SILICON NITRIDE FILMS PREPARED BY PLASMA-ENHANCED CHEMICAL VAPOUR DEPOSITION (PECVD) OF SiH//4/NH//3/N//2 MIXTURES: SOME PHYSICAL PROPERTIES.

Abstract

Experimental data are presented on the effects of varying deposition parameters of SiH//4/NH//3 gas flow ratio, rf power, deposition pressure and substrate temperature, on the deposition rate, refractive index, hydrogen content and etch rates of PECVD silicon nitride films. BHF etch rate in these films are generally high and this is shown to be associated with the high hydrogen content. N-H and Si-H bond concentrations are measured in the range 1-4 multiplied by 10**2**2 cm** minus **3. The substrate temperature dependence of the etch rate exhibits a maximum for films deposited at 150 degree C. The behaviour is attributed to the incorporation of both hydrogen and oxygen, the effects on the etch rate of which are suggested to act in opposing directions.