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.

Effects of Microwave-Assisted Heat Treatments on the Nanostructural Evolution of Amorphous Silicon Oxycarbide Thin Films

This study investigated the effects of heat treatment on changes in the nanostructure of amorphous silicon oxycarbide thin films. Hydrogenated amorphous silicon oxycarbide (a-Si0.6C0.3O0.1:H) thin films were prepared via plasma-enhanced chemical vapor deposition. The films were subjected to post-deposition heat treatments via microwave-assisted heating, which resulted in the formation of nanocrystals of SiC and Si in the a-Si0.6C0.3O0.1:H matrix at temperatures as low as ~800 °C. The crystallization activation energies of SiC and Si were determined to be 1.32 and 1.04 eV, respectively lower than those obtained when the sample was heat-treated via conventional heating (CH). Microwaves can be used to fabricate nanocrystals at a temperature approximately ~300 °C lower than that required for CH. The optical and nanostructural evolutions after post-deposition heat treatments were examined using photoluminescence (PL) and X-ray diffraction. The position of the PL peaks of the nanocrystals varied from ~425 to ~510 nm as the annealing temperature was increased from 800 to 1000 °C. In this study the optical band gap of SiC and Si varied from ~2.92 to ~2.40 eV and from ~2.00 to ~1.79 eV, as the size of the SiC and Si nanocrystals varied with respect to the heating temperature and isothermal holding time, respectively.