TMR Device with Novel Free Layer Structure

• US 20150248902A1
• Filed: 05/15/2015
• Published: 09/03/2015
• Est. Priority Date: 09/22/2008
• Status: Active Grant

• Current Assignee: Headway Technologies Incorporated
• Original Assignee: Headway Technologies Incorporated
• Inventors: Zhao, Tong, Wang, Hui-Chuan, Zhou, Yu-Chen, Li, Min, Zhang, Kunliang
• Granted Patent: US 9,577,184 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: G01R 33/098 comprising tunnel junctions, e.g. tunnel magnetoresistance sensors
• CPC Class Codes: G11B 2005/3996 large or giant magnetoresistive effects [GMR], e.g. as generated in spin-valve [SV] devices
• CPC Class Codes: G11B 5/3909 Arrangements using a magnetic tunnel junction
• CPC Class Codes: G11B 5/3929 Disposition of magnetic thin films not used for directly coupling magnetic flux from the track to the MR film or for shielding
• CPC Class Codes: H10N 50/01 Manufacture or treatment
• CPC Class Codes: H10N 50/10 Magnetoresistive devices
• CPC Class Codes: H10N 50/85 Magnetic active materials
• CPC Class Codes: Y10T 428/1114 having tunnel junction effect
• CPC Class Codes: Y10T 428/1121 Multilayer
• CPC Class Codes: Y10T 428/1143 with defined structural feature

Abstract

A TMR sensor that includes a free layer having at least one B-containing (BC) layer made of CoFeB, CoFeBM, CoB, CoBM, or CoBLM, and a plurality of non-B containing (NBC) layers made of CoFe, CoFeM, or CoFeLM is disclosed where L and M are one of Ni, Ta, Ti, W, Zr, Hf, Tb, or Nb. One embodiment is represented by (NBC/BC)_n where n≧2. A second embodiment is represented by (NBC/BC)_n/NBC where n≧1. In every embodiment, a NBC layer contacts the tunnel barrier and NBC layers each with a thickness from 2 to 8 Angstroms are formed in alternating fashion with one or more BC layers each 10 to 80 Angstroms thick. Total free layer thickness is <100 Angstroms. The free layer configuration described herein enables a significant noise reduction (SNR enhancement) while realizing a high TMR ratio, low magnetostriction, low RA, and low Hc values.

Claims

1. A magnetoresistive element in a magnetic device, comprising:

(a) a SyAP pinned layer;

(b) a free layer comprised of (CoFe/CoFeB)_n/CoFe, (CoFeM/CoFeB)_n/CoFeM, (CoFe/CoFeBM)_n/CoFe, (CoFeM/CoFeBM)_n/CoFeM, (CoFeLM/CoFeB)_n/CoFeLM, or (CoFeLM/CoFeBM)_n/CoFeLM wherein n≧

1, L and M are one of Ni, Ta, Ti, W, Zr, Hf, Tb, or Nb, and L is unequal to M, and each of said CoFeB or CoFeBM layers has a greater thickness than each of said CoFe, CoFeM, or CoFeLM layers, and;

(c) a tunnel barrier layer having a first surface that contacts the SyAP pinned layer and a second surface that contacts a CoFe, CoFeM, or CoFeLM layer in said free layer wherein said second surface is opposite said first surface.

2. The magnetoresistive element of claim 1 wherein the boron content in each of said CoFeB layers is between about 10 and 40 atomic % and the boron content in each of said CoFeBM layers is between about 5 and 40 atomic %.

3. The magnetoresistive element of claim 1 wherein each of said CoFe, CoFeM, or CoFeLM layers has a thickness between about 2 and 8 Angstroms and each of said CoFeB or CoFeBM layers has a thickness from about 10 to 80 Angstroms.

4. The magnetoresistive element of claim 1 wherein the M content in said CoFeM alloy and the L+M content in said CoFeLM alloy is less than about 10 atomic %.

5. A magnetoresistive element in a magnetic device, comprising:

(a) a SyAP pinned layer;

(b) a free layer comprised of (CoFe/CoB)_n, (CoFeM/CoB)_n, (CoFeLM/CoB)_n, (CoFe/CoBM)_n, (CoFeM/CoBM)_n, (CoFeLM/CoBM)_n, (CoFe/CoBLM)_n, (CoFeM/CoBLM)_n, or (CoFeLM/CoBLM)_n wherein n≧

2, L and M are one of Ni, Ta, Ti, W, Zr, Hf, Tb, or Nb, and L is unequal to M, and each of said CoB, CoBM, or CoBLM layers has a greater thickness than each of said CoFe, CoFeM, or CoFeLM layers, and;

(c) a tunnel barrier layer having a first surface that contacts the SyAP pinned layer and a second surface that contacts a CoFe, CoFeM, or CoFeLM layer in said free layer wherein said second surface is opposite said first surface.

6. The magnetoresistive element of claim 5 wherein the boron content in each of said CoB layers is between about 5 and 30 atomic %.

7. The magnetoresistive element of claim 5 wherein each of said CoFe, CoFeM, or CoFeLM layers has a thickness between about 2 and 8 Angstroms and each of said CoB, CoBM, or CoBLM layers has a thickness from about 10 to 80 Angstroms.

8. The magnetoresistive element of claim 5 wherein the tunnel barrier layer is comprised of MgO, MgZnO, ZnO, Al₂O₃, TiOx, AlTiO, HfOx, ZrOx, or a combination of two or more of the aforementioned materials.

9. A magnetoresistive element in a magnetic device, comprising:

(a) a SyAP pinned layer;

(b) a free layer comprised of (CoFe/CoB)_n/CoFe, (CoFeM/CoB)_n/CoFeM, (CoFeLM/CoB)_nCoBLM, (CoFe/CoBM)_n/CoFe, (CoFeM/CoBM)_n/CoFeM, (CoFeLM/CoBM)_n/CoFeLM, (CoFe/CoBLM)_n/CoFe, (CoFeM/CoBLM)n/CoFeM, or (CoFeLM/CoBLM)_n/CoFeLM wherein n≧

1, L and M are one of Ni, Ta, Ti, W, Zr, Hf, Tb, or Nb, and L is unequal to M, and each of said CoB, CoBM, or CoBLM layers has a greater thickness than each of said CoFe, CoFeM, or CoFeLM layers, and;

(c) a tunnel barrier layer having a first surface that contacts the SyAP pinned layer and a second surface that contacts a CoFe, CoFeM, or CoFeLM layer in said free layer wherein said second surface is opposite said first surface.

10. The magnetoresistive element of claim 9 wherein the boron content in each of said CoB layers is between about 5 and 30 atomic %.

11. The magnetoresistive element of claim 9 wherein each of said CoFe, CoFeM, or CoFeLM layers has a thickness between about 2 and 8 Angstroms and each of said CoB, CoBM, or CoBLM layers has a thickness from about 10 to 80 Angstroms.

12. The magnetoresistive element of claim 9 wherein the M content in said CoFeM alloy and the L+M content in said CoFeLM alloy is less than about 10 atomic %.