Non-uniform channel profile via enhanced diffusion

The present invention relates generally to a semiconductor device with transistors, and to a method of manufacturing the semiconductor device. The present invention has particular applicability in semiconductor devices comprising high density metal oxide semiconductor field effect transistors (MOSFETs) with submicron dimensions. A semiconductor device with reduced leakage current is obtained by forming a non-uniform channel doping profile. A high impurity region of the opposite conductive type of a source region is formed between the channel region and source region by transient enhanced diffusion (TED). The high impurity region substantially reduces the threshold voltage rolling off problem.