Feasibility of using vanadium to form damascene structures with an air gap

We have studied the feasibility of fabricating multi-level interconnects using air as an interlayer dielectric material. In particular, we fabricated dual damascene structures using the via-first approach without etch stop layers required for trench formation, which opens up the possibility of further lowering the effective dielectric constant. Dual damascene structures were formed by sequential deposition of vanadium and vanadium pentoxide layers, which was followed by etching with hydrogen peroxide and water, respectively. Use of vanadium, vanadium pentoxide, and hydrogen peroxide was found suitable for the conventional silicon technology. Based on the findings in this study a novel process for the air gap formation was proposed, which may be applied even to the substrate level.