Amorphous and polycrystalline silicon nanolaminate

Abstract

A method for forming a uniform layered structure comprising an ultra-thin layer of amorphous silicon and its thermal oxide is disclosed. In one aspect, a method for forming a nanolaminate of silicon oxide on a substrate is disclosed. In another aspect, a method for forming a patterned hard mask on a substrate is disclosed. The patterned hard mask includes a nanolaminate of silicon and silicon oxide. The methods are characterized by the oxidation of an amorphous silicon layer using atomic oxygen.

We claim:  
     
         1 . A method for forming a nanolaminate of a silicon-containing material and an oxide on a substrate, the method comprising the steps of: 
 depositing a film containing amorphous silicon onto the substrate, the film having an initial thickness;    oxidizing the amorphous silicon-containing film by exposing the substrate to a gaseous mixture comprising atomic oxygen and molecular oxygen, wherein the ratio of atomic oxygen to molecular oxygen is about 0.00001 to 100, thereby forming a layer of oxide on the film, wherein after oxidation the film has a final thickness less than the initial thickness; and    removing the oxide.    
     
     
         2 . The method of  claim 1 , wherein the initial thickness of the film is about 100 to 200 Å.  
     
     
         3 . The method of  claim 1 , wherein the final thickness of the film is less than 100 Å.  
     
     
         4 . The method of  claim 1 , wherein the initial thickness of the film is about 150 Å and the final thickness of the film is about 50 Å.  
     
     
         5 . The method of  claim 1  further comprising, after oxidation of the amorphous silicon-containing film, the step of annealing the amorphous silicon-containing film to form a film containing polycrystalline silicon.  
     
     
         6 . The method of  claim 1 , wherein the oxide is removed using a selective wet chemistry stripping process.  
     
     
         7 . The method of  claim 6 , wherein the oxide is removed using hydrofluoric acid (HF).  
     
     
         8 . A method for forming a patterned hard mask on a substrate, the patterned hard mask including a nanolaminate of a silicon-containing material and an oxide, the method comprising the steps of: 
 depositing a film containing amorphous silicon onto the substrate, the film having an initial thickness;    oxidizing the amorphous silicon-containing film by exposing the substrate to a gaseous mixture comprising atomic oxygen and molecular oxygen, wherein the ratio of atomic oxygen to molecular oxygen is about 0.00001 to 100, thereby forming a layer of oxide on the film, wherein after oxidation the film has a final thickness less than the initial thickness; and    patterning the layer of oxide using a lithography process, thereby exposing preselected areas of the amorphous silicon-containing film.    
     
     
         9 . A semiconductor structure comprising: 
 a substrate; and    a polycrystalline silicon-containing film on said substrate, the silicon-containing film having a thickness of less than about 100 Å and a thickness variation of less than about 30%.    
     
     
         10 . The structure of  claim 9 , wherein said silicon-containing film has a thickness of about 50 Å.  
     
     
         11 . The structure of  claim 9 , further comprising a patterned thermal oxide film on said silicon-containing film, the patterned thermal oxide film having a thickness of at least about 200 Å.  
     
     
         12 . The structure of  claim 9 , further comprising: 
 an insulating layer on said silicon-containing film; and    an electrode layer on said insulating layer, said electrode having an electrical bias with respect to said silicon-containing film such that an electrical field is created across said insulating layer.    
     
     
         13 . The structure of  claim 12 , wherein said silicon-containing film has a thickness of about 30 Å to about 80 Å.  
     
     
         14 . The structure of  claim 12 , wherein said silicon-containing film is doped.  
     
     
         15 . The structure of  claim 12 , wherein said insulating layer comprises a material selected from the group consisting of silicon-rich silicon nitride, hafnium oxide, zirconium oxide, tungsten oxide, tantalum oxide, hafnium silicate, zirconium silicate, tungsten silicate, tantalum silicate, hafnium oxynitride, zirconium oxynitride, tungsten oxynitride, and tantalum oxynitride.  
     
     
         16 . The structure of  claim 12 , wherein the electrical bias of said electrode is positive with respect to said silicon-containing film.  
     
     
         17 . The structure of  claim 16 , wherein said insulating layer has a thickness of about 10 Å to about 100 Å.  
     
     
         18 . The structure of  claim 12 , wherein the electrical bias of said electrode is negative with respect to said silicon-containing film.  
     
     
         19 . The structure of  claim 18 , wherein said insulating layer has a thickness of about 6 Å to about 25 Å.