Structure-designable method to form super low-k SiOC film (k = 2.2) by neutral-beam-enhanced chemical vapour deposition

Abstract

To precisely control the dielectric constant and the structure of a low-k SiOC film, we have developed a neutral-beam-enhanced chemical vapour deposition (NBECVD) method. Using Ar NBECVD, we can precisely control the dielectric constant and the film modulus of low-k SiOC deposited on Si substrates because this method avoids precursor dissociation that results from electron collisions and UV photons in plasma. Optimizing the ratio between Si–O and Si–(CH3)x as well as the proportions of linear (two-dimensional SiOC), network and cage (three-dimensional SiOC) structures by changing the precursor, we obtained a k value of 2.2 and a reasonable modulus by using dimethyl dimethoxy silane as a precursor. Additionally, the NBECVD process is applicable as a method for damage-free super-low-k film deposition on the underlying low-k film that is sensitive to damage by the plasma.