Headway Technologies, Incorporated

Magic Technologies, Inc.

Hui-Chuan Wang

Tong Zhao

Min Li

Kunliang Zhang

Chyu-Jiuh Torng

Cherng-Chyi Han

Yun-Fei Li

Ru-Ying Tong

Cheng Tzong Horng

Kochan Ju

Yu-Hsia Chen

Mao-Min Chen

Junjie Quan

Yimin Guo

Yu-Chen Zhou

Jei-Wei Chang

Cherng Chyi Han

Po-Kang Wang

Rongfu Xiao

Chen-Jung Chien

Chao-Peng Chen

Kevin K Lin

Yewhee Chye

Minghui Yu

Chyu-Jiuh Trong

Zheng Gao

Tai Min

Simon H Liao

Min Zheng

Sangmun Oh

Shohei Kawasaki

Shengyuan Wang

Jianing Zhou

Rodney E Lee

Ruhang Ding

Rong-Fu Xiao

Po-Kang Wan

Yongchang Feng

The present embodiments relate to a tunnel magnetoresistance (TMR) element. The TMR element can include a free layer comprising a metallic alloy that is doped using a dopant element. In some instances, the metallic alloy comprises a cobalt-iron (CoFe) alloy. The present embodiments relate to doping a small amount of an element (e.g., hafnium (Hf), tantalum (Ta), Yttrium (Y)) in a high flux CoFe layer of a tunnel magnetoresistance (TMR) element. The small amount of dopant can suppress a long-range order in the CoFe film. The amorphous state of a CoFe alloy can be induced by the dopant and result in a magnetically soft layer. A resistance of the TMR element can be modified based on an application of an external magnetic field to the free layer and the pin layer.

Tunneling magnetoresistance device with magnetically soft high moment free layer

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 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)where n&#x2267;2. A second embodiment is represented by (NBC/BC)/NBC where n&#x2267;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 &#x3c;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.

TMR device with novel free layer structure

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 TMR sensor with a free layer having a FL1/FL2/FL3 configuration is disclosed in which FL1 is FeCo or a FeCo alloy with a thickness between 2 and 15 Angstroms. The FL2 layer is made of CoFeB or a CoFeB alloy having a thickness from 2 to 10 Angstroms. The FL3 layer is from 10 to 100 Angstroms thick and has a negative &#x3bb; to offset the positive &#x3bb; from FL1 and FL2 layers and is comprised of CoB or a CoBQ alloy where Q is one of Ni, Mn, Tb, W, Hf, Zr, Nb, and Si. Alternatively, the FL3 layer may be a composite such as CoB/CoFe, (CoB/CoFe)where n is &#x2267;2 or (CoB/CoFe)/CoB where m is &#x2267;1. The free layer described herein affords a high TMR ratio above 60% while achieving low values for &#x3bb; (&#x3c;5&#xd7;10), RA (1.5 ohm/&#x3bc;m), and Hc (&#x3c;6 Oe).

TMR device with novel free layer

A method of fabricating 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. 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 &#x3c;100 Angstroms. The TMR sensor may be annealed with a one step or two step process. 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.

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 high performance TMR sensor is fabricated by employing a free layer comprised of CoNiFeB or CoNiFeBM where M is V, Ti, Zr, Nb, Hf, Ta, or Mo and the M content in the alloy is &#x3c;10 atomic %. The free layer may have a FeCo/FeB/CoNiFeB, FeCo/CoFe/CoNiFeB, FeCo/CoFeB/CoNiFeB, or FeCo/CoNiFeB/CoFeB configuration. A CoNiFeBM layer may be formed by co-sputtering CoB with CoNiFeM. A 15 to 30% in improvement in TMR ratio over a conventional CoFe/NiFe free layer is achieved while maintaining low Hc and RA&#x3c;3 ohm-um. The CoNiFeB or CoNiFeBM layer has a magnetostriction (&#x3bb;) value between &#x2212;5&#xd7;10and 5&#xd7;10.

TMR device with low magnetostriction free layer

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)where n&#x2267;2. A second embodiment is represented by (NBC/BC)/NBC where n&#x2267;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 &#x3c;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.

An annealing process for a TMR or GMR sensor having an amorphous free layer is disclosed and employs at least two annealing steps. A first anneal at a temperature Tof 200&#xb0; C. to 270&#xb0; C. and for a tof 0.5 to 15 hours is employed to develop the pinning in the AFM and pinned layers. A second anneal at a temperature Tof 260&#xb0; C. to 400&#xb0; C. where T&#x3e;Tand t&#x3e;tis used to crystallize the amorphous free layer and complete the pinning. An applied magnetic field of about 8000 Oe is used during both anneal steps. The mechanism for forming a sensor with high MR and robust pinning may involve structural change in the tunnel barrier or at an interface between two of the layers in the spin valve stack. A MgO tunnel barrier and a CoFe/CoB free layer are preferred.

Two step annealing process for TMR device with amorphous free layer

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.

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

A two part ion beam etch sequence involving low energy (&#x3c;300 eV) is disclosed for fabricating a free layer width (FLW) as small as 20-25 nm in a MTJ element. A first etch process has one or more low incident angles and accounts for removal of 70% to 100% of the MTJ stack that is not covered by an overlying photoresist layer. The second etch process employs one or more high incident angles and a sweeping motion that is repeated during a plurality of cycles. Sidewall slope may be adjusted by varying the incident angle during either of the etch processes. FLW is about 30 nm less than an initial critical dimension in the photoresist layer while maintaining a MR ratio over 60% and low RA (resistance&#xd7;area) value of 1.0 ohm-&#x3bc;m.

Two step method to fabricate small dimension devices for magnetic recording applications

A three step ion beam etch (IBE) sequence involving low energy (&#x3c;300 eV) is disclosed for trimming a sensor critical dimension (free layer width=FLW) to less than 50 nm. A first IBE step has a steep incident angle with respect to the sensor sidewall and accounts for 60% to 90% of the FLW reduction. The second IBE step has a shallow incident angle and a sweeping motion to remove residue from the first IBE step and further trim the sidewall. The third IBE step has a steep incident angle to remove damaged sidewall portions from the second step and accounts for 10% to 40% of the FLW reduction. As a result, FLW approaching 30 nm is realized while maintaining high MR ratio of over 60% and low RA of 1.2 ohm-&#x3bc;m. Sidewall angle is manipulated by changing one or more ion beam incident angles.

Growing community of inventors

Pleasanton, CA, United States of America

Hui-Chuan Wang