Semiconductor device and method of fabricating the same

A method of fabricating a semiconductor device, comprising the steps of:

• forming a plurality of first trenches in a first region of a semiconductor substrate and a plurality of second trenches in a second region of said semiconductor substrate;
• increasing a curvature of a top edge portion of said second trench;
• filling said first and second trenches with an insulating material;
• and
• forming a first element in said first region and a second element in said second region, a voltage higher than that of said first element being supplied to said second element.

A method of fabricating a semiconductor device, comprising the steps of:

• forming a first insulating film in first and second regions of a semiconductor substrate;
• forming, on said first insulating film, a second insulating film formed of a material different from that of said first insulating film;
• patterning said second insulating film;
• etching said first insulating film and said semiconductor substrate by use of said second insulating film as a mask, forming a first trench in said first region of said semiconductor substrate, and forming a second trench in said second region of said semiconductor substrate;
• side-etching only said first insulating film of said second region;
• oxidizing inner surfaces of said first trench and second trench;
• forming a first element-isolating film and a second element-isolating film by filling said first and second trenches with an insulating material;
• and
• removing said second insulating film.

A method of fabricating a semiconductor device, comprising the steps of:

• forming a first insulating film in a first region of a semiconductor substrate and a second insulating film in a second region, said second insulating film being formed of the same insulating material as said first insulating film, said second insulating film having a film thickness lager than that of said first insulating film;
• forming, on said first and second insulating films, a third insulating film formed of an insulating material different from those of said first and second insulating films;
• patterning said third insulating film;
• etching said first and second insulating films and said semiconductor substrate by use of said third insulating film as a mask, and forming a first trench in said first region and a second trench in said second region;
• oxidizing inner surfaces of said first and second trenches;
• forming a first element-isolating film and a second element-isolating film by filling said first and second trenches with an insulating material;
• and
• removing said second insulating film.

A method of fabricating a semiconductor device, comprising the steps of:

• forming a first insulating film in a first region of a semiconductor substrate and a second region of said semiconductor substrate;
• forming, on said first insulating film, a second insulating film formed of an insulating material different from that of said first insulating film;
• forming a resist film on said second insulating film and patterning the resist film of said second region;
• etching said second insulating film, said first insulating film and said semiconductor substrate in said second region by use of said resist film as a mask, and forming a first trench having a width smaller than that of an opening of said resist film;
• removing said resist film;
• patterning said second insulating film in said first region;
• etching said first insulating film and said semiconductor substrate by use of said second insulating film in said first region as a mask, and forming a second trench having the same width as that of the opening of said second insulating film in said first region;
• oxidizing inner surfaces of said first and second trenches;
• forming a first element-isolating film and a second element-isolating film by filling said first and second trenches with an insulating material;
• and
• removing said second insulating film.

A method of fabricating a semiconductor device, comprising the steps of:

• forming a first insulating film in a first region of a semiconductor substrate and a second insulating film in a second region of said semiconductor substrate, said second insulating film being formed of the same insulating material as said first insulating film, said second insulating film having a film thickness larger than that of said first insulating film;
• forming a semiconductor film on said first and second insulating films;
• forming, on said semiconductor film, a third insulating film formed of an insulating material different from that of said first and second insulating films;
• patterning said third insulating film;
• etching said semiconductor film, said first and second insulating films and said semiconductor substrate by use of said third insulating film as a mask, forming a first trench in said first region and forming a second trench in said second region;
• oxidizing inner surfaces of said first and second trenches;
• and
• forming a first element-isolating film and a second element-isolating film by filling said first and second trenches with an insulating material.

A method of fabricating a semiconductor device, comprising the steps of:

• forming a first insulating film in a first region of a semiconductor substrate and in a second region of the semiconductor substrate;
• forming, on said first insulating film, a second insulating film formed of an insulating material different from that of said first insulating film;
• forming a first trench by etching the second insulating film, said first insulating film and said semiconductor substrate in said second region;
• forming a gap between a top edge portion of said first trench and said first insulating film by performing heat treatment in a hydrogen atmosphere;
• forming a second trench by etching said second insulating film, said first insulating film and said semiconductor substrate in said first region;
• oxidizing inner surfaces of said first and second trenches;
• forming a first element-isolating film and a second element-isolating film by filling said first and second trenches with an insulating material;
• and
• removing said second insulating film.

A method of fabricating a semiconductor device, comprising the steps of:

• forming a first insulating film in a first region of a semiconductor substrate and in a second region of the semiconductor substrate;
• forming, on said first insulating film, a second insulating film formed of an insulating material different from that of said first insulating film;
• forming a first trench by etching said second insulating film, said first insulating film and said semiconductor substrate in said second region;
• oxidizing a surface of said first trench;
• forming a second trench by etching said second insulating film, said first insulating film and said semiconductor substrate in said first region;
• making, by oxidizing a surface of said second trench and further oxidizing a surface of said first trench, a curvature of an interface between a top edge portion of said first trench and said semiconductor substrate being larger than a curvature of an interface between a top edge portion of said second trench and said semiconductor substrate;
• forming a first element-isolating film and a second element-isolating film by filling said first and second trenches with an insulating material;
• and
• removing said second insulating film.

A semiconductor device, comprising:

• a semiconductor substrate;
• a shallow trench including a trench being formed in said semiconductor substrate and an insulator being embedded in the trench, said shallow trench isolating said semiconductor substrate to form a plurality of element regions;
• a gate-insulating film formed on said element region of said semiconductor substrate;
• and
• a gate electrode formed on said gate-insulating film;
• wherein a curved surface is formed in an edge portion of said element region in a cross section of said semiconductor substrate by performing oxidation with a volume of oxygen being supplied to the edge portion kept larger than a volume of oxygen being supplied to a central portion.