Nanoporous structures by reactive ion etching

A method of forming a porous metal structure, the method comprising:

• forming a metal structure above a substrate, wherein the metal structure comprises a first end region, a second end region, and an intermediate region between the first end region and the second end region;
• forming a masking layer above the metal structure, wherein the masking layer covers the metal structure;
• forming a protective layer above the first end region and the second end region;
• and
• etching the masking layer away from above the intermediate region using a reactive ion etching process with a mask etchant and a metal etchant, wherein etching the masking layer forms a plurality of pores in the intermediate region.

A metal structure comprising:

• a first metal end region;
• a second metal end region;
• and
• an intermediate region between the first end region and the second end region, wherein the intermediate region comprises a metal nanostructure having a plurality of pores.