Leakage current lowering and film densification of ZrO2 high-k gate dielectrics by layer-by-layer, in-situ atomic layer hydrogen bombardment

Abstract

A layer-by-layer, in-situ H2 plasma treatment in each cycle of atomic layer deposition, referred to as “atomic layer hydrogen bombardment” (ALHB), is applied to improve electrical properties of ZrO2 high-k gate dielectrics. The H2 plasma bombardment facilitates the adatom migration due to energy delivery to each as-deposited monolayer from the H2 plasma. In addition, the H2 plasma treatment contributes to the removal of precursor ligands for the release of steric hindrance. Hence the ALHB treatment leads to film densification and suppression of oxygen vacancies of ZrO2, as evidenced by X-ray reflectivity and X-ray photoelectron spectroscopy characterizations. As a result, ~90% decrease of gate leakage current is achieved in the ZrO2 high-k gate dielectrics with capacitance equivalent thicknesses of ~1.3 nm and ~0.6 nm in metal-insulator-semiconductor and metal-insulator-metal capacitors, respectively. The results manifest that the ALHB treatment is a promising technique to enhance dielectric and electrical characteristics of nanoscale thin films, for further progress of advanced devices such as sensors, solar cells, memories, and nanoelectronics.