Memory cell with phonon-blocking insulating layer
View Patent ↗An apparatus and associated method for a non-volatile memory cell with a phonon-blocking insulating layer. In accordance with various embodiments, a magnetic stack has a tunnel junction, ferromagnetic free layer, pinned layer, and an insulating layer that is constructed of an electrically and thermally insulative material that blocks phonons while allowing electrical transmission through at least one conductive feature.
1. A magnetic stack comprising a tunnel junction, ferromagnetic free layer, pinned layer, and at least one insulating layer that is constructed of an electrically and thermally insulative material that blocks phonons while allowing electrical transmission through at least one conductive feature, the at least one conductive feature configured with a width less than a phonon signal wavelength.
2. The magnetic stack of claim 1 , wherein the conductive feature is dimensioned to allow electrical conductivity while blocking phonon transmission.
3. The magnetic stack of claim 1 , wherein the conductive feature blocks phonons due to the electrical signal wavelength being smaller than a phonon wavelength.
4. The magnetic stack of claim 1 , wherein the electrical transmission is a programming current.
5. The magnetic stack of claim 4 , wherein the programming current has a uniform spin to impart a common spin torque on the free layer.
6. The magnetic stack of claim 1 , wherein the electrical transmission is a read current and the free layer is programmed with a magnetic field.
7. The magnetic stack of claim 1 , wherein the conductive feature has a lower magnetic field resistance than the insulating layer.
8. The magnetic stack of claim 1 , wherein the insulating layer comprises NiO.
9. The magnetic stack of claim 1 , wherein the insulating layer is a phonon-blocking electron transmitting (PBET) material.
10. The magnetic stack of claim 1 , wherein the conductive feature is filled with a phonon-blocking electron transmitting (PBET) material.
11. The magnetic stack of claim 1 , wherein the conductive feature extends from the pinned layer through the insulating layer.
12. The magnetic stack of claim 1 , wherein a plurality of conductive features are arranged in a predetermined pattern that has a selected length and width within the insulating layer.
13. The magnetic stack of claim 1 , wherein a first insulating layer with conductive features and a first density is contactingly adjacent a second insulating layer with no conductive features and a second density that is greater than the first density.
14. The magnetic stack of claim 13 , wherein the first and second insulating layers are constructed of the same material.
15. The magnetic stack of claim 1 , wherein a first insulating layer is contactingly adjacent the pinned layer and a second insulating layer is contactingly adjacent the free layer.
16. A method comprising:
forming a tunnel junction, ferromagnetic free layer, pinned layer, and at least one insulating layer, the at least one insulating layer constructed of an electrically and thermally insulative material; and
configuring the at least one insulating layer to block phonons while allowing electrical transmission through at least one conductive feature of the insulating layer, the at least one conductive feature configured with a width less than a phonon signal wavelength.
17. The method of claim 16 , wherein the conductive feature is formed by passing a predetermined current through a conductive material to inject the material into the insulating material with a predetermined width.
18. The method of claim 16 , wherein the conductive feature is formed by removing portions of the insulating layer with a predetermined width and filling the removed portions with phonon-blocking electron transmitting (PBET) material.
19. The method of claim 16 , wherein the insulating layer retains heat in near the tunnel junction to lower the current required to program a magnetization in the free layer.
20. A memory cell comprising:
a tunnel junction, ferromagnetic free layer, and a pinned layer; and
a first and second insulating layer that are each constructed of an electrically and thermally insulative material, the first insulating layer having at least one conductive feature configured with a width less than a phonon signal wavelength to block phonons while allowing electrical transmission through the first insulating layer, the second insulating layer absent of any conductive features and having a density that is greater than the first insulating layer.