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

Surface reactivities for ${\mathrm{CF}}_{\mathrm{2}}$ radicals formed in a ${\mathrm{CHF}}_{\mathrm{3}}$ 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 ${\mathrm{CF}}_{\mathrm{2}}$ radicals interacting with ${\mathrm{SiO}}_{\mathrm{2}},$ ${\mathrm{Si}}_{\mathrm{3}}{\mathrm{N}}_{\mathrm{4}},$ 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 ${\mathrm{CF}}_{\mathrm{2}}$ radicals on all substrates. These extremely large scattering coefficients (>1.0) indicate that ${\mathrm{CF}}_{\mathrm{2}}$ molecules are generated through plasma interactions with the substrate. Possible ${\mathrm{CF}}_{\mathrm{2}}$ surface generation mechanisms are discussed, with consideration of CF and ion bombardment contributions to the generation of ${\mathrm{CF}}_{\mathrm{2}}.$