Memory device and method of manufacturing the same

1. A memory device, comprising:

a magnetic track layer extending on a substrate, the magnetic track layer having a folded structure that is two-dimensionally villi-shaped;

a plurality of reading units including a plurality of fixed layers and a tunnel barrier layer between the magnetic track layer and each of the plurality of fixed layers; and

a plurality of bit lines extending on different ones of the plurality of reading units, the plurality of reading units being between the magnetic track layer and corresponding ones of the plurality of bit lines.

2. The memory device as claimed in claim 1 , wherein the magnetic track layer includes:

a plurality of extended track layers extending in one direction, and

at least two connecting track layers connecting two extended track layers among the plurality of extended track layers to define the two-dimensionally villi-shaped folded structure of the magnetic track layer.

3. The memory device as claimed in claim 2 , further comprising:

a first connecting contact plug connected to a first end of the magnetic track layer; and

a common source line connected to a second end of the magnetic track layer, the first and second ends being opposite to each other in a first horizontal direction, and the magnetic track layer being between the first connecting contact plug and the common source line.

4. The memory device as claimed in claim 3 , wherein each of the plurality of extended track layers extends in the first horizontal direction and each of the plurality of bit lines extends in a second horizontal direction perpendicular to the first horizontal direction.

5. The memory device as claimed in claim 4 , wherein each of the plurality of reading units is arranged on a part of each of the plurality of extended track layers.

6. The memory device as claimed in claim 3 , wherein each of the plurality of extended track layers extends in a second horizontal direction perpendicular to the first horizontal direction and each of the plurality of bit lines extends in the second horizontal direction.

7. The memory device as claimed in claim 6 , wherein each of the plurality of reading units is arranged on a part of each of the at least two connecting track layers.

8. The memory device as claimed in claim 1 , further comprising an etch stop layer on the substrate, the magnetic track layer extending along an upper surface of the etch stop layer.

9. The memory device as claimed in claim 8 , wherein the plurality of reading units are arranged on an upper surface of the magnetic track layer.

10. The memory device as claimed in claim 8 , wherein the plurality of reading units are arranged on a lower surface of the magnetic track layer, the etch stop layer surrounding the plurality of reading units.

11. A memory device, comprising:

a substrate having a memory region and a connection region, the memory region and the connection region being adjacent to each other along a first horizontal direction;

a plurality of memory stacks on the substrate, each of the plurality of memory stacks having a stair profile in the connection region and including a magnetic track layer extending over the memory region and the connection region with a folded structure that is two-dimensionally villi-shaped, the magnetic track layer including:

a plurality of extended track layers two-dimensionally extending in one direction, and

at least two connecting track layers connecting two extended track layers among the plurality of extended track layers;

a plurality of reading units including a plurality of fixed layers and a tunnel barrier layer between the magnetic track layer and each of the plurality of fixed layers;

a plurality of bit lines extending on different ones of the plurality of reading units, the plurality of reading units being between the magnetic track layer and corresponding ones of the plurality of bit lines;

a plurality of connecting contact plugs in the connection region, each of the plurality of connecting contact plugs being connected to a pad track layer at a first end of a corresponding magnetic track layer of the plurality of memory stacks; and

a common source line in the memory region, the common source line being connected to a second end of the corresponding magnetic track layer of the plurality of memory stacks, the first and second ends being spaced apart from each other along the first horizontal direction.

12. The memory device as claimed in claim 11 , wherein each of the plurality of extended track layers extends in the first horizontal direction and each of the plurality of bit lines extends in a second horizontal direction perpendicular to the first horizontal direction.

13. The memory device as claimed in claim 11 , wherein each of the plurality of extended track layers and each of the plurality of bit lines extends in a second horizontal direction perpendicular to the first horizontal direction.

14. The memory device as claimed in claim 11 , wherein the magnetic track layer extends with a uniform horizontal width.

15. The memory device as claimed in claim 11 , wherein a horizontal width of the pad track layer of the corresponding magnetic track layer is greater than that of each of the plurality of extended track layers and that of each of the at least two connecting track layers.

16. The memory device as claimed in claim 11 , wherein each of the plurality of memory stacks further includes an etch stop layer, the magnetic track layer extending along an upper surface of the etch stop layer, and the plurality of reading units being on an upper surface of the magnetic track layer.

17. The memory device as claimed in claim 11 , further comprising an etch stop layer surrounding the plurality of reading units, the plurality of reading units being on a lower surface of the magnetic track layer.

18. A memory device, comprising:

a substrate including a memory region, a first connection region in a first horizontal direction of the memory region, and a second connection region in a second horizontal direction perpendicular to the first horizontal direction of the memory region;

a plurality of memory stacks on the substrate, each of the plurality of memory stacks having a stair profile in the first connection region and the second connection region, and including an etch stop layer laminated on the substrate;

a magnetic track layer extending along an upper surface of the etch stop layer over the memory region and the first connection region with a folded structure that is two-dimensionally villi-shaped, the magnetic track layer including:

a plurality of extended track layers two-dimensionally extending in one direction,

at least two connecting track layers connecting two extended track layers among the plurality of extended track layers, and

a plurality of magnetic domains;

a plurality of reading units including a plurality of fixed layers and a tunnel barrier layer between the magnetic track layer and each of the plurality of fixed layers;

a plurality of bit lines extending on different ones of the plurality of reading units, the plurality of reading units being between the magnetic track layer and corresponding ones of the plurality of bit lines to define a magnetic tunnel junction (MTJ);

a plurality of first connecting contact plugs in the first connection region, each of the plurality of first connecting contact plugs being connected to a pad track layer at a first end of a corresponding magnetic track layer of the plurality of memory stacks;

a common source line connected to the magnetic track layers of the plurality of memory stacks in the memory region opposite to the first connection region in the first horizontal direction; and

a plurality of second connecting contact plugs in the second connection region, each of the plurality of second connecting contact plugs being connected to a partial bit line pad unit of a magnetic track layer that is a part of the bit line of the plurality of memory stacks.

19. The memory device as claimed in claim 18 , wherein, in a direction in which the magnetic track layer extends, a distance between the common source line and a reading unit of the plurality of reading units that is adjacent to the common source line is equal to or greater than ½ of a distance between two adjacent reading units of the plurality of reading units.

20. The memory device as claimed in claim 18 , wherein, in a direction in which the magnetic track layer extends, a distance between the first connecting contact plug and a reading unit of the plurality of reading units that is adjacent to the first connecting contact plug is equal to or greater than ½ of a distance between two adjacent reading units of the plurality of reading units.