A study of the dielectric constant of low-k SiOC film

As silicon devices keep shrinking in size while the circuits become more complex, they require low dielectric constant materials instead of silicon dioxide. SiOC films as low dielectric constant materials deposited by chemical vapor deposition were analyzed by Fourier transform infrared spectroscopy, elipsometry and nano-indentation to find the correlation between the dielectric constant and properties according to the flow rates. SiOC film showed a chemical shift according to an increase of the intensity of the Si-O bond in the main bond near 1000 cm−. Although the variation of the chemical shift was quite small in the FTIR spectra, the hardness and electronic properties such as the dielectric constant showed large differences. The blue shift in the main bond induced an increase in the hardness because of lowering the surface energy and a reduction of the carbon content which decreased the polarity, thickness and dielectric constant. The reduction of the dielectric constant and thickness of the SiOC film was caused by the reduction of ionic polarization owing to the elongation effect by the attractive force between atoms, and made a fine cross linked structure which contributed to a flat surface on substrates.