Magnetic Spin Shift Register Memory

• US 20130005053A1
• Filed: 09/13/2012
• Published: 01/03/2013
• Est. Priority Date: 07/09/2010
• Status: Active Grant

• Current Assignee: Globalfoundries US Incorporated (GlobalFoundries, Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Joseph, Eric A., Parkin, Stuart S. P., Rothwell, Mary B.
• Granted Patent: US 8,518,718 B2
• Time in Patent Office: Days
• US Class Current: 438/3
• CPC Class Codes: G11C 11/14 using thin-film elements
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: G11C 11/1675 Writing or programming circuits or methods
• CPC Class Codes: G11C 19/0808 using magnetic domain propagation

Abstract

A method for forming a memory device includes forming a cavity having an inner surface with an undulating profile in a substrate, depositing a ferromagnetic material in the cavity, forming a reading element on the substrate proximate to a portion of the ferromagnetic material, and forming a writing element on the substrate proximate to a second portion of the ferromagnetic material.

Claims

1. A method for forming a memory device, the method including:

forming a cavity having an inner surface with an undulating profile in a substrate;

depositing a ferromagnetic material in the cavity;

forming a reading element on the substrate proximate to a portion of the ferromagnetic material; and

forming a writing element on the substrate proximate to a second portion of the ferromagnetic material.

2. The method of claim 1, wherein the cavity is formed by an isotropic etching and passivating polymer deposition processes operative to form the undulating profiled inner surface in the cavity.

3. The method of claim 1, wherein the undulating profile of the cavity includes rib portions operative to define domain walls defining magnetic domains in the ferromagnetic material.

4. The method of claim 1, wherein the ferromagnetic material defines a shift register in the ferromagnetic material.

5. The method of claim 2, wherein the isotropic etching and passivating polymer deposition processes includes a plurality of cycles each cycle including:

1800 watts applied to a plasma source;

110 watts applied to the substrate;

an equivalent chamber pressure of approximately 65 milliTorr, controlled by a fixed pumping speed; and

exposing the substrate to a flow of SF₆ at 300 standard cubic centimeters per minute (sccm) for 7 seconds.

6. The method of claim 5, wherein the plurality of cycles includes exposing the substrate to a flow of C₄F₈ at 150 sccm for 2 seconds at −

10°

C. following the exposure of the substrate to the flow of SF₆.

7. The method of claim 1, wherein the substrate includes a silicon material.

8. The method of claim 1, wherein the cavity is formed by a cryogenic etching process.

9. A method for forming a memory device, the method including:

forming a first cavity having rib portions in a substrate using an isotropic etching and passivating polymer deposition processes;

depositing a ferromagnetic material in the cavity, the ferromagnetic material including magnetic domains partially defined by the undulating profile of the cavity;

forming a reading element proximal to a portion of the ferromagnetic material.

10. The method of claim 9, wherein the method further includes forming a writing element proximal to a second portion of the ferromagnetic material.

11. The method of claim 9, wherein the isotropic etching and passivating polymer deposition processes includes a plurality of cycles each cycle including:

1800 watts applied to a plasma source;

110 watts applied to the substrate;

an equivalent chamber pressure of approximately 65 milliTorr, controlled by a fixed pumping speed; and

exposing the substrate to a flow of SF₆ at 300 standard cubic centimeters per minute (sccm) for 7 seconds.

12. The method of claim 11, wherein the plurality of cycles includes exposing the substrate to a flow of C₄F₈ at 150 sccm for 2 seconds at −

10°

C. following the exposure of the substrate to the flow of SF₆.

13. The method of claim 11, wherein the cavity is formed by a cryogenic etching process.

14. The method of claim 11, wherein the rib portions are defined by an intersection of curved surfaces of an inner surface of the cavity.

15. The method of claim 11, wherein the rib portions define domain walls in the ferromagnetic material.