Side shielded magnetoresistive (MR) read head with perpendicular magnetic free layer

Patent metadata

Field	Value
Publication number	US-9520147-B2
Application number	US-201414581141-A
Country	US
Kind code	B2
Filing date	Dec 23, 2014
Priority date	May 5, 2010
Publication date	Dec 13, 2016
Grant date	Dec 13, 2016

Abstract

A MR sensor is disclosed that has a free layer (FL) with perpendicular magnetic anisotropy (PMA) which eliminates the need for an adjacent hard bias structure to stabilize free layer magnetization and minimizes shield-FL interactions. In a TMR embodiment, a seed layer, free layer, junction layer, reference layer, and pinning layer are sequentially formed on a bottom shield. After patterning, a conformal insulation layer is formed along the sensor sidewall. Thereafter, a top shield is formed on the insulation layer and includes side shields that are separated from the FL by a narrow read gap. The sensor is scalable to widths <50 nm when PMA is greater than the FL self-demag field. Effective bias field is rather insensitive to sensor aspect ratio which makes tall stripe and narrow width sensors a viable approach for high RA TMR configurations. Sensor sidewalls may extend into the seed layer or bottom shield.

First claim

We claim:

1. A magneto-resistive (MR) sensor, comprising:
(a) a bottom shield having a top surface;
(b) a patterned sensor stack of layers including a seed layer, magnetic free layer, junction layer, magnetic reference layer, and an exchange pinning layer that are sequentially formed on a pedestal portion of the bottom shield top surface, the pedestal portion has a side that extends below a bottom surface of the seed layer, and said free layer has a magnetization and magnetic anisotropy formed perpendicular to the top surface of the bottom shield in a zero field environment, and parallel to the bottom shield top surface when a magnetic field is applied in an in-plane direction, the reference layer has a magnetization parallel to the bottom shield top surface wherein the reference layer's magnetization direction is maintained by exchange coupling from the exchange pinning layer, and each of the layers in the sensor stack adjoins an air bearing surface (ABS);
(c) an insulation layer adjoining the side of the pedestal portion and formed on a portion of the bottom shield top surface adjacent to the pedestal portion; and
(d) a top shield contacting a top surface of the patterned sensor stack such that there is electrical contact between the top and bottom shields, said top shield includes side shield sections formed on and adjoining the insulation layer, the side shield sections have a bottom surface formed below a top surface of the pedestal portion of the bottom shield.

2. The MR sensor of claim 1 wherein the seed layer promotes perpendicular magnetic anisotropy in the free layer.

3. The MR sensor of claim 1 wherein the seed layer is selected from one of Ta, Ru, Ti, Cu, Ag, Au, NiCr, NiFeCr, CrTi, or a combination of one or more of the aforementioned elements and alloys including a composite that is Ta/Ti/Cu.

4. The MR sensor of claim 1 wherein the free layer is a (Co/Ni) x multilayer or a (CoFe/Ni) x multilayer where x is from about 5 to 50.

5. The MR sensor of claim 1 wherein the free layer is made of (Co/Pt) Y , (Fe/Pt) Y , (CoFe/Pt) Y , or (Co/Pd) Y where y is an integer, or is a single layer of FePt, CoPt, or CoCrPt.

6. The MR sensor of claim 1 wherein the free layer is a composite with an upper FL1 soft magnetic layer contacting the junction layer, and a lower FL2 layer having perpendicular magnetic anisotropy, said FL1 layer has a magnetization perpendicular to the plane of the free layer because of exchange coupling with the FL2 layer.

7. The MR sensor of claim 6 wherein the FL1 layer is comprised of CoFe, CoFeB, or combinations thereof.

8. The MR sensor of claim 1 wherein the reference layer is a soft magnetic layer made of one or more of Co, Fe, Ni, B, and Ta, or is a composite comprising CoFeB and CoFe.

9. The MR sensor of claim 1 wherein the exchange pinning layer is an anti-ferromagnetic (AFM) layer that pins the reference layer.

Assignees

• Headway Tech Inc

Inventors

• Zhou Yuchen
• Zhang Kunliang
• Bai Zhigang

Classifications

• H01F10/3259

  Spin-exchange-coupled multilayers comprising at least a nanooxide layer [NOL], e.g. with a NOL spacer · CPC title

• G01R33/093

  using multilayer structures, e.g. giant magnetoresistance sensors (thin magnetic films H01F10/00) · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• G11B5/3906

  Details related to the use of magnetic thin film layers or to their effects · CPC title

• H01L43/08

  Electricity · mapped topic