Semiconductor device having interconnection layer with multiply layered sidewall insulation film
View Patent ↗The semiconductor device comprises an interconnection layer 14 formed on a substrate 10 , a cap insulation film 22 formed on the upper surface of the interconnection layer 14 , and a sidewall insulation film which is formed on the side walls of the interconnection layer 14 and the cap insulation film 22 and which includes a larger layer number of insulation films 24, 26 28 covering the side wall of the interconnection layer 14 at the side wall of the cap insulation film 22 than a layer number of insulation films 24, 26 at the side wall of the cap insulation film 22 . Accordingly, the sidewall insulation film can be thickened at the side wall of the interconnection layer 14 , whereby a parasitic capacitance between the interconnection layer 14 and the electrodes 32 adjacent to the interconnection layer 14 through the sidewall insulation film can be low.
1. 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;
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;
forming a fourth insulation film on the substrate with the interconnection layer and the first, second and third sidewall insulation films, the fourth insulation film contacting to the third sidewall insulation film; and
anisotropically etching the fourth insulation film and the third insulation film with the cap insulation film and the first to the third insulation films as a stopper to form a contact hole down to the substrate in the fourth insulation film and the third insulation film.
2. A method for fabricating a semiconductor device according to claim 1 , further comprising the step of:
removing the third insulation film in the contact hole after the step of forming a contact hole.
3. A method for fabricating a semiconductor device comprising the steps of:
forming above a substrate an interconnection layer having a side surface;
forming a first sidewall insulation film to cover the side surface of the interconnection layer;
forming a second sidewall insulation film whose etching rate is different from that of the first sidewall insulation film and covering the side surface of the interconnection layer through the first sidewall insulation film;
forming a third sidewall insulation film whose etching rate is the same as that of the first sidewall insulation film and covering the side surface of the interconnection layer through the first and second sidewall insulation films;
forming a fourth insulation film on the substrate with the interconnection layer and the first, second and third sidewall insulation films, the fourth insulation film contacting to the third sidewall insulation film; and
anisotropically etching the fourth insulation film with the third sidewall insulation film as a stopper to form a contact hole down to the substrate in the fourth insulation film.