Method for fabricating a semiconductor device with a gate-all-around and device formed thereby

摘要

Gate-all-around (GAA) architecture semiconductor device production, by gate formation around a bridge structure formed by removing material below a silicon layer (5) having a thin single crystal central portion (5a), is new. A semiconductor device of GAA architecture is produced from a substrate (1) having a central active semiconductor region (2) surrounded by a peripheral insulating region (3) by (a) selective epitaxy of a single crystal Ge or SiGe alloy layer on the active region main surface; (b) non-selective epitaxy of a silicon layer (5) which is monocrystalline above the single crystal layer and which is polycrystalline above the insulating region surface; (c) masking and etching of the silicon layer (5) and the single crystal layer to form, on the active region main surface, a stack with two opposite side walls exposing the single crystal layer; (d) selective etching away of the single crystal layer so that the silicon layer forms a bridge structure having side walls, an external surface and an internal surface defining, with the active region main surface, a tunnel (7); (e) formation of a dielectric thin film (8, 9), which does not fill the tunnel, on the external and internal surfaces and on the side walls of the bridge structure; (f) deposition of conductive material to cover the bridge structure and to fill the tunnel; and (g) masking and etching of the conductive material to form an all-around gate region (10) of desired dimensions and geometry. An Independent claim is also included for a semiconductor device produced by the above process, the central part (5a) of the bridge structure (5) being of single crystal silicon and being 1-50 nm thick.