiconductor device are explained with reference to  FIGS. 1-2 .  FIG. 1  is a block diagram showing a mounting equipment for mounting the semiconductor component on a substrate according to a first embodiment of the present invention.  FIG. 2  is a cross-sectional view showing a bump pressing portion in the mounting equipment.  
      As shown in  FIG. 1 , a mounting equipment  10  includes a transfer path  11  disposed on a base (not illustrated) along a main direction of the base. A semiconductor component supply portion  12  and a substrate supply portion  13  are arranged in one side opposed to the transfer path  11 . A temporary position alignment portion  14 , a bump pressing portion  15 , a flux coating portion  16  and a semiconductor component disposing portion  17  are arranged in the other side having the transfer path  11 .  
      The semiconductor component supply portion  12  supplies a semiconductor component having a solder bump, such as a CPU chip or a memory chip, housed in a magazine to the temporary position alignment portion  14  by using a loader. The substrate supply portion  13  also supplies a substrate having the solder bump, such as a ceramic package, housed in the magazine to the temporary position alignment portion  14  by the loader.  
      In the temporary position alignment portion  14 , a direction of the semiconductor component and the substrate are aligned and the semiconductor component and the substrate are transferred into a tray. The semiconductor component and the substrate are removed from the try by a transfer head (not illustrated) and are transferred along the transfer path  11  while being retained by the transfer head.  
      The semiconductor component and the substrate retained by the transfer head is heated in the bump pressing portion  15 . The solder bump is pressed onto a stage with an asperity in the bump pressing portion  15  so as to crush the end portion of the solder bump and to form a newly exposed surface. In the flux coating portion  16 , the solder bump of the semiconductor component and the substrate retained by the transfer head is contacted on the stage coated with a thin flux so as to transfer the flux on the newly exposed surface of the solder bump.  
      The solder bump of the semiconductor component is disposed on the solder bump of the substrate in the semiconductor component disposing portion  17  and subsequently the semiconductor component is disposed on the substrate so as to tentatively fasten between the semiconductor component and the substrate. The semiconductor component and the substrate are transferred to a solder reflow portion  18  in a reflow equipment which is a different from the mounting equipment  10 .  
      As shown in  FIG. 2 , the bump pressing portion  15  includes a transfer head  21 , a first stage  22  with asperity at an upper surface and a gas nozzle  23 .  
      The transfer head  21  has a function of horizontal and vertical movement with respect to the transfer path  11 . The transfer head  21  includes a vacuum chuck  24  having a heater  25 . A semiconductor component  26  is retained by the vacuum chuck  24  and heated by the heater  25  at a prescribed temperature that the solder bump  26   a  does not melt.  
      The first stage  22  includes a heater  27 , and an upper surface of the first stage  22   a  is mechanically processed to have asperity, such as protrusions  22   b.  The solder bump  26   a  of the semiconductor component  26  is absorbed to the upper surface of the first stage  22   a  retained by the vacuum chuck  24  and is pressed by the transfer head  21 . The upper surface of the first stage  22   a  is heated by the heater  27  at a prescribed temperature that the solder bump  26   a  does not melt.  
      A performance of the heater  25 ,  27  involve not to make the solder bump melt  26   a  in rising temperature. In this case, the heater  25 ,  27  may not be restricted, however, a thin film heater embedded in the vacuum chuck  24  is desirable.  
      One end of the gas nozzle  23  is coupled to an inactive gas source, such as a nitrogen gas supply line (not illustrated), the other end of the gas nozzle  23  is arranged near the first stage  22 . Blowing an inactive gas from a gas ejection portion  23   a  to the upper surface of the first stage  22   a  results in controlling of atmosphere near the upper surface of the first stage  22   a  as a non-oxidizing gas.  
      A method of mounting the semiconductor component on the substrate by the mounting equipment  10  is explained in detail.  
       FIGS. 3A-3I  are cross-sectional views showing process steps of mounting the semiconductor component on the substrate in order to steps.  FIGS. 3A-3C  are cross-sectional views showing a pressing process of the solder bump.  FIGS. 3D-3F  are cross-sectional views showing a coating process of a flux on the solder bump.  FIGS. 3G-3I  are cross-sectional views showing a disposing process of the semiconductor component on the substrate and a coupling process of the solder bump.  
      As shown in  FIG. 3A , the solder bump  26   a  of the semiconductor component  26  is retained by the vacuum chuck  24  where the surface of the semiconductor component  26  is faced to downward and is transferred from a tray (not illustrated) of the temporary position alignment portion  14  to an upper portion of the first stage  22 .  
      The heater  27  preliminarily rises a temperature of the upper surface of the first stage  22   a  below melting point of the solder bump  26   a,  such as 100˜270° C. Nitrogen gas blew from the gas nozzle  23  retains the upper surface of the first stage  22   a  and near there as non-oxidizing atmosphere. In this stage, the heater  25  is put off.  
      As shown in  FIG. 3B , after the heater  25  is put on, descending the transfer head  21  retaining the semiconductor component  26  conducts the semiconductor component  26  having the solder bump  26   a  onto the upper surface of the first stage  22   a.  Subsequently, the transfer head  21  presses the semiconductor component  26  having the solder bump  26   a  on the upper surface of the first stage  22   a  at a prescribed pressing-load.  
      A solder alloy is softened by heating, subsequently the protrusions  22   b  burst through an oxide skin film (not illustrated) and cover the surface of the solder alloy by using pressing. The solder bump  26   a  is stuck by the protrusions  22   b  and a lower end portion of the solder bump  26   a  crushed by pressing so as to be deformed. Accordingly, a newly exposed surface area can be sufficiently formed by lower pressing strength.  
      A diameter of the protrusions  22   b  can be such as 10%-20% of that of the solder bump. For example, when the solder bump has a diameter of 100 μm, it is suitable that the protrusions  22   b  have a height of 10 μm and a length of 10 μm. The substrate  22  having the protrusions  22   b  enable to form a newly exposed surface having about 100 protrusions in the lower portion of the solder bump so as to have twice area as compared with a plane surface.  
      As shown in  FIG. 3C , after the heater  25  is put off, the transfer head  21  retaining the semiconductor component  26  is again raised up. The semiconductor component  26  is retained in non-oxidizing atmosphere until a temperature of the semiconductor component  26  is rapidly decreased to a range which the solder bump  26   a  is not oxidized in the atmosphere.  
      Accordingly, the solder bump  26   a  having the same protrusions  26   b  in shape as the protrusions  22   a  and sufficiently having newly exposed surface area is obtained.  
      As shown in  FIG. 3D , the transfer head  21  retaining the semiconductor component  26  is moved over a second stage  31  of the flux coating portion  16 , subsequently the transfer head  21  is descended. The semiconductor component  26  having the solder bump  26   a  is descended on the upper surface of the second stage  31   a.  The coated flux film  32  with a prescribed film-thickness is formed on the upper surface of the second stage  31   a.    
      As shown in  FIG. 3E , the solder bump  26   a  of the semiconductor component  26  contacts with the upper surface of the second stage  31   a  and the solder bump  26   a  is immersed in the flux film  32 .  
      As shown in  FIG. 3F , the transfer head  21  is again ascended from the second stage  31 . The flux film  32  is coated on the lower end portion of the solder bump  26   a  by transferring technique. As a result, a newly exposed surface formed in the under surface of solder bump  26   a  is protected by a surface film  32   a  of the flux film  32  and is prevented from oxidizing.  
      A newly exposed surface is formed on the solder bump and the flux is coated on the substrate. The processing steps are basically the same as those in the above-mentioned steps and the explanations on the processing steps are omitted.  
      As shown in  FIG. 3G , the transfer head  21  retaining the semiconductor component  26  is moved above a third stage  41  of a semiconductor component disposing portion  17 . The transfer head  21  is descended onto an upper surface of the third stage  41   a.  The substrate  42  including the solder bump  42   a  and being formed the newly exposed surface is arranged on the third stage  41   a.    
      As shown in  FIG. 3H , the solder bump  26   a  of the semiconductor component  26  is positioned to the solder bump  42   a  of the substrate  42 . The solder bump  26   a  of the semiconductor component  26  is disposed on the solder bump  42   a  of the substrate  42  and the semiconductor component  26  is disposed on the substrate  42  by descending the transfer head  21 .  
      As shown in  FIG. 3I , the substrate  42  including the solder bump  42   a  disposed on the semiconductor component  26  including the solder bump  26   a  is transferred to the reflow portion  18 . Heating the substrate  42  in the reflow portion  18  causes melting and mixing the solder bump  26   a,    42   a  so as to be formed the solder bump coupling portion  43 . Finally, the semiconductor device  44  is completed. The semiconductor device  44  has the semiconductor component  26  including the solder bump mounted on the substrate  42  including the solder bump  42   a.    
      As mentioned above, the solder alloy is softened by heating in the method of mounting the semiconductor component, and subsequently the solder bump is pressed on a stage having asperity to be deforming. Accordingly, a newly exposed surface having a sufficient area can be formed in the solder bump by lower pressing strength.  
      Coupling between the semiconductor component and the substrate at the newly exposed surface provides a high reliable performance on the coupling area. Accordingly, a highly reliable semiconductor device having high packing density can be provided.  
      Next, according to a second embodiment of the present invention, a mounting process is explained with reference to  FIG. 4 .  
       FIG. 4  is a cross-sectional view showing a method of mounting of a semiconductor component called no-flow-under-fill method in order of steps by using a mounting equipment. The no-flow-under-fill method conducts simultaneously coupling between solder bumps and sealing over the coupling portion with a resin to airproof the coupling portion.  
      In the second embodiment, a portion of a same composition as the first embodiment is attached the same number and explanation of the portion of the same composition is omitted.  
      The second embodiment has a different point from the first embodiment as mentioned below. A resin is coated on a substrate so as to bury the solder bump  42   a;  the semiconductor component  26  is successively disposed on the substrate.  
      As shown in  FIG. 4A , the substrate  42  formed a newly exposed surface having a sufficient area is disposed on the upper surface of a third stage  41   a.  A resin  51  being a thickness of such as 100˜150 μm is coated on the solder bump  42   a.    
      The solder bump  26   a  of the semiconductor component  26  is positioned to the solder bump  42   a  of the substrate  42 , and subsequently is disposed on the solder bump  42   a  of the substrate  42  and the semiconductor component  26  is disposed on the substrate  42  by descending the transfer head  21 .  
      The resin  51  may have heat resistance against melting point of the solder and adhesiveness with the solder, therefore a silicon resin is suitable, for example. Furthermore, the resin  51  is coated on the substrate  42  by a dispenser (not illustrated).  
      As shown in  FIG. 4B , the substrate  42  disposed on the semiconductor component  26  is transferred to a reflow portion  18  (not illustrated). Heating the substrate  42  in the reflow portion  18  causes melting and mixing the solder bump  26   a,    42   a  so as to be formed a solder bump coupling portion  52 . Finally, a semiconductor device  53  is completed. The semiconductor device  44  has the semiconductor component  26  including the solder bump mounted on the substrate  42  including the solder bump  42   a.    
      As mentioned above, coupling between the solder bumps without a flux and filling a resin into a space between a semiconductor component and a substrate are simultaneously performed by the no-flow-under-fill method. As a newly exposed surface with a sufficient area is formed, coupling between the semiconductor component and the substrate at the newly exposed surface provides a high reliable performance on the coupling area.  
      In the method of mounting the semiconductor component according to the second embodiment, the no-flow-under-fill method without the flux can provide a high reliable performance on the coupling area, as the newly exposed surface with a sufficient area is formed.  
      In this way, semiconductor device having a high reliable coupling can be obtained by relatively less process steps.  
      Accordingly, a highly reliable semiconductor device having high packing density can be provided.  
      Other embodiments of the present invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and example embodiments be considered as exemplary only, with a true scope and spirit of the invention being indicated by the claims that follow. The invention can be carried out by being variously modified within a range not deviated from the gist of the invention.  
      For example, a newly exposed surface may be formed on a semiconductor component or a solder bump in a range of specific coupling strength.  
      Moreover, a sheet having protrusions may be disposed on an upper surface of a first stage. Melting and mixing solder bump of a semiconductor component and a solder bump of a substrate by heating may start simultaneously with disposing the semiconductor component on the substrate. Moreover, atmosphere in a heating process may be reductive.