AVS 58th Annual International Symposium and Exhibition
    Plasma Science and Technology Division Thursday Sessions
       Session PS+TF-ThM

Paper PS+TF-ThM1
High Quality SiNx by Microwave RLSA Plasma Enhanced Atomic Layer Deposition

Thursday, November 3, 2011, 8:00 am, Room 202

Session: Plasma Deposition and Plasma Enhanced ALD
Presenter: Takayuki Karakawa, Tokyo Electron Technology Development Institute, INC., Japan
Authors: T. Karakawa, Tokyo Electron Technology Development Institute, INC., Japan
M. Oka, Tokyo Electron Technology Development Institute, INC., Japan
N. Fukiage, Tokyo Electron Technology Development Institute, INC., Japan
H. Ueda, Tokyo Electron Technology Development Institute, INC., Japan
T. Nozawa, Tokyo Electron Technology Development Institute, INC., Japan
Correspondent: Click to Email
Shrinking critical dimensions of Ultra Large Scale Integration (ULSI) and optical device structures continue to drive advances in semiconductor fabrication processes. Three dimensional (3D) and metal gate structures for example, require low temperature dielectric layers (e.g., SiO2 and SiNx) with dimensions and film quality that may be met only by Plasma Enhanced Atomic Layer Deposition (PEALD) [1]. In addition to film quality and conformality, minimizing plasma damage in the PEALD process sequence is imperative. Prior to this work we characterized PEALD SiO2 deposition in a Radial Line Slot Antenna (RLSA) plasma source using bis-tertiaryl-buthyl-amino-silane (BTBAS) as a precursor [2]. In this study, we determined RLSA ALD process conditions favorable for SiNx film formation. The Si ALD precursor was dichlorosilane (DCS) and nitridation employed a NH3, N2 and Ar RLSA plasma. The wafer temperature was controlled below 400°C during the ALD process. Precursor adsorption time, process temperature, nitration time, plasma power were varied in order to determine the RLSA Plasma conditions resulting in the best SiNx ALD film quality. We obtained very high quality SiNx films having almost the same HF wet-etching rate as thermal LP-CVD SiNx (720°C) film. In this presentation, the results of Angle Resolved X-ray Photoelectron Spectroscopy (ARXPS) analyzed RLSA ALD deposited SiNx films will be presented. We found that the sub-nitride bonding ratio of the SiNx film was strongly correlated with the HF wet-etching rate, a measure of the film quality. The lower sub-nitride bonded SiNx film such as Si3N4 was created by the RLSA plasma at low temperature with low plasma damage. The reason so little damage occurs is the low rate of ion bombardment on new Si3N4 surfaces during plasma nitridation.

[1] S. Yokoyama et al., Applied Surface Science 112 (1997) 75-81

[2] Y. Osawa et al., Proceedings DPS-2009, 2-P51