A resistive random access memory (ReRAM) device is provided. The ReRAM device includes a first electrode including a first conductive layer sandwiching a second conductive layer, the second conductive layer being wider than the first conductive layer; a resistive switching element layer formed in contact with sidewalls of the first electrode, a first portion of the resistive switching element layer that is in contact with the sidewalls of the first conductive layer having a width that is greater than a second portion of the resistive switching element layer that is in contact with the sidewalls of the second conductive layer; and a second electrode that is in contact with the resistive switching element layer.

A method for making a memory device, includes: forming a first dielectric layer over a bottom electrode; forming a first void extending through the first dielectric layer to expose a portion of an upper boundary of the bottom electrode; forming a first conductive structure lining along respective sidewalls of the first void and the exposed portion of the upper boundary of the bottom electrode; filling the first void with the first dielectric layer; and forming a phase change material layer over the first dielectric layer to cause the phase change material layer to contact at least a portion of a sidewall of the first conductive structure.

Spacer-based patterning for tight-pitch and low-variability random access memory (RAM) bit cells, and the resulting structures, are described. In an example, a semiconductor structure includes a substrate having a top layer. An array of non-volatile random access memory (RAM) bit cells is disposed on the top layer of the substrate. The array of non-volatile RAM bit cells includes columns of non-volatile RAM bit cells along a first direction and rows of non-volatile RAM bit cells along a second direction orthogonal to the first direction. A plurality of recesses is in the top layer of the substrate, along the first direction between columns of the array of non-volatile RAM bit cells.

A vertical variable resistance memory device including gate electrodes spaced apart from each other in a first direction on a substrate, each of the gate electrodes including graphene and extending in a second direction, the first direction being substantially perpendicular to an upper surface of the substrate and the second direction being substantially parallel to the upper surface of the substrate; first insulation patterns between the gate electrodes, each of the first insulation patterns including boron nitride (BN); and at least one pillar structure extending in the first direction through the gate electrodes and the first insulation patterns on the substrate, wherein the at least one pillar structure includes a vertical gate electrode extending in the first direction; and a variable resistance pattern on a sidewall of the vertical gate electrode.

A method for making a memory device, includes: forming a first dielectric layer over a bottom electrode; forming a first void extending through the first dielectric layer to expose a portion of an upper boundary of the bottom electrode; forming a first conductive structure lining along respective sidewalls of the first void and the exposed portion of the upper boundary of the bottom electrode; filling the first void with the first dielectric layer; and forming a phase change material layer over the first dielectric layer to cause the phase change material layer to contact at least a portion of a sidewall of the first conductive structure.

A memory device structure includes a substrate, a memory stacked structure, and a spacer. The memory stacked structure is formed on the substrate by stacking a first electrode layer, a memory material layer, and a second electrode layer. The memory material layer has a tilted sidewall, or the memory material layer and the first electrode layer have a tilted sidewall. The tilted sidewall is indented with respect to a sidewall of the second electrode layer. The spacer is disposed on the tilted sidewall.

A three-dimensional semiconductor device includes multiple semiconductor device layers on a substrate, wherein each layer includes a first stacked structure, a first gate dielectric layer, a first semiconductor layer, a first channel layer, a first source region, a first drain region, and a first resistive random access memory cell. The first stacked structure on the substrate includes a first insulating layer and a first gate conductor layer. The first gate dielectric layer surrounds a sidewall of the first stacked structure. The first semiconductor layer surrounds a sidewall of the first gate dielectric layer. The first channel layer is in the first semiconductor layer. The first source region and the first drain region are on both sides of the first channel layer in the first semiconductor layer. The first resistive random access memory cell is on a first sidewall of the first semiconductor layer and connected to the first drain region.

A vertical nonvolatile memory device including memory cell strings using a resistance change material is provided. Each of the memory cell strings of the nonvolatile memory device includes a semiconductor layer extending in a first direction; a plurality of gates and a plurality of insulators alternately arranged in the first direction; a gate insulating layer extending in the first direction between the plurality of gates and the semiconductor layer and between the plurality of insulators and the semiconductor layer; and a resistance change layer extending in the first direction on a surface of the semiconductor layer. The resistance change layer includes a metal-semiconductor oxide including a mixture of a semiconductor material of the semiconductor layer and a transition metal oxide.

A memory device that includes at least one memory cell is introduced. Each of the at least one memory cell is coupled to a bit line and a word line. Each of the at least one memory cell includes a memory element and a selector element, in which the memory element is configured to store data of the at least one memory cell. The selector element is coupled to the memory element in series and is configured to select the memory element for a read operation and amplify the data stored in the memory element in the read operation.

A non-volatile memory cell includes a bottom electrode, a top electrode having a conductive material, a resistive layer interposed between the bottom electrode and the top electrode, and side portions covering sides of the top electrode and the resistive layer. The side portions contain an oxide of the conductive material. The non-volatile memory cell further includes a contact wire disposed on the top electrode. A width of the contact wire is less than a width between lateral outer surfaces of the side portions.