In situ monitoring of hafnium oxide atomic layer deposition

Atomic layer deposition (ALD) is increasingly being utilized as a method of depositing the thin (nanometerscale), conformal layers required for microelectronics applications such as high K gate dielectric layers and diffusion barriers. However, significant process development issues remain for implementation of this technology in many applications. One potential solution to some process development issues is in situ monitoring. In situ monitoring of atomic layer deposition processes has the potential to yield insights that will enable efficiencies in film growth, in the development of deposition recipes, and in the design and qualification of reactors. However, demonstrations of in situ monitoring of actual atomic layer deposition processes are limited. In this work, the species present in the gas phase during atomic layer deposition of hafnium oxide were investigated in an attempt to gain insight into the chemistry of this system and evaluate potential in situ gas phase optical monitors. Hafnium oxide was deposited on a silicon substrate using tetrakis(ethylmethylatnino) hafnium (TEMAH) and water as the hafnium and oxygen sources, respectively. In situ infrared absorption spectroscopic measurements were performed near the growth surface in a research-grade, horizontal-flow reactor under a range of deposition conditions. Density functional theory quantum calculations of vibrational frequencies of expected species were used to facilitate identification of observed spectral features.