Biconvex low resistance metal wire

A method of forming a semiconductor structure, said method comprising:

• forming a dielectric material layer having at least one opening located in said dielectric material layer, said at least one opening having a biconvex shape and said forming said dielectric material layer having said at least one opening comprises forming at least one initial opening in said dielectric material layer, said at least one initial opening having sidewall surfaces that are perpendicular to a topmost surface and a bottommost surface of said dielectric material layer, and performing an etch to provide said biconvex shape to said at least one initial opening, wherein said etch comprises first ashing of sidewall surfaces of said dielectric material layer exposed by said at least one initial opening using a mixture of oxygen, carbon dioxide, and carbon monoxide, and then performing a wet etch in hydrofluoric acid;
• forming a diffusion barrier material in said at least one opening and on said topmost surface of said dielectric material layer;
• forming a reflow enhancement layer on said diffusion barrier liner;
• forming a layer of a metal or metal alloy on said reflow enhancement layer;
• performing a reflow anneal to completely fill a remaining volume of said at least one opening with said metal or metal alloy of said layer of metal or metal alloy;
• and
• removing said layer of metal or metal alloy, said reflow enhancement layer, and said diffusion barrier material located outside of said at least one opening, wherein a portion of said of metal or metal alloy, a portion of said reflow enhancement layer, and a portion of said diffusion barrier material remaining within said at least one opening.