Asymmetrical transistor having a gate dielectric which is substantially resistant to hot carrier injection

Abstract

Abstract A transistor fabrication process is provided which derives a benefit from having an asymmetrical LDD structure. A gate oxide layer is grown across a silicon-based substrate. A polysilicon layer is then deposited across the gate oxide layer. Portions of the polysilicon layer and the oxide layer are removed to form a gate conductor and gate oxide, thereby exposing source-side and drain-side junctions within the substrate. The source-side and drain-side junctions are implanted with a dopant to form LDD areas therein. The source-side junction may then be exclusively implanted to form a heavily doped source region in the source-side junction. An etch stop material may be formed upon opposed sidewall surfaces of the gate conductor, the upper surface of the gate conductor, and the source-side and drain-side junctions. Spacers may then be formed laterally adjacent the etch stop material located upon sidewall surfaces of the gate conductor. The unmasked portions of the source-side and drain-side junctions are heavily doped, resulting in source and drain regions that are aligned to the exposed lateral edges of the spacers. The drain-side spacer is removed and barrier atoms are forwarded through the exposed etch stop material and into a substrate/gate oxide interface region near the drain junction. The barrier atoms help reduce hot electron effects by blocking diffusion avenues of carriers (holes or electrons) from the drain-side junction into the gate oxide.

Inventors

• 👤 H. Jim Fulford
• 👤 Mark I. Gardner

Bibliographic Details