Vacuum ultraviolet and ultraviolet radiation-induced effect of hydrogenated silicon nitride etching: Surface reaction enhancement and damage generation

Photon-enhanced etching of SiN :H films caused by the interaction between vacuum ultraviolet (VUV)/ultraviolet (UV) radiation and radicals in the fluorocarbon plasma was investigated by a technique with a novel sample setup of the pallet for plasma evaluation. The simultaneous injection of UV radiation and radicals causes a dramatic etch rate enhancement of SiN :H films. Only UV radiation causes the film shrinkage of SiN :H films owing to hydrogen desorption from the film. Capacitance-voltage characteristics of SiN :H/Si substrates were studied before and after UV radiation. The interface trap density increased monotonically upon irradiating the UV photons with a wavelength of 248 nm. The estimated effective interface trap generation probability is 4.74 × 10 eV ·photon . Therefore, the monitoring of the VUV/UV spectra during plasma processing and the understanding of its impact on the surface reaction, film damage and electrical performance of underlying devices are indispensable to fabricate advanced devices. © 2012 The Japan Society of Applied Physics.