Physical and Electrical Effects of the Dep-Anneal-Dep-Anneal (DADA) Process for HfO2 in High K/Metal Gate Stacks

Abstract

In this work we present physical and electrical characterization of HfO2 films deposited using the Dep-Anneal-Dep-Anneal (DADA) deposition scheme. Electrical results from MOSCAP devices fabricated using a low temperature (Gate Last-like) integration flow are presented. In addition we report detailed physical analyses of the films and changes in the films versus as-deposited ALD HfO2 and films undergoing a single post-deposition anneal and show the correlation between observed physical changes in the film and electrical results. Observed physical changes using HR-RBS, HR-TEM, SIMS, XPS and XRR include crystallization, densification, Si intermixing, reduction of in-film carbon and improved etch resistance leading to improved leakage vs. EOT and electrical non-uniformity. Dependence of these changes on the underlying interface layer (e.g. SiO2 vs SiON) is also described.