Semiconductor package including flex circuit, interconnects and dense array external contacts

Abstract

A chip scale semiconductor package and a method for fabricating the package are provided. The package includes a semiconductor die and a flex circuit bonded to the face of the die. The flex circuit includes a polymer substrate with a dense array of external contacts, and a pattern of conductors in electrical communication with the external contacts. The package also includes interconnects configured to provide separate electrical paths between die contacts (e.g., bond pads), and the conductors on the flex circuit. Several different embodiments of interconnects are provided including: bumps on the die contacts, bonded to the flex circuit conductors with a conductive adhesive layer; polymer bumps on the conductors, or die contacts, applied in a semi-cured state and then fully cured; solder bumps on the die contacts and conductors, bonded to one another using a bonding tool; rivet-like bonded connections between the conductors and die contacts, formed using metal bumps and a wire bonding or ball bonding apparatus; single point bonded connections between the conductors and die contacts, formed with a bonding tool; and wire bonds between the conductors and die contacts.

1 - 69 . (canceled)  
   
   
       70 . A method for fabricating a semiconductor package comprising: 
 providing a semiconductor die comprising a plurality of die contacts and a plurality of bumps on the die contacts;    providing a flex circuit comprising a polymer substrate a plurality of external contacts on the polymer substrate, and a plurality of conductors on the polymer substrate in electrical communication with the external contacts;    bonding the bumps to the conductors; and    forming an adhesive layer between the die and the polymer substrate.    
   
   
       71 . The method of  claim 70  wherein the forming the adhesive layer step comprises drawing a material into a gap between the die and the polymer substrate.  
   
   
       72 . The method of  claim 70  wherein each conductor comprises a conductive via in the polymer substrate.  
   
   
       73 . The method of  claim 70  wherein the bumps comprise a polymer base material and a plurality of dendritic metal particles in the polymer base material.  
   
   
       74 . The method of  claim 70  wherein the bonding step comprises providing the bumps on the die contacts as semi-cured polymer bumps, placing the semi-cured polymer bumps in contact with the conductors, and then curing the semi cured polymer bumps.  
   
   
       75 . The method of  claim 70  wherein the die is contained on a semiconductor wafer and a singulating step is performed following the bonding step for separating the die from the wafer.  
   
   
       76 . A method for fabricating a semiconductor package comprising: 
 providing a semiconductor die comprising a plurality of first bumps;    providing a flex circuit comprising a polymer substrate having a plurality of external contacts, and a plurality of second bumps in electrical communication with the external contacts;    bonding the first bumps to the second bumps; and    forming an adhesive layer between the die and the second side.    
   
   
       77 . The method of  claim 76  wherein the flex circuit comprises a plurality of conductors having the second bumps thereon.  
   
   
       78 . The method of  claim 76  wherein the flex circuit comprises a plurality of conductive vias in the polymer substrate in electrical communication with the conductors.  
   
   
       79 . The method of  claim 76  wherein the forming the adhesive layer step comprises drawing a material into a gap between the die and the polymer substrate.  
   
   
       80 . The method of  claim 76  wherein the first bumps comprise a conductive polymer.  
   
   
       81 . The method of  claim 76  wherein the first bumps comprise a conductive polymer and the second bumps comprise a metal.  
   
   
       82 . The method of  claim 76  wherein the first bumps and the second bumps comprise a metal.  
   
   
       83 . A method for fabricating a semiconductor package comprising: 
 providing a semiconductor die comprising a plurality of die contacts;    providing a flex circuit comprising a polymer substrate having a plurality of openings, a plurality of external contacts on the polymer substrate, and a plurality of conductors on the polymer substrate in electrical communication with the external contacts;    attaching the polymer substrate to the die with the openings aligned with the die contacts; and    bonding a plurality of wires through the openings to the die contacts and to the conductors.    
   
   
       84 . The method of  claim 83  wherein the bonding step comprises wire bonding.  
   
   
       85 . The method of  claim 83  wherein the conductors include portions proximate to the openings and the wires are bonded to the portions.  
   
   
       86 . The method of  claim 83  wherein the die and the polymer substrate have matching peripheral outlines.  
   
   
       87 . A method for fabricating a semiconductor package comprising: 
 providing a semiconductor wafer comprising a plurality of semiconductor dice having a plurality of die contacts;    providing a flex circuit comprising a polymer substrate having a plurality of openings, a plurality of external contacts on the polymer substrate, and a plurality of conductors on the polymer substrate in electrical communication with the external contacts;    attaching the polymer substrate to the wafer with the openings aligned with the die contacts;    wire bonding a plurality of wires through the openings to the die contacts and to the conductors; and    singulating the dice from the wafer.    
   
   
       88 . The method of  claim 87  wherein the attaching step comprises forming an adhesive layer between the wafer and the flex circuit.  
   
   
       89 . The method of  claim 87  wherein following the singulating step, each package includes a semiconductor die and a portion of the flex circuit having matching peripheral outlines.  
   
   
       90 . The method of  claim 87  wherein the wires comprise aluminum or gold.  
   
   
       91 . A method for fabricating a semiconductor package comprising: 
 providing a semiconductor die comprising a plurality of die contacts;    providing a flex substrate comprising a plurality of first openings, and a plurality of conductors having a plurality of second openings aligned with the first openings; and    forming bonded connections in the second openings bonded to the conductors and to the die contacts.    
   
   
       92 . The method of  claim 91  wherein the die contacts comprise first metal bumps and the bonded connections comprise portions of the first metal bumps bonded to the conductors.  
   
   
       93 . The method of  claim 91  wherein the conductors comprise second metal bumps and the bonded connections comprise portions of the second metal bumps bonded to the conductors.  
   
   
       94 . The method of  claim 91  wherein the forming the bonded connections step comprises placing a bonding tool through the first openings configured to form the bonded connections.  
   
   
       95 . The method of  claim 91  wherein the forming the bonded connections step comprises placing a bonding tool through the first openings and forming bumps in the second openings having portions bonded to the conductors.  
   
   
       96 . The method of  claim 91  wherein the forming the bonded connections step comprises placing a bonding tool through the first openings and forming bumps on the die contacts having portions bonded to the conductors.