Al‐Cu‐Si/TiW interface reaction due to thermal treatments

Abstract

AbstractThe Al‐0.5 wt.% Cu‐1 wt.% Si/TiW interface reaction due to thermal treatments in nitrogen was investigated using SIMS, x‐ray diffraction (XRD), TEM, XPS and SEM. Titanium starts to diffuse into the Al alloy layer at low temperatures such as 350°C. However, Ti has hardly any effect on the sheet resistance. Tungsten diffuses and reacts with Al above 450°C. The rugged interfacial reaction product formed after annealing at 450°C, which may be W(Al, Si)2, does not affect the sheet resistance. The needle‐shaped reaction product formed after annealing above 500°C, which is Al12 W, is responsible for the large increase in sheet resistance. An aluminium oxide layer, several nanometres thick, formed on the Al alloy surface after annealing at 500°C acts as a W diffusion barrier.