Forming of the periphery of a schottky diode with MOS trenches

Abstract

A method for forming a component of TMBS type having its periphery formed of a trench with insulated walls filled with a conductor, including the steps of depositing on a semiconductor substrate a thick layer of a first insulating material and a thin layer of a second material; simultaneously digging a peripheral trench and the trenches of the component; isotropically etching the first material so that a cap overhanging a recess remains; forming a thin insulating layer; and filling the trenches and said recess with a conductive material.

1 . A method for forming a component of TMBS type having its periphery formed of a trench with insulated walls filled with a conductor, comprising the steps of: 
 depositing on a semiconductor substrate a thick layer of a first insulating material;    depositing a thin layer of a second material;    simultaneously digging the peripheral trench and the trenches of the component into the stacking of layers of second and first materials as well as into an upper portion of the substrate, all the trenches having a same width;    isotropically etching the first material to remove the portions of the thick layer of the first material between two trenches, whereby the thin layer of the second material only remains in place beyond the peripheral trench and forms a cap overhanging a recess;    forming a thin insulating layer on the surface of the portions of the semiconductor layer exposed by the etching step;    depositing a layer of a conductive material to fill the trenches and said recess; and    etching the layer of the conductive material and the underlying thin insulating layer to expose the surface of said semiconductor layer between two trenches and maintain the conductive material in the trenches and said recess.    
   
   
       2 . The method of  claim 1 , wherein the layer of the first material is a silicon oxide layer of a thickness ranging between 0.8 and 1 μm.  
   
   
       3 . The method of  claim 1 , wherein the layer of the second material is a silicon nitride layer of a thickness ranging between 100 and 200 nm.  
   
   
       4 . The method of  claim 1 , wherein the thin insulating layer is a silicon oxide layer.  
   
   
       5 . The method of  claim 1 , wherein the conductive material is doped polysilicon.  
   
   
       6 . The method of  claim 1 , wherein the trenches have a width ranging between 0.5 and 2 μm and the interval between two trenches ranges between 0.5 and 2 μm.  
   
   
       7 . The method of  claim 6 , wherein the layer of the conductive material deposited to fill the trenches and the recess has a thickness ranging between 0.8 and 1.2 μm.  
   
   
       8 . A method for forming a Schottky diode, comprising: 
 forming a periphery according to  claim 1;  and    forming a layer of a material capable of forming a Schottky junction with the semiconductor layer.    
   
   
       9 . A TMBS type component, having a periphery formed of a trench with insulated walls filled with a conductor, wherein the trench forming the periphery exhibits a width which is uniform in transverse cross-section view and equal to the width of the component trenches, and is at a constant distance from an opening in a field oxide.  
   
   
       10 . The component of  claim 9 , wherein the trench width ranges between 0.5 and 2 μm.