Preparation of a-SiNx thin film with low hydrogen content by inductively coupled plasma enhanced chemical vapor deposition

Amorphous silicon nitride (a-SiNx) thin films are deposited at low temperature by remote-type inductively coupled plasma enhanced chemical vapor deposition (ICP-CVD) using N-2/SiH4 gases as reactant gases to obtain low hydrogen content in the films. Refractive index, deposition rate, stoichiometry, hydrogen content, and hydrogen configuration in the films are analyzed with the varation of deposition parameters. As RF power and N-2 flow rate increase, refractive index decreases due to the decrease of Si/N ratio, total hydrogen content is constant with N-H changing hydrogen bond configurations (Si-H, N-H) reversely. However, as substrate temperature increases, refractive index increases due to the reduction of Si/N ratio, and total hydrogen content as well as both hydrogen bond configurations (Si-PI, N-H) decrease. In remote-type ICP-CVD using N-2/SiH4 gases, N rich a-SiNx films with low refractive index and density are deposited due to efficient dissociation of N-2 gas by high density plasma, and hydrogen content in the films is greatly reduced.