Semiconductor structures and manufacturing methods

Abstract

A method for forming substantially uniformly thick, thermally grown, silicon dioxide material on a silicon body independent of bon axis. A trench is formed in a surface of the silicon body, such trench having sidewalls disposed in different crystallographic planes, one of such planes being the <100> crystallographic plane and another one of such planes being the <110> plane. A substantially uniform layer of silicon nitride is formed on the sidewalls. The trench, with the with substantially uniform layer of silicon nitride, is subjected to a silicon oxidation environment with sidewalls in the <110> plane being oxidized at a higher rate than sidewalls in the <100> plane producing silicon dioxide on the silicon nitride layer having thickness over the <110> plane greater than over the <100> plane. The silicon dioxide is subjected to an etch to selectively remove silicon dioxide while leaving substantially un-etched silicon nitride to thereby remove portions of the silicon dioxide over the <100> plane and to thereby expose underlying portions of the silicon nitride material while leaving portions of the silicon dioxide over the <110> plane on underlying portions of the silicon nitride material. Exposed portions of the silicon nitride material are selectively removed to expose underlying portions of the sidewalls of the trench disposed in the <100> plane while leaving substantially un-etched portions of the silicon nitride material disposed on sidewalls of the trench disposed in the <110> plane. The structure is then subjected to an silicon oxidation environment to produce the substantially uniform silicon dioxide layer on the sidewalls of the trench.

1 . A single crystal semiconductor body having a trench with sidewall portions disposed in different crystallographic planes of the body, such sidewall portions having thereon substantially uniformly thick, thermally grown, silicon dioxide material.  
     
     
         2 - 4 . (Cancelled)  
     
     
         5 . A single crystal semiconductor body comprising: 
 a trench formed in a surface of said single crystal semiconductor body, having sidewall portions being disposed in different crystallographic planes of the body;    first sidewall portions disposed in a first one of the different crystallographic planes;    a first layer of silicon dioxide material grown on said first sidewall portions at a first rate and to a first thickness when subjected to a thermal oxidation process;    second sidewall portions disposed in a second one of the different crystallographic planes; and    a second layer of silicon dioxide grown on said second sidewall portion at a second rate and on said first layer of said silicon dioxide material at a rate slower than said second rate wherein said first and second sidewall portions of the trench are subjected to a thermal oxidation process such that the thickness of said second layer of silicon dioxide on said second sidewall portions is substantially equal to the thickness of both said first and second layers of silicon dioxide on said first sidewall portions.    
     
     
         6 . A single crystal semiconductor body comprising: 
 a surface having portions thereof disposed in a different crystallographic planes    a relatively thin material on selected ones of the surface portions, said selected ones of the surface portions residing in a first crystallographic plane;    a layer of silicon dioxide grown over said relatively thin material at a first rate by a thermal oxidation process to a selected thickness; and    said silicon dioxide grown at a second rate during said thermal oxidation process on unselected surface portions in a different crystallographic plane, said second rate different than said first rate such that the thickness of said silicon dioxide grown over both the selected surface portions and the unselected surface portions are substantially uniform.    
     
     
         7 . The semiconductor body of  claim 5  wherein said first sidewall portions are disposed in the <100> crystallographic plane and said second sidewall portions are disposed in the <110> crystallographic plane.  
     
     
         8 . The semiconductor body of  claim 6  wherein the relatively thin material is silicon nitride.  
     
     
         9 . The semiconductor body of  claim 6  further comprising another layer of silicon dioxide formed on said relatively thin material such that said another layer of silicon dioxide and said layer of silicon dioxide grown over said relatively thin material have a combined thickness substantially the same as the thickness of said layer of silicon dioxide grown on said unselected surface portions of said semiconductor body.  
     
     
         10 . The semiconductor body of  claim 6  wherein the relatively thin material is less than approximately 20 Angstroms.  
     
     
         11 . The semiconductor body of  claim 6  wherein the relatively thin material forms a layer which is thinner than the corresponding oxide layer grown on the selected and unselected surface portions.