Effect of N2 Gas Flow Ratio in Plasma-Enhanced Chemical Vapor Deposition with SiH4--NH3--N2--He Gas Mixture on Stress Relaxation of Silicon Nitride

The effects of N 2 gas flow ratios in silicon nitride deposition with SiH 4 --NH 3 --N 2 --He gas mixtures at a temperature of 275 \mbox{ \circ C} on stress relaxation have been investigated. We have demonstrated that film stress can be controlled in the range from $-692$ MPa (compression) to 170 MP...

Full description

Saved in:
Bibliographic Details
Published in:Jpn J Appl Phys 2010-08, Vol.49 (8), p.08JF08-08JF08-4
Main Authors: Murata, Tatsunori, Miyagawa, Yoshihiro, Matsuura, Masazumi, Asai, Koyu, Miyatake, Hiroshi
Format: Article
Language:English
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The effects of N 2 gas flow ratios in silicon nitride deposition with SiH 4 --NH 3 --N 2 --He gas mixtures at a temperature of 275 \mbox{ \circ C} on stress relaxation have been investigated. We have demonstrated that film stress can be controlled in the range from $-692$ MPa (compression) to 170 MPa (tension) by increasing N 2 gas flow ratio. From the evaluation of the composition ratio of N/Si, film density, and bonding structure, the relationships between film stress and these properties are investigated. The amount of nitrogen incorporated into the film as N--H bonds increased with increasing N 2 flow ratio, resulting in a higher composition ratio of N/Si. At a higher N 2 gas flow ratio, excess N 2 gas in the plasma may disturb the ion bombardment of ionized species on the film surface, resulting in a decrease in the film density. The higher N 2 gas flow ratio leads to the generation of a Si--N bonding structure with a larger bond angle at the nitrogen atom site due to bond-strain relaxation, leading to a higher frequency of Si--N stretching vibration. Therefore, a nitrogen-richer SiN film with many N--H bonds and a lower film density exhibits bonding structures with a lower bond strain, leading to the relief of film stress.
ISSN:0021-4922
1347-4065
DOI:10.1143/JJAP.49.08JF08