Storage node after three-node access device formation for vertical three dimensional (3d) memory

A method for forming arrays of vertically stacked memory cells, having horizontally oriented access devices and vertically oriented access lines, comprising:

• depositing alternating layers of a dielectric material and a sacrificial material to form a vertical stack;
• forming a plurality of first vertical openings, having a first horizontal direction and a second horizontal direction, through the vertical stack and extending predominantly in the second horizontal direction to form elongated vertical, pillar columns with sidewalls in the vertical stack;
• conformally depositing first conductive material on a gate dielectric material in the first vertical openings;
• removing portions of the first conductive material to form a plurality of separate, vertical access lines along the sidewalls of the elongated vertical, pillar columns;
• forming a second vertical opening through the vertical stack and extending predominantly in the first horizontal direction to expose a first region of the sacrificial material;
• selectively removing the first region to form a first horizontal opening in the sacrificial material extending a first distance from the second vertical opening;
• using an atomic layer deposition (ALD) process to sequentially deposit a first source/drain material, a channel material, and a second source/drain material in the first horizontal opening to form a horizontally oriented three-node access device without a body contact;
• forming a third vertical opening through the vertical stack and extending predominantly in the first horizontal direction to expose a second region of the sacrificial material;
• selectively removing the second region to form a second horizontal opening in the sacrificial material extending a second distance from the second vertical opening;
• and
• using an atomic layer deposition (ALD) process to sequentially deposit:
• a first electrode electrically forming electrical contact with the first source/drain material;
• a high-k dielectric material on the first electrode;
• and
• a second electrode on the high-k dielectric subsequent to formation of the horizontally oriented three-node access device.

A method for forming arrays of vertically stacked memory cells, having horizontally oriented access devices and vertically oriented access lines, comprising:

• depositing alternating layers of a dielectric material and a sacrificial material to form a vertical stack;
• forming a plurality of first vertical openings, having a first horizontal direction and a second horizontal direction, through the vertical stack and extending predominantly in the second horizontal direction to form elongated vertical, pillar columns with sidewalls in the vertical stack;
• conformally depositing first conductive material on a gate dielectric material in the first vertical openings;
• removing portions of the first conductive material to form a plurality of separate, vertical access lines along the sidewalls of the elongated vertical, pillar columns;
• forming a second vertical opening through the vertical stack and extending predominantly in the first horizontal direction to expose first sidewalls adjacent a first region of the sacrificial material;
• selectively removing the first region to form a first horizontal opening in the sacrificial material;
• sequentially forming a first source/drain material, a channel material, and a second source/drain material in the first horizontal opening to form a horizontally oriented access device without a body contact, wherein the first source/drain material is selected to provide ohmic contact to a first electrode of a storage node;
• forming a third vertical opening through the vertical stack and extending predominantly in the first horizontal direction to expose second sidewalls adjacent a second region of the sacrificial material;
• selectively removing the second region to form a second horizontal opening in the sacrificial material extending to the first source/drain material, using the first source/drain material as an etch stop, after formation of the horizontally oriented access device;
• and
• selectively depositing the first electrode of the storage node on the first source/drain material in the second horizontal opening to form direct electrical contact therewith.