Remote plasma-enhanced chemical vapor deposition of nanoporous low-dielectric constant SiCOH films using vinyltrimethylsilane

Abstract

Low dielectric constant (low-k) films have been prepared by remote plasma-enhanced chemical vapor deposition from vinyltrimethylsilane which has one vinyl group along with three methyl groups attached to silicon. The films have been characterized as-deposited and after annealing at 450degreesC. As-deposited films showed a SiCOH/CxHy dual-phase nanostructure, and the formation of nanopores was observed from annealing as confirmed by transmission electron microscope. The structure and composition of the films were investigated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The growth rate decreased with increasing substrate temperature in the range of room temperature to 100degreesC, and above 70degreesC a substantial film growth was not observed. The relative carbon content and dielectric constant were observed to decrease after annealing. It was observed that a thermally unstable phase (CxHy) is removed after annealing and the desorption of the labile phase makes additional nanopores in the film. After annealing, the increase of porosity was 15-20% against the thermal oxide, calculating from the Lorentz-Lorentz equation. SiCOH films showed a low dielectric constant of 2.1 and a leakage current density of 3 x 10(-7) A/cm(2) at 1 MV/cm at an optimum condition. (C) 2002 The Electrochemical Society.