Investigation of Ti_1-x Al_x N Films as Diffusion Barrier Between Cu and Si

Abstract

Films of (Ti,Al)N have been grown onto Si(100) by direct current reactive magnetron sputtering from a Ti–Al alloy target (Ti/Al=90/10 at.-%) at different nitrogen flowrates and bias voltages. The effects of nitrogen flowrate and bias voltage on the electrical resistance of Ti_1-x Al_x N films were studied. The feasibility of using Ti_1-x Al_x N films as a diffusion barrier between Cu and Si was investigated. Results indicated that the atomic ratio of Ti/Al decreased, however nitrogen increased with an increase in the nitrogen flowrate. A higher critical nitrogen flowrate was required to obtain the stoichiometric composition for Ti_1-x Al_x N films deposited under lower bias voltages. The resistivity of Ti_1-x Al_x N films was substantially affected by the effects of stoichiometric structure and grain size. Results of sheet resistivity and Auger electron spectroscopy suggest the feasibility of using Ti_1-x Al_x N as a diffusion barrier material between Cu and Si up to 700°C.