Layered microelectronic contact and method for fabricating same

Abstract

A microelectronic spring contact for making electrical contact between a device and a mating substrate and method of making the same are disclosed. The spring contact has a compliant pad adhered to a substrate of the device and spaced apart from a terminal of the device. The compliant pad has a base adhered to the substrate, and side surfaces extending away from the substrate and tapering to a smaller end area distal from the substrate. A trace extends from the terminal of the device over the compliant pad to its end area. At least a portion of the compliant pad end area is covered by the trace, and a portion of the trace that is over the compliant pad is supported by the compliant pad. A horizontal microelectronic spring contact and method of making the same are also disclosed. The horizontal spring contact has a rigid trace attached at a first end to a terminal of a substrate. The trace is free from attachment at its second end, and extends from the terminal in a direction substantially parallel to a surface of the substrate to the second end. At least a distal portion of the trace extending to the second end is spaced apart from the surface of the substrate. The spaced-apart distal portion is flexible in a plane parallel to the substrate.

1 - 23 . (canceled)  
   
   
       24 . A resilient microelectronic contact, comprising an at least partially self-supporting trace attached at a first end to a terminal of a substrate and free from attachment at a second end thereof, extending from the terminal to the second end, having at least a distal portion extending to the second end spaced apart from the surface of the substrate and free to flex in a plane parallel to the surface of the substrate.  
   
   
       25 . The microelectronic contact of  claim 24 , wherein the distal portion has at least one bend for resiliency of the trace in a plane parallel to the substrate.  
   
   
       26 . The microelectronic contact of  claim 24 , wherein the distal portion of the trace is patterned to follow a path having a shape selected from zigzag, crenulated, hair-pin shaped, and serpentine.  
   
   
       27 . The microelectronic contact of  claim 24 , further comprising a contact tip connected to the second end of the rigid trace.  
   
   
       28 . The microelectronic contact of  claim 27 , wherein the contact tip is flat and pad-shaped.  
   
   
       29 . The microelectronic contact of  claim 27 , further comprising a dollop of bonding material on the contact tip.  
   
   
       30 . The microelectronic contact of  claim 29 , wherein the bonding material is a solder paste.  
   
   
       31 . The microelectronic contact of  claim 27 , further comprising a compliant pad disposed on the substrate under the contact tip.  
   
   
       32 . The microelectronic contact of  claim 31 , wherein the compliant pad has a base adhered to the substrate, and side surfaces extending away from the substrate tapering to a end area distal from the substrate, wherein the end area is substantially smaller than the base.  
   
   
       33 . The microelectronic contact of  claim 31 , wherein the compliant pad is at least partially supporting the contact tip.  
   
   
       34 . A method for making a resilient microelectronic contact, comprising: 
 depositing a first layer of a sacrificial material on a semiconductor device;    patterning the first layer to expose a terminal of the device;    depositing a conductive seed layer over the first layer and terminal;    depositing a second layer of a sacrificial material directly over the seed layer;    patterning the second layer to expose the seed layer along a path running from the terminal to a position distal from the terminal;    plating a metallic material along the path of the exposed seed layer; and    removing the first layer, the second layer, and an unplated portion of the seed layer, thereby exposing a resilient microelectronic contact attached at a first end to a terminal of a substrate and free from attachment at a second end thereof.    
   
   
       35 . The method of  claim 34 , wherein the patterning step further comprises exposing the path having at least one bend.  
   
   
       36 . The method of  claim 34 , wherein the patterning step further comprises exposing the path having a shape selected from zigzag, crenulated, hairpin-shaped and serpentine.  
   
   
       37 . The method of  claim 34 , further comprising placing a dollop of bonding material on the distal portion of the microelectronic contact.  
   
   
       38 . The method of  claim 34 , further comprising attaching a compliant pad to the substrate prior to the first depositing step.  
   
   
       39 . The method of  claim 38 , wherein the attaching step further comprises attaching the compliant pad having a base adhered to the semiconductor device, side surfaces extending away from the semiconductor device and tapering to a end area distal from the semiconductor device, wherein the end area is substantially smaller than the base.  
   
   
       40 . The method of  claim 39 , wherein the patterning step further comprises exposing the path leading to a tip portion of the compliant pad.  
   
   
       41 . A semiconductor device configured for flip-chip mounting to a substrate, comprising: 
 a semiconductor device having a plurality of terminals on a surface thereof;    a plurality of resilient microelectronic contacts, each comprising a rigid trace attached at a first end to each terminal of the device and free from attachment at a second end thereof, extending from each terminal in a direction substantially parallel to the surface of the device to the second end, and having at least a distal portion extending to the second end spaced apart from the surface and compliant in a plane parallel to the surface of the semiconductor device.    
   
   
       42 . The semiconductor device of  claim 41 , wherein the plurality of terminals are spaced apart from one another for a first pitch distance within a first portion of the surface, and wherein the surface has a second portion that is essentially free of terminals, the second portion being larger than the first portion.  
   
   
       43 . The semiconductor device of  claim 42 , wherein the second ends of the plurality of contacts are disposed over the second portion of the surface and spaced apart from one another for a second pitch distance, the second pitch distance being greater than the first pitch distance.  
   
   
       44 . The semiconductor device of  claim 41 , wherein the distal portion of each microelectronic contact has at least one bend for resiliency of the microelectronic contact in a direction parallel to the substrate.  
   
   
       45 . The semiconductor device of  claim 41 , wherein the distal portion of each microelectronic contact has a shape selected from zigzag, crenulated, hairpin-shaped and serpentine.  
   
   
       46 . The semiconductor device of  claim 41 , wherein the surface of the semiconductor device is essentially free of elastomer material.  
   
   
       47 . The semiconductor device of  claim 41 , further comprising a dollop of a bonding material disposed on a distal tip of the distal portion of each microelectronic contact.  
   
   
       48 . The semiconductor device of  claim 41 , further comprising a compliant pad disposed between a distal tip of the distal portion of each microelectronic contact and the substrate.  
   
   
       49 . The semiconductor device of  claim 48 , wherein the compliant pad has a base adhered to the semiconductor device and side surfaces extending away from the semiconductor device and tapering to a end area distal from the semiconductor device, and wherein the end area is substantially smaller than the base.