The effect of composition on the bond structure and refractive index of silicon nitride deposited by HWCVD and PECVD
article
Silicon nitride (SiNx) is a material with many applications and can be deposited with various deposition techniques. Series of SiNx films were deposited with HWCVD, RF PECVD,MWPECVD and LF PECVD. The atomic densities are quantified using RBS and ERD. The influence of the atomic densities on the SiN and SiSi bond structure is studied. The density of NN bonds is found to be negligible. NewSiN FTIR proportionality factors are determined which increase with increasing N/Si ratio from 1.2?ñ019 cm-1 for Si rich films (N/Si=0.2) to 2.4?ñ019cm-1 forNrich films (N/Si=1.5). The peak position of the SiHstretchingmode in the FTIR spectrumis discussed using the chemical induction model. It is shown that especially for Si-rich films the hydrogen content affects the SiHpeak position. The influence of the composition on the refractive index of the films is discussed on the basis of the LorentzLorenz equation and the KramersKronig relation. The decreasing refractive index with increasing N/Si ratio is primarily caused by an increase of the band gap.
TNO Identifier
846379
Publisher
ECN
Collation
4 p.
Place of publication
Petten
Files