Displacement reactions between metal ions and nitride barrier layer/silicon substrate

Abstract

Nitride materials such as TiN and TaN have been used in the integrated circuit industry. These materials serve as the crucial barrier layer between copper and the dielectric layer, and hence should be chemically inert. However, a displacement reaction still occurs between these nitride barriers and some metal ions such as Cu2+, Ag+, and Pd2+ in the presence of F-. This spontaneous reaction results in the deposition of metal, and a similar reaction takes place between the metal ions and the underlying silicon substrate. Three possible mechanisms are proposed and discussed in this study. The proposed mechanisms and the details of displacement reaction were elucidated by using Auger electron spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, nuclear magnetic resonance spectroscopy, inductively coupled plasma atomic emission spectrometer, Raman and infrared spectroscopy. TiN was found to oxidize with the formation of TiF6 2-. Despite being regarded as a contaminant, the deposited Pd was found to be capable of serving as the platform on nitride barrier for subsequent electrodeposition of Cu. © 2002 The Electrochemical Society. All rights reserved.