Method and composition for plasma etching of a self-aligned contact opening

Abstract

A method of forming a self-aligned contact opening in an insulative layer formed over a substrate in a semiconductor device involves etching the insulative layer with at least one fluorocarbon and ammonia.

1 - 46 . (canceled)  
   
   
       47 . A method of etching a semiconductor device comprising: 
 generating plasma etching gas comprising ammonia and at least two fluorocarbons, wherein said at least two fluorocarbons are selected from the group consisting of fluorohydrocarbons, chlorofluorocarbons, and chlorofluorohydrocarbons.    
   
   
       48 . The method of  claim 47 , wherein said ammonia is flowed to a reaction chamber containing said device at a flow rate within the range of about 2 sccm to about 6 sccm.  
   
   
       49 . The method of  claim 48 , wherein said ammonia is flowed to said reaction chamber at a flow rate within the range of about 2 sccm to about 5 sccm.  
   
   
       50 . The method of  claim 49 , wherein said ammonia is flowed to said reaction chamber at a flow rate not exceeding about 4 sccm.  
   
   
       51 . The method of  claim 50 , wherein said at least two fluorocarbons are flowed into said reaction chamber with said ammonia.  
   
   
       52 . The method of  claim 51 , wherein said fluorocarbons are flowed into said reaction chamber so as to have a flow rate which is not less than about 15 times the flow rate of said ammonia.  
   
   
       53 . The method of  claim 52 , wherein the flow rate ratio of said fluorocarbons to said ammonia is within the range of about 3:1 to about 40:1.  
   
   
       54 . The method of  claim 53 , wherein said flow rate ratio is within the range of about 4:1 to about 20:1.  
   
   
       55 . The method of  claim 52 , wherein the flow rate ratio of said fluorocarbons to said ammonia is not greater than about 20:1.  
   
   
       56 . The method of  claim 47 , wherein said ammonia is added substantially simultaneously with said fluorocarbons.  
   
   
       57 . (canceled)  
   
   
       58 . The method of  claim 50 , wherein said ammonia is added to a mixture comprising at least three fluorocarbons.  
   
   
       59 . A method of preserving a side wall spacer surrounding a gate stack during a self-aligned contact etch, wherein said gate stack is formed over a substrate in a semiconductor device, which comprises contacting said spacer with a combination of at least two fluorocarbons and ammonia so as to form a protective layer over said spacer, wherein said at least two fluorocarbons are selected from the group consisting of fluorohydrocarbons, chlorofluorocarbons, and chlorofluorohydrocarbons.  
   
   
       60 . The method of  claim 59 , wherein said protective layer is formed to a thickness which is about 5 to 200 Angstroms in thickness.  
   
   
       61 . The method of  claim 60 , wherein said at least two fluorocarbons and said ammonia are flowed together over said side wall spacer such that the flow rate ratio of said two fluorocarbons to said ammonia is not less than about 3:1.  
   
   
       62 . The method of  claim 61 , wherein said flow rate ratio is within the range of about 3:1 to about 20:1.  
   
   
       63 . The method of  claim 62 , wherein said self-aligned contact etch provides an opening to said substrate through an insulative layer formed over said substrate.  
   
   
       64 - 70 . (canceled)  
   
   
       71 . A process for forming an opening in an insulative layer formed over a substrate in a semiconductor device, said process comprising: 
 forming a pair of adjacent gate stacks over said substrate;    forming sidewall spacers on sidewalls of said adjacent gate stacks;    forming an insulative layer over said substrate;    forming a patterned photoresist mask layer over said insulative layer; and,    etching an opening in said insulative layer defined at least in part by said sidewall spacers through an aperture in said patterned photoresist mask layer, using an etch solution comprising ammonia and at least one fluorocarbon, wherein said at least one fluorocarbon is selected from the group consisting of C 4 F 8 , C 4 F 6 , C 5 F 8 , CF 4 , C 2 F 6 , CHF 3 , CH 2 F 2  and C 3 F 8 .    
   
   
       72 . The process of claim  38 , wherein said at least one fluorocarbon and said ammonia are flowed into said reaction chamber such the flow rate ratio of said at least one fluorocarbon to said ammonia is about 3:1 to about 10:1.  
   
   
       73 . The process of claim  42 , wherein said opening is formed between said sidewall spacers on said pair of adjacent gate stacks.  
   
   
       74 . The process of claim  43 , wherein said etching is performed at a temperature within the range of about −50 to about 80 degrees Celsius.