Multi-state memory and method for manufacturing the same

Patent metadata

Field	Value
Publication number	US-10991877-B2
Application number	US-201916560357-A
Country	US
Kind code	B2
Filing date	Sep 4, 2019
Priority date	Mar 19, 2019
Publication date	Apr 27, 2021
Grant date	Apr 27, 2021

Abstract

A multi-state memory and a method for manufacturing the same. A magnetoresistive tunnel junction is disposed on a spin-orbit coupling layer, and thermal annealing is performed after dopant ions are injected from a side of the magnetoresistive tunnel junction. The concentration of dopant ions in the magnetoresistive tunnel junction has a gradient variation along the direction that is perpendicular to the direction of the current and within the plane in which the spin-orbit coupling layer is located. Symmetry along the direction perpendicular to the direction of the current is broken. In a case a current flows into the spin-orbit coupling layer, resistance are outputted in multiple states in linearity with the current. The multi-state storage is achieved. It can meet a requirement on hardware of neural network synapses, and is applicable to calculation in a neural network.

First claim

The invention claimed is:

1. A method for manufacturing a multi-state memory, comprising:
providing a substrate;
forming a spin-orbit coupling layer on the substrate;
forming a magnetoresistive tunnel junction on the spin-orbit coupling layer, wherein the magnetoresistive tunnel junction comprises a first magnetic layer, a tunneling layer and a second magnetic layer that are sequentially stacked from bottom to top, and the first magnetic layer and the second magnetic have perpendicular anisotropy;
injecting dopant ions from a side of the magnetoresistive tunnel junction; and
performing thermal annealing;
wherein injecting the dopant ions from a side of the magnetoresistive tunnel junction comprises:
injecting the dopant ions to the magnetoresistive tunnel junction that is exposed, wherein there is an angle between a direction of the injecting and a direction perpendicular to the substrate, a projection of the direction of the injecting on the substrate is non-parallel to a direction of a current in the spin-orbit coupling layer.

2. The method according to claim 1 , wherein injecting the dopant ions from a side of the magnetoresistive tunnel junction comprises:
forming a mask layer on another side of the magnetoresistive tunnel junction, wherein the side of the magnetoresistive tunnel junction is not covered with the mask layer;
injecting the dopant ions; and
removing the mask layer.

3. The method according to claim 1 , wherein the thermal annealing is Joule thermal annealing, annealing-furnace annealing, or rapid thermal annealing.

4. The method according to claim 1 , wherein the dopant ions comprise N ions, As ions, Ar ions, Be ions, or P ions.

5. The method according to claim 1 , wherein:
the magnetoresistive tunnel junction further comprises a pinning layer and a protective layer, and
the pinning layer is disposed on the second magnetic layer, and the protective layer is disposed on the pinning layer.

6. The method according to claim 1 , wherein the current is applied to switch magnetic moment in the magnetoresistive tunnel junction.

7. A multi-state memory, comprising:
a spin-orbit coupling layer; and
a magnetoresistive tunnel junction, disposed on the spin-orbit coupling layer, wherein the magnetoresistive tunnel junction comprises a first magnetic layer, a tunneling layer and a second magnetic layer which are sequentially stacked from bottom to top, and the first magnetic layer and the second magnetic have perpendicular anisotropy;
wherein the magnetoresistive tunnel junction comprises dopant ions, and a gradient of a concentration of the dopant ions is formed in the magnetoresistive tunnel junction along a first direction, a projection of the first direction on the substrate is non-parallel to a direction of a current in the spin-orbiting layer, and the current is applied to switch magnetic moment in the magnetoresistive tunnel junction.

8. The multi-state memory according to claim 7 , wherein the dopant ions comprise N ions, As ions, Ar ions, Be ions, or P ions.

9. The multi-state memory according to claim 7 , wherein:
the magnetoresistive tunnel junction further comprises a pinning layer and a protective layer, and
the pinning layer is disposed on the second magnetic layer, and the protective layer is disposed on the pinning layer.

10. The multi-state memory according to claim 7 , wherein a material of the first magnetic layer and the second magnetic layer is Co, Fe, CoFeB, or FePt.

11. The multi-state memory according to claim 7 , wherein the gradient of the concentration of the dopant ions changes monotonously along the first direction.

Assignees

• Inst Of Microelectronics Cas

Inventors

• Yang Meiyin
• Luo Jun
• Wang Sumei
• Xu Jing
• Li Yanru
• Li Junfeng
• Cui Yan
• Wang Wenwu
• Ye Tianchun

Classifications

• H10N50/85

  Materials of the active region · CPC title

• H01F41/32

  for applying conductive, insulating or magnetic material on a magnetic film {, specially adapted for a thin magnetic film} · CPC title

• G11C11/161 Primary

  details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell · CPC title

• H01F10/329

  Spin-exchange coupled multilayers wherein the magnetisation of the free layer is switched by a spin-polarised current, e.g. spin torque effect · CPC title

• H01F41/308

  lift-off processes, e.g. ion milling, for trimming or patterning · CPC title