Stray magnetic shielding for a non-volatile MRAM

• US 5,902,690 A
• Filed: 02/25/1997
• Issued: 05/11/1999
• Est. Priority Date: 02/25/1997
• Status: Expired due to Term

• Current Assignee: Everspin Technologies Incorporated
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Chen, Eugene, Zhu, Theodore, Tracy, Clarence J., Durlam, Mark, Tehrani, Saied N.
• Primary Examiner(s): PIANALTO, BERNARD D
• Application Number:
  US08/806,275
• Time in Patent Office: 805 Days
• Field of Search: 427/131, 427/132, 427/129, 427/130, 428/694 MM, 428/694 TP, 428/694 TM, 428/693
• US Class Current: 428/814
• CPC Class Codes: G11C 11/15 using multiple magnetic layers G11C11/155 takes precedence
• CPC Class Codes: H10B 61/22 of the field-effect transistor [FET] type
• CPC Class Codes: Y10S 977/838 Magnetic property of nanomaterial
• CPC Class Codes: Y10T 428/1164 with protective film

Abstract

A non-volatile magneto-resistive memory positioned on a semiconductor substrate is shielded from stray magnetic fields by a passivation layer partially or completely surrounding the non-volatile magneto-resistive memory. The passivation layer includes non-conductive ferrite materials, such as Mn--Zn-Ferrite, Ni--Zn-Ferrite, MnFeO, CuFeO, FeO, or NiFeO, for shielding the non-volatile magneto-resistive memory from stray magnetic fields. The non-conductive ferrite materials may also be in the form of a layer which focuses internally generated magnetic fields on the non-volatile magneto-resistive memory to reduce power requirements.

Claims

1. A non-volatile magneto-resistive memory with stray magnetic shielding comprising:

a non-volatile magneto-resistive memory positioned on a substrate and defining an upper surface; and

a passivation layer at least partially surrounding the non-volatile magneto-resistive memory, the passivation layer including ferrite materials for shielding the non-volatile magneto-resistive memory from stray magnetic fields.

2. A non-volatile magneto-resistive memory with stray magnetic shielding as claimed in claim 1 wherein the ferrite materials include one of Mn--Zn-Ferrite, Ni--Zn-Ferrite, MnFeO, CuFeO, FeO, and NiFeO.

3. A non-volatile magneto-resistive memory with stray magnetic shielding as claimed in claim 1 wherein the ferrite materials are in the form of a powder intermixed with an encapsulation material.

4. A non-volatile magneto-resistive memory with stray magnetic shielding as claimed in claim 1 wherein the ferrite materials are in the form of a layer of the ferrite material positioned adjacent the non-volatile magneto-resistive memory.

5. A non-volatile magneto-resistive memory with stray magnetic shielding comprising:

a non-volatile magneto-resistive memory positioned on a substrate and defining an upper surface, the non-volatile magneto-resistive memory including at least first and second layers of magneto-resistive material separated by a layer of non-magnetic material;

a layer of high permeability, non-conductive magnetic material positioned adjacent the upper surface of the non-volatile magneto-resistive memory so as to focus internally generated magnetic fields on at least one of the first and second layers of magneto-resistive material and shield the non-volatile magneto-resistive memory from stray magnetic fields; and

a passivation layer at least partially surrounding the layer of high permeability, non-conductive magnetic material and the non-volatile magneto-resistive memory.

6. A non-volatile magneto-resistive memory with stray magnetic shielding as claimed in claim 5 wherein the layer of high permeability, non-conductive magnetic material includes ferrite materials.

7. A non-volatile magneto-resistive memory with stray magnetic shielding as claimed in claim 6 wherein the ferrite materials include one of Mn--Zn-Ferrite, Ni--Zn-Ferrite, MnFeO, CuFeO, FeO, and NiFeO.

8. A non-volatile magneto-resistive memory with stray magnetic shielding as claimed in claim 5 wherein the passivation layer includes ferrite materials.

9. A non-volatile magneto-resistive memory with stray magnetic shielding comprising:

a non-volatile magneto-resistive memory positioned on a semiconductor substrate, the non-volatile magneto-resistive memory including an array of individual cells with each cell including at least first and second layers of magneto-resistive material separated by a layer of non-magnetic material, the non-volatile magneto-resistive memory further including integrated circuitry addressing and controlling the individual cells with input/output terminals; and

a layer of high permeability, non-conductive magnetic material coating at least an upper surface of the non-volatile magneto-resistive memory so as to focus internally generated magnetic fields on at least one of the first and second layers of magneto-resistive material in each of the individual cells and shield the non-volatile magneto-resistive memory from stray magnetic fields.

10. A non-volatile magneto-resistive memory with stray magnetic shielding as claimed in claim 9 wherein the layer of high permeability, non-conductive magnetic material includes ferrite materials.

11. A non-volatile magneto-resistive memory with stray magnetic shielding as claimed in claim 10 wherein the ferrite materials include one of Mn--Zn-Ferrite, Ni--Zn-Ferrite, MnFeO, CuFeO, FeO, and NiFeO.

12. A non-volatile magneto-resistive memory with stray magnetic shielding as claimed in claim 9 including in addition a passivation layer at least partially surrounding the layer of high permeability, non-conductive magnetic material and the non-volatile magneto-resistive memory.

13. A non-volatile magneto-resistive memory with stray magnetic shielding as claimed in claim 12 wherein the passivation layer includes ferrite materials.

14. A non-volatile magneto-resistive memory with stray magnetic shielding as claimed in claim 13 wherein the ferrite materials include one of Mn--Zn-Ferrite, Ni--Zn-Ferrite, MnFeO, CuFeO, FeO, and NiFeO.

15. A non-volatile magneto-resistive memory with stray magnetic shielding as claimed in claim 13 wherein the layer of high permeability, non-conductive magnetic material includes openings therethrough for access to the input/output terminals.