Semiconductor device and method for fabricating the same

Abstract

Into a channel formation region of a semiconductor substrate of p-type silicon, indium ions are implanted at an implantation energy of about 70 keV and a dose of about 5×10 13 /cm 2 , thereby forming a p-doped channel layer. Next, germanium ions are implanted into the upper portion of the semiconductor substrate at an implantation energy of about 250 keV and a dose of about 1×10 16 /cm 2 , thereby forming an amorphous layer in a region of the semiconductor substrate deeper than the p-doped channel layer.

1 - 17 . (canceled)  
   
   
       18 . A semiconductor device comprising: 
 a gate insulating film on a semiconductor substrate;    a gate electrode on the gate insulating film;    a diffused channel layer of a first conductivity type including a first dopant and formed below a region of the gate insulating film in the semiconductor substrate; and    a germanium-containing layer formed in a region deeper than the diffused channel layer in the semiconductor substrate.    
   
   
       19 . The semiconductor device of  claim 18 , 
 wherein the diffused channel layer contains germanium.    
   
   
       20 . The semiconductor device of  claim 19 , 
 wherein the diffused channel layer has a lower dopant concentration of germanium than the first dopant.    
   
   
       21 . The semiconductor device of  claim 18 , 
 wherein the first dopant includes heavy ions with a large mass number.    
   
   
       22 . The semiconductor device of  claim 18 , 
 wherein the first dopant includes indium.    
   
   
       23 . The semiconductor device of  claim 18 , 
 wherein an interface between the gate insulating film and the semiconductor substrate has a higher dopant concentration of germanium than a lower side of the diffused channel layer.    
   
   
       24 . The semiconductor device of  claim 18 , 
 wherein a dopant concentration of germanium contained in an interface between the gate insulating film and the semiconductor substrate is about 5×10 18  to 5×10 21  atoms/cm 3  and the dopant concentration of germanium contained in a lower side of the diffused channel layer is about 1×10 15  to 1×10 17  atoms/cm 3 .    
   
   
       25 . The semiconductor device of  claim 18 , 
 wherein a region of the diffused channel layer slightly deeper than a surface of the semiconductor substrate has a higher dopant concentration of the first dopant than the surface of the semiconductor substrate.    
   
   
       26 . The semiconductor device of  claim 18 , further comprising: 
 sidewalls formed on side surfaces of the gate electrode; and    diffused extension layers of a second conductivity type including a second dopant and formed below the sidewalls in the semiconductor substrate,    wherein the diffused extension layers contain germanium.    
   
   
       27 . The semiconductor device of  claim 26 , further comprising: 
 diffused pocket layers of the first conductivity type including the first dopant and formed below the diffused extension layers in the semiconductor substrate,    wherein the diffused pocket layers have a higher dopant concentration of the first dopant than the diffused channel layer.    
   
   
       28 . The semiconductor device of  claim 26 , further comprising: 
 heavily diffused extension layers of a second conductivity type including a third dopant, formed below a side region of the sidewalls in the semiconductor substrate, connected to the diffused extension layers and having a junction deeper than the diffused extension layers,    wherein the heavily diffused extension layers contain germanium.    
   
   
       29 . The semiconductor device of  claim 28 , 
 wherein the germanium-containing layer is formed to a region deeper than the heavily diffused extension layers.    
   
   
       30 . The semiconductor device of  claim 18 , 
 wherein the plane orientation of the semiconductor substrate is the { 100 } plane.    
   
   
       31 . The semiconductor device of  claim 18 , 
 wherein the semiconductor substrate comprises silicon.    
   
   
       32 . The semiconductor device of  claim 18 , 
 wherein the semiconductor substrate includes, in the upper portion thereof, an epitaxial layer formed by epitaxially growing silicon.    
   
   
       33 . The semiconductor device of  claim 18 , 
 wherein the semiconductor substrate includes, in the upper portion thereof, a strained silicon layer having a crystal lattice of a larger lattice constant than a normal lattice constant.    
   
   
       34 . The semiconductor device of  claim 18 , 
 wherein the semiconductor substrate includes:    a buffer layer containing silicon germanium and formed in the upper portion of the semiconductor substrate; and    a strained silicon layer formed on the buffer layer.