Composition Limited Hydrogen Effusion Rate of a-SiNx:H Passivation Stack

Hydrogen effusion measurements have been carried out for a-SiN:H films prepared by plasma enhanced chemical vapor deposition of NH3/SiH4 gas mixture. Additional FTIR measurements were performed to assure the compositional dependence of the Hydrogen release. A correlation between bonding changes in silicon nitride films and the peak temperature of Hydrogen effusion is presented. A shift in the Hydrogen temperature release was observed by increasing N atoms from 800 degrees C in the Si rich layer to 1000 degrees C for a N rich layer which reduced the Hydrogen loss by 40% at critical contact firing temperature. Moreover the Hydrogen evolution rate suppressed drastically by applying N-gradient stack layers of SiN. The result of peak analysis shows that the de-convoluted spectra of Hydrogen evolution spectrum contain maximum of three peak components depending on SiN film composition. There was seen an obvious correlation between the early Hydrogen effusion peaks and formation of surface blistering.