MOS transistor

摘要

A method of fabricating a semiconductor transistor device comprises the steps as follows. Provide a semiconductor substrate with a gate dielectric layer thereover and a lower gate electrode structure formed over the gate dielectric layer with the lower gate electrode structure having a lower gate top. Form a planarizing layer over the gate dielectric layer leaving the gate top of the lower gate electrode structure exposed. Form an upper gate structure over the lower gate electrode structure to form a T-shaped gate electrode with an exposed lower surface of the upper gate surface and exposed vertical sidewalls of the gate electrode. Remove the planarizing layer. Form source/drain extensions in the substrate protected from the short channel effect. Form sidewall spacers adjacent to the exposed lower surface of the upper gate and the exposed vertical sidewalls of the T-shaped gate electrode. Form source/drain regions in the substrate. Form silicide layers on top of the T-shaped gate electrode and above the source/drain regions.