Semiconductor device equipped with antifuse elements and a method for manufacturing an FPGA

Claim 1

A semiconductor device comprising: a semiconductor substrate; a first electrode formed over the semiconductor substrate and comprised of an Al connection layer formed over the semiconductor substrate and a first barrier metal layer having a surface and an exposed portion provided on, and electrically connected to, the Al connection layer, the first barrier metal layer serving as a barrier against the Al; an insulating film having an opening, which is defined by an inner wall of the insulating film, so that the insulating film partially covers the first electrode while allowing a portion of the surface of the first barrier metal layer of the first electrode to be exposed, the opening having a tapered structure such that its width is smaller near the first barrier metal layer and an angle between the inner wall of the opening and the surface of the first barrier metal layer is greater than 90° in the vicinity of where the inner wall meets the first barrier metal layer; an antifuse film partially covering the insulating film and formed such that the antifuse film contacts the tapered inner wall of the opening and the exposed portion of the first barrier metal layer of the first electrode, the antifuse film being formed of a silicon nitride whose nitrogen/silicon atomic composition ratio Ni/Si) ranges from 0.6 to 1.2, a leak current of the antifuse film being less than 10 -11 A/μm 2 and a capacitance of the antifuse film being less than about 4 fF/μm 2 ; and a second electrode provided on the antifuse film and electrically connectable with the first electrode with the antifuse film interposed therebetween, the second electrode having a second barrier metal layer to serve as a barrier.