Semiconductor device and a method of manufacturing the same

A method of manufacturing a semiconductor device, comprising:

• the first step of forming a first insulating film on a semiconductor substrate;
• at the second step of selectively removing said first insulating film to partially expose said semiconductor substrate;
• the third step of removing said semiconductor substrate exposed conforming to a shape of said first insulating film, thereby forming a first trench having a side wall formed by an inclined surface making a predetermined angle with a surface of said semiconductor substrate;
• the fourth step of forming a second insulating film to cover an inner wall surface of the first trench including the inclined surface;
• the fifth step of removing said second insulating film from a bottom surface of the first trench to expose said semiconductor substrate on the bottom surface of the first trench;
• the sixth step of removing said semiconductor substrate exposed on the bottom surface of the first trench, thereby forming a second trench which continues from a side wall of the first trench and has a side wall substantially perpendicular to the surface of said semiconductor substrate;
• the seventh step of forming a third insulating film on an entire surface including inner surfaces of the first and second trenches, thereby filling the first and second trenches;
• the eighth step of removing said third insulating film until said first insulating film is exposed;
• and
• the ninth step of removing said first insulating film.

A method of manufacturing a semiconductor device, comprising:

• the first step of forming a first insulating film on a semiconductor substrate;
• the second step of forming a second insulating film on said first insulating film;
• the third step of selectively removing said second insulating film to form an opening through which said first insulating film is exposed;
• the fourth step of forming an oxidizable film on an entire surface of said semiconductor substrate;
• the fifth step of removing said oxidizable film until said first insulating film is exposed in the opening, thereby forming a first side wall made of said oxidizable film at a side wall of said second insulating film in the opening;
• the sixth step of forming a third insulating film on the entire surface of said semiconductor substrate;
• the seventh step of removing said third insulating film until said semiconductor substrate is exposed in the opening, thereby forming a second side wall made of said third insulating film so as to cover said first side wall;
• the eighth step of removing said semiconductor substrate exposed in the opening by using said second insulating film and said second side wall as a mask, thereby forming a trench in said semiconductor substrate;
• the ninth step of forming a fourth insulating film on the entire surface of said semiconductor substrate to fill the trench;
• the 10th step of removing said fourth insulating film until said second insulating film is exposed;
• the 11th step of removing said first and second insulating films to expose said underlying semiconductor substrate;
• and
• the 12th step of heat-treating said semiconductor substrate to thermally oxidize said first side wall made of said oxidizable film.

A method of manufacturing a semiconductor device, comprising:

• the first step of forming a first insulating film on a semiconductor substrate;
• the second step of selectively removing said first insulating film to form an opening through which said semiconductor substrate is exposed;
• the third step of forming an oxidizable film on an entire surface of said semiconductor substrate;
• the fourth step of heat-treating said semiconductor substrate to form a thermal oxide film of said oxidizable film;
• the fifth step of removing said thermal oxide film on said first insulating film to form a side wall made of said thermal oxide film at a side wall of said first insulating film in the opening;
• the sixth step of removing said semiconductor substrate exposed in the opening by using said first insulating film and said side wall as a mask, thereby forming a trench in said semiconductor substrate;
• the seventh step of forming a second insulating film on an entire surface of said semiconductor substrate to fill the trench;
• the eighth step of removing said second insulating film until said first insulating film is exposed;
• and
• the ninth step of removing said first insulating film to expose said underlying semiconductor substrate.

A method of manufacturing a semiconductor device, comprising:

• the first step of forming a first insulating film on a semiconductor substrate;
• the second step of forming a second insulating film on said first insulating film;
• the third step of selectively removing said second insulating film to form an opening through which said first insulating film is exposed;
• the fourth step of forming an oxidizable film on an entire surface of said semiconductor substrate;
• the fifth step of removing said oxidizable film until said first insulating film is exposed in the opening, thereby forming a first side wall made of said oxidizable film at a side wall of said second insulating film in the opening;
• the sixth step of forming a third insulating film on the entire surface of said semiconductor substrate;
• the seventh step of removing said third insulating film and said first insulating film until said semiconductor substrate is exposed in the opening, thereby forming a second side wall made of said third insulating film so as to cover said first side wall;
• the eighth step of removing said semiconductor substrate exposed in the opening by using said second insulating film and said second side wall as a mask, thereby forming a first trench having a side wall formed by an inclined surface making a predetermined angle with the surface of said semiconductor substrate;
• the ninth step of forming a fourth insulating film on an inner wall surface of the first trench including the inclined surface;
• the 10th step of removing said fourth insulating film from a bottom surface of the first trench, thereby exposing said semiconductor substrate on the bottom surface of the first trench;
• the 11th step of removing said semiconductor substrate exposed on the bottom surface of the first trench, thereby forming a second trench which continues from a side wall of the first trench and has a side wall substantially perpendicular to the surface of said semiconductor substrate;
• the 12th step of forming a fifth insulating film on an entire surface including inner surfaces of the first and second trenches, thereby filling the first and second trenches;
• the 13th step of removing said fifth insulating film until said second insulating film is exposed;
• the 14th step of removing said first and second insulating films to expose said underlying semiconductor substrate;
• and
• the 15th step of heat-treating said semiconductor substrate to thermally oxidize the first side wall made of said oxidizable film.

A method of manufacturing a semiconductor device, comprising:

• the first step of forming a first insulating film on a semiconductor substrate;
• the second step of selectively removing said first insulating film to form an opening through which said semiconductor substrate is exposed;
• the third step of forming an oxidizable film on an entire surface of said semiconductor substrate;
• the fourth step of heat-treating said semiconductor substrate to form a thermal oxide film of said oxidizable film;
• the fifth step of removing said thermal oxide film until the surface of said semiconductor substrate is exposed in the opening, thereby forming a side wall made of said thermal oxide film at side walls of said first and second insulating films in the opening;
• the sixth step of removing said semiconductor substrate exposed in the opening by using said first insulating film and said side wall as a mask, thereby forming a first trench having a side wall formed by an inclined surface making a predetermined angle with the surface of said semiconductor substrate;
• the seventh step of forming a second insulating film on an inner wall surface of the first trench including the inclined surface;
• the eighth step of removing said second insulating film from a bottom surface of the first trench to expose said semiconductor substrate on the bottom surface of the first trench;
• the ninth step of removing said semiconductor substrate exposed on the bottom surface of the first trench, thereby forming a second trench which continues from a side wall of the first trench and has a side wall substantially perpendicular to the surface of said semiconductor substrate;
• the 10th step of forming a third insulating film on an entire surface including inner surfaces of the first and second trenches, thereby filling the first and second trenches;
• the 11th step of removing said third insulating film until said first insulating film is exposed;
• and
• the 12th step of removing said first insulating film.