Cu coating inside small (15 µm) and ultrahigh-aspect-ratio (>130) through-holes using supercritical CO2 fluid

Abstract

In this article, we describe novel process and equipment for fabricating through-hole interconnects embedded in an interposer. Through-holes are three-dimensionally cranked and have a small diameter (15 µm) and an ultrahigh aspect ratio (>130). This work demonstrated Cu coating inside these through-holes. Cu deposition was carried out by supercritical fluid chemical deposition. The equipment was designed to generate a large differential pressure between the entrance and exit of the through-holes on the basis of the principle of flow reduction. The generated differential pressure assisted the transport of the Cu precursor to the exit of the through-holes. The deposition of Cu inside 1400 through-holes spreading over the glass interposer substrate was successfully demonstrated.