Source: http://patents.com/us-9972770.html
Timestamp: 2018-10-16 21:14:01
Document Index: 187669300

Matched Legal Cases: ['arth\n7130167', 'arth\n7564152', 'Application No. 2016', 'Application No. 201480013988', 'Application No. 10', 'Application No. 201480013988', 'Application No. 14779178']

US Patent # 9,972,770. Methods of forming memory cells, arrays of magnetic memory cells, and semiconductor devices - Patents.com
United States Patent 9,972,770
Methods of forming memory cells, arrays of magnetic memory cells, and semiconductor devices
Chen; Wei (White Plains, NY), Murthy; Sunil (White Plains, NY), Kula; Witold (Gilroy, CA)
Family ID: 1000003293923
15/194,875
US 20160308118 A1 Oct 20, 2016
13797185 Mar 12, 2013 9379315
Current CPC Class: H01L 43/02 (20130101); H01L 43/12 (20130101); H01L 43/10 (20130101); H01L 43/08 (20130101)
Current International Class: G11B 5/31 (20060101); H01L 43/08 (20060101); H01L 43/12 (20060101); H01L 43/02 (20060101); H01L 43/10 (20060101)
4882936 November 1989 Garshelis
5768069 June 1998 Mauri
6166948 December 2000 Parkin et al.
6258470 July 2001 Sakakima et al.
6275363 August 2001 Gill
6363000 March 2002 Penner et al.
6387476 May 2002 Iwasaki et al.
6483741 November 2002 Iwasaki et al.
6560135 May 2003 Matsuoka et al.
6611405 August 2003 Inomata et al.
6703249 March 2004 Okazawa et al.
6771534 August 2004 Stipe
6806096 October 2004 Kim et al.
6845038 January 2005 Shukh
6970376 November 2005 Fukuzumi
6980468 December 2005 Ounadjela
6998150 February 2006 Li et al.
7026671 April 2006 Mizuguchi et al.
7095933 August 2006 Barth
7130167 October 2006 Gill
7189583 March 2007 Drewes
7239489 July 2007 Lin et al.
7274080 September 2007 Parkin
7372674 May 2008 Gill
7378698 May 2008 Ha et al.
7379280 May 2008 Fukumoto et al.
7486552 February 2009 Apalkov et al.
7514160 April 2009 Nagahama et al.
7563486 July 2009 Barth
7564152 July 2009 Clark et al.
7602033 October 2009 Zhao
7660153 February 2010 Yamane et al.
7682841 March 2010 Dahmani et al.
7732881 June 2010 Wang
7750421 July 2010 Horng et al.
7791844 September 2010 Carey et al.
7835173 November 2010 Ma et al.
7863060 January 2011 Belen et al.
7885105 February 2011 Li et al.
7919794 April 2011 Gu et al.
7929370 April 2011 Min
7932572 April 2011 Tsujiuchi
7948044 May 2011 Horng et al.
8009465 August 2011 Nakayama et al.
8043732 October 2011 Anderson et al.
8048492 November 2011 Fukuzawa et al.
8068317 November 2011 Gill
8072800 December 2011 Chen et al.
8080432 December 2011 Horng et al.
8089137 January 2012 Lung et al.
8102700 January 2012 Liu et al.
8138561 March 2012 Horng et al.
8324697 December 2012 Worledge
8334148 December 2012 Jeong et al.
8338004 December 2012 Shin et al.
8357962 January 2013 Marukame et al.
8385107 February 2013 Prejbeanu
8411498 April 2013 Kim et al.
8422286 April 2013 Ranjan et al.
8470462 June 2013 Horng et al.
8492169 July 2013 Cao et al.
8570798 October 2013 Meade et al.
8587043 November 2013 Natori et al.
8623452 January 2014 Zhou
8749003 June 2014 Horng et al.
8779538 July 2014 Chen et al.
8803265 August 2014 Lim et al.
8823118 September 2014 Horng et al.
9281466 March 2016 Sandhu et al.
2002/0089874 July 2002 Nickel et al.
2002/0105827 August 2002 Redon et al.
2003/0011939 January 2003 Gill
2003/0103371 June 2003 Kim et al.
2003/0199104 October 2003 Leuschner et al.
2004/0075959 April 2004 Gill
2004/0174740 September 2004 Lee et al.
2004/0224243 November 2004 Yoshizawa et al.
2004/0233760 November 2004 Guo et al.
2005/0036361 February 2005 Fukuzumi
2005/0068683 March 2005 Gill
2005/0087511 April 2005 Sharma et al.
2005/0106810 May 2005 Pakala et al.
2005/0164414 July 2005 Deak
2005/0173698 August 2005 Drewes
2005/0189574 September 2005 Nguyen et al.
2005/0211973 September 2005 Mori et al.
2006/0038213 February 2006 Mori et al.
2006/0042930 March 2006 Mauri
2006/0114714 June 2006 Kanegae
2006/0118842 June 2006 Iwata
2007/0008661 January 2007 Min et al.
2007/0035890 February 2007 Sbiaa
2007/0053112 March 2007 Papworth Parkin
2007/0086121 April 2007 Nagase et al.
2007/0217071 September 2007 Inamura et al.
2007/0297220 December 2007 Yoshikawa et al.
2008/0164502 July 2008 Fukumoto et al.
2008/0164548 July 2008 Ranjan et al.
2008/0205130 August 2008 Sun et al.
2008/0225581 September 2008 Yamane et al.
2008/0278867 November 2008 Fukumoto et al.
2009/0015958 January 2009 Nakamura et al.
2009/0039450 February 2009 Lee et al.
2009/0079018 March 2009 Nagase et al.
2009/0096043 April 2009 Min et al.
2009/0190262 July 2009 Murakami
2009/0229111 September 2009 Zhao
2009/0257151 October 2009 Zhang et al.
2010/0034014 February 2010 Ohno et al.
2010/0080036 April 2010 Liu et al.
2010/0080048 April 2010 Liu et al.
2010/0096716 April 2010 Ranjan
2010/0102406 April 2010 Xi et al.
2010/0109110 May 2010 Wang et al.
2010/0110783 May 2010 Liu et al.
2010/0148167 June 2010 Whig et al.
2010/0171086 July 2010 Lung et al.
2010/0176472 July 2010 Shoji
2010/0177557 July 2010 Liu et al.
2010/0177561 July 2010 Liu et al.
2010/0200899 August 2010 Marukame et al.
2010/0230769 September 2010 Ozaki et al.
2010/0327248 December 2010 Khoueir et al.
2011/0007429 January 2011 Dimitrov et al.
2011/0007543 January 2011 Khoury
2011/0014500 January 2011 Horng et al.
2011/0031569 February 2011 Watts et al.
2011/0049657 March 2011 Tsukamoto et al.
2011/0049658 March 2011 Zheng et al.
2011/0051503 March 2011 Hu et al.
2011/0062537 March 2011 Oh et al.
2011/0064969 March 2011 Chen et al.
2011/0121366 May 2011 Or-Bach et al.
2011/0145514 June 2011 Lee et al.
2011/0149646 June 2011 Liu et al.
2011/0149670 June 2011 Heo et al.
2011/0170339 July 2011 Wunderlich et al.
2011/0170341 July 2011 Butler
2011/0241138 October 2011 Hsieh et al.
2011/0260274 October 2011 Zheng et al.
2011/0266642 November 2011 Viala et al.
2011/0269251 November 2011 Kim et al.
2011/0293967 December 2011 Zhang et al.
2011/0303995 December 2011 Worledge
2011/0303997 December 2011 Wang et al.
2011/0309418 December 2011 Nakayama et al.
2012/0012952 January 2012 Chen et al.
2012/0012953 January 2012 Lottis et al.
2012/0012954 January 2012 Yamada et al.
2012/0015099 January 2012 Sun et al.
2012/0040207 February 2012 Horng et al.
2012/0069647 March 2012 Kramer
2012/0074511 March 2012 Takahashi et al.
2012/0075922 March 2012 Yamada et al.
2012/0075927 March 2012 Chen et al.
2012/0106233 May 2012 Katti
2012/0134201 May 2012 Ogimoto
2012/0135273 May 2012 Horng et al.
2012/0146167 June 2012 Huai et al.
2012/0148874 June 2012 Ohmori et al.
2012/0155156 June 2012 Watts et al.
2012/0205758 August 2012 Jan et al.
2012/0217594 August 2012 Kajiyama
2012/0218813 August 2012 Oh et al.
2012/0225499 September 2012 Nozieres et al.
2012/0236631 September 2012 Park et al.
2012/0241878 September 2012 Hu et al.
2012/0267733 October 2012 Hu et al.
2012/0280336 November 2012 Jan et al.
2012/0286382 November 2012 Jan et al.
2012/0299134 November 2012 Jan et al.
2012/0299137 November 2012 Worledge
2013/0005052 January 2013 Hu et al.
2013/0028013 January 2013 Ikeda et al.
2013/0042081 February 2013 Park et al.
2013/0059168 March 2013 Tahmasebi et al.
2013/0064011 March 2013 Liu et al.
2013/0069185 March 2013 Saida et al.
2013/0140658 June 2013 Yamane et al.
2013/0146996 June 2013 Yu et al.
2013/0228884 September 2013 Zheng et al.
2013/0229866 September 2013 Ranjan et al.
2013/0250661 September 2013 Sandhu et al.
2013/0313665 November 2013 Rhie et al.
2013/0334630 December 2013 Kula et al.
2013/0334631 December 2013 Kinney et al.
2014/0099735 April 2014 Horng et al.
2014/0264663 September 2014 Chen et al.
2015/0028439 January 2015 Kula et al.
2015/0076485 March 2015 Sandhu et al.
2015/0076633 March 2015 Siddik et al.
2015/0249202 September 2015 Siddik et al.
102543176 Jul 2012 CN
1353443 Oct 2003 EP
2385548 Nov 2011 EP
2541554 Jan 2013 EP
2015307 Apr 2013 EP
2343308 May 2000 GB
2002314049 Oct 2002 JP
2004104076 Apr 2004 JP
2008098523 Apr 2008 JP
2009021352 Jan 2009 JP
2009021532 Jan 2009 JP
2009194366 Aug 2009 JP
2011060918 Mar 2011 JP
1020040092342 Nov 2004 KR
1020070094431 Sep 2007 KR
1020080029852 Apr 2008 KR
1020120008295 Jan 2012 KR
2010026831 Mar 2010 WO
2010134378 Nov 2010 WO
2011001746 Jan 2011 WO
2011149274 Dec 2011 WO
2011159422 Dec 2011 WO
2012128891 Sep 2012 WO
2012148587 Nov 2012 WO
2012160937 Nov 2012 WO
Japanese Office Action for Japanese Application No. 2016-500998, (dated Dec. 6, 2016), 10 pages including translation of boxed portions. cited by applicant .
Chinese Office Action and Search Report for Chinese Application No. 201480013988.3, (dated Nov. 8, 2016), 19 pages including translation. cited by applicant .
Notice of Reasons for Rejection for Korean Application No. 10-2015-7026735, (dated May 19, 2017), 12 pages including English translation. cited by applicant .
Second Office Action for Chinese Application No. 201480013988.3, (dated May 26, 2017), 11 pages including English translation. cited by applicant .
Apalkov et al., Comparison of Scaling of In-Plane and Perpendicular Spin Transfer Switching Technologies by Micromagnetic Simulation, IEEE Transactions on Magnetics, vol. 46, Issue 6, (Jun. 2010), pp. 2240-2243 (abstract only). cited by applicant .
Auwarter et al., Co on h-Bn/Ni(1 1 1): From Island to Island-Chain Formation and Co Intercalation, Surface Science, vol. 511, (2002), pp. 379-386. cited by applicant .
Bai et al., Boron Diffusion Induced Symmetry Reduction and Scattering in CoFeB/MgO/CoFeB Magnetic Tunnel Junctions, Phys. Rev. B, vol. 87, (Jan. 23, 2013), pp. 014114 (abstract only). cited by applicant .
Braun et al., Strain-Induced Perpendicular Magnetic Anisotropy in Ultrathin Ni Films on Cu3Au(0 0 1), Journal of Magnetism and Magnetic Materials, vol. 171, (1997), pp. 16-28. cited by applicant .
Carrey et al., Influence of Interface Alloying on the Magnetic Properties of Co/Pd Multilayers, Applied Physics Letters, vol. 83, No. 25, (Dec. 22, 2003), pp. 5259-5261. cited by applicant .
Cha et al., Atomic-Scale Spectroscopic Imaging of CoFeB/Mg-B-O/CoFeB Magnetic Tunnel Junctions, Applied Physics Letters, vol. 95, (2009), pp. 032506-1-032506-3. cited by applicant .
Chen et al., Advances and Future Prospects of Spin-Transfer Torque Random Access Memory, IEEE Transactions on Magnetics, vol. 26, No. 6, (Jun. 2010), pp. 1873-1878. cited by applicant .
Diao et al., Spin Transfer Switching in Dual MgO Magnetic Tunnel Junctions, Applied Physics Letters, vol. 90, (2007), pp. 132508-1-132508-3. cited by applicant .
Djayaprawira et al., 230% Room-Temperature Magnetoresistance in CoFeB/MgO/CoFeB Magnetic Tunnel Junctions, Applied Physics Letters, vol. 86, Issue 9, (2005), abstract only, 2 pages. cited by applicant .
Farle et al., The Temperature Dependence of Magnetic Anisotropy in Ultra-Thin Films, Journal of Magnetism and Magnetic Materials, vol. 165, (1997), pp. 74-77. cited by applicant .
Gan et al., Origin of the Collapse of Tunnel Magnetoresistance at High Annealing Temperature in CoFeB/MgO Perpendicular Magnetic Tunnel Junctions, Applied Physics Letters, vol. 99, (2011), pp. 252507-1-252507-3. cited by applicant .
Gao et al., Combinatorial Exploration of Rare-Earth-Free Permanent Magnets: Magnetic and Microstructural Properties of Fe-Co-W Thin Films, Applied Physics Letters, vol. 102, (2013), pp. 022419-1-022419-4. cited by applicant .
Hayakawa et al., Dependence of Giant Tunnel Magnetoresistance of Sputtered CoFeB/MgO/CoFeB Magnetic Tunnel Junctions on MgO Barrier Thickness and Annealing Temperature, Japanese Journal of Applied Physics, vol. 44, No. 19, (2005), pp. L587-L589. cited by applicant .
Heczko et al., Strain and Concurrent Magnetization Changes in Magnetic Shape Memory Ni-Mn-Ga Single Crystals--Experiment and Model, Materials Science and Engineering A, vol. 481-482, (2008), pp. 283-287. cited by applicant .
Hendrych et al., Magnetic Behavior and Domain Structure in As-Quenched, Annealed, and Stress-Annealed CoFeCrSiB Ribbons, Journal of Magnetism and Magnetic Materials, vol. 321, (2009), pp. 3771-3777. cited by applicant .
Ikeda et al., Tunnel Magnetoresistance of 604% at 300 K by Suppression of Ta Diffusion in CoFeB/MgO/CoFeB Pseudo-Spin-Valves Annealed at High Temperature, Applied Physics Letters, vol. 93, (2008), pp. 082508-1-082508-3. cited by applicant .
International Search Report for PCT/US2014/022555, (dated Jul. 21, 2014), 3 pages. cited by applicant .
Written Opinion of the International Searching Authority for PCT/US2014/022555, (dated Jul. 21, 2014), 8 pages. cited by applicant .
Ke et al., Oxygen-Vacancy-Induced Diffusive Scatting in Fe/MgO/Fe Magnetic Tunnel Junctions, Physical Review Letters, vol. 105, Dec. 3, 2010, pp. 236801-1-236801-4. cited by applicant .
Kim et al., Effect of Annealing on Magnetic Exchange Coupling in CoPt/Co Bilayer Thin Films, Journal of Applied Physics, vol. 87, No. 9, (May 1, 2000), pp. 6140-6142. cited by applicant .
Kim et al., Enhancement of Data Retention and Write Current Scaling for Sub-20nm STT-MRAM by Utilizing Dual Interfaces for Perpendicular Magnetic Anisotropy, VLSI Technology (VLSIT), 2012 Symposium, (Jun. 12-14 2012), abstract, 1 page. cited by applicant .
Ko et al., Effects of MgO and MgO/Pd Seed-Layers on Perpendicular Magnetic Anisotropy of CoPd Thin Films, Thin Solid Films, vol. 519, (2011), pp. 8252-8255. cited by applicant .
Kohda et al., Width and Temperature Dependence of Lithography-Induced Magnetic Anisotropy in (Ga,Mn)As Wires, Physica E, vol. 42, (2010), pp. 2685-2689. cited by applicant .
Lavrijsen et al., Tuning the Interlayer Exchange Coupling Between Single Perpendicularly Magnetized CoFeB Layers, Appl. Phys. Lett., vol. 100, (2012), pp. 052411-1-052411-5. cited by applicant .
Lohndorf et al., Characterization of Magnetostrictive TMR Pressure Sensors by MOKE, Journal of Magnetism and Magnetic Materials, vol. 316, (2007), pp. e223-e225. cited by applicant .
Ma et al., NiO-Thickness Dependent Magnetic Anisotropies in Fe/NiO/Au(001) and Fe/NiO/MgO(001) Systems, Journal of Magnetism and Magnetic Materials, vol. 324, (2012), pp. 528-533. cited by applicant .
Maehara et al., Tunnel Magnetoresistance Above 170% and Resistance-Area Product of 1 .OMEGA. (.mu.m)2 Attained by In Situ Annealing of Ultra-Thin MgO Tunnel Barrier, Applied Physics Express, vol. 4, (2011), abstract only, 2 pages. cited by applicant .
Matsumoto et al., Dependence on Annealing Temperatures of Tunneling Spectra in High-Resistance CoFeB/MgO/CoFeB Magnetic Tunnel Junctions, Solid State Communications, vol. 143, (2007), pp. 574-578. cited by applicant .
Matsumoto et al., Tunneling Spectra of Sputter-Deposited CoFeB/MgO/CoFeB Magnetic Tunnel Junctions Showing Giant Tunneling Magnetoresistance Effect, Solid State Communications, vol. 136, (2005), pp. 611-615. cited by applicant .
Miao et al., Disturbance of Tunneling Coherence by Oxygen Vacancy in Epitaxial Fe/MgO/Fe Magnetic Tunnel Junctions, Physical Review Letters, vol. 100, Jun. 20, 2008, pp. 246803-1-246803-4. cited by applicant .
Miracle et al., An Assessment of Binary Metallic Glasses: Correlations Between Structure, Glass Forming Ability and Stability (Preprint), Air Force Research Laboratory, (2011), 97 pages. cited by applicant .
Miura et al., CoFeB/MgO Based Perpendicular Magnetic Tunnel Junctions with Stepped Structure for Symmetrizing Different Retention Times of "0" and "1" Information, 2011 Symposium on VLSI Technology (VLSIT), (Jun. 14-16, 2011), 19 pages. cited by applicant .
Moroz et al., Modeling the Impact of Stress on Silicon Processes and Devices, Materials Science in Semiconductor Processing, vol. 6, (2003), pp. 27-36. cited by applicant .
Moutis et al., Voltage-Induced Modification in Magnetic Coercivity of Patterned Co50Fe50 Thin Film on Piezoelectric Substrate, Journal of Magnetism and Magnetic Materials, vol. 320, (2008), pp. 1050-1055. cited by applicant .
Nishitani et al., Magnetic Anisotropy in a Ferromagnetic (Ga,Mn)Sb Thin Film, Physica E, vol. 42, (2010), pp. 2681-2684. cited by applicant .
Piramanayagam, S. N., Perpendicular Recording Media for Hard Disk Drives, Journal of Applied Physics, vol. 102, (2007), pp. 011301-1-011301-22. cited by applicant .
Resnik et al., Mechanical Stress in Thin Film Microstructures on Silicon Substrate, Vacuum, vol. 80, (2005), pp. 236-240. cited by applicant .
Rodmacq et al., Influence of Thermal Annealing on the Perpendicuular Magnetic Anisotropy of Pt/Co/AlOx Trilayers, Physical Review B, vol. 79, (2009), pp. 024423-1-024423-8. cited by applicant .
Sato et al., Perpendicular-Anisotropy CoFeB-MgO Magnetic Tunnel Junctions with a MgO/CoFeB/Ta/CoFeB/MgO Recording Structure, Applied Physics Letters, vol. 101, (2012), pp. 022414-1-022414-4. cited by applicant .
Stone et al., Tuning of Ferromagnetism Through Anion Substitution in Ga-Mn-Pnictide Ferromagnetic Semiconductors, Physica B, vol. 401-402, (2007), pp. 454-457. cited by applicant .
Tao et al., Uniform Wafer-Scale Chemical Vapor Deposition of Graphene on Evaporated Cu (1 1 1) Film with Quality Comparable to Exfoliated Monolayer, J. Physical Chemistry, vol. 116, (2012), pp. 24068-24074. cited by applicant .
Vitos et al., The Surface Energy of Metals, Surface Science, vol. 411, (1998), pp. 186-202. cited by applicant .
Wang et al., Exchange Coupling Between Ferromagnetic and Antiferromagnetic Layers Via Ru and Application for a Linear Magnetic Field Sensor, Journal of Applied Physics, vol. 99, (2006), pp. 08H703-1-08H703-3. cited by applicant .
Wang et al., C-Spin Kickoff Meeting Presentation, Semiconductor Research Corp., (Mar. 26, 2013), Minneapolis, Minnesota, (available at https://www.src.org/library/publication/p066203/), 195 pages. cited by applicant .
Wilson et al., New Materials for Micro-Scale Sensors and Actuators: An Engineering Review, Materials Science and Engineering R, vol. 56, (2007), pp. 1-129. cited by applicant .
Worledge et al., Magnetoresistance Measurement of Unpatterned Magnetic Tunnel Junction Wafers by Current-in-Plane Tunneling, Applied Physics Letters, vol. 83, No. 1, (Jul. 7, 2013), pp. 84-86. cited by applicant .
Worledge et al., Spin Torque Switching of Perpendicular Ta|CoFeB|MgO-Based Magnetic Tunnel Junctions, Applied Physics Letters, vol. 98, (2011), pp. 022501-1-022501-3. cited by applicant .
Wu et al., Tuning Magnetic Anisotropies of Fe Films on Si(111) Substrate Via Direction Variation of Heating Current, Scientific Reports, vol. 3, (Mar. 26, 2013), pp. 1-5. cited by applicant .
You et al., Spin Transfer Torque and Tunneling Magnetoresistance Dependences on Finite Bias Voltages and Insulator Barrier Energy, Thin Solid Films, vol. 519, (2011), pp. 8247-8251. cited by applicant .
Yu et al., 1/f Noise in MgO Double-Barrier Magnetic Tunnel Junctions, Applied Physics Letters, vol. 98, (2011), pp. 112504-1-112504-3. cited by applicant .
Zhang, Anisotropic Magnetomechanical Effect in Tb0.3Dy0.7Fe2 Alloy, Journal of Magnetism and Magnetic Materials, vol. 324, (2012), pp. 190-195. cited by applicant .
Zhu et al., Magnetic Tunnel Junctions, MaterialsToday, vol. 9, No. 11, (Nov. 2006), pp. 36-45. cited by applicant .
Extended European Search Report for European Patent Application No. 14779178.4, (date of completion of search Oct. 17, 2016), 7 pages. cited by applicant.
This application is a divisional of U.S. patent application Ser. No. 13/797,185, filed Mar. 12, 2013, now U.S. Pat. No. 9,379,315, issued Jun. 28, 2016, the disclosure of which is hereby incorporated in its entirety herein by this reference.
1. A method of forming a memory cell, the method comprising: forming a magnetic material over a substrate; forming an oxide material over the magnetic material; forming another magnetic material over the oxide material; forming another oxide material over the another magnetic material; forming, by magnetron sputtering, an iron-based material, to a thickness of less than about ten angstroms, between the another magnetic material and one of the oxide material and the another oxide material; and patterning the magnetic material, the oxide material, the another magnetic material, the another oxide material, and the iron-based material to form a magnetic cell core comprising a free region formed from one of the magnetic material and the another magnetic material, a fixed region formed from another of the magnetic material and the another magnetic material, an electrically insulating region disposed between the free region and the fixed region and formed from the oxide material, a magnetic interface region formed from the iron-based material, and an oxide capping region disposed above the free region and the fixed region and formed from the another oxide material, the magnetic material and the another magnetic material exhibiting a vertical magnetic orientation.
2. The method of claim 1, further comprising annealing the oxide material, the magnetic material, the another oxide material, and the iron-based material.
3. The method of claim 1, wherein forming an iron-based material comprises forming the iron-based material to contact the oxide material and to exhibit a same crystal orientation as exhibited by the oxide material.
4. The method of claim 1, wherein forming an iron-based material comprises forming a material consisting of iron.
5. The method of claim 1, wherein forming an iron-based material, to a thickness of less than about ten angstroms, comprises forming a monolayer of the iron-based material.
6. The method of claim 1, wherein forming an iron-based material between the another magnetic material and one of the oxide material and the another oxide material comprises forming the iron-based material directly between the another magnetic material and the oxide material.
7. The method of claim 1, wherein forming an iron-based material between the another magnetic material and one of the oxide material and the another oxide material comprises forming the iron-based material directly between the another magnetic material and the another oxide material.
8. The method of claim 1, further comprising forming another iron-based material spaced from the iron-based material by at least a portion of one of the magnetic material and the another magnetic material.
9. A method of forming an array of magnetic memory cells, the method comprising: forming a material structure, comprising: forming a magnetic material over a substrate, the magnetic material exhibiting a switchable magnetic orientation; forming another magnetic material over the substrate, the another magnetic material exhibiting a fixed magnetic orientation; forming a nonmagnetic material vertically between the magnetic material and the another magnetic material; forming an oxide-based nonmagnetic material separated from the nonmagnetic material by the magnetic material; and forming a monolayer of an iron-based material in contact with one of the magnetic material and the another magnetic material; patterning the material structure to form at least one cell core of a magnetic memory cell of the array.
10. The method of claim 9, wherein forming a magnetic material, forming another magnetic material, and forming a nonmagnetic material comprise: forming the another magnetic material before forming the magnetic material and before forming the nonmagnetic material; forming the nonmagnetic material above the another magnetic material; and forming the magnetic material above the nonmagnetic material.
11. The method of claim 9, wherein forming the material structure further comprises forming another monolayer of an iron-based material in contact with the one of the magnetic material and the another magnetic material, the monolayer of the iron-based material spaced from the another monolayer of the iron-based material.
12. The method of claim 9, wherein forming the material structure further comprises forming another monolayer of an iron-based material in contact with another of the magnetic material and the another magnetic material.
13. The method of claim 9, wherein forming a monolayer of an iron-based material comprises forming the monolayer of the iron-based material internal to the one of the magnetic material and the another magnetic material.
14. The method of claim 9, wherein forming a monolayer of an iron-based material comprises forming a monolayer of cobalt-iron (CoFe).
15. A method of forming a semiconductor device comprising at least one STT-MRAM cell, the method comprising: forming a material structure, comprising: forming a magnetic material over a nonmagnetic oxide material, the magnetic material exhibiting a switchable magnetic orientation; forming another nonmagnetic oxide material over the magnetic material; forming another magnetic material spaced from the magnetic material by one of the nonmagnetic oxide material and the another nonmagnetic oxide material, the another magnetic material exhibiting a fixed magnetic orientation; and forming, by magnetron sputtering, an iron-based material between the nonmagnetic oxide material and the another nonmagnetic oxide material, the iron-based material defining a thickness of less than about ten angstroms; and patterning the material structure to form at least one cell core of the at least one STT-MRAM cell.
16. The method of claim 15, wherein forming the material structure further comprises forming another iron-based material defining a thickness of less than about ten angstroms, the iron-based material spaced from the another iron-based material.
17. The method of claim 16, wherein: forming an iron-based material comprises forming the iron-based material directly adjacent a surface of the one of the nonmagnetic oxide material and the another nonmagnetic oxide material; and forming another iron-based material comprises forming the another iron-based material directly adjacent another surface of the one of the nonmagnetic oxide material and the another nonmagnetic oxide material.
18. The method of claim 15, wherein forming an iron-based material between the nonmagnetic oxide material and the another nonmagnetic oxide material comprises forming the iron-based material between sub-regions of the magnetic material.
19. The method of claim 18, wherein forming the iron-based material between sub-regions of the magnetic material comprises forming the iron-based material directly adjacent a spacer material between the sub-regions of the magnetic material.
20. The method of claim 15: wherein forming another magnetic material precedes forming the magnetic material and forming the another nonmagnetic oxide material; and further comprising, before forming the magnetic material, forming the nonmagnetic oxide material over the another magnetic material.
Magnetic Random Access Memory (MRAM) is a non-volatile computer memory technology based on magnetoresistance. One type of MRAM cell is a spin torque transfer MRAM (STT-MRAM) cell, which includes a magnetic cell core supported by a substrate. The magnetic cell core includes at least two magnetic regions, for example, a "fixed region" and a "free region," with a non-magnetic region in-between. The fixed region includes a magnetic material that has a fixed (e.g., a non-switchable) magnetic orientation, while the free region includes a magnetic material that has a magnetic orientation that may be switched, during operation of the cell, between a "parallel" configuration, in which the magnetic orientation of the fixed region and the magnetic orientation of the free region are directed in the same direction (e.g., north and north, east and east, south and south, or west and west, respectively), and an "anti-parallel" configuration, in which the magnetic orientation of the fixed region and the magnetic orientation of the free region are directed in opposite directions (e.g., north and south, east and west, south and north, or west and east, respectively).
In the parallel configuration the STT-MRAM cell exhibits a lower electrical resistance across the magnetoresistive elements, i.e., the fixed region and free region. This state of relatively low electrical resistance may be defined as a "0" state of the MRAM cell. In the anti-parallel configuration, the STT-MRAM cell exhibits a higher electrical resistance across the magnetoresistive elements, i.e., the regions of magnetic material, e.g., the fixed region and free region. This state of relatively high electrical resistance may be defined as a "1" state of the MRAM cell. Switching of the magnetic orientation of the free region and the resulting high or low resistance states across the magnetoresistive elements enables the write and read operations of the conventional MRAM cell. Ideally, the amount of programming current required to switch the free region from the parallel configuration to the anti-parallel configuration is essentially the same amount of programming current required to switch from the anti-parallel configuration to the parallel configuration. Such equal programming current for switching is referred to herein as "symmetric switching."
The free regions and fixed regions of STT-MRAM cells may exhibit magnetic orientations that are either horizontally oriented ("in-plane") or perpendicularly oriented ("out-of-plane") with the width of the regions. In STT-MRAM cells that have perpendicularly-oriented magnetic regions, the magnetic materials exhibiting the vertical magnetic orientation may be characterized by a strength of the magnetic materials' perpendicular magnetic anisotropy ("PMA"). The strength (also referred to herein as the "magnetic strength" or the "PMA strength") is an indication of the magnetic materials' resistance to alteration of the magnetic orientation. A magnetic material exhibiting a vertical magnetic orientation with a high PMA strength may be less prone to alteration of its magnetic orientation out of the vertical orientation than a magnetic material exhibiting a vertical magnetic orientation with a lower magnetic strength. However, achieving a high PMA strength may not be sufficient, in and of itself, for successful STT-MRAM cell operation. For example, a low resistance-area (RA), a low switching current, a low switching voltage, and symmetric switching may also contribute to successful operation of an STT-MRAM cell. However, finding materials and designs in which a high PMA strength is exhibited without adversely affecting the other characteristics of the STT-MRAM cell's operation, particularly the RA of the cell, may present a challenge.
FIG. 4 is a cross-sectional, elevational, schematic illustration of a magnetic cell core of an STT-MRAM cell including a magnetic interface region disposed within a free region.
FIG. 7 is a cross-sectional, elevational, schematic illustration of a magnetic cell core of an STT-MRAM cell including one magnetic interface region within a free region and another magnetic interface region on top of a fixed region.
FIG. 11 is a graph displaying measurements of PMA strength for a magnetic cell core incorporating a magnetic interface region in comparison with a magnetic cell core lacking the magnetic interface region.
Memory cells, semiconductor device structures including such memory cells, memory systems, and methods of forming such memory cells are disclosed. The memory cells include a magnetic region, such as a free region or a fixed region, exhibiting a vertical magnetic orientation. The memory cells also include at least one oxide region, such one or more of an oxide-based magnetic tunnel junction ("MTJ") region and an oxide capping region. Disposed, directly or indirectly, between the magnetic region and the oxide region is a magnetic interface region that is configured to increase the PMA strength of the memory cell, compared to memory cells lacking the magnetic interface region, but without significantly adversely affecting other characteristics of the memory cell, such as the resistance-area of the memory cell. For example, a low RA (e.g., less than about 20 .OMEGA..mu.m.sup.2 (Ohms.times.microns squared)) may be maintained even with enhanced PMA strength (e.g., a uniaxial anisotropy field (H.sub.k) exceeding about 4,000 Oe (Oersted)). Accordingly, the magnetic interface region may enhance operational performance of the magnetic region (e.g., the free region or the fixed region) within a magnetic memory cell structure that accommodates high data retention time and low power operation.
As used herein, the term "substrate" means and includes a base material or other construction upon which components, such as those within memory cells, are formed. The substrate may be a semiconductor substrate, a base semiconductor material on a supporting structure, a metal electrode, or a semiconductor substrate having one or more materials, structures, or regions formed thereon. The substrate may be a conventional silicon substrate or other bulk substrate including a semiconductive material. As used herein, the term "bulk substrate" means and includes not only silicon wafers, but also silicon-on-insulator ("SOT") substrates, such as silicon-on-sapphire ("SOS") substrates or silicon-on-glass ("SOG") substrates, epitaxial layers of silicon on a base semiconductor foundation, or other semiconductor or optoelectronic materials, such as silicon-germanium (Si.sub.1-xGe.sub.x, where x is, for example, a mole fraction between 0.2 and 0.8), germanium (Ge), gallium arsenide (GaAs), gallium nitride (GaN), or indium phosphide (InP), among others. Furthermore, when reference is made to a "substrate" in the following description, previous process stages may have been utilized to form materials, regions, or junctions in the base semiconductor structure or foundation.
As used herein, the term "horizontal" means and includes a direction that is parallel to at least one of the width and length of the respective region. "Horizontal" may also mean and include a direction that is parallel to a primary surface of the substrate on which the STT-MRAM cell is located.
As used herein, the term "magnetic material" means and includes ferromagnetic materials, ferrimagnetic materials, and antiferromagnetic materials.
As used herein, the term "iron-based material" means and includes a material that includes iron. For example, and without limitation, iron-based materials include pure iron, an iron alloy, and materials including cobalt and iron. The composition of the iron-based material may be altered due to annealing of the iron-based material during fabrication of the magnetic memory cell, but such material may, nonetheless, be referred to herein as an "iron-based material."
As used herein, the term "magnetic region" means a region that exhibits magnetism. A magnetic region includes a magnetic material and may also include one or more non-magnetic materials.
As used herein, the term "fixed region" means and includes a magnetic region within the STT-MRAM cell that includes magnetic material and that has a fixed magnetic orientation during use and operation of the STT-MRAM cell in that a current or applied field effecting a change in the magnetization direction of one magnetic region, e.g., the free region, of the cell core may not effect a change in the magnetization direction of the fixed region. The fixed region may include one or more magnetic materials and, optionally, one or more non-magnetic materials. For example, the fixed region may be configured as a synthetic antiferromagnet (SAF) including a sub-region of ruthenium (Ru) adjoined by magnetic sub-regions. Each of the magnetic sub-regions may include one or more materials and one or more regions therein. As another example, the fixed region may be configured as a single, homogenous magnetic material. Accordingly, the fixed region may have uniform magnetization or sub-regions of differing magnetization that, overall, effect the fixed region having a fixed magnetic orientation during use and operation of the STT-MRAM cell.
As used herein, the term "oxide region" means and includes a region within the STT-MRAM cell that includes an oxide material. For example, and without limitation, an oxide region may include an oxide-based MTJ region, an oxide capping region, or both.
As used herein, the term "between" is a spatially relative term used to describe the relative disposition of one material, region, or sub-region relative to at least two other materials, regions, or sub-regions. The term "between" can encompass both a disposition of one material, region, or sub-region directly adjacent to the other materials, regions, or sub-regions and a disposition of one material, region, or sub-region not directly adjacent to the other materials, regions, or sub-regions.
As used herein, reference to an element as being "on" or "over" another element means and includes the element being directly on top of, adjacent to, underneath, or in direct contact with the other element. It also includes the element being indirectly on top of, adjacent to, underneath, or near the other element, with other elements present therebetween. In contrast, when an element is referred to as being "directly on" or "directly adjacent to" another element, there are no intervening elements present.
As used herein, other spatially relative terms, such as "beneath," "below," "lower," "bottom," "above," "upper," "top," "front," "rear," "left," "right," and the like, may be used for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Unless otherwise specified, the spatially relative terms are intended to encompass different orientations of the materials in addition to the orientation as depicted in the figures. For example, if materials in the figures are inverted, elements described as "below" or "beneath" or "under" or "on bottom of" other elements or features would then be oriented "above" or "on top of" the other elements or features. Thus, the term "below" can encompass both an orientation of above and below, depending on the context in which the term is used, which will be evident to one of ordinary skill in the art. The materials may be otherwise oriented (rotated 90 degrees, inverted, etc.) and the spatially relative descriptors used herein interpreted accordingly.
Embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations. Accordingly, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein are not to be construed as limited to the particular shapes or regions as illustrated, but include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as box-shaped may have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the materials, features, and regions illustrated in the figures are schematic in nature, and their shapes are not intended to illustrate the precise shape of a material, feature, or region and do not limit the scope of the present claims.
Unless the context indicates otherwise, the materials described herein may be formed by any suitable technique including, but not limited to, spin coating, blanket coating, chemical vapor deposition ("CVD"), atomic layer deposition ("ALD"), plasma enhanced ALD, or physical vapor deposition ("PVD"). Alternatively, the materials may be grown in situ. Depending on the specific material to be formed, the technique for depositing or growing the material may be selected by a person of ordinary skill in the art.
A memory cell is disclosed. The memory cell includes at least one magnetic region (e.g., a free region or a fixed region) exhibiting a vertical magnetic orientation and an oxide region (e.g., an MTJ region or an oxide capping region) with a magnetic interface region disposed, directly or indirectly, therebetween. The magnetic interface region may enhance the PMA strength of the magnetic memory cell. The magnetic interface region may be disposed adjacent to or within its respective magnetic region. In some embodiments, the memory cell may include only one magnetic interface region; however, in other embodiments, more than one magnetic interface region may be included in the memory cell.
FIG. 1 illustrates a magnetic cell core 100 of an STT-MRAM cell according to an embodiment of the present disclosure. The magnetic cell core 100 is supported by a substrate 102. The magnetic cell core 100 includes at least two magnetic regions, for example, a "fixed region" 110 and a "free region" 120 with a nonmagnetic region 130 in between. One or more lower intermediary regions 140 and one or more upper intermediary regions 150 may, optionally, be disposed under and over, respectively, the magnetic regions (e.g., the fixed region 110 and the free region 120) of the magnetic cell core 100 structure.
The STT-MRAM cell may be configured to exhibit a vertical magnetic orientation in at least one of the magnetic regions (e.g., the fixed region 110 and the free region 120). The vertical magnetic orientation exhibited may be characterized by the perpendicular magnetic anisotropy ("PMA") strength. As illustrated in FIG. 1 by arrows 112 and 122, in some embodiments, each of the fixed region 110 and the free region 120 may exhibit a vertical magnetic orientation. The magnetic orientation of the fixed region 110 may remain directed in essentially the same direction throughout operation of the STT-MRAM cell, for example, in the direction indicated by arrows 112 of FIG. 1. The magnetic orientation of the free region 120, on the other hand, may be switched, during operation of the cell, between a "parallel" configuration and an "anti-parallel" configuration, as indicated by double-pointed arrows 122 of FIG. 1. In the parallel orientation, the magnetic orientation 122 of the free region 120 is directed in essentially the same direction (e.g., north) as the magnetic orientation 112 of the fixed region 110 (e.g., north), producing a lower electrical resistance across the magnetoresistive elements, i.e., the fixed region 110 and the free region 120, in what may be defined as the "0" state of the STT-MRAM cell. In the anti-parallel configuration, the magnetic orientation 122 of the free region 120 is directed essentially in the opposite direction (e.g., south) of the magnetic orientation 112 of the fixed region 110 (e.g. north), producing a higher electrical resistance across the magnetoresistive elements, i.e., the fixed region 110 and the free region 120, in what may be defined as the "1" state of the STT-MRAM cell.
In use and operation, a programming current may be caused to flow through an access transistor (not shown) and the magnetic cell core 100. The fixed region 110 within the magnetic cell core 100 polarizes the electron spin of the programming current. The spin-polarized electron current interacts with the free region 120 by exerting a torque on the free region 120. When the torque of the spin-polarized electron current passing through the free region 120 is greater than a critical switching current density (J.sub.c) of the free region 120, the torque exerted by the spin-polarized electron current is sufficient to switch the direction of the magnetization of the free region 120, e.g., between a north-directed magnetic orientation and a south-directed magnetic orientation. Thus, the programming current can be used to cause the magnetic orientation 122 of the free region 120 to be aligned either parallel to or anti-parallel to the magnetic orientation 112 of the fixed region 110.
The free region 120 and the fixed region 110 may be formed from or comprise ferromagnetic materials, such as Co, Fe, Ni, or their alloys, NiFe, CoFe, CoNiFe, or doped alloys CoX, CoFeX, CoNiFeX (X=B, Cu, Re, Ru, Rh, Hf, Pd, Pt, C), or other half-metallic ferromagnetic materials, such as, for example, NiMnSb and PtMnSb. In some embodiments, for example, the free region 120, the fixed region 110, or both may be formed from Co.sub.xFe.sub.yB.sub.z, wherein x=10 to 80, y=10 to 80, and z=0 to 50. In other embodiments, the free region 120, the fixed region 110, or both may be formed of iron (Fe) and boron (B) and not include cobalt (Co). The compositions and structures (e.g., the thicknesses and other physical dimensions) of the free region 120 and the fixed region 110 may be the same or different.
Alternatively or additionally, in some embodiments, the free region 120, the fixed region 110, or both, may be formed from or comprise a plurality of materials, some of which may be magnetic materials and some of which may be nonmagnetic materials. For example, some such multi-material free regions, fixed regions, or both, may include multiple sub-regions. For example, and without limitation, the free region 120, the fixed region 110, or both, may be formed from or comprise repeating sub-regions of cobalt and platinum, wherein a sub-region of platinum may be disposed between sub-regions of cobalt. As another example, without limitation, the free region 120, the fixed region 110, or both, may comprise repeating sub-regions of cobalt and nickel, wherein a sub-region of nickel may be disposed between sub-regions of cobalt.
The nonmagnetic region 130, disposed between the fixed region 110 and the free region 120, may include nonmagnetic materials (such as a nonmagnetic oxide material, e.g., magnesium oxide (MgO), aluminum oxide (Al.sub.2O.sub.3), titanium oxide (TiO.sub.2), or other oxide materials of conventional MTJ regions). Accordingly, such oxide-including MTJ region may be referred to herein as an "oxide-based MTJ region" or an "oxide-based nonmagnetic region." The nonmagnetic region 130 may include one or more such nonmagnetic materials. Alternatively or additionally, the nonmagnetic region 130 may include sub-regions of one or more nonmagnetic materials.
As illustrated in FIG. 1, the magnetic cell core 100 may, in some embodiments, include an oxide capping region 170, which may include oxides such as MgO, TiO.sub.2, tantalum pentoxide (Ta.sub.2O.sub.5), or combinations thereof. Accordingly, such oxide-including capping region may be referred to herein, also, as an "oxide-based nonmagnetic region." In some embodiments, the oxide capping region 170 may include the same materials, structure, or both of the nonmagnetic region 130. For example, the oxide capping region 170 and the nonmagnetic region 130 may both include a magnesium oxide (e.g., MgO), an aluminum oxide, a titanium oxide, a zinc oxide, hafnium oxide, a ruthenium oxide, or a tantalum oxide.
The optional upper intermediary regions 150, if present, may include materials configured to ensure a desired crystal structure in neighboring materials of the magnetic cell core 100. The upper intermediary regions 150 may alternatively or additionally include metal materials configured to aid in patterning processes during fabrication of the magnetic cell core 100, barrier materials, or other materials of conventional STT-MRAM cell core structures. In some embodiments, such as that illustrated in FIG. 1, the upper intermediary regions 150 may include a conductive capping region, which may include one or more materials such as copper, tantalum, titanium, tungsten, ruthenium, tantalum nitride, or titanium nitride.
The magnetic cell core 100, according to the present disclosure, also includes a magnetic interface region 180 disposed between one of the magnetic regions or magnetic sub-regions (e.g., the fixed region 110, a magnetic sub-region of the fixed region 110, the free region 120, or a magnetic sub-region of the free region 120) and one of the oxide regions (e.g., the nonmagnetic region 130 and the oxide capping region 170). As illustrated in FIG. 1, the magnetic interface region 180 may be disposed directly adjacent to one of the magnetic regions or magnetic sub-regions and one of the oxide regions. According to the embodiment illustrated in FIG. 1, the magnetic interface region 180 may be disposed directly on top of the nonmagnetic region 130 and directly beneath the free region 120. As situated, the magnetic interface region 180 may be disposed between two oxide regions, i.e., between an oxide-based MTJ (e.g., the nonmagnetic region 130) and the oxide capping region 170.
The magnetic interface region 180 may be configured to enhance the PMA strength of the magnetic cell core 100, or, more particularly, of its neighboring magnetic region, e.g., the free region 120 according to the embodiment illustrated in FIG. 1. The increased PMA may be achieved while maintaining a low resistance-area (e.g., less than about 20 .OMEGA..mu.m.sup.2 (Ohms.times.microns squared)) of the magnetic cell core 100. The magnetic interface region 180 may be formed of a magnetic material, such as an iron-based material, e.g., iron (Fe) alone, an iron alloy, or, in some embodiments, a cobalt-iron (CoFe) based material.
The material of the magnetic interface region 180 may be in the form of a monolayer of iron or other iron-including compound disposed between the nonmagnetic region 130 and the oxide capping region 170. Alternatively or additionally, the magnetic interface region 180 may have a thickness (i.e., a height along an axis perpendicular to an upper surface of the substrate 102) that is less than about 10 .ANG. (e.g., less than about 5 .ANG., e.g., about 3 .ANG.). As such, the magnetic interface region 180 may be thinner than its neighboring regions. For example, the overlying free region 120 of FIG. 1 may be formed to have a thickness of about 15 .ANG. to about 30 .ANG., and the underlying nonmagnetic region 130 of FIG. 1 may be formed to have a thickness of about 7 .ANG. to about 10 .ANG..
The magnetic interface region 180 may be formed from a material formulated or otherwise configured to have the same crystal orientation as that of the material upon which it is formed. For example, according to the embodiment illustrated in FIG. 1, the magnetic interface region 180 may be formed from iron (Fe) in such a manner (e.g., by magnetron sputtering) as to have the same crystal orientation as MgO within the nonmagnetic region 130.
Following formation of the materials of the magnetic cell core 100, the materials may be patterned to form the magnetic cell core 100 comprising the various regions thereof. Techniques for forming and patterning the materials of the lower and upper regions of the magnetic cell core 100 are known in the art and, therefore, are not described in detail herein. For example, the magnetic cell core 100 may be formed by forming each of the materials of the regions thereof in sequential order, from base to top, and then patterning the materials to define the magnetic cell core 100. The magnetic cell core 100 structure may be annealed at a temperature of at least 150.degree. C. (e.g., between about 150.degree. C. and about 400.degree. C.) before or after patterning. Alternatively or additionally, materials of the magnetic cell core 100 structure may be annealed during fabrication of the magnetic cell core 100 structure, e.g., after formation of one or more materials of the magnetic cell core 100 structure and before other materials thereof are formed.
In embodiments such as that illustrated in FIG. 1, in which the magnetic interface region 180 is disposed directly between the nonmagnetic region 130 and the free region 120, and in which the magnetic interface region 180 is disposed between the nonmagnetic region 130 and the oxide capping region 170, it is contemplated that, without being bound to any one particular theory, the magnetic interface region 180 enables iron-oxygen bonding between iron in the magnetic interface region 180 and oxygen in the oxide material of the neighboring oxide-based region, e.g., the nonmagnetic region 130. Iron-oxygen bonding may contribute to interfacial PMA strength. It is contemplated that the contribution to interfacial PMA strength by iron-oxygen bonding may be greater than a contribution from other oxygen bonding, such as cobalt-oxygen bonding. Accordingly, the inclusion of the magnetic interface region 180 in the magnetic cell core 100 may enable a stronger PMA than that achieved by a magnetic cell core structure lacking a magnetic interface region 180 between a magnetic region such as the free region 120 and an oxide region such as the nonmagnetic region 130.
With reference to FIG. 2, illustrated is a magnetic cell core 200 in which the magnetic interface region 180 is disposed between the nonmagnetic region 130 and the oxide capping region 170, but above the free region 120. Thus, the nonmagnetic region 130 is disposed to one side of, e.g., underneath, the free region 120 while the magnetic interface region 180 is disposed to another side of, e.g., above, the free region 120. The materials of the magnetic cell core 200 may be the same as those of the magnetic cell core 100 (FIG. 1) described above. The magnetic cell core 200 may be formed by forming each of the materials of the regions thereof in sequential order, from base to top, and then patterning the materials to define the magnetic cell core 200 structure. Thus, the magnetic interface region 180 may be formed directly on the free region 120, and the oxide capping region 170 may be formed directly on the magnetic interface region 180. In other embodiments (not shown in FIG. 2), the positions of the free region 120 and the fixed region 110 may be interchanged such that the magnetic interface region 180 would be disposed between the oxide capping region 170 and the fixed region 110, which would be positioned above the nonmagnetic region 130.
With reference to FIG. 3, in some embodiments, a magnetic cell core 300 according to the present disclosure may include magnetic regions, such as the free region, the fixed region, or both, having a multi-material structure. For example, the fixed region 110 of the embodiment of FIG. 3, or any of the preceding or following described embodiments, may be configured as an SAF with a Ru sub-region neighbored on top and bottom by a magnetic sub-region. As another example, as illustrated, the magnetic cell core 300 may include a multi-material free region 320. The multi-material free region 320 may include an upper magnetic sub-region 324 spaced from (i.e., not directly in physical contact with) a lower magnetic sub-region 326 by a spacer 328. In other embodiments, the multi-material free region 320 may lack the spacer 328. In still other embodiments, the multi-material free region 320 may have more than two magnetic sub-regions, more than one spacer 328, or both.
The material or materials from which the upper magnetic sub-region 324 and the lower magnetic sub-region 326 are formed may be the same material or materials, respectively, from which the free region 120 may be formed, as described above. For example, and without limitation, each of the upper magnetic sub-region 324 and the lower magnetic sub-region 326 may be formed from Co.sub.xFe.sub.yB.sub.z, wherein x=1, y=50 to 60, and z=1 to 30, e.g., CoFe.sub.50B.sub.30. As another example, the upper magnetic sub-region 324 may be formed of CoFeB.sub.60 while the lower magnetic sub-region 326 may be formed of CoFe.sub.50B.sub.30.
Each of the upper magnetic sub-region 324 and the lower magnetic sub-region 326 may be formed to each be thicker than the spacer 328. In some embodiments, the lower magnetic sub-region 326 may have a thickness of about 10 .ANG., and the upper magnetic sub-region 324 may have a thickness of about 6 .ANG.. In other embodiments, the upper magnetic sub-region 324 and the lower magnetic sub-region 326 may be formed to have approximately equal thicknesses, e.g., from about 6 .ANG. to about 10 .ANG..
The spacer 328 may be formed from a conductive material such as, for example and without limitation, tantalum (Ta). The spacer 328 may be relatively thin compared to the overlying and underlying sub-regions. For example, the spacer 328 may have a thickness of less than about 3 .ANG., e.g., about 1.5 .ANG..
According to the embodiment of FIG. 3, the magnetic interface region 180 may be formed over the multi-material free region 320, so as to be disposed between the nonmagnetic region 130 and the oxide capping region 170. Thus, the magnetic interface region 180 may be directly between the upper magnetic sub-region 324 and the oxide capping region 170.
With reference to FIG. 4, a magnetic cell core 400, according to the present disclosure, having a multi-material free region 420 comprising the upper magnetic sub-region 324, the lower magnetic sub-region 326, and the spacer 328, may be structured to also comprise the magnetic interface region 180. That is, the magnetic interface region 180 may be disposed directly adjacent to, either above or below, the spacer 328 and one of the upper magnetic sub-region 324 and the lower magnetic sub-region 326. In this structure, the magnetic interface region 180 is spaced from both of the oxide-based regions, i.e., the nonmagnetic region 130 and the oxide capping region 170. Nonetheless, the presence of the magnetic interface region 180 may enhance the PMA strength of at least the magnetic region incorporating the magnetic interface region 180, which, as illustrated in FIG. 4, may be the free region (e.g., the multi-material free region 420). For example, the PMA strength of the magnetic region (e.g., the multi-material free region 420) may be greater than about 4,000 Oersted (e.g., greater than about 5,000 Oersted).
In a structure such as that of the magnetic cell core 400 of FIG. 4, the upper magnetic sub-region 324 and the lower magnetic sub-region 326 may be of the same thicknesses. Alternatively, the total thickness of the magnetic interface region 180 and the one of the upper magnetic sub-region 324 and the lower magnetic sub-region 326 to which the magnetic interface region 180 is adjacent may be about equal to the thickness of the other of the upper magnetic sub-region 324 and the lower magnetic sub-region 326. For example, the lower magnetic sub-region 326 may have a thickness of about 10 .ANG., while the upper magnetic sub-region 324 may have a thickness of about 6 .ANG. and the magnetic interface region 180 may have a thickness of about 4 .ANG..
With reference to FIG. 6, in some embodiments a magnetic cell core 600 may include more than two magnetic interface regions 180, such as one magnetic interface region 180 directly on each of the top and bottom of each of the magnetic regions (e.g., the free region 120 and the fixed region 110) of the magnetic cell core 600. Again, the materials of the magnetic cell core 600 may be formed sequentially, from base to top, and may be thereafter patterned to form the magnetic cell core 600.
With reference to FIG. 7, it is contemplated that one of the magnetic regions of a magnetic cell core 700, such as the free region or, for example, a multi-material free region 720 may incorporate the magnetic interface region 180 while another magnetic region of the magnetic cell core 700, such as the fixed region 110 may be adjacent to another magnetic interface region 180. Again, the materials of such magnetic cell core 700 may be formed sequentially, from base to top.
Accordingly, the number of magnetic interface regions 180 and the disposition of such magnetic interface regions 180 may be tailored according to the desired STT-MRAM structure and operability. Likewise, the exact composition and thickness of the magnetic interface region 180 may be tailored to achieve a desired PMA strength, which may be the highest PMA strength (e.g., H.sub.k (Oe)) achievable without adversely impacting the operation of the STT-MRAM cell. It is contemplated that the thickness of the magnetic interface region 180 may be optimized, through testing, to be of a thickness great enough to enhance the PMA strength while less than the thickness that would negatively impact the operation characteristics of the STT-MRAM cell.
Following formation of the magnetic cell core (e.g., one of magnetic cell cores 100-700), the semiconductor device structure may be subjected to additional fabrication steps, as known in the art, to form an operational semiconductor device, such as an STT-MRAM cell, an array of STT-MRAM cells, an STT-MRAM system, a processor-based system, or any combination thereof.
With reference to FIG. 8, illustrated is an STT-MRAM system 800 that includes peripheral devices 812 in operable communication with an STT-MRAM cell 814, a plurality of which may be fabricated to form an array of memory cells in a grid pattern including a number of rows and columns, or in various other arrangements, depending on the system requirements and fabrication technology. The STT-MRAM cell 814 includes a cell core 802, an access transistor 803, a conductive material that may function as a data/sense line 804 (e.g., a bit line), a conductive material that may function as an access line 805 (e.g., a word line), and a conductive material that may function as a source line 806. The peripheral devices 812 of the STT-MRAM system 800 may include read/write circuitry 807, a bit line reference 808, and a sense amplifier 809. The cell core 802 may be any one of the magnetic cell cores 100-700 described above. Due to the structure of the cell core 802, i.e., the inclusion of the magnetic interface region 180 (FIGS. 1-7) that is spaced from the nonmagnetic region 130, e.g., the tunnel region or MTJ, or from the oxide capping region 170 and the resultant enhancement of the PMA strength of the STT-MRAM cell 814, the STT-MRAM cell 814 may exhibit a higher data retention time and operate effectively at lower power than a conventional STT-MRAM cell.
To initiate programming of the STT-MRAM cell 814, the read/write circuitry 807 may generate a write current to the data/sense line 804 and the source line 806. The polarity of the voltage between the data/sense line 804 and the source line 806 determines the switch in magnetic orientation of the free region in the cell core 802. By changing the magnetic orientation of the free region with the spin polarity, the free region is magnetized according to the spin polarity of the programming current, the programmed state is written to the STT-MRAM cell 814.
To read the STT-MRAM cell 814, the read/write circuitry 807 generates a read voltage to the data/sense line 804 and the source line 806 through the cell core 802 and the access transistor 803. The programmed state of the STT-MRAM cell 814 relates to the resistance across the cell core 802, which may be determined by the voltage difference between the data/sense line 804 and the source line 806. In some embodiments, the voltage difference may be compared to the bit line reference 808 and amplified by the sense amplifier 809.
FIG. 8 illustrates one example of an operable STT-MRAM system 800. It is contemplated, however, that the magnetic cell cores 100-700 (FIGS. 1-7) may be incorporated and utilized within any STT-MRAM system configured to incorporate a magnetic cell core having magnetic regions exhibiting vertical magnetic orientations. Notably, because the thickness of the magnetic interface region 180 (FIGS. 1-7) may be relatively thin, relative to other regions of the magnetic cell cores 100-700, the total height of the magnetic cell cores 100-700 may be the same or not much greater than the height of a conventional magnetic cell core of an STT-MRAM cell. Further, because the magnetic interface region 180 may be formed using techniques the same as or similar to techniques used to form other regions of the magnetic cell cores 100-700, the overall fabrication process may not be significantly altered to accomplish formation of the magnetic cell cores 100-700 in accordance with embodiments of the present disclosure.
With reference to FIG. 9, illustrated is a simplified block diagram of a semiconductor device structure 900 implemented according to one or more embodiments described herein. The semiconductor device structure 900 includes a memory array 902 and a control logic component 904. The memory array 902 may include a plurality of the STT-MRAM cells 814 (FIG. 8) including any of the magnetic cell cores 100-700 (FIGS. 1-7) discussed above, which magnetic cell cores 100-700 (FIGS. 1-7) may have been formed according to a method described above. The control logic component 904 may be configured to operatively interact with the memory array 902 so as to read from or write to any or all memory cells (e.g., STT-MRAM cell 814) within the memory array 902.
Accordingly, disclosed is a semiconductor device structure comprising a spin torque transfer magnetic random access memory (STT-MRAM) array comprising a plurality of STT-MRAM cells. Each STT-MRAM cell of the plurality comprises a cell core comprising a nonmagnetic region between a magnetic region and another magnetic region. Each of the magnetic region and the another magnetic region are configured to exhibit a vertical magnetic orientation. An oxide region is spaced from the nonmagnetic region by one of the magnetic region and the another magnetic region. A magnetic interface region is disposed between the oxide region and the nonmagnetic region.
With reference to FIG. 10, depicted is a processor-based system 1000. The processor-based system 1000 may include various electronic devices manufactured in accordance with embodiments of the present disclosure. The processor-based system 1000 may be any of a variety of types such as a computer, pager, cellular phone, personal organizer, control circuit, or other electronic device. The processor-based system 1000 may include one or more processors 1002, such as a microprocessor, to control the processing of system functions and requests in the processor-based system 1000. The processor 1002 and other subcomponents of the processor-based system 1000 may include magnetic memory devices manufactured in accordance with embodiments of the present disclosure.
The processor-based system 1000 may include a power supply 1004. For example, if the processor-based system 1000 is a portable system, the power supply 1004 may include one or more of a fuel cell, a power scavenging device, permanent batteries, replaceable batteries, and rechargeable batteries. The power supply 1004 may also include an AC adapter; therefore, the processor-based system 1000 may be plugged into a wall outlet, for example. The power supply 1004 may also include a DC adapter such that the processor-based system 1000 may be plugged into a vehicle cigarette lighter or a vehicle power port, for example.
Various other devices may be coupled to the processor 1002 depending on the functions that the processor-based system 1000 performs. For example, a user interface 1006 may be coupled to the processor 1002. The user interface 1006 may include input devices such as buttons, switches, a keyboard, a light pen, a mouse, a digitizer and stylus, a touch screen, a voice recognition system, a microphone, or a combination thereof. A display 1008 may also be coupled to the processor 1002. The display 1008 may include an LCD display, an SED display, a CRT display, a DLP display, a plasma display, an OLED display, an LED display, a three-dimensional projection, an audio display, or a combination thereof. Furthermore, an RF sub-system/baseband processor 1010 may also be coupled to the processor 1002. The RF sub-system/baseband processor 1010 may include an antenna that is coupled to an RF receiver and to an RF transmitter (not shown). A communication port 1012, or more than one communication port 1012, may also be coupled to the processor 1002. The communication port 1012 may be adapted to be coupled to one or more peripheral devices 1014, such as a modem, a printer, a computer, a scanner, or a camera, or to a network, such as a local area network, remote area network, intranet, or the Internet, for example.
The processor 1002 may control the processor-based system 1000 by implementing software programs stored in the memory. The software programs may include an operating system, database software, drafting software, word processing software, media editing software, or media playing software, for example. The memory is operably coupled to the processor 1002 to store and facilitate execution of various programs. For example, the processor 1002 may be coupled to system memory 1016, which may include one or more of spin torque transfer magnetic random access memory (STT-MRAM), magnetic random access memory (MRAM), dynamic random access memory (DRAM), static random access memory (SRAM), racetrack memory, and other known memory types. The system memory 1016 may include volatile memory, non-volatile memory, or a combination thereof. The system memory 1016 is typically large so that it can store dynamically loaded applications and data. In some embodiments, the system memory 1016 may include semiconductor device structures, such as the semiconductor device structure 900 of FIG. 9, memory cells including any of magnetic cell cores 100-700 (FIGS. 1-7), or a combination thereof.
The processor 1002 may also be coupled to non-volatile memory 1018, which is not to suggest that system memory 1016 is necessarily volatile. The non-volatile memory 1018 may include one or more of STT-MRAM, MRAM, read-only memory (ROM) such as an EPROM, resistive read-only memory (RROM), and Flash memory to be used in conjunction with the system memory 1016. The size of the non-volatile memory 1018 is typically selected to be just large enough to store any necessary operating system, application programs, and fixed data. Additionally, the non-volatile memory 1018 may include a high capacity memory such as disk drive memory, such as a hybrid-drive including resistive memory or other types of non-volatile solid-state memory, for example. The non-volatile memory 1018 may include semiconductor device structures, such as the semiconductor device structure 900 of FIG. 9, memory cells including any of magnetic cell cores 100-700 (FIGS. 1-7), or a combination thereof.
The following example is presented to illustrate an embodiment of the present disclosure in more detail. This example is not to be construed as being exhaustive or exclusive as to the scope of this disclosure.
A partial magnetic cell core structure, without a magnetic contribution from a fixed region, was fabricated to evaluate the PMA strength of a free region fabricated according to an embodiment of the present disclosure. The partial magnetic cell core structure included a conductive seed region having a thickness of about 50 .ANG.; an overlying dummy fixed region of CoFeB having a thickness of about 5 .ANG.; an overlying nonmagnetic region of MgO having a thickness of about 12 .ANG.; an overlying multi-material free region comprising a lower magnetic sub-region of CoFeB having a thickness of about 10 .ANG., an overlying spacer of Ta having a thickness of about 1.5 .ANG., and an overlying upper magnetic sub-region of CoFeB, with slightly different B concentration than the lower magnetic sub-region, having a thickness of about 6 .ANG.; an overlying magnetic interface region of Fe having a thickness of about 4 .ANG.; an overlying oxide capping region of MgO having a thickness of about 7 .ANG.; and an overlying upper conductive capping region having a thickness of about 500 .ANG.. This partial magnetic cell core structure exhibited a PMA strength (measured by H.sub.k (Oe)) of 5,007 Oe, as indicated by data line 1200 of FIG. 11. This compares to a PMA strength of 2,992 Oe, as indicated by data line 1100 of FIG. 11, exhibited by the same structure lacking the magnetic interface region of Fe. Accordingly, the magnetic cell core structure with the magnetic interface region disposed over the free region, adjacent to the oxide capping region, exhibited a more than 50% increase in PMA strength compared to the same structure without the magnetic interface region.
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