Transistor element with reduced lateral electrical field
In sophisticated semiconductor devices, the lateral electric field in fully depleted transistor elements operated at elevated supply voltages may be significantly reduced by establishing a laterally graded dopant profile at edge regions of the respective channel regions. In some illustrative embodiments to this end, one or more dopant species may be incorporated prior to completing the gate electrode structure.
1. A method, comprising:
forming an isolation trench for laterally bordering an active region of a transistor element along one lateral direction, said active region including a channel region;
forming a doped material in said isolation trench so as to provide an increased concentration of a dopant species laterally adjacent to said channel region;
forming a laterally graded dopant profile in at least one of a first edge region and an oppositely positioned second edge region of said channel region, wherein forming said laterally graded dopant profile comprises initiating diffusion of said dopant species; and
after forming said laterally graded dopant profile, forming a gate electrode structure on said channel region, said channel region at least partially overlapping said first and second edge regions.
2. The method of claim 1 , wherein initiating said diffusion of said dopant species comprises performing an anneal process.