Enhancement of Device Performance in LDMOSFET by Using Dual-Work-Function-Gate Technique

Abstract

In this letter, we propose a new lateral double-diffused metal-oxide-semiconductor field-effect transistor (LDMOSFET) with dual-work-function-gate (DWG) structure fabricated by utilizing silicidation of poly-Si layer. The step-etched poly-Si layer in the source side of the gate was totally converted to Ni-rich silicide, which resulted in a higher work function. On the other hand, in the drain side, only the upper part of the nonetched poly-Si layer was silicided, and the remaining lower part of the poly-Si layer was considered to be a gate with a lower work function. The fabricated DWG-LDMOSFET demonstrated remarkable improvement in device performances, such as 16.7, 16.4, 3.3, and 6.4% improvement in saturation drain current, in field-effect mobility, in subthreshold slope, and in the on resistance, respectively, while keeping almost the same breakdown voltage of 26 V and exhibiting less self-heating effect compared with the conventional single-work-function-gate LDMOSFET.