Bottom electrode geometry for phase change memory
AssigneeMicron Technology, Inc.
InventorJun Liu
Life of this patent
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Abstract
A PCRAM cell has a gradated or layered resistivity bottom electrode with higher resistivity closer to a phase change material, to provide partial heating near the interface between the cell and the bottom electrode, preventing separation of the amorphous GST region from the bottom electrode, and reducing the programming current requirements. The bottom electrode can also be tapered to have a smaller cross-sectional area at the top of the bottom electrode than at the bottom of the bottom electrode.
Claims21
A method of forming a phase change memory cell, comprising:
- forming a bottom electrode having a resistivity gradient with increasing resistivity between a bottom of the bottom electrode and a top of the bottom electrode;
- forming a phase change memory element above the bottom electrode;
- and
- forming a top electrode over the phase change memory element.
A method of forming a phase change memory cell, comprising:
- forming a resistivity gradated layer of bottom electrode material over a metal contact, the resistivity gradated layer having increasingly high resistivity from a lowest resistivity at a bottom of the bottom electrode to a highest resistivity at a top of the bottom electrode;
- and
- tapering the bottom electrode to a shape having its largest cross-sectional area at its lowest resistivity and its smallest cross-sectional area at its highest resistivity.
A method of operating a phase change memory cell, comprising:
- changing a phase of a phase change material of the memory cell in part using heating from a bottom electrode of the memory cell, wherein heating from a bottom electrode comprises:
- heating with resistive heating in a top portion of a resistivity gradated bottom electrode having a higher resistivity at the top portion than at a bottom portion.
A method of switching a phase of a phase change memory cell, comprising:
- heating a programmable volume of a phase change cell material with a bottom electrode having a resistivity gradient with a lower resistivity at a bottom of the bottom electrode and a higher resistivity at a top of the bottom electrode.
Dependencies are inferred from the claim text.