Method for fabricating high-performance submicron mosfet with lateral asymmetric channel and a lightly doped drain

摘要

The present invention provides a method for fabricating a submicron metal-oxide semiconductor field-effect transistor (MOSFET). The method includes providing a gate on a substrate, the substrate having a source side and a drain side, the drain side having a spacer area; forming a spacer at the spacer area; performing a halo implant at the source side and the drain side, wherein the spacer prevents implantation in the spacer area, where the spacer facilitates formation of a lateral asymmetric channel; forming heavily doped extensions in the source side and the drain side, where the spacer prevents doping in the spacer area; removing the spacer; and forming a lightly doped extension in the drain side, where the heavily doped extensions and the lightly doped extension prevent hot carrier injection. In the preferred embodiment, the spacer is formed by depositing an oxide layer on the gate and substrate, and then avoiding nitrogen implantation of the oxide layer in the spacer area while implanting nitrogen in the remainder of the oxide layer. The difference in the etch rates of oxide implanted with nitrogen and oxide not implanted with nitrogen allows for a selective etch of the oxide layer, resulting in the spacer in the spacer area. A lateral asymmetric channel is thus formed, and the speed of the submicron MOSFET is increased while simultaneously preventing hot carrier injection.