Silicon-on insulator (SOI) substrate having dual surface crystallographic orientations and method of forming same

Abstract

A method is provided of forming a silicon-on-insulator (SOI) substrate having at least two exposed surface crystal orientations. The method begins by providing an SOI substrate having a first silicon layer with a surface having a first crystal orientation located on a first buried oxide layer. The buried oxide layer is located on a silicon substrate having a surface with a second crystal orientation. The first silicon layer and the first buried oxide layer are selectively removed from a first portion of the SOI substrate to expose a first surface portion of the silicon substrate. A second silicon layer is epitaxially grown over the first surface portion of the silicon substrate. The second silicon layer has a surface with a second crystal orientation. A second buried oxide layer is formed in the second silicon layer. Subsequent to the fabrication of the SOI substrate, N and P type MOSFETS may be formed on the surfaces with different crystal orientations.

1 . An SOI substrate, comprising: 
 a silicon substrate having a surface with a first crystal orientation;    first and second buried oxide layers each extending over and in contact with different portions of the silicon substrate surface;    first and second silicon layers located over said first and second buried oxide layers, respectively, said first and second silicon layers having surfaces with different crystal orientations, one of said different orientations being said first crystal orientation.    
     
     
         2 . The SOI substrate of  claim 1  wherein the first crystal orientation is a (110) orientation and the second crystal orientation is a (100) orientation.  
     
     
         3 . The SOI substrate of  claim 1  wherein the first crystal orientation is a (100) orientation and the second crystal orientation is a (110) orientation.