Process of fabricating semiconductor devices having lightly-doped drain

Claim 1

A process for fabricating a semiconductor device having an active region and having a gate structure formed on a substrate, said gate structure having a gate thickness, said process comprising the steps of: forming a sidewall spacer on at least one sidewall of said gate structure by depositing a single insulating layer over the substrate and the gate structure and etching back the insulating layer to form the sidewall spacer, said sidewall spacer having a sidewall spacer thickness measured in a depth direction of said substrate such that an impurity implantation applied to said sidewall spacer is only obstructed but not blocked by said sidewall spacer thickness, said sidewall spacer thickness being less than said gate thickness; and implanting impurities to form at least one lightly-doped region underneath said sidewall spacer while at the same time forming at least one heavily-doped region in the area not obstructed by said sidewall spacer, said at least one lightly-doped region being adjacent to said at least one heavily-doped region and defining with the adjacent heavily-doped region said active region of said semiconductor device.