Characterization of Ultrathin Electroless Barriers Grown by Self-Aligned Deposition on Silicon-Based Dielectric Films

Abstract

A self-aligned, electrochemically integrated seeding/plating approach is developed for fabricating patterns of cobalt- (or nickel-) based metallic barriers and copper films selectively on silicon-based dielectric (hybrid siloxane-organic polymer and films using electroless plating. High-resolution X-ray absorption spectroscopy, transmission electron microscopy, atomic force microscopy, and grazing-incidence X-ray diffractometry indicate that, after they have been appropriately pretreated by a gaseous plasma or and basic aqueous solutions that contain sufficient amounts of peroxide hydrogen the dielectric films can adsorb highly populated metallic (nickel or cobalt) precipitates of sizes between 2 and 4 nm, which catalyze the deposition of ultrathin (⩽20 nm) barriers. The barriers are initially highly resistive and contain ultrafine (3-5 nm) crystallites embedded in amorphous-like, 20 nm grains, but become highly conductive (50-80 μΩ-cm) following optimal annealing at temperatures ⩾470°C because of crystallization, grain growth, and precipitation of Finally, the capacity of this method to fabricate "self-aligned" patterns of barrier and copper is established, and the adhesion strength and effectiveness of the barriers against copper's diffusion/drift are quantified. The importance of the plasma pretreatment and the use of hydrogen peroxide (in the SC-1 solution) is also addressed. © 2004 The Electrochemical Society. All rights reserved.