Low-Temperature Low-Resistivity PEALD TiN Using TDMAT under Hydrogen Reducing Ambient

Abstract

Titanium nitride (TiN) films were deposited using plasma-enhanced atomic layer deposition (PEALD) from the organometallic precursor tetrakis-dimethyl-amino-titanium (TDMAT) with hydrogen (H-2) as a coreactant. Low-resistivity values lying from 210 to 275 mu Omega cm were achieved for 10 nm thick films deposited at low temperature: 150 degrees C. The effects of temperature, plasma time, and plasma power were investigated. It was demonstrated that the chemical reaction is complementary and self-limiting. A minimum energy is necessary to reach the low-resistivity plateau. Chemical and physical properties of the films are also reported and a surface reaction mechanism is proposed. It is suggested that after TDMAT chemisorption to the surface, amines are removed by hydrogen radicals, and at the same time, titanium carbide bonds (Ti-C) are formed. The low resistivity results from the presence of Ti2C or Ti2N phases in the PEALD TiN film. The industrial viability of this process was also evaluated on 300 mm wafers. Good performances were obtained on wafer-to-wafer uniformity and step coverage, while some improvements related to the within-wafer uniformity are required. (C) 2008 The Electrochemical Society.