TMR device with low magnetostriction free layer

• US 9,214,170 B2
• Filed: 04/29/2015
• Issued: 12/15/2015
• Est. Priority Date: 11/08/2007
• Status: Active Grant

• Current Assignee: Headway Technologies Incorporated
• Original Assignee: Headway Technologies Incorporated
• Inventors: Wang, Hui-Chuan, Zhao, Tong, Li, Min, Zhang, Kunliang
• Primary Examiner(s): EVANS, JEFFERSON A
• Application Number:
  US14/699,121
• Publication Number:
  US 20150235660A1
• Time in Patent Office: 230 Days
• Field of Search: 360/324.12, 360/324.2
• 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 33/093 using multilayer structures, e.g. giant magnetoresistance sensors thin magnetic films H01F10/00
• CPC Class Codes: G01R 33/18 Measuring magnetostrictive properties
• 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 5/3906 Details related to the use of magnetic thin film layers or to their effects
• CPC Class Codes: G11B 5/3909 Arrangements using a magnetic tunnel junction
• CPC Class Codes: G11B 5/3912 Arrangements in which the active read-out elements are transducing in association with active magnetic shields, e.g. magnetically coupled shields G11B5/3916 takes precedence
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: H01F 10/3254 the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
• CPC Class Codes: H01F 10/3272 by use of anti-parallel coupled [APC] ferromagnetic layers, e.g. artificial ferrimagnets [AFI], artificial [AAF] or synthetic [SAF] anti-ferromagnets
• CPC Class Codes: H01F 10/3295 Spin-exchange coupled multilayers wherein the magnetic pinned or free layers are laminated without anti-parallel coupling within the pinned and free layers
• 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

Abstract

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 <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<3 ohm-um². The CoNiFeB or CoNiFeBM layer has a magnetostriction (λ) value between −5×10⁻⁶ and 5×10⁻⁶.

Claims

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

(a) a stack of layers comprised of a seed layer, anti-ferromagnetic (AFM) layer, and a pinned layer sequentially formed on a substrate;

(b) a tunnel barrier layer made of MgO on the pinned layer;

(c) a free layer having a trilayer configuration including a FeCo layer which contacts the tunnel barrier layer, a second layer that is one of FeB, CoFeB, or CoFe wherein a Fe content is unequal to a Fe content in the FeCo layer, and a third layer that is Co_PNi_RFe_SB_T wherein p is from about 5 to 90 atomic %, r is from about 5 to 20 atomic %, s is between about 5 and 90 atomic %, and t is from about 1 to 30 atomic to give a FeCo/FeB/Co_PNi_RFe_SB_T, FeCo/CoFe/Co_PNi_RFe_SB_T, FeCo/CoFeB/Co_PNi_RFe_SB_T, or FeCo/Co_PNi_RFe_SB_T/CoFeB free layer configuration, and

(d) a capping layer on the free layer.

2. The magnetoresistive element of claim 1 wherein the Fe content in the FeCo layer is from 0 to 100 atomic %, and the FeCo layer has a thickness between about 2 and 10 Angstroms.

3. The magnetoresistive element of claim 1 wherein the CoFeB layer has a thickness of about 5 to 20 Angstroms, and a composition represented by Co_UFe_WB_Z where u is from about 1 to 95 atomic %, w is from 0 to about 70 atomic %, and z is from about 1 to 30 atomic %.

4. The magnetoresistive element of claim 1 wherein the Fe content in the CoFe layer is from 0 to 100 atomic %, and the CoFe layer has a thickness between about 2 and 10 Angstroms.

5. The magnetoresistive element of claim 1 wherein the FeB layer has a thickness of about 2 to 10 Angstroms.

6. The magnetoresistive element of claim 1 wherein the Co_PNi_RFe_SB_T layer has a magnetostriction value between −

5×

10<sup>−

6</sup> and 5×

10<sup>−

6</sup>.

7. The magnetoresistive element of claim 1 wherein the Co_PNi_RFe_SB_T layer is further comprised of an element M where M is one of V, Ti, Zr, Nb, Hf, Ta, or Mo to give a CoNiFeBM layer.

8. The magnetoresistive element of claim 7 wherein the CoFeNiBM layer has a magnetostriction value between −

5×

10<sup>−

6</sup> and 5×

10<sup>−

6</sup>.