Compositional analysis of amorphous SiNx:H films by ERDA and infrared spectroscopy

The composition of amorphous SiN x : H films grown by the electron cyclotron resonance (ECR) plasma method was studied by heavy-ion elastic recoil detection analysis (ERDA) with 129 Xe ion beams of 1.1 and 1.8 MeV amu -1 and time-of-light (ToF) mass separation. This technique allows simultaneous determination of the absolute atomic concentrations and depth profiles of all involved elements, including hydrogen. Radiation damage at extended ion beam exposure was found to decrease the N/Si ratio and the hydrogen concentration. By measuring the dose dependence, this effect was quantified in order to support correction to zero dose conditions. Monitoring the damage effects by infrared (IR) spectroscopy revealed an increase of the Si-H bond density at the expense of N-H bonds. The results suggest that the damage process is initiated by breaking of N-H bonds and that recapturing of hydrogen by Si appears as an effective competitive process to hydrogen release. Combining the ERDA and IR data, the oscillator strength ratio of the N-H and Si-H stretching bands is found to be 1.4 ± 0.2.