US Patent 7688167 Contact electrode for microdevices and etch method of manufacture

A contact electrode for a device is made using an etching process to etch the surface of the contact electrode to form a corrugated contact surface wherein the outer edges of at least one grain is recessed from the outer edges of adjacent grains and is recessed by at least about 0.05 μm from the contact plane. By having such a corrugated surface, the contact electrode is likely to contact another conductor with at least one pure metal grain. This etching treatment reduces contact resistance and contact resistance variability throughout many cycles of use of the contact electrode.