Problems with Silicon and oxygen Self diffusion at Cu/CuZr interface

OLIVA, M.I.; ZHOU, S.H.; NAPOLITANO, R.E; KRAMER, M.J; KRACHER, A

Mérida

Congreso; 11th Interamerican Congress of Electron Microscopy CIASEM 2011; 2011

Sociedad Interamericana de Microscopia

In recent works Zhou and Napolitano employed First-principles calculations and experimental methods to investigate the relative stability of intermetallic phases in the Cu–Zr system [1] and investigated the martensitic transformation products formed upon rapid cooling of the CuZr-B2 phase [2]. CuZr binary alloys are widely studied because the competition between stable and metastable phases is a topic of great interest with applications related to high glass formation and it is very important technological materials, for example as interconnects in integrated circuits [3,4]. The major technological challenge for Cu interconnects is both, how to prevent the Cu oxidation and to avoid the Cu diffusion into Si or SiO2. Different approaches to solves each one of this challenges are been proposed, such as add a diffusion barrier like as Cu/TaN/Si, Cu/Ta/SiO2 Cu/TaN/SiO2 [5,6], or the addition of elements to self grown a diffusion barrier [1]. These works was focused in thin or tick films deposited on Si or SiO2 substrate studying microstructure, oxidation resistance and Cu diffusion. In this work, we focus on directional solidification studies in the Cu-Zr system to determine the diffusion composition profile for the Cu-Zr binary liquid alloy. To measure the composition profile the samples were preparer in hand build diffusion equipment which are two alumina crucibles with Cu and CuZr. Two thin Quartz tubes (150 mm Length and 0.8 mm inner diameter in this work) with closed top end are moved into the crucibles then are moved out turn 180º and move again in the crucible. The method of preparation and the equipment are well described in reference [1]. The specimens for diffusion were pure Cu and Cu/Zr alloy in two composition two temperatures, Cu- CuZr 71% Wt (1176 ºC) sample SBZ08 and Cu- CuZr 65% Wt (1142 ºC) sample SBZ09. The obtained samples were characterized by using a electron probe microanalyzer JEOL JX8200 and the composition profile was determined using Wavelength Dispersive Spectrometers (WDS).