Investigation of O2 and SF6 plasma interactions on thermally stable damage resistant poly phenyl-methyl silsesquioxane low-k films

Abstract

The need for improved device performance has led the microelectronics industry to consider alternate materials to use as interlayer dielectrics. Thermally stable low dielectric constant (low-k) materials, with minimal dielectric constant variation during plasma exposure are essential for microelectronic applications. Here we report on the deposition and characterisation of low-k poly phenyl-methyl silsesquioxane films having less k-variation upon interaction with O2 and SF6 plasmas compared to the other reported silsesquioxane materials. Structural transformation and thermal stability of the films during annealing was studied using Fourier transform infrared spectroscopy (FTIR). Even though significant removal of the film occurred with SF6 plasma exposure, no considerable variation of the k-value was observed with both O2 and SF6 plasma exposures. X-ray photoelectron spectroscopic (XPS) analysis was used to investigate the surface modification of the films resulting from plasma exposure. The higher dielectric stability is due to the insignificant moisture intake of the films after plasma treatment which is clear from the FTIR and XPS analysis.