Perpendicular magnetic tunnel junction memory cells having vertical channels
A transistor structure, according to one embodiment, includes: an epitaxially grown vertical channel, a word line which surrounds a middle portion of the vertical channel, and a p-MTJ sensor coupled to a first end of the vertical channel. The second side of the vertical channel is opposite the first side of the vertical channel along a plane perpendicular to a deposition direction. A magnetic device, according to another embodiment, includes: a plurality of transistor structures, each of the transistor structures comprising: an epitaxially grown vertical channel, a word line which surrounds a middle portion of the vertical channel, and a p-MTJ sensor coupled to a first end of the vertical channel.
1. A magnetic memory device, comprising:
a semiconductor substrate having a surface, a portion of the surface being treated to form a source line within the surface of the substrate;
a vertical semiconductor channel formed on the source line;
a word line which surrounds a middle portion of the vertical channel;
an oxide layer located between the surface of the substrate and the word line, the oxide layer having an opening extending to the substrate;
another oxide layer located on the word line and the oxide layer; and
a perpendicular magnetic tunnel junction (p-MTJ) sensor coupled to an end of the vertical channel that is opposite to the source line;
wherein the vertical semiconductor channel comprises a pillar of semiconductor material having doped source and drain regions and grown epitaxially only on a region of the substrate that is within the opening of the oxide layer;
wherein the oxide layer has a thickness that is chosen to provide a desired source gate overlap, the source gate overlap being a distance between the source line and the word line, the source gate overlap being chosen to minimize parasitic resistance while also minimizing gate capacitance between the word line and the source line; and
wherein a deposition thickness of the oxide layer is between about 20 nanometers (nm) and about 30 nm and the deposition thickness of the another oxide layer is greater than the deposition thickness of the oxide layer.
2. The magnetic memory device as recited in claim 1 , wherein the epitaxially grown semiconductor channel is electrically coupled with the source line.
3. The magnetic memory device as recited in claim 2 , comprising:
a gate dielectric layer located between the word line and the epitaxially grown vertical semiconductor channel.
4. The magnetic memory device as recited in claim 1 , wherein the source line includes an n+ doped portion of the surface of the substrate.
5. The magnetic memory device as recited in claim 1 , wherein the source line includes a p+ doped portion of the surface of the substrate.
6. The magnetic memory device as recited in claim 1 , comprising:
an annular cylindrical gate dielectric layer positioned between the vertical semiconductor channel and the word line.
7. The magnetic memory device as recited in claim 6 , wherein a thickness of the gate dielectric layer is between about 1 nm and about 2 nm.
8. The magnetic memory device as recited in claim 6 , wherein the gate dielectric layer includes a material selected from a group consisting of: ZrO 2 , A 1 2 O 3 , and HfO 2 .
9. The magnetic memory device as recited in claim 1 , comprising:
a common bit line electrically coupled to the p-MTJ sensor.
10. A magnetic device, comprising:
a semiconductor substrate having a surface, a portion of the surface being treated to form an electrically conductive source line;
a plurality of transistor structures, each of the transistor structures comprising: a vertical semiconductor channel formed on the source line; a word line which surrounds a middle portion of the vertical channel;
an oxide layer located between the word line and the surface of the semiconductor substrate, the oxide layer having an opening extending to the substrate;
another oxide layer located on the word line and the oxide layer; and
a perpendicular magnetic tunnel junction (p-MTJ) sensor coupled to a first end of the vertical channel of each of the transistor structures;
wherein the vertical semiconductor channel comprises a pillar of a single semiconductor material having doped source and drain regions and grown epitaxially only on a region of the substrate that is within the opening of the oxide layer;
wherein the oxide layer has a thickness that is chosen to provide a desired gate source overlap, the source gate overlap being a distance between the source line and the word line, the source gate overlap being chosen to minimize parasitic resistance while also minimizing gate capacitance between the word line and the source line;
wherein a deposition thickness of the oxide layer is between about 20 nanometers (nm) and about 30 nm and the deposition thickness of the another oxide layer is greater than the deposition thickness of the oxide layer.
11. The magnetic device as recited in claim 10 , wherein the plurality of transistor structures includes two transistor structures.
12. The magnetic device as recited in claim 10 , wherein the plurality of transistor structures includes four transistor structures.
13. The magnetic device as recited in claim 10 , wherein the plurality of transistor structures includes eight transistor structures.
14. The magnetic device as recited in claim 10 , wherein the plurality of transistor structures includes sixteen transistor structures.
15. The magnetic device as recited in claim 10 , wherein the plurality of transistor structures includes thirty-two transistor structures.
16. The transistor structure as recited in claim 10 , each of the transistor structures comprising:
an annular cylindrical gate dielectric layer positioned between the vertical channel and the word line.
17. The transistor structure as recited in claim 11 , each of the transistor structures comprising:
a common bit line electrically coupled to the p-MTJ sensor.