Compositional effects on electrical and mechanical properties in carbon-doped oxide dielectric films: Application of Fourier-transform infrared spectroscopy

Abstract

Organosilicate glasses, also known as carbon-doped oxides (CDO), have been studied for application as interlayer dielectrics in microprocessors. Fourier-transform infrared (FTIR) spectroscopy is used here to monitor CDO film compositions prepared by plasma-enhanced chemical vapor deposition of dimethyldimethoxysilane. The Si–CH3/Si–O peak area ratios represent the relative content of these functional groups within the films, and indicate compositional changes in the films produced. Additionally, a close inspection of the C–H stretching modes shows a large peak at 2962 cm−1 due to the CH3 asymmetric stretch and a smaller shoulder to the right, made up of up to three other C–H stretching modes. The shoulder intensity divided by the asymmetric stretch intensity provides another metric that tracks compositional changes in the film. Product compositions indicated by FTIR also correlate well with physical properties such as dielectric constant, hardness, bulk modulus, and cohesive strength.