Semiconductor device having interconnection layer with multiply layered sidewall insulation film

A semiconductor device comprising:

• an interconnection layer formed above a substrate;
• a cap insulation film formed above the upper surface of the interconnection layer;
• and
• a sidewall insulation film which is formed on side walls of the interconnection layer and the cap insulation film, which includes at least 3 or more layers of insulation films at least one of which has a dielectric constant different from those of the others, and which is thicker at the side wall of the interconnection layer than at the side wall of the cap insulation film.

A semiconductor device comprising:

• an interconnection layer formed above a substrate;
• a cap insulation film formed above the upper surface of the interconnection layer;
• and
• a sidewall insulation film which is formed on side walls of the interconnection layer and the cap insulation film, which includes a first insulation film having a height substantially equal to that of the cap insulation film and a second insulation film having a height equal to that of at least the interconnection layer, and which is thicker at the side wall of the interconnection layer than at the side wall of the cap insulation film.

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

• forming above a substrate an interconnection layer having an upper surface covered by a cap insulation film;
• forming a first insulation film on the substrate with the cap insulation film and the interconnection layer formed on;
• forming a second insulation film whose etching rate is higher than that of the first insulation film on the first insulation film;
• anisotropically etching the second insulation film and the first insulation film to leave the first insulation film selectively on side walls of the interconnection layer and the cap insulation film and leave the second insulation film selectively on a lower region of a side wall of the first insulation film;
• and
• forming a third insulation film on an upper region of the side wall of the first insulation film and a side wall of the second insulation film.

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

• forming above a substrate an interconnection layer having an upper surface covered by a cap insulation film;
• forming a first insulation film on the substrate with the cap insulation film and the interconnection layer formed on;
• forming a second insulation film whose etching rate is higher than that of the first insulation film on the first insulation film;
• anisotropically etching the second insulation film and the first insulation film to leave the first insulation film selectively on side walls of the interconnection layer and the cap insulation film and thin the second insulation film selectively in an upper region of a side wall of the first insulation film;
• and
• forming a third insulation film on an upper region of the side wall of the first insulation film and a side wall of the second insulation film.

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

• forming above a substrate an interconnection layer having an upper surface covered by a cap insulation film;
• forming a first insulation film on the substrate with the cap insulation film and the interconnection layer formed on;
• anisotropically etching the first insulation film to leave the first insulation film selectively on a side wall of the interconnection layer while exposing at least a part of a side wall of the cap insulation film;
• and
• forming a second insulation film on a side wall of the first insulation film and a side wall of the cap insulation film.