Evaluation of Property Changes due to Radiation, Radicals, and Ions on Organic Low-k Films in H₂/N₂ Plasma Etching

An organic low-dielectric constant (low-k) film, polyallylene (PAr), is a prospective candidate for low-k interlayer films for ultra large-scale integrated circuits (ULSIs). PAr films are caused the property changes such as increases of the dielectric constant during plasma etching and ashing. In a previous study, we have developed a novel technique called pallet for plasma evaluation (PAPE) for separately evaluating the property changes caused by radiation, radicals, and ions in process plasmas and clarified the mechanism of plasma-induced property changes on low-k porous SiOCH films. In this study, using the PAPE technique, we investigated the changes on the surface of a PAr film due to radiation, radicals, radiation with radicals, and ions in dual-frequency capacitively coupled H₂/N₂ plasmas. The property changes were characterized by ellipsometry and X-ray photoelectron spectroscopy. The property changes on the PAr films due to radiation and radicals were considerably smaller compared to those on the low-k porous SiOCH films.