Semiconductor device and method of manufacturing a semiconductor device

Abstract

A semiconductor device comprises a semiconductor substrate having a substrate top surface on which a device should be formed; a gate electrode having an opposed surface opposed to said substrate top surface, and electrically insulated from said semiconductor substrate by a gate insulating film, a trench formed through said gate electrode into said semiconductor substrate to electrically isolate a device region for forming a device from the remainder region of said substrate top surface, a first boundary end portion, which is defined between a substrate side surface of said semiconductor substrate forming a part of the side surface of said trench and said substrate top surface, and a second boundary end portion, which is defined between a gate side surface of said gate electrode forming another part of the side surface of said trench and said opposed surface, wherein said first boundary end portion and said second boundary end portion have spherical shapes having a curvature radius not smaller than 30 angstrom.

1 .- 8 . (canceled)  
   
   
       9 . A semiconductor device manufacturing method, comprising: 
 forming a gate insulating film on a semiconductor substrate;    forming a gate electrode on said gate insulating film to be electrically insulated from said semiconductor substrate;    etching said gate electrode, said gate insulating film and said semiconductor substrate to form a trench which electrically isolates a device region for forming a device from a remainder region on said substrate top surface; and    oxidizing a substrate side surface of said semiconductor substrate, which forms a part of a side surface of said trench, and a gate side surface of said gate electrode, which forms another part of the side surface of said trench, in a hydrogen H 2  and oxygen O 2  atmosphere.    
   
   
       10 . A semiconductor device manufacturing method, comprising: 
 forming a gate insulating film on a semiconductor substrate;    forming a gate electrode on said gate insulating film to be electrically insulated from said semiconductor substrate;    etching said gate electrode, said gate insulating film and said semiconductor substrate to form a trench which electrically isolates a device region for forming a device from a remainder region on said substrate top surface; and    oxidizing a substrate side surface of said semiconductor substrate, which forms a part of a side surface of said trench, and a gate side surface of said gate electrode, which forms another part of the side surface of said trench, in an ozone O 3  atmosphere.    
   
   
       11 . A method for manufacturing a semiconductor device, comprising: 
 forming a gate insulating film on a semiconductor substrate;    forming a gate electrode on said gate insulating film to be electrically insulated from said semiconductor substrate;    etching said gate electrode, said gate insulating film, and said semiconductor substrate to form a trench;    oxidizing an inner side surface of the trench by an oxygen radical; and    burying an insulating material in the trench.