Constant Current N 2 O Plasma Anodization of Silicon

Abstract

A helical resonator plasma source was used to perform constant‐current plasma anodization of silicon. Growth rates in plasmas were lower than those in plasmas. Angle‐resolved x‐ray photoelectron spectroscopy (ARXPS) was used to study nitrogen incorporation in the oxides as a function of oxidation time and annealing temperature. At an oxide thickness of 4.5 nm, a bonding structure was observed in the interfacial region. Growth of a 9.4 nm oxide revealed the same bonding structure at the interface, with low intensity and broad signals at higher binding energies in the bulk oxide. Distinct peaks at higher binding energies in the bulk oxide corresponding to oxynitride bonding structures emerged in 15 nm oxides. Both 9.4 and 15 nm oxides were etched to 4.5 nm in HF solution and analyzed using angle‐resolved x‐ray photoelectron spectroscopy for comparison of nitrogen incorporation within the same oxide/interfacial region. Within the 4.5 nm region, longer oxidation times yielded higher nitrogen concentrations and the formation of oxynitride bonding arrangements in addition to the bonding structure. Nitrogen annealing at temperatures above 500°C decreased the total nitrogen concentration, primarily due to a reduction of nitrogen in the oxynitride bonding arrangement.