Headway Technologies, Incorporated

Junjie Quan

Min Li

Kunliang Zhang

Yewhee Chye

Hui-Chuan Wang

Glen A Garfunkel

Yan Wu

Wenyu Chen

Ruhang Ding

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

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

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 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 method of forming a magnetoresistive (MR) sensor with a composite tunnel barrier comprised primarily of magnesium oxynitride and having a MR ratio of at least 70%, resistance x area (RA) product &#x3c;1 ohm-&#x3bc;m, and fewer pinholes than a conventional MgO layer is disclosed. The method involves forming a Mg/MgON/Mg, Mg/MgON/MgN, MgN/MgON/MgN, or MgN/MgON/Mg intermediate tunnel barrier stack and then annealing to drive loosely bound oxygen into adjacent layers thereby forming MgO/MgON/Mg, MgO/MgON/MgON, MgON/MgON/MgON, and MgON/MgON/MgO composite tunnel barriers, respectively, wherein oxygen content in the middle MgON layer is greater than in upper and lower MgON layers. The MgON layer in the intermediate tunnel barrier may be formed by a sputtering process followed by a natural oxidation step and has a thickness greater than the Mg and MgN layers.

Magnetic read head with magnetoresistive (MR) enhancements toward low resistance X area (RA) product

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

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

The blocking temperature of the AFM layer in a TMR sensor has been raised by inserting a magnetic seed layer between the AFM layer and the bottom shield. This gives the device improved thermal stability, including improved SNR and BER.

Magnetic seed for improving blocking temperature and shield to shield spacing in a TMR sensor

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 process for manufacturing a TMR sensor is disclosed wherein the blocking temperature of the AFM layer in the TMR sensor has been raised by inserting a magnetic seed layer between the AFM layer and the bottom shield. This gives the device improved thermal stability, including improved SNR and BER.

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Fremont, CA, United States of America

Junjie Quan