Mass spectrometric studies of plasma etching of silicon nitride

Abstract

Basic chemical processes in a CF4/O2 plasma during etching of silicon nitride have been investigated using mass spectrometry. Samples of the discharge are extracted through a quartz capillary and the resulting variations in species abundance at a nitride/oxide interface yield information on etch reaction pathways. Mechanisms of F and CF2 attack and SiF4, N2, NO, and CN product formation are proposed. The experimental data are suitable for application in mass spectrometric endpoint detection.