Effect of Precursor Entrance Sequence during Atomic Layer Deposition on the Al₂O₃/Ge Interface by X-ray Photoelectron Spectroscopy

Abstract

The effect of precursor entrance sequence during atomic layer deposition (ALD) on the chemical and electronic characteristics of Al2O3/Ge interface is investigated by X-ray photoelectron spectroscopy (XPS) and capacitance-voltage (C-V) measurement. The trimethyla-luminium (TMA) or H2O precursor is first introduced into the chamber to grow Al2O3 dielectric on cleaned Ge. An abrupt Al2O3/Ge interface without interlayer is obtained for both cases. The valence band offset (VBO) at the Al2O3/Ge interface becomes smaller when the TMA precursor is first introduced. It is due to the lower CNL of gap states at Al2O3/Ge interface which is induced by the TMA treatment of Ge surface. Comparable gap state density at Al2O3/Ge interface are observed by C-V, indicating that the density states of gap states is not affected by the precursor pulse sequence. As a result, the precursor pulse sequence affects the CNL of gap states but not their density.