Three-dimensional memory device containing cobalt capped copper lines and method of making the same

A method of forming a memory device, comprising:

• forming a laterally alternating sequence of in-process first conductive rails and first dielectric rails, wherein each of the in-process first conductive rails and the first dielectric rails laterally extend along a first horizontal direction, and wherein each of the in-process first conductive rails comprises a first liner contacting sidewalls and a bottom surface of a first copper-containing fill portion;
• selectively growing a first cobalt-containing cap liner from physically exposed surfaces of the first copper-containing fill portion while suppressing growth of cobalt from physically exposed surfaces of the first dielectric rails, wherein each contiguous combination of an in-process first conductive rail and a first cobalt-containing cap liner constitutes a first conductive rail;
• forming a rectangular array of first memory pillar structures over top surfaces of the first conductive rails, wherein each first memory pillar structure comprises a respective first resistive memory element;
• and
• forming second conductive rails laterally extending along a second horizontal direction and overlying top surfaces of the rectangular array of first memory pillar structures.

A method of forming a memory device, comprising:

• forming a laterally alternating sequence of in-process first conductive rails and first dielectric rails, wherein each of the in-process first conductive rails and the first dielectric rails laterally extend along a first horizontal direction, and wherein each of the in-process first conductive rails comprises a first fill portion selected from cobalt, ruthenium, molybdenum, a cobalt alloy, a ruthenium alloy, a molybdenum alloy, copper or a copper based metallic material;
• selectively growing a first cobalt-containing cap liner from physically exposed surfaces of the first fill portion while suppressing growth of cobalt from physically exposed surfaces of the first dielectric rails, wherein each contiguous combination of an in-process first conductive rail and a first cobalt-containing cap liner constitutes a first conductive rail;
• forming a rectangular array of first memory pillar structures over top surfaces of the first conductive rails, wherein each first memory pillar structure comprises a respective first resistive memory element;
• and
• forming second conductive rails laterally extending along a second horizontal direction and overlying top surfaces of the rectangular array of first memory pillar structures.

A memory device comprising:

• first conductive rails laterally extending along a first horizontal direction over a substrate, wherein each of the first conductive rails comprises a fill portion selected from cobalt, ruthenium, molybdenum, a cobalt alloy, a ruthenium alloy, a molybdenum alloy, copper or a copper based metallic material, and a first cobalt-containing cap liner contacting a top surface of the fill portion;
• a rectangular array of first memory pillar structures overlying top surfaces of the first conductive rails, wherein each first memory pillar structure comprises a respective first resistive memory element;
• and
• second conductive rails laterally extending along a second horizontal direction and overlying top surfaces of the rectangular array of first memory pillar structures.