Methods and apparatus for filling high aspect ratio structures with

Abstract

Filling of narrow and/or high aspect ratio gaps and trenches with silicate glass is accomplished at reduced temperatures and without reflow by etching the glass concurrently with thermal chemical vapor deposition of the glass such that the deposition rate will exceed the etching rate by a relatively small net deposition rate near the surface with the excess deposition rate increasing over the depth of the trench or gap. The as-deposited glass film is made dense and stable by carrying out the concurrent etch and deposition process at an elevated temperature but which is within the maximum temperature and heat budget which can be tolerated by structures formed by previously performed processes. Fluorine can be incorporated in the silicate glass film as a dopant in sufficient concentration to reduce dielectric constant of the film. Phosphorus and/or boron can be incorporated into the film, as well, and may enhance void-free filling of trenches and gaps.