Effect of hydrogen content on dielectric strength of the silicon nitride film deposited by ICP-CVD

The inductively coupled plasma chemical vapor deposition (ICP-CVD) deposited silicon nitride (SiN_x) thin film was evaluated for its application as the electrical insulating film for a capacitor device. In order to achieve highest possible dielectric strength of SiN_x, the process parameters of ICP-CVD were carefully tuned to control hydrogen in SiN_x films by means of tuning N₂/SiH₄ ratio and radio frequency (RF) power. Besides electrical measurements, the hydrogen content in the films was measured by dynamic secondary ion mass spectrometry (D-SIMS). Fourier transform infrared spectroscopy (FTIR) and micro Raman spectroscopy were used to characterize the SiN_x films by measuring Si-H and N-H bonds' intensities. It was found that the more Si-H bonds lead to the higher dielectric strength.