a-SiN:H films modified by ArF excimer laser irradiation

Abstract

Hydrogenated amorphous silicon nitride (a:SiN:H) films produced by CO₂ and ArF laser-induced CVD in parallel configuration using silane/ammonia or disilane/ammonia gas mixtures were subjected to room temperature multiple pulse ArF excimer laser irradiations in an inert gas atmosphere. Modifications in their chemical composition, refractive index, and surface morphology were systematically followed up through Fourier-transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDS), single wavelength ellipsometry and atomic force microscopy (AFM), respectively. The observed film modifications involving large reductions in hydrogen (Si-H and N-H ) with the first few shots accompanied by a progressive incorporation of oxygen (Si-O and Si-OH) and a reduction of Si-N bonds that are attributed to UV-induced photochemistry where the atmospheric water incorporated in the films between successive irradiations plays an important role. Comparison among the different films indicated that the extent of bonded hydrogen in the films and their surface morphology influence their oxidation resistance.