The mechanism of Si incorporation and the digital control of Si content during the metallorganic atomic layer deposition of Ti-Si-N thin films

Titanium-silicon-nitride thin films were grown by metallorganic atomic layer deposition (MOALD) using tc tetrakis(dimethylamido)titanium (TDMAT), ammonia. and silane at 180 degrees C. When the reactants are injected into the reactor in the sequence of TDMAT pulse, SiH4 pulse, and NH3 pulse, the Si content in the Ti-Si-N films is saturated at 18 atom %. By changing the supplying sequence in the order of TDMAT, NH3, and SiH4, the Si content is increased to 21 atom %. The Si content in the films is almost insensitive to the SiH4 partial pressure over a wide range of 0.27 and 13.3 Pa, because it is self-limited by the quantity of SiH4, molecules absorbed on the film surface. By utilizing these inherent characteristics of MOALD. digital control of Si content in Ti-Si-N thin film is possible by controlling the number of SIH4 pulses during film deposition. The MOALB Ti-Si-N films have almost 100% step coverage on a 0.3 mu m diam hole with an aspect ratio of 10:1. MOALD is considered to be a promising deposition method for less than 10 nm thick Ti-Si-N films as a Cu diffusion barrier film. (C) 2000 The Electrochemical Society. S0013-4651(00)02-024-3. All rights reserved.