Method for forming microelectronic spring structures on a substrate

Abstract

A method for fabricating microelectronic spring structures is disclosed. In an initial step of the method, a layer of sacrificial material is formed over a substrate. Then, a contoured surface is developed in the sacrificial material, such as by molding the sacrificial material using a mold or stamp. The contoured surface provides a mold for at least one spring form, and preferably for an array of spring forms. If necessary, the sacrificial layer is then cured or hardened. A layer of spring material is deposited over the contoured surface of the sacrificial material, in a pattern to define at least one spring form, and preferably an array of spring forms. The sacrificial material is then at least partially removed from beneath the spring form to reveal at least one freestanding spring structure. A separate conducting tip is optionally attached to each resulting spring structure, and each structure is optionally plated or covered with an additional layer or layers of material, as desired. An alternative method for making a resilient contact structure using the properties of a fluid meniscus is additionally disclosed. In an initial step of the alternative method, a layer of material is provided over a substrate. Then, a recess is developed in the material, and fluid is provided in the recess to form a meniscus. The fluid is cured or hardened to stabilize the contoured shape of the meniscus. The stabilized meniscus is then used to define a spring form in the same manner as the molded surface in the sacrificial material.

1 - 67 . (canceled)  
   
   
       68 . A method of forming a molded surface on a substrate using a stamping tool having at least a portion that is translucent, said method comprising: 
 pressing said stamping tool into a layer of moldable material on said substrate;    directing a curing stimulus through at least a portion of said translucent portion of said stamping tool, wherein at least a portion of said moldable material is cured;    
   
   
       69 . The method of  claim 68  further comprising repeating said pressing and said directing to create a plurality of cured molded surfaces.  
   
   
       70 . The method of  claim 69  further comprising forming contact structures at least in part on said cured molded surfaces.  
   
   
       71 . The method of  claim 68 , wherein: 
 said stamping tool comprises a tooth, said tooth comprising a first portion and a second portion,    said first portion corresponds to an opening to a surface of said substrate to be formed in said moldable material, and    said second portion corresponds to a molded surface.    
   
   
       72 . The method of  claim 71 , wherein said stamping tool further comprises: 
 a plurality of said teeth, each comprising a first portion and a second portion, and third portion(s) separating adjacent ones of said teeth.    
   
   
       73 . The method of  claim 68 , wherein said curing stimulus is ultraviolet light.  
   
   
       74 . The method of  claim 68 , further comprising forming a contact structure at least in part on said cured portion of said moldable material.  
   
   
       75 . The method of  claim 68 , wherein said substrate is an electronic component comprising a plurality of electrically conductive contact elements.  
   
   
       76 . The method of  claim 75 , further comprising: 
 placing said electronic component in a mold; and    injecting said moldable material into said mold.    
   
   
       77 . The method of  claim 75  further comprising planarizing said layer of moldable material on said electronic component.  
   
   
       78 . The method of  claim 68 , wherein said pressing further comprises heating said stamping tool.  
   
   
       79 . The method of  claim 78 , wherein said pressing further comprises, after heating said stamping tool, cooling said stamping tool while said stamping tool is pressed into said moldable material.  
   
   
       80 . The method of  claim 68 , wherein said pressing further comprises cooling said stamping tool while said stamping tool is pressed into said moldable material.  
   
   
       81 . The method of  claim 72 , wherein at least one of said second portions comprises a ribbed surface.  
   
   
       82 . The method of  claim 72 , wherein at least one of said second portions comprises a corrugated surface.  
   
   
       83 . The method of  claim 72 , wherein at least one of said second portions is selected from a group consisting of a V shape, a U shape, or a bifurcation.  
   
   
       84 . The method of  claim 68  further comprising: 
 after pressing said stamping tool into said moldable material, removing said stamping tool and depositing a seed layer of conductive material over said moldable material;    patterning a layer of masking material over said seed layer, wherein patterns in said masking material correspond to patterns for a plurality of electrically conductive contact structures; and    depositing a contact material onto said seed layer through said patterns in said masking material.    
   
   
       85 . The method of  claim 84  further comprising removing said masking material and said moldable material.  
   
   
       86 . The method of  claim 68 , wherein said stamping tool further comprises a plurality of reentrant teeth disposed to form a plurality of lips in said moldable material.  
   
   
       87 . The method of  claim 86 , wherein said moldable material is elastic.  
   
   
       88 . The method of  claim 68 , further comprising forming a plurality of contact structures.  
   
   
       89 . The method of  claim 88 , wherein the forming comprises depositing a contact structure material using an electroless deposition process.  
   
   
       90 . The method of  claim 75 , wherein said electronic component comprises a plurality of dies composing an unsingulated semiconductor wafer.