Structure and method for releasing stressy metal films

Abstract

A method and structure for forming a spring structure that avoids undesirable kinks in the spring is described. The method converts a portion of a release layer such that the converted portion resists etching. The converted portion then serves as an anchor region for a spring structure deposited over the release layer. When the non-converted portions of the release layer are etched, the spring curls out of the plane of a plane.

1 . An intermediate structure for forming a spring comprising: 
 a substrate;    a release material deposited as a release layer, the release region including two regions with different etch characteristics, the two regions including an anchor region that resists a selective etch and a release region that is susceptible to a selective etch, the different etch characteristics caused by a treating at least one of the two different regions to change the chemical structure of at least one of the two different region; and,    an overlying material deposited over the release layer, an anchor portion of the overlying material deposited over the anchor region and a release portion of the overlying material deposited over the release region.    
   
   
       2 . The intermediate structure of  claim 1  wherein the treating of the at least one of the two different regions occurs after the deposition of the overlying material.  
   
   
       3 . The intermediate structure of  claim 1  wherein the anchor region is an oxidized release material.  
   
   
       4 . The intermediate structure of  claim 1  wherein the anchor region is a cross linked polymer.  
   
   
       5 . The intermediate structure of  claim 1  wherein the anchor region includes boron and silicon.  
   
   
       6 . The intermediate structure of  claim 1  wherein the anchor region and the release region are the same thickness.  
   
   
       7 . The intermediate structure of  claim 1  wherein the anchor region is thicker than the release region.  
   
   
       8 . The intermediate structure of  claim 1  wherein the spring material is a metal that includes a plurality of sublayers, the atomic spacing of the lower sublayers is smaller such that an internal stress gradient exists in the spring material.  
   
   
       9 . A spring structure comprising: 
 a substrate;    a release layer deposited over the substrate, at least one region of the release layer has been chemically altered such that an anchor region resists a selective etch and a release region is susceptible to a selective etch; and,    a spring material including an anchor portion coupled to the anchor region of the release layer, the spring material further including a release portion that curls out of a plane parallel to the substrate.