Memory devices

A memory device, comprising:

• a plurality of first conductive lines on a substrate and extending in a first horizontal direction;
• a plurality of second conductive lines on the plurality of first conductive lines and extending in a second horizontal direction that is perpendicular to the first horizontal direction;
• and
• a plurality of memory cells respectively between the plurality of first conductive lines and the plurality of second conductive lines, each memory cell of the plurality of memory cells including:
• a lower electrode, an intermediate electrode, an upper electrode, a variable resistance memory layer and a buffer resistance layer, which are connected between the intermediate electrode and the upper electrode in parallel, and a switch material pattern between the lower electrode and the intermediate electrode,
• wherein:
• the variable resistance memory layer includes a recess that is concave,
• the recess in the variable resistance memory layer is in side walls thereof, and
• the buffer resistance layer has an inner side wall that is convex to fill the recess.

A memory device, comprising:

• a plurality of first conductive lines on a substrate and extending in a first horizontal direction;
• a plurality of second conductive lines on the plurality of first conductive lines and extending in a second horizontal direction that is perpendicular to the first horizontal direction;
• and
• a plurality of memory cells respectively between the plurality of first conductive lines and the plurality of second conductive lines, each memory cell of the plurality of memory cells including:
• a lower electrode, an intermediate electrode, an upper electrode, a variable resistance memory layer and a buffer resistance layer, which are connected between the intermediate electrode and the upper electrode in parallel, and a switch material pattern between the lower electrode and the intermediate electrode,
• wherein:
• the variable resistance memory layer has a circular horizontal cross-section, and
• the buffer resistance layer has a ring-shaped horizontal cross-section surrounding a periphery of the variable resistance memory layer, the buffer resistance layer including a material having a resistivity that is less than a resistivity of the variable resistance memory layer in a high-resistance state and greater than a resistivity of the variable resistance memory layer in a low-resistance state.