Method to form low resistance contact

A semiconductor device, comprising:

• a source/drain region disposed over a semiconductor material layer;
• an interconnect structure disposed over and in electrical contact with the source/drain region, the interconnect structure including a conductive liner disposed over the source/drain region and a conductive fill layer disposed over the conductive liner, wherein the interconnect structure has a reentrant profile in which a horizontal critical dimension in an upper portion of the interconnect structure is smaller than a horizontal critical dimension in a lower portion of the interconnect structure by virtue of a width of the conductive fill layer being smaller at an upper portion of the conductive fill layer than the width is at a lower portion of the conductive fill layer;
• and
• a conductive contact in electrical contact with sidewalls and a top surface of the interconnect structure.

A method of forming a semiconductor device, comprising:

• forming a semiconductor material layer over a semiconductor substrate, the semiconductor material layer having alternating source/drain and channel regions;
• forming a metallization architecture over and extending between plural source/drain regions;
• patterning and etching the metallization architecture to form an interconnect structure over at least one source/drain region, including:
• forming a conductive liner of the interconnect structure over the at least one source/drain region;
• and
• forming a conductive fill layer of the interconnect structure over the conductive liner and with a reentrant profile in which an external sidewall of the conductive fill layer forms an angle with a horizontal surface external of the conductive fill layer of between 90° and 150°;
• and
• forming a dielectric layer over the interconnect structure;
• forming a contact opening from the top of the dielectric layer to expose a portion of the conductive fill layer;
• and
• forming a conductive contact in the opening such that the conductive contact extends from a top surface of the dielectric layer to make direct contact with the exposed portion of the conductive fill layer.