Thermal etching of ruthenium

Abstract

Embodiments of methods are provided for thermal dry etching of a ruthenium (Ru) metal layer. In the disclosed embodiments, a substrate containing a Ru metal layer formed thereon is exposed to a gas pulse sequence, while the substrate is held at a relatively high substrate temperature (e.g., a temperature greater than or equal to about 160° C.), to provide thermal etching of the Ru metal layer. As described further herein, the gas pulse sequence may generally include a plurality of gas pulses, which are supplied to the substrate sequentially with substantially no overlap between gas pulses. The gas pulses supplied to the substrate form: (i) volatile reaction products that are vaporized from the Ru surface, and (ii) non-volatile oxide surface layers that are removed from the Ru surface by the next gas pulse, resulting in atomic layer etching (ALE) of the Ru metal layer.