Electroless atomic layer deposition of copper

Abstract

Electrochemical ALD enables the atomically-precise deposition of Cu films; however, in the traditional embodiment of electrochemical ALD, the underpotential deposition (UPD) step necessitates external electrode potential manipulation. This renders the process unsuitable for uniform deposition onto highly-resistive or electrically-isolated micro-patterned surfaces. To address this deficiency, we report herein the feasibility of electroless Cu ALD process consisting of: (i) Electroless UPD of a sacrificial Zn adlayer mediated by an organic reductant, followed by (ii) Spontaneous surface-limited redox replacement of the Zn adlayer by a Cu monolayer. These steps when repeated sequentially enable multilayered Cu films with minimal roughness.