Beveled magneto-resistive random access memory pillar structure
A memory device includes a magnetic tunnel junction pillar located between, and electrically connected to, a bottom electrode and a top electrode. The magnetic tunnel junction pillar is composed of a plurality of device layers vertically stacked above the bottom electrode. Each of the plurality of device layers, the top electrode, and the bottom electrode is formed at a first bevel angle. A bottommost portion of each of the plurality of device layers in the magnetic tunnel junction pillar has a width that is greater than a width of a topmost portion of each preceding device layer. An encapsulation layer is disposed along opposite sidewalls of the top electrode, opposite sidewalls of the bottom electrode, and opposite sidewalls of each of the plurality of device layers.
1 . A memory device, comprising:
a magnetic tunnel junction pillar located between, and electrically connected to, a bottom electrode and a top electrode, the magnetic tunnel junction pillar including a plurality of device layers vertically stacked above the bottom electrode, each of the plurality of device layers, the top electrode, and the bottom electrode being at a first bevel angle;
a bottommost portion of each of the plurality of device layers in the magnetic tunnel junction pillar having a width that is greater than a width of a topmost portion of each preceding device layer; and
an encapsulation layer disposed along opposite sidewalls of the top electrode, opposite sidewalls of the bottom electrode, and opposite sidewalls of each of the plurality of device layers,
wherein the plurality of device layers further comprises:
a magnetic reference layer disposed above the bottom electrode, the magnetic reference layer including first beveled sidewalls comprising a first positive taper profile,
a tunnel barrier layer disposed above the magnetic reference layer, the tunnel barrier layer including second beveled sidewalls comprising a second positive taper profile, and
a magnetic free layer disposed above the tunnel barrier layer, the magnetic free layer including third beveled sidewalls comprising a third positive taper profile, and
wherein the bottommost portion of each of the plurality of device layers being greater than the topmost portion of each preceding device layer further comprises:
a bottommost portion of the magnetic reference layer being greater than a topmost portion of the bottom electrode,
a bottommost portion of the tunnel barrier layer being greater than a topmost portion of the magnetic reference layer,
a bottommost portion of the magnetic free layer being greater than a topmost portion of the tunnel barrier layer, and
a bottommost portion of the top electrode being greater than a topmost portion of the magnetic free layer.
2 . The memory device of claim 1 , wherein the top electrode includes fourth beveled sidewalls comprising a fourth positive taper profile, and the bottom electrode includes fifth beveled sidewalls comprising a fifth positive taper profile.
3 . The memory device of claim 1 , wherein the encapsulation layer disposed along opposite sidewalls of the top electrode and opposite sidewalls of the bottom electrode includes at least one of a first nitride material and a metal-oxide material.
4 . The memory device of claim 3 , wherein the first nitride material comprises SiN, and the metal-oxide material comprises at least one of RuO 2 and IrO 2 .
5 . The memory device of claim 1 , wherein the encapsulation layer disposed along the opposite sidewalls of each of the plurality of device layers comprises a second nitride material disposed along opposite sidewalls of the magnetic reference layer, opposite sidewalls of the tunnel barrier layer, and opposite sidewalls of the magnetic free layer.
6 . The memory device of claim 5 , wherein the second nitride material comprises SiN.
7 . The memory device of claim 5 , wherein the encapsulation layer disposed along opposite sidewalls of each of the plurality of device layers comprises an oxynitride material disposed along the opposite sidewalls of the magnetic reference layer, and the second nitride material disposed along the opposite sidewalls of the tunnel barrier layer, and the opposite sidewalls of the magnetic free layer.
8 . The memory device of claim 7 , wherein the oxynitride material comprises AlON.
9 . A method of forming a memory device, comprising:
forming a magnetic tunnel junction pillar between, and electrically connected to, a bottom electrode and a top electrode, the magnetic tunnel junction pillar including a plurality of device layers vertically stacked above the bottom electrode, each of the plurality of device layers, the top electrode, and the bottom electrode being at a first bevel angle, wherein a bottommost portion of each of the plurality of device layers in the magnetic tunnel junction pillar has a width that is greater than a width of a topmost portion of each preceding device layer; and
forming an encapsulation layer along opposite sidewalls of the top electrode, opposite sidewalls of the bottom electrode, and opposite sidewalls of each of the plurality of device layers,
wherein forming the magnetic tunnel junction pillar including the plurality of device layers further comprises:
forming a magnetic reference layer above the bottom electrode, the magnetic reference layer including first beveled sidewalls comprising a first positive taper profile;
forming a tunnel barrier layer above the magnetic reference layer, the tunnel barrier layer including second beveled sidewalls comprising a second positive taper profile; and
forming a magnetic free layer above the tunnel barrier layer, the magnetic free layer including third beveled sidewalls comprising a third positive taper profile, and
wherein the bottommost portion of each of the plurality of device layers being greater than the topmost portion of each preceding device layer further comprises:
a bottommost portion of the magnetic reference layer being greater than a topmost portion of the bottom electrode,
a bottommost portion of the tunnel barrier layer being greater than a topmost portion of the magnetic reference layer,
a bottommost portion of the magnetic free layer being greater than a topmost portion of the tunnel barrier layer, and
a bottommost portion of the top electrode being greater than a topmost portion of the magnetic free layer.
10 . The method of claim 9 , wherein the top electrode includes fourth beveled sidewalls comprising a fourth positive taper profile, and the bottom electrode includes fifth beveled sidewalls comprising a fifth positive taper profile.
11 . The method of claim 9 , wherein the encapsulation layer along opposite sidewalls of the top electrode and the opposite sidewalls of the bottom electrode comprises at least one of a first nitride material and a metal-oxide material.
12 . The method of claim 11 , wherein the first nitride material comprises SiN, and the metal-oxide material comprises at least one of RuO 2 and IrO 2 .
13 . The method of claim 9 , wherein the encapsulation layer along the opposite sidewalls of each of the plurality of device layers comprises a second nitride material disposed along opposite sidewalls of the magnetic reference layer, opposite sidewalls of the tunnel barrier layer, and opposite sidewalls of the magnetic free layer.
14 . The method of claim 13 , wherein the second nitride material comprises SiN.
15 . The method of claim 13 , wherein the encapsulation layer along opposite sidewalls of each of the plurality of device layers comprises an oxynitride material along the opposite sidewalls of the magnetic reference layer, and the second nitride material along opposite sidewalls of the tunnel barrier layer, and the opposite sidewalls of the magnetic free layer.
16 . The method of claim 15 , wherein the oxynitride material comprises AlON.