Advanced Dual Metal Gate MOSFETs with High-k Dielectric for CMOS Application

Abstract

This paper reports the fabrication of MOSFETs with dual metal gate electrodes. Low threshold voltage (Vt) was achieved using TaC for nFETs and MoNx for pFETs. The transistors show excellent Ion-Ioff performance with well-controlled short channel effects. Benefited from a novel approach in base oxide formation, high mobility at ~90% of poly/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> was achieved on thick HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (30A). Improvement in current drivability by the incorporation of conventional cap stressor was also presented. The data demonstrates one of the best MOSFETs to date with dual metal gates on high-k dielectrics. It is further observed that high-k crystallization induces Vt non-uniformity in small devices. To our knowledge, the impact of crystallization to high- k manufacturability is addressed here for the first time