Surface interactions of CF2 radicals during deposition of amorphous fluorocarbon films from CHF3 plasmas

Abstract

Surface reactivities for CF2 radicals formed in a CHF3 plasma molecular beam are measured during film deposition on a variety of substrates. The imaging of radicals interacting with surfaces (IRIS) technique was used to collect spatially resolved laser-induced fluorescence (LIF) images of CF2 radicals interacting with SiO2, Si3N4, Si, 304 stainless steel, and system 8 photoresist substrates. Films deposited during IRIS experiments were characterized using x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy and were found to be nearly identical in composition on all substrates. Simulation of LIF cross-sectional data shows high scattering coefficients for CF2 radicals on all substrates. These extremely large scattering coefficients (>1.0) indicate that CF2 molecules are generated through plasma interactions with the substrate. Possible CF2 surface generation mechanisms are discussed, with consideration of CF and ion bombardment contributions to the generation of CF2.