Selective ruthenium removal by microwave oxidation plasma

Abstract

Methods and apparatus for forming semiconductor devices, and more specifically to methods for filling ruthenium features for forming low resistivity electrical connections. In one aspect, a method of forming a film on a semiconductor substrate is provided. The method includes a cyclic deposition-etch process. The cyclic deposition-etch process includes depositing a ruthenium layer over a bottom surface and sidewall surfaces that define an opening of a feature. The cyclic deposition-etch process further includes trimming the ruthenium layer by exposing the ruthenium layer to microwave radiation to remove at least a first portion of the ruthenium layer formed over the sidewall surfaces. The method further includes bottom-up growth of ruthenium from the ruthenium layer formed over the bottom surface.

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