RECENT PROGRESS OF PERPENDICULAR ANISOTROPY MAGNETIC TUNNEL JUNCTIONS FOR NONVOLATILE VLSI

We review recent developments in magnetic tunnel junctions with perpendicular easy axis (p-MTJs) for nonvolatile very large scale integrated circuits (VLSIs). So far, a number of material systems such as rare-earth/transition metal alloys, L10-ordered (Co, Fe)–Pt alloys, Co/(Pd, Pt) multilayers, and ferromagnetic-alloy/oxide stacks have been proposed as electrodes in p-MTJs. Among them, p-MTJs with single or double ferromagnetic-alloy/oxide stacks, particularly CoFeB–MgO, were shown to have high potential to satisfy major requirements for integration.

[1]  S. Yuasa,et al.  Giant room-temperature magnetoresistance in single-crystal Fe/MgO/Fe magnetic tunnel junctions , 2004, Nature materials.

[2]  P. Hansen,et al.  Magnetic and magneto‐optical properties of rare‐earth transition‐metal alloys containing Dy, Ho, Fe, Co , 1989 .

[3]  Spin-dependent tunneling conductance in TbCoFe/Pr6O11/TbCoFe films , 2008 .

[4]  P. Carcia.  Perpendicular magnetic anisotropy in Pd/Co and Pt/Co thin‐film layered structures , 1988 .

[5]  Shoji Ikeda,et al.  Dependence of Giant Tunnel Magnetoresistance of Sputtered CoFeB/MgO/CoFeB Magnetic Tunnel Junctions on MgO Barrier Thickness and Annealing Temperature , 2005 .

[6]  H. Ohno,et al.  Fabrication of a Nonvolatile Full Adder Based on Logic-in-Memory Architecture Using Magnetic Tunnel Junctions , 2008 .

[7]  I. Sato,et al.  Fabrication and properties of CoPt patterned media with perpendicular magnetic anisotropy , 2001 .

[8]  Bernard Rodmacq,et al.  Crossover from in-plane to perpendicular anisotropy in Pt/CoFe/AlOx sandwiches as a function of Al oxidation: A very accurate control of the oxidation of tunnel barriers , 2002 .

[9]  T. Ito,et al.  Electric field effects on magnetocrystalline anisotropy in ferromagnetic Fe monolayers , 2010 .

[10]  B. Diény,et al.  Magnetoresistance in Co∕Pt based magnetic tunnel junctions with out-of-plane magnetization , 2008 .

[11]  H. Ohno,et al.  Perpendicular-anisotropy CoFeB-MgO magnetic tunnel junctions with a MgO/CoFeB/Ta/CoFeB/MgO recording structure , 2012 .

[12]  J. Slonczewski.  Current-driven excitation of magnetic multilayers , 1996 .

[13]  T. Schulthess,et al.  Spin-dependent tunneling conductance of Fe | MgO | Fe sandwiches , 2001 .

[14]  H. Ohno,et al.  Junction size effect on switching current and thermal stability in CoFeB/MgO perpendicular magnetic tunnel junctions , 2011 .

[15]  C. C. Wang,et al.  Electric field effects in low resistance CoFeB-MgO magnetic tunnel junctions with perpendicular anisotropy , 2012 .

[16]  H. Ohno,et al.  Dependence of magnetic anisotropy on MgO thickness and buffer layer in Co20Fe60B20-MgO structure , 2011 .

[17]  Simon C. Li,et al.  Comparison of the interfacial structure between MgO and Al–O oxidation layers for perpendicular magnetic tunnel junction , 2006 .

[18]  Shoji Ikeda,et al.  A 32-Mb SPRAM With 2T1R Memory Cell, Localized Bi-Directional Write Driver and `1'/`0' Dual-Array Equalized Reference Scheme , 2010, IEEE Journal of Solid-State Circuits.

[19]  M. Nakayama,et al.  Spin transfer switching in TbCoFe∕CoFeB∕MgO∕CoFeB∕TbCoFe magnetic tunnel junctions with perpendicular magnetic anisotropy , 2008 .

[20]  H. Ohno,et al.  Transmission electron microscopy study on the effect of various capping layers on CoFeB/MgO/CoFeB pseudo spin valves annealed at different temperatures , 2012 .

[21]  H. Ohno,et al.  Dependence of Magnetic Anisotropy in Co20Fe60B20 Free Layers on Capping Layers in MgO-Based Magnetic Tunnel Junctions with In-Plane Easy Axis , 2012 .

[22]  T. Miyazaki,et al.  Epitaxial Mn2.5Ga thin films with giant perpendicular magnetic anisotropy for spintronic devices , 2009 .

[23]  H. Meng,et al.  Spin transfer in nanomagnetic devices with perpendicular anisotropy , 2006 .

[24]  G. Hu,et al.  Intrinsic distribution of magnetic anisotropy in thin films probed by patterned nanostructures. , 2006, Physical review letters.

[25]  S. Ikeda,et al.  2 Mb SPRAM (SPin-Transfer Torque RAM) With Bit-by-Bit Bi-Directional Current Write and Parallelizing-Direction Current Read , 2008, IEEE Journal of Solid-State Circuits.

[26]  J. Zhu,et al.  Co∕Pt multilayer based magnetic tunnel junctions using perpendicular magnetic anisotropy , 2008 .

[27]  T. Miyazaki,et al.  Composition dependence of magnetic properties in perpendicularly magnetized epitaxial thin films of Mn-Ga alloys , 2012 .

[28]  Hitoshi Kubota,et al.  High Magnetoresistance Ratio and Low Resistance–Area Product in Magnetic Tunnel Junctions with Perpendicularly Magnetized Electrodes , 2010 .

[29]  S. Yuasa,et al.  High Tunnel Magnetoresistance at Room Temperature in Fully Epitaxial Fe/MgO/Fe Tunnel Junctions due to Coherent Spin-Polarized Tunneling , 2004 .

[30]  S. Ikeda,et al.  CoFeB Thickness Dependence of Thermal Stability Factor in CoFeB/MgO Perpendicular Magnetic Tunnel Junctions , 2012, IEEE Magnetics Letters.

[31]  Koichiro Inomata,et al.  Magnetic Tunnel Junctions with Perpendicular Anisotropy Using a Co2FeAl Full-Heusler Alloy , 2012 .

[32]  Bernard Rodmacq,et al.  Pt/Co/oxide and oxide/Co/Pt electrodes for perpendicular magnetic tunnel junctions , 2009 .

[33]  H. Ohno,et al.  Tunnel magnetoresistance of 604% at 300K by suppression of Ta diffusion in CoFeB∕MgO∕CoFeB pseudo-spin-valves annealed at high temperature , 2008 .

[34]  J. Katine,et al.  Current-induced magnetization reversal in nanopillars with perpendicular anisotropy , 2006 .

[35]  Shoji Ikeda,et al.  A 3.14 um2 4T-2MTJ-cell fully parallel TCAM based on nonvolatile logic-in-memory architecture , 2012, 2012 Symposium on VLSI Circuits (VLSIC).

[36]  M. Gajek,et al.  Spin torque switching of 20 nm magnetic tunnel junctions with perpendicular anisotropy , 2012 .

[37]  Z. Wen,et al.  Perpendicular magnetization of Co2FeAl full-Heusler alloy films induced by MgO interface , 2011 .

[38]  Yang-Hua Chang,et al.  Perpendicular Magnetic Tunneling Junction With Double Barrier Layers for MRAM Application , 2007, IEEE Transactions on Magnetics.

[39]  T. Daibou,et al.  Tunnel Magnetoresistance Over 100% in MgO-Based Magnetic Tunnel Junction Films With Perpendicular Magnetic L1$_{0}$-FePt Electrodes , 2008, IEEE Transactions on Magnetics.

[40]  Wei-gang Wang,et al.  Electric-field-assisted switching in magnetic tunnel junctions. , 2012, Nature materials.

[41]  H. Ohno,et al.  Origin of the collapse of tunnel magnetoresistance at high annealing temperature in CoFeB/MgO perpendicular magnetic tunnel junctions , 2011 .

[42]  Mt Johnson,et al.  Magnetic anisotropy in metallic multilayers , 1996 .

[43]  J. Nowak,et al.  Spin torque switching of perpendicular Ta∣CoFeB∣MgO-based magnetic tunnel junctions , 2011 .

[44]  H. Ohno,et al.  A perpendicular-anisotropy CoFeB-MgO magnetic tunnel junction. , 2010, Nature materials.

[45]  R. P. Robertazzi,et al.  Effect of subvolume excitation and spin-torque efficiency on magnetic switching , 2011 .

[46]  J. Katine,et al.  Time-resolved reversal of spin-transfer switching in a nanomagnet. , 2004, Physical review letters.

[47]  W. D. Jonge,et al.  Perpendicular anisotropy in Pd/Co multilayers , 1988 .

[48]  Robert A. Buhrman,et al.  Spin-polarized current switching of a Co thin film nanomagnet , 2000 .

[49]  H. Ohno,et al.  Pd Layer Thickness Dependence of Tunnel Magnetoresistance Properties in CoFeB/MgO-Based Magnetic Tunnel Junctions with Perpendicular Anisotropy CoFe/Pd Multilayers , 2011 .

[50]  Hideo Ohno,et al.  Electric-field effects on thickness dependent magnetic anisotropy of sputtered MgO/Co40Fe40B20/Ta structures , 2010 .

[51]  Hitoshi Kubota,et al.  High efficient spin transfer torque writing on perpendicular magnetic tunnel junctions for high density MRAMs , 2010 .

[52]  Bernard Rodmacq,et al.  Analysis of oxygen induced anisotropy crossover in Pt/Co/MOx trilayers , 2008 .

[53]  T. Miyazaki,et al.  Tunneling magnetoresistance of magnetic tunnel junctions using perpendicular magnetization L10-CoPt electrodes , 2008 .

[54]  Shoji Ikeda,et al.  Domain Structure in CoFeB Thin Films With Perpendicular Magnetic Anisotropy , 2011, IEEE Magnetics Letters.

[55]  Shoji Ikeda,et al.  1Mb 4T-2MTJ nonvolatile STT-RAM for embedded memories using 32b fine-grained power gating technique with 1.0ns/200ps wake-up/power-off times , 2012, 2012 Symposium on VLSI Circuits (VLSIC).

[56]  S. Ikeda,et al.  MgO barrier-perpendicular magnetic tunnel junctions with CoFe/Pd multilayers and ferromagnetic insertion layers , 2009, 0910.4204.

[57]  Yasuo Ando,et al.  Magnetization Dynamics in CoFeB Buffered Perpendicularly Magnetized Co/Pd Multilayer , 2010, IEEE Transactions on Magnetics.

[58]  W. X. Wang,et al.  Effect of annealing on the magnetic tunnel junction with Co/Pt perpendicular anisotropy ferromagnetic multilayers , 2010 .

[59]  H. Ohno,et al.  Electric field-induced magnetization reversal in a perpendicular-anisotropy CoFeB-MgO magnetic tunnel junction , 2012 .

[60]  Margaret Evans Best,et al.  High K/sub u/ materials approach to 100 Gbits/in/sup 2/ , 2000 .

[61]  H. Okumura,et al.  Magnetic hardening and coercivity mechanisms in L10 ordered FePd ferromagnets , 1995 .

[62]  B. Diény,et al.  Magnetization dynamics and thermal stability in patterned media , 2005 .

[63]  Z. Li,et al.  Thermally assisted magnetization reversal in the presence of a spin-transfer torque , 2003 .

[64]  Tadahiko Hirai,et al.  Magnetic tunnel junction device with perpendicular magnetization films for high-density magnetic random access memory , 2002 .

[65]  Fabrication of Perpendicular MgO-Based Magnetic Tunnel Junctions With TbFe/FeCo Electrodes , 2011, IEEE Transactions on Magnetics.

[66]  H. Muraoka,et al.  Switching Field and Thermal Stability of CoPt/Ru Dot Arrays With Various Thicknesses , 2007, IEEE Transactions on Magnetics.

[67]  Kelly,et al.  Prediction and confirmation of perpendicular magnetic anisotropy in Co/Ni multilayers. , 1992, Physical review letters.

[68]  S. Araki,et al.  Magnetism and magnetoresistance of Au/Co multilayers , 1989 .

[69]  K. Tsunekawa,et al.  230% room temperature magnetoresistance in CoFeB/MgO/CoFeB magnetic tunnel junctions , 2005, INTERMAG Asia 2005. Digests of the IEEE International Magnetics Conference, 2005..

[70]  S. Ikeda,et al.  CoFeB/MgO based perpendicular magnetic tunnel junctions with stepped structure for symmetrizing different retention times of “0” and “1” information , 2011, 2011 Symposium on VLSI Technology - Digest of Technical Papers.

[71]  T. Miyazaki,et al.  Long-lived ultrafast spin precession in manganese alloys films with a large perpendicular magnetic anisotropy. , 2011, Physical review letters.

[72]  B. Diény,et al.  Sizable room-temperature magnetoresistance in cobalt based magnetic tunnel junctions with out-of-plane anisotropy , 2008 .

[73]  M. Oogane,et al.  Fabrication of L10-MnAl perpendicularly magnetized thin films for perpendicular magnetic tunnel junctions , 2012 .

[74]  J. Renard,et al.  Magnetoresistance of very thin cobalt-gold multilayers with perpendicular anisotropy , 1988 .

[75]  H. Ohno,et al.  Magnetic Anisotropy Modulation in Ta/ CoFeB/ MgO Structure by Electric Fields , 2011 .

[76]  T. Miyazaki,et al.  Magnetoresistance effect in L10-MnGa/MgO/CoFeB perpendicular magnetic tunnel junctions with Co interlayer , 2012 .

[77]  Berger.  Emission of spin waves by a magnetic multilayer traversed by a current. , 1996, Physical review. B, Condensed matter.

[78]  H. Ohno,et al.  Magnetic Tunnel Junctions for Spintronic Memories and Beyond , 2007, IEEE Transactions on Electron Devices.

[79]  Huseyin Kurt,et al.  High spin polarization in epitaxial films of ferrimagnetic Mn3Ga , 2011 .

[80]  Tunnel magnetoresistance properties and annealing stability in perpendicular anisotropy MgO-based magnetic tunnel junctions with different stack structures , 2011 .

[81]  A. Umerski,et al.  Theory of tunneling magnetoresistance of an epitaxial Fe/MgO/Fe(001) junction , 2001 .

[82]  Ralph,et al.  Current-driven magnetization reversal and spin-wave excitations in Co /Cu /Co pillars , 1999, Physical review letters.

[83]  Claudia Felser,et al.  Mn3Ga, a compensated ferrimagnet with high Curie temperature and low magnetic moment for spin torque transfer applications , 2007 .

[84]  H. Ohno,et al.  Current-Induced Magnetization Switching in MgO Barrier Magnetic Tunnel Junctions With CoFeB-Based Synthetic Ferrimagnetic Free Layers , 2008, IEEE Transactions on Magnetics.

[85]  Shigeki Nakagawa,et al.  Perpendicular magnetic tunnel junction with tunneling magnetoresistance ratio of 64% using MgO (100) barrier layer prepared at room temperature , 2008 .

[86]  H. Ohno,et al.  Perpendicular Magnetic Tunnel Junctions with CoFe/Pd Multilayer Electrodes and an MgO Barrier , 2009, IEEE Transactions on Magnetics.

[87]  Kay Yakushiji,et al.  Spin-polarized current-induced magnetization reversal in perpendicularly magnetized L10-FePt layers , 2006 .

[88]  Tetsuo Endoh,et al.  Fully parallel 6T-2MTJ nonvolatile TCAM with single-transistor-based self match-line discharge control , 2011, 2011 Symposium on VLSI Circuits - Digest of Technical Papers.

[89]  S. Yuasa,et al.  Ultrathin Co/Pt and Co/Pd superlattice films for MgO-based perpendicular magnetic tunnel junctions , 2010 .

[90]  T. Miyazaki,et al.  Gilbert damping in perpendicularly magnetized Pt/Co/Pt films investigated by all-optical pump-probe technique , 2010 .

[91]  T. Miyazaki,et al.  Gilbert Damping in Ni/Co Multilayer Films Exhibiting Large Perpendicular Anisotropy , 2011 .

[92]  Daisuke Suzuki,et al.  Fabrication of a nonvolatile lookup-table circuit chip using magneto/semiconductor-hybrid structure for an immediate-power-up field programmable gate array , 2009, 2009 Symposium on VLSI Circuits.

[93]  T. Chong,et al.  Effects of Ta seed layer and annealing on magnetoresistance in CoFe/Pd-based pseudo-spin-valves with perpendicular anisotropy , 2007 .

[94]  Weisheng Zhao,et al.  High Speed, High Stability and Low Power Sensing Amplifier for MTJ/CMOS Hybrid Logic Circuits , 2009, IEEE Transactions on Magnetics.

[95]  O. Hellwig,et al.  Ultrafast magnetization dynamics in high perpendicular anisotropy †Co/Pt‡ n multilayers , 2007 .

[96]  W J Gallagher,et al.  Demonstration of Ultralow Bit Error Rates for Spin-Torque Magnetic Random-Access Memory With Perpendicular Magnetic Anisotropy , 2011, IEEE Magnetics Letters.