Semiconductor memory device

A semiconductor memory device, comprising:

• a substrate;
• a first conductive line on the substrate and extending in a first direction;
• a second conductive line on the first conductive line and extending in a second direction, the second direction intersecting the first direction;
• a third conductive line on the second conductive line and extending in the first direction;
• a first memory cell between the first conductive line and the second conductive line, the first memory cell including a first electrode, a first ovonic threshold switch (OTS) film, and a second electrode sequentially stacked;
• and
• a second memory cell between the second conductive line and the third conductive line, the second memory cell including a third electrode, a second OTS film, a first high-concentration electrode, and a fourth electrode sequentially stacked, a concentration of nitrogen in the first high-concentration electrode being greater than a concentration of nitrogen in the fourth electrode.

A semiconductor memory device, comprising:

• a substrate;
• a first conductive line on the substrate and extending in a first direction;
• a second conductive line on the first conductive line and extending in a second direction, the second direction intersecting the first direction;
• a third conductive line on the second conductive line and extending in the first direction;
• a first memory cell between the first conductive line and the second conductive line, the first memory cell including a first electrode, a first ovonic threshold switch (OTS) film, and a second electrode sequentially stacked, and a dimension in each of the first direction and the second direction of the first OTS film gradually decreases as the first OTS film extends away from the substrate;
• and
• a second memory cell between the second conductive line and the third conductive line, the second memory cell including a third electrode, a second OTS film, a first high-concentration electrode, and a fourth electrode sequentially stacked, and a dimension in each of the first direction and the second direction of the second OTS film gradually increases as the second OTS film extends away from the substrate.