Headway Technologies, Incorporated

Yewhee Chye

Min Li

Kunliang Zhang

Junjie Quan

Glen A Garfunkel

Wenyu Chen

Ruhang Ding

Yan Wu

Hui-Chuan Wang

A hard magnet stabilization scheme is disclosed for a top shield and junction shields for double or triple dimension magnetic reader structures. In one design, the hard magnet (HM) adjoins a top or bottom surface of all or part of a shield domain such that the HM is recessed from the air bearing surface to satisfy reader-to-reader spacing requirements and stabilizes a closed loop magnetization in the top shield. The HM may have a height and width greater than that of the top shield. The top shield may have a ring shape with a HM formed above, below, or within the ring shape, and wherein the HM stabilizes a vortex magnetization. HM magnetization is set or reset from room temperature to 100&#xb0; C. to maintain a desired magnetization direction in the top shield, junction shield, and free layer in the sensor.

Hard magnetic stabilized shield for double (2DMR) or triple (3DMR) dimension magnetic reader structures

The use of supermalloy-like materials such as NiFeMe where Me is one or more of Mo, Cr, and Cu for the side and top shields of a magnetic bit sensor is shown to provide better shielding protection from stray fields because of their extremely high permeability. Moreover, the side shield may comprise a stack in which a Ni, Fe, Co, FeNi, CoFe, or FeCo is sandwiched between two NiFeMe layers to enhance the bias field on an adjacent free layer. Including NiFeMe in a side shield results in an increase in readback amplitude under the same asymmetric sigma. For these sensors, the signal to noise ratio was higher and the bit error rate was lower than with conventional materials in the side shield. A method is disclosed for forming a magnetic bit sensor having supermalloy-like materials in the side shields.

Supermalloy and MU metal side and top shields for magnetic read heads

Hard magnet stabilized shield for double (2DMR) or triple (3DMR) dimension magnetic reader structures

A process flow is disclosed for forming a MR sensor having an antiferromagnetic (AFM) layer recessed behind a bottom shield to reduce reader shield spacing and improve pin related noise. An AP/AFM coupling layer/APstack that extends from an air bearing surface to the MR sensor backside is formed above the AFM layer. The APlayer is pinned by the AFM layer, and the APlayer serves as a reference layer to an overlying free layer during a read operation. The APand APlayers have improved resistance to magnetization flipping because back portions thereof have a full cross-track width 'w' between MR sensor sides thereby enabling greater pinning strength from the AFM layer. Front portions of the AP/APlayers lie under the free layer and have a track width less than 'w'. The bottom shield may have an anti-ferromagnetic coupling structure.

Magnetic reader sensor with shield spacing improvement and better pin flip robustness

A hard magnet stabilization scheme is disclosed for a top shield and junction shields for double or triple dimension magnetic reader structures. In one design, the hard magnet (HM) adjoins a top or bottom surface of all or part of a shield domain such that the HM is recessed from the air bearing surface to satisfy reader-to-reader spacing requirements and stabilizes a closed loop magnetization in the top shield. Alternatively, the HM may replace a shield domain. The top shield may have various shapes including a ring shape in which the HM stabilizes a vortex magnetization. In a whole shield coupling design, the HM contacts all of the top shield bottom surface except over the sensor and junction shield. HM magnetization is set or reset from room temperature to 100&#xb0; C. to maintain a desired magnetization direction in the top shield, junction shield, and free layer in the sensor.

A MR sensor is disclosed with an antiferromagnetic (AFM) layer recessed behind a bottom shield to reduce reader shield spacing and improve pin related noise. Above the AFM layer is an AP2/AFM coupling layer/AP1 stack that extends from an air bearing surface to the MR sensor backside. The AP2 layer is pinned by the AFM layer, and the AP1 layer serves as a reference layer to an overlying free layer during a read operation. The AP1 and AP2 layers have improved resistance to magnetization flipping because back portions thereof have a full cross-track width 'w' between MR sensor sides thereby enabling greater pinning strength from the AFM layer. Front portions of the AP1/AP2 layers lie under the free layer and have a track width less than 'w'. The bottom shield may have an anti-ferromagnetic coupling structure. A process flow is provided for fabricating the MR sensor.

Magnetic reader sensor with shield spacing improvement and better pin flop robustness

A read head is longitudinally biased unidirectionally by laterally abutting soft magnetic layers or multilayers. The soft magnetic layers are themselves magnetically stabilized by layers of antiferromagnetic material that are exchange coupled to them. The same layers of antiferromagnetic materials can be used to stabilize a unidirectional anisotropy of an overhead shield by means of exchange coupling. By including the antiferromagnetic material layer within the patterned biasing structure itself, an additional layer of antiferromagnetic material that normally covers the entire sensor structure is eliminated. The elimination of an entire layer is also advantageous for reducing the inter-sensor spacing in a TDMR (two dimensional magnetic recording) configuration where two sensor are vertically stacked on top of each other.

Bias layer and shield biasing design

A TMR stack or a GMR stack, ultimately formed into a sensor or MRAM element, include insertion layers of Fe or iron rich layers of FeX in its ferromagnetic free layer and/or the AP1 layer of its SyAP pinned layer. X is a non-magnetic, metallic element (or elements) chosen from Ta, Hf, V, Co, Mo, Zr, Nb or Ti whose total atom percent is less than 50%. The insertion layers are between 1 and 10 angstroms in thickness, with between 2 and 5 angstroms being preferred and, in the TMR stack, they are inserted adjacent to the interfaces between a tunneling barrier layer and the ferromagnetic free layer or the tunneling barrier layer and the AP1 layer of the SyAP pinned layer in the TMR stack. The insertion layers constrain interdiffusion of B and Ni from CoFeB and NiFe layers and block NiFe crystalline growth.

Magnetic read head with MR enhancements

The use of supermalloy-like materials for the side and top shields of a magnetic bit sensor is shown to provide better shielding protection from stray fields because of their extremely high permeability.

Supermalloy and mu metal side and top shields for magnetic read heads

A MR sensor is disclosed with an antiferromagnetic (AFM) layer recessed behind a first stack of layers including a free layer and non-magnetic spacer to reduce reader shield spacing and enable increased areal density. The AFM layer may be formed on a first pinned layer in the first stack that is partially embedded in a second pinned layer having a front portion at an air bearing surface (ABS) to improve pinning strength and avoid a morphology effect. In another embodiment, the AFM layer is embedded in a bottom shield and surrounds the sidewalls and back side of an overlying free layer in the sensor stack to reduce reader shield spacing. Pinning strength is improved because of increased contact between the AFM layer and a pinned layer. The free layer is aligned above a bottom shield center section.

Reader designs of shield to shield spacing improvement

A composite side shield structure is disclosed for providing biasing to a free layer in a sensor structure. The sensor is formed between a bottom shield and top shield each having a magnetization in a first direction that is parallel to an ABS. The side shield is stabilized by an antiferromagnetic (AFM) coupling scheme wherein a bottom (first) magnetic layer is AFM coupled to a second magnetic layer which in turn is AFM coupled to an uppermost (third) magnetic layer. First and third magnetic layers each have a magnetization aligned in the first direction and are coupled to bottom and top shields, respectively, for additional stabilization. The top shield may be modified to include an AFM scheme for providing additional stabilization and guidance to magnetic moments within AFM coupled magnetic layers in the top shield, and to the third magnetic layer in the side shield.

Thin seeded antiferromagnetic coupled side shield for sensor biasing applications

A wrap around shield structure is disclosed for biasing a free layer in a sensor and includes a bottom shield, side shields, and top shield in which each shield element comprises a high moment layer with a magnetization saturation greater than that of NiFe. The high moment layers provide a better micro read width performance. Side shield structure includes a stack of antiferromagnetically (AFM) coupled magnetic layers on a second high moment layer. A first (lower) magnetic layer in each side shield is ferromagnetically coupled to the second high moment layer, and to a first high moment layer in the bottom shield. A third (upper) magnetic layer in each side shield is ferromagnetically coupled to a third high moment layer in the top shield for improved stabilization. Sensor sidewalls may terminate at a top surface of a reference layer to decrease reader shield spacing.

High moment wrap-around shields for magnetic read head improvements

A magnetically stable, read sensor uses low-coercivity magnetic material without seed layers in side shields for longitudinal biasing in order to improve micro-magnetic read width of the sensor. The sensor is formed between an upper and lower shield and includes a symmetric pair of abutting side shields adjacent to the sides of the sensor. In one configuration the side shields are partially covered by a layer of high magnetic moment material that extends along a bottom surface and side surface of the side shields and is contiguous and conformal with the layer of insulating material, but does not cover the backside of the sensor. The high moment layer focuses flux at the sensor sides and also improves the micro-magnetic read width. The side shields include a multiplicity of horizontal ferromagnetic layers that are antiferromagnetically coupled to each other and magnetically coupled to the upper shield.

Growing community of inventors

Hayward, CA, United States of America

Yewhee Chye