Dresden 2006 – scientific programme

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MM: Metall- und Materialphysik

MM 37: Nanostructured Materials I

MM 37.1: Talk

Thursday, March 30, 2006, 14:45–15:00, IFW D

Early stages of Al/Cu thin-film reaction — •Constantin Buzau Ene¹, Guido Schmitz², Talaat Al-Kassab¹, and Reiner Kirchheim¹ — ¹Institut für Materialphysik, Georg-August-Universität Göttingen, Friedrich-Hund Platz 1, D-37077, Göttingen, Germany — ²Institut für Materialphysik, Westf. Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 10, D-48149 Münster, Germany

Aluminium and Copper are important components of current day metallization of semi-conductor devices, so that their initial reaction is technologically important. Al/Cu/Al triple layers with approximately 10nm single layer thickness were deposited onto needle shaped W tips and analyzed in the early stages of interreaction by means of atom probe tomography (TAP). Owing to the outstanding sensitivity of the method, even minor chemical modifications on the nanometer scale can be detected. After thermal treatments we were able to recognize the formation of the Al₂Cu phase starting after 5 min annealing at 110^∘C and its parabolic growth as a dense layer to a maximum thickness of 6 nm after 80 min annealing at 110^∘C. As a particularity of the tip-shaped tungsten tips we observed a remarkable asymmetry in the growth rate of the new phases. The thickness of the reaction product close to the W substrate is approximately 1.5 times thicker than the other one close to the surface. We suggest that this asymmetry is induced by different vacancy annihilation mechanisms at the two Al/Cu interfaces.