Semiconductor device having a trench isolation and method of fabricating the same

A method of fabricating a semiconductor device comprising at least one kind of a MOS transistor on a semiconductor layer, and a trench isolation oxide film for defining at lest one active region as a region in which said MOS transistor is formed and electrically isolating said MOS transistor, comprising the steps of:

• (a) forming an auxiliary film for forming said trench isolation oxide film on said semiconductor layer;
• (b) forming a trench penetrating said auxiliary film and reaching a predetermined depth in said semiconductor layer;
• (c) forming said trench isolation oxide film by filling said trench with an oxide film and removing said trench isolation oxide film to a predetermined thickness;
• (d) after said step (c), implanting ions of an impurity of a conduction type different from that of a source/drain layer of said MOS transistor with energy by which the ions pass through said trench isolation oxide film and a peak of a profile is generated in said semiconductor layer under said trench isolation oxide film in a state where said auxiliary film is left on said active region, thereby forming channel stop layers in said semiconductor layer under said trench isolation oxide film;
• and
• (e) after formation of said channel stop layers, further reducing the thickness of said trench isolation oxide film.

A method of fabricating a semiconductor device comprising at least one kind of a MOS transistor on a semiconductor layer, and a trench isolation oxide film for defining at lest one active region as a region in which said MOS transistor is formed and electrically isolating said MOS transistor, comprising the steps of:

• (a) forming an auxiliary film for forming said trench isolation oxide film on said semiconductor layer;
• (b) forming a side wall spacer of an insulating film on an inner wall of said trench after forming a trench penetrating said auxiliary film and reaching a predetermined depth in said semiconductor layer;
• (c) implanting ions of an impurity of a conduction type different from that of a source/drain layer of said MOS transistor with energy by which a peak of a profile is formed in said semiconductor layer on the bottom of said trench in a state where said side wall spacer is formed, thereby forming channel stop layers in said semiconductor layer on the bottom of said trench;
• and
• (d) forming said trench isolation oxide film by filling said trench with an oxide film after formation of said channel stop layer.

A method of fabricating a semiconductor device comprising a trench isolation oxide film for defining an active region as a region in which a MOS transistor is formed on a semiconductor layer having crystallizability and electrically isolating said MOS transistor, comprising the steps of:

• (a) forming said trench isolation oxide film in a main surface of said semiconductor layer;
• and
• (b) implanting ions of an impurity of a conduction type different from that of a source/drain layer of said MOS transistor at an angle that the implanted ions cause channeling at the time of implantation of ions to said semiconductor layer, wherein
• said impurity implantation is performed with energy by which the impurity passes through said trench isolation oxide film and a peak of a profile is generated in said semiconductor layer under said trench isolation oxide film.

A method of fabricating a semiconductor device comprising a trench isolation oxide film for defining an active region as a region in which a MOS transistor is formed on a semiconductor layer and electrically isolating said MOS transistor, comprising the steps of:

• (a) forming said trench isolation oxide film in a main surface of said semiconductor layer;
• (b) forming a channel stop layer in said semiconductor layer under said trench isolation oxide film;
• (c) forming said MOS transistor on said active region;
• (d) forming a nitride film so as to cover at least a gate electrode of said MOS transistor and said active region;
• and
• (e)performing thermal oxidation after said step (d).