Self-forming Mn-based diffusion barriers on low-k substrates

Abstract

In this work, we report on a self-forming barrier process in Cu-Mn alloys. Cu-Mn alloy films were directly deposited onto low-k substrates by co-sputtering and then subjected to an annealing treatment at various temperatures. X-ray diffraction patterns obtained for the Cu-Mn alloys showed Cu(111), Cu(200), and Cu(220) peaks, while transmission electron microscopy images revealed that a uniform Mn-based interlayer self-formed at the Cu-Mn/low-k interface after annealing. In order to evaluate the barrier properties of the Mn-based interlayer, thermal stability measurements were carried out with the low-k dielectrics. The Cu-Mn alloy showed improved thermal stability when compared to a pure Cu reference sample. The chemical composition of the self-formed interlayers on the low-k substrates was ultimately investigated by X-ray photoelectron spectroscopy analysis. Our results show that the composition of the self-formed interlayers depends on the oxide and carbon concentrations in the low-k material. (C) 2014 The Japan Society of Applied Physics