IP Library Granted Patent US 6,975,533
Granted Patent B2
US 6,975,533 · App. 10/974,037 · Granted Dec 13, 2005

Hybrid semiconductor—magnetic spin based memory with low transmission barrier

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Quick Facts
Patent No.
US 6,975,533
App. No.
10/974,037
Granted
Dec 13, 2005
Kind
B2
Abstract

A nonvolatile hybrid memory cell is provided which includes magnetic and semiconductor components. The cell uses a thin film stack of ferromagnetic layers situated over a silicon substrate to store data in the form of variable impedance to a spin polarized current. The cell data is isolated by semiconductor isolation elements.

Claims (46)

1. A thin film hybrid magnetoelectronic spin-based memory cell comprising:

i) a first thin film ferromagnetic layer with a first changeable magnetization state that can be altered to store a data value;

wherein said first thin film ferromagnetic layer is coupled to a first electrode;

ii) a second thin film ferromagnetic layer with a second non-changeable magnetization state;

wherein said second thin film ferromagnetic layer is coupled to a second electrode;

iii) a third thin film layer which is less than 1 micron in thickness and is situated between said first thin film ferromagnetic layer and said second thin film ferromagnetic layer, said third thin film layer comprising a low transmission barrier material with electron bands that are not significantly affected by an electron spin;

wherein a spin polarized current flows in a path through a thin film stack situated over a silicon substrate, including at least said second electrode, said second thin film ferromagnetic layer, said third thin film layer, said first thin film ferromagnetic layer and said first electrode respectively;

further wherein said data value can be determined by measuring a value of said variable spin polarized current which varies in accordance with a relationship between said first changeable magnetization state and said second non-changeable magnetization state.

2. The thin film hybrid magnetoelectronic spin-based memory cell of claim 1 , further including a memory cell selector coupled to said thin film stack, said memory cell selector including a semiconductor based isolation element.

3. The thin film hybrid magnetoelectronic spin-based memory cell of claim 2 , wherein said memory cell selector is coupled to a bit line, and further including a second semiconductor based transistor isolation element coupling said electron spin-based memory element to a bit reference line.

4. The thin film hybrid magnetoelectronic spin-based memory cell of claim 2 wherein the semiconductor based transistor isolation element is a field effect transistor (FET).

5. The thin film hybrid magnetoelectronic spin-based memory cell of claim 2 wherein the semiconductor based transistor isolation element is a bipolar junction transistor (BJT).

6. The thin film hybrid magnetoelectronic spin-based memory cell of claim 1 , wherein said thin film stack is situated over a semiconductor based FET and is separated therefrom by an insulation layer.

7. The thin film hybrid magnetoelectronic spin-based memory cell of claim 1 wherein a spin transimpedance increases as said thin film stack decreases in size.

8. The thin film hybrid magnetoelectronic spin-based memory cell of claim 1 , further including a read line coupled to read data from said electron spin-based memory element, and at least one separate write line coupled to write data.

9. The thin film hybrid magnetoelectronic spin-based memory cell of claim 8 , wherein said write line uses a single polarity current pulse.

10. The thin film hybrid magnetoelectronic spin-based memory cell of claim 8 , wherein said write line includes two partially overlapping write lines.

11. The thin film hybrid magnetoelectronic spin-based memory cell of claim 10 , wherein a data value stored in such cell can only change state when a current pulse is present on both of said two overlapping write lines.

12. The thin film hybrid magnetoelectronic spin-based memory cell of claim 1 , wherein said thin film stack is configured as a spin transistor.

13. The thin film hybrid magnetoelectronic spin-based memory cell of claim 1 , wherein said third thin film layer is electrically grounded.

14. The thin film hybrid magnetoelectronic spin-based memory cell of claim 1 , wherein both a current pulse and a voltage pulse are used to read data.

15. The thin film hybrid magnetoelectronic spin-based memory cell of claim 1 , further including a separate low transmission barrier interface associated with said second thin film ferromagnetic layer.

16. A thin film hybrid magnetoelectronic spin-based memory cell comprising:

i) a first thin film ferromagnetic layer with a first magnetization state comprising permalloy and/or cobalt;

ii) a second thin film ferromagnetic layer with a second magnetization state also comprising permalloy and/or cobalt;

iii) a third thin film layer which is less than 1 micron in thickness and is situated between said first ferromagnetic layer and said second ferromagnetic layer, said third thin film layer comprising an aluminum based material;

wherein said third thin film layer includes a low transmission barrier interface to said first ferromagnetic layer;

a memory cell selector coupled to said thin film stack, said memory cell selector including a semiconductor based isolation element;

wherein a spin polarized current flows through a thin film stack situated over a silicon substrate and the semiconductor based isolation element, including in a path including at least said second thin film ferromagnetic layer, said third thin film layer, and said first thin film ferromagnetic layer;

further wherein a data value can be stored in the thin film hybrid magnetoelectronic spin-based memory cell by altering only said first magnetization state so as to change an impedance to a spin polarized current, which impedance varies in accordance with a relationship between said first magnetization state and said second magnetization state.

17. The thin film hybrid magnetoelectronic spin-based memory cell of claim 16 , wherein said thin film stack is stacked on top of a second thin film hybrid magnetoelectronic spin-based memory cell.

18. The thin film hybrid magnetoelectronic spin-based memory cell of claim 16 , wherein said memory cell selector is shared with a second thin film hybrid magnetoelectronic spin-based memory cell.

19. The thin film hybrid magnetoelectronic spin-based memory cell of claim 16 , wherein said cell is a three terminal, current biased device.

20. The thin film hybrid magnetoelectronic spin-based memory cell of claim 16 , wherein said third thin film layer includes a conductive paramagnetic base layer adapted to create a nonequilibrium population of spin polarized electrons and an equivalent nonequilibrium magnetization M.

21. The thin film hybrid magnetoelectronic spin-based memory cell of claim 20 , wherein said nonequilibrium magnetization M in said paramagnetic conductive paramagnetic base layer base generates an electric field at an interface with said first thin film ferromagnetic layer.

22. The thin film hybrid magnetoelectronic spin-based memory cell of claim 16 , wherein said spin polarized current has an amplitude that varies based on whether said first changeable magnetization state and said second non-changeable magnetization state are parallel or antiparallel.

23. A thin film hybrid magnetoelectronic spin-based memory cell comprising:

i) a first thin film ferromagnetic layer with a changeable magnetization state comprising permalloy and/or cobalt;

ii) a second thin film ferromagnetic layer with a non-changeable magnetization state also comprising permalloy and/or cobalt;

iii) a third thin film layer which is less than 1 micron in thickness and is situated between said first thin film ferromagnetic layer and said second thin film ferromagnetic layer, said third thin film layer comprising a material with equilibrium levels which are substantially equal for two different electron spins present in a spin polarized current;

iv) a low transmission barrier interface between said third thin film layer and said first thin film ferromagnetic layer, said low transmission barrier interface being configured to effectuate a unipolar voltage output for the thin film hybrid magnetoelectronic spin-based memory cell;

a semiconductor based isolation element adapted to isolate a data value stored in the thin film hybrid magnetoelectronic spin-based memory cell.

24. The thin film hybrid magnetoelectronic spin-based memory cell of claim 23 , further wherein said low transmission barrier interface is configured to effectuate an impedance for the third thin film layer which is larger than a transimpedance of the thin film hybrid magnetoelectronic spin-based memory cell.

25. The thin film hybrid magnetoelectronic spin-based memory cell of claim 23 , further including a second low transmission barrier interface associated with said second thin film ferromagnetic layer.

26. The thin film hybrid magnetoelectronic spin-based memory cell of claim 23 , wherein said base layer is a conductive paramagnetic material.

27. The thin film hybrid magnetoelectronic spin-based memory cell of claim 23 , further including a read line coupled to read data, and a separate write line coupled to write data to the thin film hybrid magnetoelectronic spin-based memory cell.

Assignments (3)
RELEASE OF SECURITY INTEREST Recorded Jul 23, 2025
From: THE BANK OF NOVA SCOTIA
To: SEAGATE TECHNOLOGY PUBLIC LIMITED COMPANY; SEAGATE TECHNOLOGY; SEAGATE TECHNOLOGY HDD HOLDINGS; I365 INC.; SEAGATE TECHNOLOGY LLC; SEAGATE TECHNOLOGY INTERNATIONAL; SEAGATE HDD CAYMAN; SEAGATE TECHNOLOGY (US) HOLDINGS, INC.
Reel/Frame 072193/0001 →
TERMINATION AND RELEASE OF SECURITY INTEREST IN PATENT RIGHTS Recorded Jul 19, 2013
From: WELLS FARGO BANK, NATIONAL ASSOCIATION, AS COLLATERAL AGENT AND SECOND PRIORITY REPRESENTATIVE
To: SEAGATE TECHNOLOGY LLC; EVAULT INC. (F/K/A I365 INC.); SEAGATE TECHNOLOGY INTERNATIONAL; SEAGATE TECHNOLOGY US HOLDINGS, INC.
Reel/Frame 030833/0001 →
SECURITY AGREEMENT Recorded Mar 24, 2011
From: SEAGATE TECHNOLOGY INTERNATIONAL
To: THE BANK OF NOVA SCOTIA, AS ADMINISTRATIVE AGENT
Reel/Frame 026010/0871 →