Time dependent preferential sputtering in the HfO 2 layer on Si(100)

Abstract

The time dependent preferential sputtering in the HfO 2 layer on Si(100) has been investigated in-situ with X-ray photoelectron spectroscopy during Ar ion sputtering. Hf4f, O1s, and Si2p spectra show that three bonding environments (Hf 0+ from the Hf metal, Hf 2+ from HfO, and Hf 4+ from HfO 2) co-exist inside the HfO 2 layer during sputtering. The Hf 4+ doublet decreases with sputtering time in an exponential-like function. Both Hf 0+ and Hf 2+ doublets increase with sputtering time in opposite ways. Two concurrent sputtering mechanisms characterizing the formation of HfO and Hf due to preferential sputtering of oxygen within the HfO 2 layer can well explain the detailed bond breaking and re-formation process. The Hf metal is the final product and the HfO is an intermediate product during sputtering under vacuum. The HfO cannot be removed and acts as a residual component in the HfO 2 layer.