TMR Film and Head Technology. CoFeB Vpp. Abstract

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TMR TMR Film and Head Technology 58, 1, 01,2007 Al-O RA 3m 2 MR27 Ti-O MgO CoFeB Co74Fe26/NiFe MgO RA23m 2 4050 MR 100 Gbit/in 2 Al-O TMR 150 mv

resistance-area product (RA) of about 3m 2.

ratio of 40 to 50% with an RA of 2 to 3m 2 in MgO barrier MTJs by using CoFeB for the pinned layer and Co74Fe26/NiFe for the free layer.

Measurements using a synthetic ferrimagnetic medium indicated a large playback output signal of approximately 5000Vpp with a bias voltage (Vb) of 150

1 TMR TMR Film and Head Technology 58, 1, 01,2007 Al-O RA 3m 2 MR27 Ti-O MgO CoFeB Co74Fe26/NiFe MgO RA23m MR 100 Gbit/in 2 Al-O TMR 150 mv 5000Vpp Hex Abstract We have developed Al-O barrier magnetic tunnel junctions (MTJs) and achieved a magneto-resistance (MR) ratio of 27% with a resistance-area product (RA) of about 3m 2. Moreover, we conducted research on the use of Ti-O and MgO barrier magnetic tunnel junctions as new low barrier energy materials and obtained an MR ratio of 40 to 50% with an RA of 2 to 3m 2 in MgO barrier MTJs by using CoFeB for the pinned layer and Co74Fe26/NiFe for the free layer. We created Al-O barrier TMR heads that enable an areal recording density of 100 Gbit/in 2. Measurements using a synthetic ferrimagnetic medium indicated a large playback output signal of approximately 5000Vpp with a bias voltage (Vb) of 150 mv. Micromagnetic simulations of head noise showed that the dominant noise was thermal fluctuation noise and that it could be reduced by strengthening the exchange coupling field Hex between the pinned and antiferromagnetic layers. This paper describes these new TMR film and head technologies. HDD / HDD / FUJITSU.58, 1, p (01,2007) 69

2 TMR TMRTunnel Magnetoresistive RA3m 2 0.1m0.1m 300 MR TMR CPPCurrent Perpendicular to Plane RA RA CIPCurrent In Plane MRAl MTJ CPP RA CPP-GMR MR CPP-GMR Al-O MTJ Ti-OMgO TMR MTJMagnetic Tunnel Junction (1)(5) MTJ MTJ 100 Gbit/in 2 Al-O -1 MR Juliere 2P1P2/ TMR 1P1P2 (6) P1 P2 100 Gbit/in 2 NiCo Fe 100 nm P TMR 1 MR MTJ MR RA a br-h -1 Fig.1-Spin-valve-like property of magnetic tunnel junction (MTJ). 70 FUJITSU.58, 1, (01,2007)

3 TMR amr b RA -2 (a)(b) Fig.2-Annealing temperature dependence of tunnel magnetoresistance (TMR) MTJMR Fig.3-MR curve of MTJ after annealing at 300for 1 hour. MTJ -4NiFe24 nm/co1xfex10 nm/al-o1.6 nm/ Co1xFex10 nm/irmn15 nm MR CoFe Fig.4-Dependence of MR ratio on CoFe composition in NiFe (24 nm)/co1xfex (10 nm)/al-o (1.6 nm)/ Co1xFex (10 nm)/irmn (15 nm) junctions. 18 MR MTJ (1),(2) MTJ MTJ DC Si -1 (3) MR CMPChemical-Mechanical-Polished 24-2 Al2O3TiC -3 (4) Co74Fe26-6 MTJ 42 MR PtMn CoFe/Ru/CoFe -4 (5) -5 Al-O MTJ 10 1 MR RA RA A/m14 koe MTJ FUJITSU.58, 1, (01,2007) 71

4 TMR -5MTJ MR RA Fig.5-Relationship between MR ratios and resistance-area product RA in MTJs. -7 Al-O MTJ MR RA Fig.7-Dependence of MR ratio on resistance-area product RA in Al-O barrier MTJs with different natural oxidization times. -6 MTJ Fig.6-Film structure of MTJ with wedge-shaped barrier layer. -8 Ti-O MTJ MR RA Fig.8-Dependence of MR ratio on resistance-area product RA in Ti-O barrier MTJs with different radical oxidization times. MTJ Ta/PtMn/Co89Fe11/Ru/Co74Fe26/Al 0.55w. & oxid./co74fe261.5/nife3/ta 7.96 nm 0.55w A/m100 Oe & oxid. Al 0.55 nm RA3m 2 MR 27 Al-O MTJ Al-O TMR Ti-O MTJ 2Ti-O TMR Ti-O MTJ MgO MTJ Ti-O 1 Al-O MTJ Ti Al-O MTJMR RA -7 Al MTJMR RA -8 MTJ Ta/PtMn/Co74Fe26/Ru/Co74Fe26/Ti 72 FUJITSU.58, 1, (01,2007)

5 TMR -9Ti-O MTJ RA MR-11MgO MTJ MR Fig.9-Dependence of RA and MR ratio on bias in Ti- Fig.11-Dependence of MR ratio on bias in MgO O barrier MTJ. barrier MTJ. -10MgO MTJ MR RA -12MgO MTJ MR RA Fig.10-Dependence of MR ratio on resistance-area Fig.12-Dependence of MR ratio on resistance-area product RA in MgO barrier MTJs. product RA in MgO barrier MTJs. 0.45w. & oxid./co74fe261/nife3/ta MR (8)(10) Ti-O MTJ Si MgO MTJMR RA RA Ti-O MTJ -10 MgOMgO R-V MR -9 RF MTJ R-V Simmons (7) Ta/PtMn/Co74Fe26/Ru/CoFeB3/ Ti-O MTJ 0.1 ev MgO1.5w./CoFeB3/Ta Al-O MTJ MTJ 350 RA1 km ev 200 MR V1/2MR mv V1/2 V1/2 Ti-O RAMgO V1/2 200 mv Al-O MgO 1.0 nm MTJ450 mv MR RA 3MgO MTJ CoFeB MgO MTJ RA2m MR FUJITSU.58, 1, (01,2007) 73

TMR CoFeB25-14 TMR MTJ MR TEM Hc1.9910 3 A/m25 Oe TMR 110 nm CoFeB 100 nm Co74Fe26/NiFe Vb 150 mv CoFeB MTJ MR Hc3.9810 2 A/m5 Oe 5500Vpp MgO 0.971.00 1.03 nm Br 3.

6 TMR CoFeB25-14 TMR MTJ MR TEM Hc A/m25 Oe TMR 110 nm CoFeB 100 nm Co74Fe26/NiFe Vb 150 mv CoFeB MTJ MR Hc A/m5 Oe 5500Vpp MgO nm Br 3.7 Tnm37 Gm MgO MTJ MR RA -13 CIP-GMR Ta/PtMn/Co74Fe26/Ru/CoFeB/MgO/Co74Fe26 1.5/NiFe3/Ta RA2m 2 Twr 120 nm 40 MR RA MgO Twr MTJ HDD 100 Gbit/in Gbit/in 2 TMR Al-O TMR Ta/PdPtMn/CoFe/Ru/CoFe/Al & oxid./cofe/nife/ta CoCrPt TMR -14 TMR RA4m 2 TEM Fig.14-TEM image of air-bearing surface of prototype TMR head. Al-O TMR 4 TMR MgO MTJ MR RA -15 TMR Fig.13-Dependence of MR ratios on resistance-area Fig.15-Head noise spectrum of prototype TMR product RA in MgO barrier MTJs. heads. 74 FUJITSU.58, 1, (01,2007)

7 TMR 100 nm Vrms TMR TMR K. B. Klaassen (11) NJ shot 2eVbRfcoth ( evb ) Hex 2kBT 1 TMR e kb T CIP-GMR (14) R R 360 (15) -16TMR f 230 MHz 1 TMR 64Vrms 2 170Vrms Landau Lifshitz GilbertLLG Nhead 2 NJ+shot 2 d Mi MiHieff Mi(MiHieff) TMR dt MS i 12 N 2 TMR KuV 2 Mi Ku V Hi eff kbt kb T TMR V (12)(14) MTJ RA 100 Gbit/in 2-16TMR Al-O TMR Fig.16-Micromagnetic simulation model for TMR heads. 100 Gbit/in 2 FUJITSU.58, 1, (01,2007) 75

8 No i s e o ut put [m V] TMR Χ( V) mag-noise output [mv] Χ( V) H ex = 400 Oe, N mag = 156 Vrms (ns) a c throgh 500 MHz low pass filter H ex = 200 Oe, N mag = 336 Vrms (ns) b d -17Hex TMR Fig.17-Simulated output signal and thermal magnetic noise waveforms of TMR heads with different Hex. Hi eff TMR 2-17a b Hi eff Hi ther Hex A/m Oe (14)(16) 2kBT H 2 ther VcellMS (1 2 )t 3 Hex A/m -17cd Hex Hz/Oe Hex c MSVcell Hex d t 10 ps -18Hex TMR Hex / Hex3.18 /Al-O / A/m 2 Hex 120 nm110 nm 45 nm TMR 76 FUJITSU.58, 1, (01,2007)

9 TMR MTJ m 2 RA MgO MRJ HDD 200 Gbit/in 2 TMR 1T. Miyazaki and N. Tezuka Giant magnetic -18 Hex tunneling effect in Fe/Al2O3/Fe junctionj. Magn. Fig.18-Dependence of output signal and thermal Magn. Mater.Vol.139p.L231-L magnetic noise on Hex. 2J. S. Moodera, L. R. Kinder, T. M. Wong, and R. Meservey Large Magnetoresistance at Room RA Temperature in Ferromagnetic Thin Film Tunnel Hex Junctions Phys. Rev. Lett. Vol.74 No.16 Hex p M. Sato and K. Kobayashi Spin-Valve-Like Properties of Ferromagnetic Tunnel JunctionsJpn. J. Appl. Phys.Vol.36p.L200-L M. Sato and K. Kobayashi Spin-Valve-Like Properties and Annealing Effect in Ferromagnetic Tunnel JunctionsIEEE Trans. Magn.Vol RA 3m 2 No.5p Al-O MTJ 5H. Kikuchi, M. Sato, and K. KobayashiEffect of 100 Gbit/in 2 TMR CoFe composition of the spin-valve-like ferromagnetic CIP tunnel junctionj. Appl. Phys.Vol.87 No.9 CIP-GMR 4 p M. JuliereTunneling Between Ferromagnetic Films Physics Letters Vol.54A No.3 p J. G. Simmons Generalized Formula for the Electric Tunnel Effect between Similar Electrodes Separated by a Thin Insulating FilmJ. Appl. Phys. Vol.34No.6p TMR 8S. S. P. Parkin, C. Kaiser, A. Panchula, P. M. Rice, Hex B. Hughes, M. Samant, and S. H. YangGiant tunneling magnetoresistance at room temperature with MgO (100) tunnel barriersnat. Mater.Vol.3 Ti-OMgO MTJ p Ti-O RA9S. Yuasa, T. Nagahama, A. Fukushima, Y. Suzuki, 2m 2 CoFeB and K. AndoGiant room-temperature magnetoresistance Co74Fe26/NiFe MgO in single-crystal Fe/MgO/Fe magnetic tunnel FUJITSU.58, 1, (01,2007) 77

10 TMR junctionsnat. Mater.Vol.8p D. D. Djayaprawira, K. Tsunekawa, M. Nagai, H. Maehara, S. Yamagata, and N. Watanabe 230 room-temperature magnetoresistance in CoFeB/MgO/CoFeB magnetic tunnel junctionsappl. Phys. Lett.Vol.86p K. B. Klaassen, X. Xing, and J. C. L. Pippen Signal and noise aspects of magnetic tunnel junction sensors for data storageieee Trans. Magn.Vol.40 No.1p J.-G. ZhuThermal magnetic noise and spectra in spin valve headsj. Appl. Phys.Vol.91No.10 p O. Heinonen and H. S. ChoThermal magnetic noise in tunneling readersieee Trans. Magn. Vol.40No.4p H. Akimoto, H. Kanai, Y. Uehara, T. Ishizuka, and S. KameyamaAnalysis of thermal magnetic noise in spin-valve GMR heads by using micromagnetic simulationj. Appl. Phys.Vol.97 No.10p.10N H. Akimoto, N. Mukouyama, H. Kanai, and Y. Uehara Analysis of thermal magnetic noise spectrum of TMR heads by micromagnetic simulation J. Magn. Soc. Jpn.Vol.30 No.2 p W. F. Brown Jr. Thermal Fluctuations of a Single-Domain ParticlePhys. Rev.Vol.130No.5 p FUJITSU.58, 1, (01,2007)

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