A Study on the Etching and Surface Characteristics of SiOC Thin Films After C₆F₁₂O Plasma Etching

Silicon oxycarbide (SiOC) film was etched using a CF₄/C₆F₁₂O/O₂ mixed gas plasma through an inductively coupled plasma etcher. Changes in the dielectric constant and surface chemical bonding properties were investigated using ellipsometry and Fourier transform infrared spectroscopy. Plasma diagnosis was carried out using a double Langmuir probe, ultraviolet detector, and residual gas analyzer. The physical and chemical plasma properties of CHF₃ and C₆F₁₂O exhibited similar trends. However, the C₆F₁₂O mixed plasma exhibited a smaller change in dielectric constant compared to that of a conventional CHF₃ mixed plasma, because of the lower ion density, ion energy flux, and UV intensity and thinner fluorocarbon-based polymer formation. Therefore, the liquefied C₆F₁₂O gas can substitute for the existing etching process gas and reduce the change in dielectric constant.