Storage device
According to one embodiment, a storage device includes a first conductive layer, a second conductive layer, a resistance-variable layer, between the first conductive layer and the second conductive layer, that includes germanium, antimony, and tellurium, a first layer, between the resistance-variable layer and the first conductive layer, that includes carbon, a second layer, between the resistance-variable layer and the second conductive layer, that includes carbon, a third layer, between the resistance-variable layer and the first layer, that includes at least one of tungsten nitride or tungsten carbide, and a fourth layer, between the resistance-variable layer and the second layer, that includes at least one of tungsten nitride or tungsten carbide.
1. A storage device comprising:
a first conductive layer;
a second conductive layer;
a resistance-variable layer, provided between the first conductive layer and the second conductive layer, that includes germanium (Ge), antimony (Sb), and tellurium (Te);
a first layer, provided between the resistance-variable layer and the first conductive layer, that primarily includes carbon;
a second layer, provided between the resistance-variable layer and the second conductive layer, that primarily includes carbon;
a third layer, provided between the resistance-variable layer and the first layer, that includes at least one of tungsten nitride with a nitrogen concentration of 10 atomic percent or more and 25 atomic percent or less and tungsten carbide with a carbon concentration of 4 atomic percent or more and 20 atomic percent or less; and
a fourth layer, provided between the resistance-variable layer and the second layer, that includes at least one of tungsten nitride with a nitrogen concentration of 10 atomic percent or more and 25 atomic percent or less and tungsten carbide with a carbon concentration of 4 atomic percent or more and 20 atomic percent or less.
2. The storage device according to claim 1 , further comprising a switching layer, provided between the first layer and the first conductive layer, that includes germanium (Ge), selenium (Se), and arsenic (As).
3. The storage device according to claim 2 , wherein a thickness of the first layer along a first direction, along which the first conductive layer is disposed over the second conductive layer, is greater than a thickness of the second layer along the first direction.
4. The storage device according to any one of claim 3 , wherein a width of the resistance-variable layer along a second perpendicular to the first direction is less than both a width of the third layer along the second direction and a width of the fourth layer along the second direction.
5. The storage device according to claim 1 , wherein each of a carbon concentration of the first layer and a carbon concentration of the second layer is 90 atomic percent or more.
6. A storage device comprising:
a plurality of first wirings;
a plurality of second wirings intersecting with the plurality of first wirings; and
a plurality of memory cells respectively located at regions where one of the second wirings intersects with one of the first wirings,
wherein each of the memory cells includes:
a first conductive layer;
a second conductive layer;
a resistance-variable layer, provided between the first conductive layer and the second conductive layer, that includes germanium (Ge), antimony (Sb), and tellurium (Te);
a first layer, provided between the resistance-variable element and the first conductive layer, that primarily includes carbon;
a second layer, provided between the resistance-variable element and the second conductive layer, that primarily includes carbon;
a third layer, provided between the resistance-variable layer and the first layer, that includes at least one of tungsten nitride with a nitrogen concentration of 10 atomic percent or more and 25 atomic percent or less and tungsten carbide with a carbon concentration of 4 atomic percent or more and 20 atomic percent or less; and
a fourth layer, provided between the resistance-variable layer and the second layer, that includes at least one of tungsten nitride with a nitrogen concentration of 10 atomic percent or more and 25 atomic percent or less and tungsten carbide with a carbon concentration of 4 atomic percent or more and 20 atomic percent or less.
7. The storage device according to claim 6 , further comprising a switching layer, provided between the first layer and the first conductive layer, that includes germanium (Ge), selenium (Se), and arsenic (As).
8. The storage device according to claim 7 , wherein a thickness of the first layer in a first direction, along which the first conductive layer is disposed over the second conductive layer, is greater than a thickness of the second layer along the first direction.
9. The storage device according to claim 8 , wherein a width of the resistance-variable layer in a second direction, perpendicular to the first direction, is less than each of a width of the third layer along the second direction and a width of the fourth layer along the second direction.
10. The storage device according to claim 6 , wherein each of a carbon concentration of the first layer and a carbon concentration of the second layer is 90 atomic percent or more.
11. The storage device according to claim 1 , wherein the carbon concentration of tungsten carbide of each of the third layer and fourth layer is 5 atomic percent or more and 18 atomic percent or less.
12. The storage device according to claim 1 , wherein a carbon concentration of each of the first and second layer is 95 atomic percent or more.
13. The storage device according to claim 1 , wherein a thickness of the first layer along the first direction is 1.1 times or more and 2 times or less than a thickness of the second layer along the first direction.