Microwave assisted volatilization of silicon as fluoride for the trace impurity determination in silicon nitride by dynamic reaction cell inductively coupled plasma-mass spectrometry

Abstract

A low pressure microwave assisted vapor phase dissolution procedure for silicon nitride and volatilization of in situ generated SiF 4 has been developed using H 2SO 4, HF and HNO 3 for the determination of trace impurities present in silicon nitride. Sample was taken in minimum amount (0.5 mL for 100 mg) of H 2SO 4 and treated with vapors generated from HF and HNO 3 mixture in presence of microwaves in a closed container. An 80 psi pressure with ramp and hold times of 30 min and 60 min respectively, operated twice, resulted in 99.9% volatilization of Si. Matrix free solutions were analyzed for impurities using DRC-ICP-MS. The recoveries of Cr, Mn, Fe, Ni, Co, Cu, Zn, Sr, Y, Cd, Ba and Pb were between 80 and 100% after volatilization of Si. The blanks were in lower ng g −1 with method detection limits in lower ng g −1 to sub ng g −1 range. The method was applied for the analysis of two silicon nitride samples.