Manufacturable reliable diffusion-barrier

Abstract

Devices and methods are presented to fabricate diffusion barrier layers on a substrate. Presently, barrier layers comprising a nitride layer and a pure metal layer are formed using a physical vapor deposition (PVD) process that requires multiple ignition steps, and results in nitride-layer thicknesses of no less than 2 nm. This invention discloses devices and process to produce nitride-layers of less than <1 nm, while allowing for formation of a pure metal layer on the nitride-layer without re-igniting the plasma. To achieve this, the flow of nitrogen gas is cut off either before the plasma is ignited, or before the formation of a continuous-flow plasma. This ensures that a limited number of nitrogen atoms is deposited in conjunction with metal atoms on the substrate, thereby allowing for controlled thickness of the nitride layer.