Method of fabricating semiconductor device

Abstract

A method of fabricating a semiconductor device comprising a step of forming a trench selectively on a semiconductor substrate, a step of positioning said semiconductor substrate to a first position inclined to a plane vertical to ion beams, a step of injecting ions by emitting ion beams to a side-wall of the trench of the semiconductor substrate at the first position, a step of positioning said semiconductor substrate to a second position which is different from the first position by rotating it, and a step of injecting ions by emitting ion beams to a side-wall of the trench of the semiconductor substrate at the second position.

We claim:  
     
       1. A method of fabricating a semiconductor device comprising: 
       a step of forming a trench in a semiconductor substrate having a principal surface, said trench having four side-walls which extend into said substrate in a direction substantially  perpendicular to said principal surface of said semiconductor substrate and which are perpendicular to each other, and said trench having a bottom substantially  parallel to said principal surface;  
       a step of positioning said semiconductor substrate in a first position;  
       a step of implanting ions into a first side-wall of said side-walls of said trench from a direction inclined to a normal to a plane containing said principal surface of said semiconductor substrate;  
       a step of positioning said semiconductor substrate in a second position which is different from said first position by rotating said semiconductor substrate by 90° about an axis of rotation which is perpendicular to said principal surface of said semiconductor substrate;  
       a step of implanting ions of the same type and to the same extent as implanted in the first side-wall into a second side-wall of said side-walls of said trench from said direction inclined to the normal to the plane containing said principal surface of said semiconductor substrate;  
       a step of positioning said semiconductor substrate in a third position which is different from said first and second positions by rotating said semiconductor substrate by 90° about said rotation axis;  
       a step of implanting ions of the same type and to the same extent as implanted in said first and second side-walls into a third side-wall of said side-walls of said trench from said direction inclined to the normal to the plane containing said principal surface of said semiconductor substrate;  
       a step of positioning said semiconductor substrate in a fourth position which is different from said first, second and third positions by rotating said semiconductor substrate by 90° about said rotation axis;  
       a step of implanting ions of the same type and to the same extent implanted in said first, second and third side-walls into a fourth side-wall of said side-walls of said trench from said direction inclined to the normal to the plane containing said principal surface of said semiconductor substrate; and  
       a step of implanting ions into the bottom of the trench by emitting ion beams of the same type as implanted in the side-walls in a direction perpendicular to said principal surface of said semiconductor device.  
     
     
       2. A method of fabricating a semiconductor device  trench capacitor comprising: 
       a step of forming a trench in a semiconductor substrate having a principal surface, said trench having four side-walls which extend into said substrate in a direction substantially  perpendicular to said principal surface of said semiconductor substrate and which are perpendicular to each other, and said trench having a bottom substantially  parallel to said principal surface;  
       a step of forming an outer electrode including, 
       ( a ) a step of positioning said semiconductor substrate in a first position;  
       ( b ) a step of implanting ions into a first side-wall of said side-walls of said trench from a direction inclined to a normal to a plane containing said principal surface of said semiconductor substrate;  
       ( c ) a step of positioning said semiconductor substrate in a second position which is different from said first position by rotating said semiconductor substrate by 90° about an axis of rotation which is perpendicular to said principal surface of said semiconductor substrate;  
       ( d ) a step of implanting ions of the same type and to the same extent as implanted in the first side-wall into a second side-wall of said side-walls of said trench from said direction inclined to the normal to the plane containing said principal surface of said semiconductor substrate;  
       ( e ) a step of positioning said semiconductor substrate in a third position which is different from said first and second positions by rotating said semiconductor substrate by 90° about said rotation axis;  
       ( f ) a step of implanting ions of the same type and to the same extent as implanted in said first and second side-walls into a third side-wall of said side-walls of said trench from said direction inclined to the normal to the plane containing said principal surface of said semiconductor substrate;  
       ( g ) a step of positioning said semiconductor substrate in a fourth position which is different from said first, second and third positions by rotating said semiconductor substrate by 90° about said rotation axis;  
       ( h ) a step of implanting ions of the same type and to the same extent implanted in said first, second and third side-walls into a fourth side-wall of said side-walls of said trench from said direction inclined to the normal to the plane containing said principal surface of said semiconductor substrate;  
       a step of implanting ions into the bottom of the trench by emitting ion beams of the same type as implanted in the side-walls in a direction perpendicular to said principal surface is said semiconductor device; andwherein all of the steps of implanting beingare carried out such that the extent of implantation and type of ion ofare such that a trench capacitoran outer electrode is thereby formed along said four side- walls of said trench;    
       
         a step of forming an insulating layer within the trench along the outer electrode; and  
       
       
         a step of forming an inner electrode within the trench along the insulative layer.  
       
     
     
       3. A method of fabricating a semiconductor device comprising: 
       a step of forming a trench in a semiconductor substrate having a principal surface, said trench having four side-walls which extend into said substrate in a direction substantially  perpendicular to said principal surface of said semiconductor substrate and which are perpendicular to each other, and said trench having a bottom substantially  parallel to said principal surface;  
       a step of positioning said semiconductor substrate in a first position;  
       a step of implanting ions into a first side-wall of said side-walls of said trench from a direction inclined to a normal to a plane containing said principal surface of said semiconductor substrate;  
       a step of positioning said semiconductor substrate in a second position which is different from said first position by moving said semiconductor substrate;  
       a step of implanting ions of the same type and to the same extent as implanted in the first side-wall into a second side-wall of said side-walls of said trench from said direction inclined to the normal to the plane containing said principal surface of said semiconductor substrate;  
       a step of positioning said semiconductor substrate in a third position which is different from said first and second positions by moving said semiconductor substrate;  
       a step of implanting ions of the same type and to the same extent as implanted in said first and second side-walls into a third side-wall of said side-walls of said trench from said direction inclined to the normal to the plane containing said principal surface of said semiconductor substrate;  
       a step of positioning said semiconductor substrate in a fourth position which is different from said first, second and third positions by moving said semiconductor substrate;  
       a step of implanting ions of the same type and to the same extent implanted in said first, second and third side-walls into a fourth side-wall of said side-walls of said trench from said direction inclined to the normal to the plane containing said principal surface of said semiconductor substrate; and  
       a step of implanting ions into the bottom of the trench by emitting ion beams of the same type as implanted in the side-walls in a direction perpendicular to said principal surface of said semiconductor device;  
       wherein in said second position said side-walls of said trench are oriented at right angles to the positions of said side-walls in the first position, in said third position said side-walls of said trench are oriented parallel to the positions of said side-walls in the first position, and in said fourth position said side-walls are oriented parallel to said side-walls in the second position.