Patent ID: 7888722

Claim:
A structure, comprising: a substrate having a top surface defining a horizontal direction; a trench having contiguous upper, middle and lower regions, said middle region between said upper and lower regions, said lower region closed by a bottom of said trench, said trench extending from said top surface of said substrate into said substrate along an axis perpendicular to said top surface of said substrate, said axis defining a vertical direction; said upper region of said trench having a vertical sidewall profile and a first width in said horizontal direction; said middle region of said trench having a tapered sidewall profile, a width in said horizontal direction of said middle region at a juncture of said upper region and said middle region being said first width and being greater than a second width in said horizontal direction of said middle region at a juncture of said middle region and said lower region; a first dielectric liner on the bottom of said trench and on sidewalls of said trench in said lower region and on sidewalls of said trench in a lower region of said middle region, said lower region of said middle region abutting said lower region; a second dielectric liner on sidewalls of said trench in an upper region of said middle region and on lower regions of said upper region, said second dielectric liner thicker than said first dielectric liner, said upper region of said middle region abutting said lower region of said upper region; a first electrically conductive material filling remaining space in said lower region and said lower region of said middle region; a second electrically conductive material in said upper region of said middle region and said lower region of said upper region; and a third electrically conductive material in an upper region of said upper region, said upper region of said upper region abutting said lower region of said upper region.