Sti liner modification method

Abstract

A new and improved liner modification method for a liner oxide layer in an STI trench is disclosed. According to the method, an STI trench is etched in a substrate and a liner oxide layer is formed on the trench surfaces by oxidation techniques. The method further includes pre-treatment of the trench surfaces using a nitrogen-containing gas prior to formation of the liner oxide layer, post-formation nitridation of the liner oxide layer, or both pre-treatment of the trench surfaces and post-formation nitridation of the liner oxide layer. The liner modification method of the present invention optimizes the inverse narrow width effect (INWE) and gate oxide integrity (GOI) of STI structures and prevents diffusion of dopant into the liner oxide layer during subsequent processing.

1 . A shallow trench isolation structure, comprising:
 a substrate having a trench with nitrogen-containing surfaces;   a hydrogen-containing liner oxide layer on the nitrogen-containing trench surfaces; and   a trench oxide filled into the trench.   
   
   
       2 . The structure of  claim 1 , wherein the nitrogen-containing surfaces have a gradient nitrogen concentration profile, with a nitrogen concentration variation ranging from 3˜30 atomic percent. 
   
   
       3 . The structure of  claim 1 , wherein the nitrogen-containing surfaces have a nitrogen concentration above 3 atomic percent. 
   
   
       4 . The structure of  claim 1 , wherein the hydrogen-containing liner oxide layer further comprises nitrogen therein. 
   
   
       5 . The structure of  claim 4 , wherein the hydrogen-containing liner oxide layer has a nitrogen concentration above 2 atomic percent. 
   
   
       6 . The structure of  claim 4 , wherein the hydrogen-containing liner oxide layer has a nitrogen concentration about 2˜30 atomic percent. 
   
   
       7 . A shallow trench isolation structure, comprising:
 a substrate having a trench therein;   a liner oxide layer on the surfaces of the trench, containing hydrogen and nitrogen therein; and   a trench oxide filled into the trench.   
   
   
       8 . The structure of  claim 7 , wherein the surfaces of the trench comprise nitrogen therein and have a gradient nitrogen concentration profile, with a nitrogen concentration variation ranging from 3˜30 atomic percent. 
   
   
       9 . The structure of  claim 7 , wherein the surfaces of the trench comprise nitrogen therein and have a nitrogen concentration above 3 atomic percent. 
   
   
       10 . The structure of  claim 7 , wherein the liner oxide layer has a nitrogen concentration above 2 atomic percent. 
   
   
       11 . The structure of  claim 7 , wherein the liner oxide layer has a nitrogen concentration about 2˜30 atomic percent. 
   
   
       12 . A shallow trench isolation structure, comprising:
 a substrate having a trench with nitrogen-containing surfaces, wherein the nitrogen-containing surfaces have a gradient nitrogen concentration profile;   a liner oxide layer on the nitrogen-containing surfaces of the trench; and   a trench oxide filled into the trench.   
   
   
       13 . The structure of  claim 12 , wherein the gradient nitrogen concentration profile has a nitrogen concentration variation ranging from 3˜30 atomic percent. 
   
   
       14 . The structure of  claim 12 , wherein the liner oxide layer further comprises hydrogen therein. 
   
   
       15 . The structure of  claim 14 , wherein the liner oxide layer further comprises nitrogen therein. 
   
   
       16 . The structure of  claim 15 , wherein the liner oxide layer has a nitrogen concentration above 2 atomic percent. 
   
   
       17 . The structure of  claim 15 , wherein the liner oxide layer has a nitrogen concentration about 2˜30 atomic percent.