In Situ Spectroscopic Ellipsometry Study of Plasma-Enhanced ALD of Al₂O₃on Chromium Substrates

Abstract

Atomic layer deposition (ALD) of aluminum oxide thin films on chromium substrates was studied using in situ spectroscopic ellipsometry (SE). The study of the initial stages of ALD film growth on metal surfaces is an important topic in the emerging field of metal-insulator-metal (MIM) fabrication. Chromium substrates were prepared by DC magnetron sputtering and were transferred under vacuum into an ALD reaction chamber. Formation of a thin layer of chromium oxide was observed during the initial cycles of plasma-enhanced ALD of aluminum oxide. The thickness of this interfacial oxide layer depends on various process parameters including deposition temperature, order of precursors and plasma pulse length. The interfacial oxide layer was absent during thermal ALD. FTIR measurements confirmed that the Cr/Al2O3 interface is affected by the type of ALD (thermal or plasma-enhanced).