Robust ternary metal gate electrodes for dual gate CMOS devices

Abstract

This report describes thermally stable dual metal gate electrodes for surface channel Si CMOS devices. We found that the ternary metal nitrides, i.e., Ti/sub 1-x/Al/sub x/N/sub y/ (TiAlN) and TaSi/sub x/N/sub y/ (TaSiN) films, are stable up to 1000/spl deg/C. Especially, the stoichiometric TiAlN (y/spl sim/1) exhibited highly robust p-type gate electrode (p-TiAlN) properties, demonstrating a work function (/spl Phi//sub m/) of /spl sim/5.1 eV and excellent gate oxide integrity against the thermal budget of conventional Si CMOS processing. The N-deficient TiAlN (y < 1) showed /spl Phi//sub m/ for n-type electrode (n-TiAlN) with limited thermal stability. The dual gate electrodes, p-TiAlN and TaSiN, exhibited negligible EOT (equivalent oxide thickness) variation on the high-k gate dielectrics (ZrO/sub 2/, HfO/sub 2/) up to 950/spl deg/C.