Memory cell with carbon switching material having a reduced cross-sectional area and methods for forming the same

A method of forming a metal-insulator-metal (“MIM”) stack, the method comprising:

• forming a first conductive carbon layer;
• etching the first conductive carbon layer into a plurality of pillars;
• isolating the plurality of pillars from one another with dielectric fill material;
• planarizing the dielectric fill material to expose the plurality of pillars;
• removing a portion of each pillar to form a plurality of first openings of a first diameter;
• forming a spacer in each first opening to form a plurality of second openings of a second diameter that is less than the first diameter;
• forming a carbon-based switching material on sidewalls of the second openings, thereby creating third openings of a third diameter that is less than the second diameter;
• filling the third openings with dielectric fill material;
• exposing the carbon-based switching material;
• and
• forming a second conductive carbon layer above the exposed carbon-based switching material.

A method of forming a memory cell, the method comprising:

• forming a metal-insulator-metal (“MIM”) stack by:
• forming a dielectric material above a substrate, the dielectric material having an opening and a first conductive carbon layer within the opening;
• forming a spacer in the opening;
• forming a carbon-based switching material on a sidewall of the spacer;
• and
• forming a second conductive carbon layer above the carbon-based switching material,
• wherein a ratio of a cross sectional area of the opening in the dielectric material to a cross sectional area of the carbon-based switching material on the sidewall of the spacer is at least 5;
• and
• forming a steering element coupled to the MIM stack.

A method of forming a memory cell, the method comprising:

• forming a metal-insulator-metal (“MIM”) stack by:
• forming a first conductive carbon layer above a substrate;
• etching the first conductive carbon layer into a plurality of pillars;
• isolating the plurality of pillars from one another with dielectric fill material;
• planarizing the dielectric fill material to expose the plurality of pillars;
• removing a portion of each pillar to form a plurality of first openings of a first diameter;
• forming a spacer in each first opening to form a plurality of second openings of a second diameter that is less than the first diameter;
• forming a carbon-based switching material on sidewalls of the second openings, thereby creating third openings of a third diameter that is less than the second diameter;
• filling the third openings with dielectric fill material;
• exposing the carbon-based switching material;
• and
• forming a second conductive carbon layer above the exposed carbon-based switching material;
• and
• forming a steering element coupled to the MIM stack.

A metal-insulator-metal (“MIM”) stack comprising:

• a dielectric material having an opening;
• a first conductive carbon layer within the opening;
• a spacer above the first conductive carbon layer and in the opening;
• a carbon-based switching material on a sidewall of the spacer;
• and
• a second conductive carbon layer above the carbon-based switching material,
• wherein a ratio of a cross sectional area of the opening in the dielectric material to a cross sectional area of the carbon-based switching material on the sidewall of the spacer is at least 5.

A memory cell comprising:

• a metal-insulator-metal (“MIM”) stack formed above a substrate, the MIM stack having:
• a dielectric material having an opening;
• a first conductive carbon layer within the opening;
• a spacer above the first conductive carbon layer and in the opening;
• a carbon-based switching material on a sidewall of the spacer;
• and
• a second conductive carbon layer above the carbon-based switching material,
• wherein a ratio of a cross sectional area of the opening in the dielectric material to a cross sectional area of the carbon-based switching material on the sidewall of the spacer is at least 5;
• and
• a steering element coupled to the MIM stack.