Al2O3 ALD films grown using TMA + rare isotope 2H216O and 1H218O precursors

Abstract

In this work hydrogen and oxygen migration and exchange reactions in the atomic layer deposited (ALD) Al2O3 thin films were studied together with hydrogen incorporation by varying deposition parameters. Al2O3 films deposited at low temperatures can contain more than 20 at. % of hydrogen. Both higher temperature and longer purge length decrease the hydrogen and carbon concentrations significantly. In order to track the hydrogen and oxygen movement in the films, heavy water (2H216O) and oxygen-18 enriched water (1H218O) were used as precursors in combination with trimethylaluminium (TMA). Different isotopes of the same element were quantified by means of time-of-flight elastic recoil detection analysis (ToF-ERDA). It was found out that 1H/2H exchange reactions take place even at room temperature if the hydrogen concentration is high enough. On the other hand, oxygen atoms in the films do not migrate notably.