MOS transistor and fabrication process therefor

摘要

An MOS transistor comprises a semiconductor substrate having a field region; a gate electrode formed on the semiconductor substrate through the intermediatry of a gate insulating film; and source/drain regions formed in the semiconductor substrate; wherein the field region including at least a lower insulating film and an upper insulating film made of a material permitting the upper insulating film to be selectively etched with respect to the lower insulating film; the gate electrode being configured such that the gate length of a top surface thereof is greater than the gate length of a bottom surface thereof facing a channel region positioned between the source/drain regions; the gate electrode having a sidewall spacer formed of a sidewall insulating layer made of the lower insulating film and a material permitting the sidewall insulating layer to be selectively etched with respect to the upper insulating film, the sidewall spacer contacting a side wall of the gate electrode for covering an outer periphery of the channel region; and the channel region being substantially leveled with the source/drain regions. <IMAGE> <IMAGE>