Silver 

Silver (Ag) exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. It's electrical properties make it ideally suited for electrical contacts and it is used for many semiconductor devices.

It can be sputter etched with Ion Beam Etch (IBE) or by Reactive Ion Etch (RIE) it can also be etched using an Inductively Coupled Plasma (ICP) to give smooth, vertical etch profiles. It can be deposited using Ion Beam Deposition (IBD).