Method of forming semiconductor structure

Abstract

A method of forming a semiconductor structure includes following steps. A semiconductor material structure is formed over a substrate. A first pad layer is formed over the semiconductor material structure. The first pad layer and the semiconductor material structure are etched to form a trench. An oxidation process is performed on a sidewall of the semiconductor material structure to form a first oxide structure on the sidewall of the semiconductor material structure. A second oxide structure is formed in the trench.

What is claimed is: 
     
         1 . A method of forming a semiconductor structure, comprising:
 forming a semiconductor material structure over a substrate;   forming a first pad layer over the semiconductor material structure;   etching the first pad layer and the semiconductor material structure to form a trench;   performing an oxidation process on a sidewall of the semiconductor material structure to form a first oxide structure on the sidewall of the semiconductor material structure; and   forming a second oxide structure in the trench.   
     
     
         2 . The method of forming the semiconductor structure of  claim 1 , wherein the oxidation process is performed such that a sidewall of the first pad layer is free of the first oxide structure. 
     
     
         3 . The method of forming the semiconductor structure of  claim 1 , wherein forming the second oxide structure is performed such that the first oxide structure is in contact with the second oxide structure. 
     
     
         4 . The method of forming the semiconductor structure of  claim 1 , further comprising:
 prior to etching the first pad layer and the semiconductor material structure, forming a second pad layer over the first pad layer.   
     
     
         5 . The method of forming the semiconductor structure of  claim 4 , further comprising:
 etching the second pad layer.   
     
     
         6 . The method of forming the semiconductor structure of  claim 4 , wherein forming the second oxide structure in the trench further comprises forming the second oxide structure over the second pad layer. 
     
     
         7 . The method of forming the semiconductor structure of  claim 4 , further comprising:
 removing the second pad layer after forming the second oxide structure.   
     
     
         8 . The method of forming the semiconductor structure of  claim 1 , wherein the oxidation process is performed by a thermal oxidation process. 
     
     
         9 . The method of forming the semiconductor structure of  claim 1 , wherein forming the second oxide structure is performed by a flowable chemical vapor deposition process.