Method of making bondable leads using positive photoresist and structures made therefrom

Abstract

A microelectronic component having a plurality of leads are formed at their tip end with bondable material using a process including a mask of positive photoresist material. The leads can be rendered peelable from the substrate by, for example, plasma undercutting the leads. The tip ends of the leads can be bonded to contacts on an opposing microelectronic component, and separated therefrom in horizontal direction by virtue of the peelable leads to form S-shaped leads. The space between the microelectronic components can be filled with a compliant layer to form a microelectronic package.

1 . A solder pad on a lead supported on a dielectric substrate, said solder pad formed by: 
 depositing a positive photoresist material over a metal layer supported on said substrate;    forming an opening in said photoresist material exposing a portion of said metal layer;    forming a solder ball pad by depositing at least one metal through said opening onto the exposed surface of said metal layer;    enlarging said opening in said photoresist material and depositing through the enlarged opening a layer of another metal surrounding said solder ball pad;    removing portions of said metal layer using said photoresist material as a mask to define a lead extending from said solder ball pad over the surface of said substrate; and    removing said photoresist material from said metal layer.    
   
   
       2 . A microelectronic component formed by: 
 providing a dielectric substrate having a surface supporting an electrically conductive layer; 
 coating said electrically conductive layer with positive photoresist material;  
 forming a plurality of openings in said photoresist material exposing said electrically conductive layer therein;  
 forming a plurality of solder ball pads by depositing a first metal layer within said openings over the exposed electrically conductive layer;  
 selectively removing said electrically conductive layer to form leads extending over said surface of said substrate in electrical contact with said first metal layer;  
   enlarging said openings in said photoresist material and depositing through said enlarged opening a second metal layer over said first metal layer;    patterning the said photoresist material to define said leads prior to said selectively removing said electrically conductive layer; and 
 removing said photoresist material from said electrically conductive layer.  
   
   
   
       3 . A microelectronic component formed by: 
 providing a dielectric substrate having a surface supporting a metal layer;    depositing a positive photoresist material over said metal layer;    patterning said photoresist material to delineate on said metal layer a plurality of pad regions exposed through openings formed in said photoresist material;    forming a plurality of solder ball pads by depositing a first electrically conductive material onto said metal layer through said openings in said photoresist material in said pad regions;    patterning said photoresist material to delineate a plurality of lead regions covered by said photoresist material extending over said surface of said substrate from said pad regions;    removing portions of said metal layer uncovered by said later patterning of said photoresist material to form leads in electrical contact with said electrically conductive material in said pad regions;    enlarging said openings in said photoresist material and depositing a second electrically conductive material through said enlarged openings onto an exposed surface of said first electrically conductive material; and    removing residual photoresist material from said metal layer.    
   
   
       4 . A method of making a microelectronic packaging comprising: 
 providing a first microelectronic component having a front surface supporting a plurality of contacts;    providing a second microelectronic component having a surface supporting a plurality of leads and solder ball pads, said second microelectronic component made by providing a dielectric substrate having a surface supporting an electrically conductive layer; coating said electrically conductive layer with a positive photoresist material; forming a plurality of openings in said photoresist material exposing said electrically conductive layer therein; forming a plurality of solder ball pads by depositing a first metal layer within said openings over said exposed electrically conductive layer; selectively removing said electrically conductive layer to form leads extending over said surface of said substrate in electrical contact with said first metal layer; and removing said photoresist material from said electrically conductive layer;    at least partially separating said leads from said substrate;    positioning said second microelectronic component overlying said first microelectronic component;    bonding an end of said leads to said contacts with a bondable material therebetween; and    separating said first and second microelectronic components from each other into spaced apart relationship whereby the end of said leads remain bonded to said contacts and the other end of said leads remain supported by said dielectric substrate.    
   
   
       5 . The method of  claim 4 , further including enlarging said openings in said photoresist material and depositing through said enlarged openings a second metal over said first metal layer.  
   
   
       6 . The method of  claim 5 , further including depositing a bondable material onto an exposed surface of said second metal layer.  
   
   
       7 . The method of  claim 5 , wherein the thickness of said first and second metal layers is less than the thickness of said photoresist material.  
   
   
       8 . The method of  claim 4 , further including patterning said photoresist material to define said leads prior to said selectively removing said electrically conductive layer.  
   
   
       9 . The method  claim 8 , further including at least partially separating said leads from the surface of said substrate.  
   
   
       10 . The method  claim 4 , further including depositing a bondable material through said openings in said photoresist material over the exposed surface of said first metal layer.  
   
   
       11 . The method of  claim 10 , further including enlarging said openings in said photoresist material and depositing through the enlarged openings a second metal layer over said bondable material.  
   
   
       12 . The method of  claim 11 , wherein said first metal layer comprises nickel, said second metal layer comprises gold and gold alloys and said bondable material comprises tin and tin alloys.  
   
   
       13 . The method of  claim 11 , further including heating said microelectronic component to a temperature to cause said bondable material to reflow.  
   
   
       14 . The method of  claim 11 , further including at least partially separating said leads from said surface of said substrate.  
   
   
       15 . A method of making a microelectronic packaging comprising: 
 providing a first microelectronic component having a front surface supporting a plurality of contacts;    providing a second microelectronic component having a surface supporting a plurality of leads and solder ball pads, said second microelectronic component made by providing a dielectric substrate having a surface supporting a metal layer; depositing a positive photoresist material over said metal layer; patterning said photoresist material to delineate on said metal layer a plurality of pad regions exposed through openings formed in said photoresist materials; forming a plurality of solder ball pads by depositing a first electrically conductive material onto said metal layer through said openings in said photoresist material in said pad regions; patterning said photoresist material to delineate a plurality of lead regions covered by said photoresist material extending over said surface of said substrate from said pad regions; removing portions of said metal layer uncovered by said later patterning of said photoresist material to form said leads in electrical contact with said electrically conductive material in said pad regions; removing residual photoresist material from said metal layer;    at least partially separating said leads from said substrate;    positioning said second microelectronic component overlying said first microelectronic component;    bonding said leads to said contacts with a bondable material therebetween; and    separating said first and second microelectronic components from each other into spaced apart relationship whereby a portion of said leads remain bonded to said contacts and another portion of said leads remain supported by said dielectric substrate.    
   
   
       16 . The method of  claim 15 , further including enlarging said openings in said photoresist material and depositing a second electrically conductive material through said enlarged openings onto an exposed surface of said first electrically conductive material.  
   
   
       17 . The method of  claim 16 , further including depositing a bondable material onto an exposed surface of said second electrically conductive material.  
   
   
       18 . The method of  claim 16 , wherein the thickness of said first and second electrically conductive materials is less than the thickness of said photoresist material.  
   
   
       19 . The method of  claim 15 , further including depositing a bondable material through said openings onto an exposed surface of said first electrically conductive material.  
   
   
       20 . The method of  claim 19 , further including enlarging said openings in said photoresist material and depositing through said enlarged openings a second electrically conductive material over said bondable material.  
   
   
       21 . The method of  claim 20 , further including heating said microelectronic component to a temperature to cause said bondable material to reflow.  
   
   
       22 . The method  claim 20 , further including at least partially separating said leads from said surface of said substrate by removing portions of said substrate underlying said leads.  
   
   
       23 . The method of  claim 15 , further including at least partially separating said leads from said surface of said substrate by removing portions of said substrate underlying said leads.  
   
   
       24 . The method of  claim 15 , wherein said patterning of said photoresist material to delineate said pad regions occurs prior to patterning of said photoresist material to delineate said lead regions.  
   
   
       25 . A microelectronic package formed by: 
 providing a first microelectronic component having a front surface supporting a plurality of contacts;    providing a second microelectronic component having a surface supporting a plurality of leads and solder ball pads, said second microelectronic component made by providing a dielectric substrate having a surface supporting an electrically conductive layer; coating said electrically conductive layer with a positive photoresist material; forming a plurality of openings in said photoresist material exposing said electrically conductive layer therein; forming a plurality of solder ball pads by depositing a first metal layer within said openings over said exposed electrically conductive layer; selectively removing said electrically conductive layer to form leads extending over said surface of said substrate in electrical contact with said first metal layer; and removing said photoresist material from said electrically conductive layer;    at least partially separating said leads from said substrate;    positioning said second microelectronic component overlying said first microelectronic component;    bonding an end of said leads to said contacts with a bondable material therebetween; and    separating said first and second microelectronic components from each other into spaced apart relationship whereby the end of said leads remain bonded to said contacts and the other end of said leads remain supported by said dielectric substrate.    
   
   
       26 . A microelectronic package formed by: 
 providing a first microelectronic component having a front surface supporting a plurality of contacts;    providing a second microelectronic component having a surface supporting a plurality of leads and solder ball pads, said second microelectronic component made by providing a dielectric substrate having a surface supporting a metal layer; depositing a positive photoresist material over said metal layer; patterning said photoresist material to delineate on said metal layer a plurality of pad regions exposed through openings formed in said photoresist materials; forming a plurality of solder ball pads by depositing a first electrically conductive material onto said metal layer through said openings in said photoresist material in said pad regions; patterning said photoresist material to delineate a plurality of lead regions covered by said photoresist material extending over said surface of said substrate from said pad regions; removing portions of said metal layer uncovered by said later patterning of said photoresist material to form said leads in electrical contact with said electrically conductive material in said pad regions; removing residual photoresist material from said metal layer;    at least partially separating said leads from said substrate;    positioning said second microelectronic component overlying said first microelectronic component;    bonding said leads to said contacts with a bondable material therebetween; and    separating said first and second microelectronic components from each other into spaced apart relationship whereby a portion of said leads remain bonded to said contacts and another portion of said leads remain supported by said dielectric substrate.