A Comprehensive Study of Thermal Stability on Microstructure and Residual Stress for ALD HfZrO2 Films at 28nm HKMG CMOS Applications

Abstract

The influence of thermal stability on microstructure, surface morphology and residual stress for gate stack structure of HfZrO2 dielectrics grown by atomic layer deposition (ALD) were investigated. The difference of spectra, residual stress, and structures for HfZrO2 films are obtained by the changed thermal energy. A tetragonal to monoclinic phase transformation is observed during high temperature annealing for HfZrO2 films. The variations of spectra can be attributed to the different residual stress of ALD HfZrO2 films induced by the annealing temperature. The tensile residual stress of HfZrO2 films were increased when increasing annealing temperature either for N2 or O2 annealing. This work provides an extensive study for the interface characteristics of high-k/metal (HKMG) stacks at 28nm advanced CMOS technology node.