マグネティック・ナノイメージングと次世代磁気応用に関する研究会 2003.2.2７ ＥＢ描画ダマシン法によるＳｉ埋め込み 磁性体サブミクロン構造の作製と ＭＦＭ観察と非線形磁気光学効果 ２１世紀ＣＯＥ「ナノ未来材料」推進研究室 東京農工大学 佐藤勝昭 協力者：石橋隆幸・森下義隆・纐纈明伯・松本剛・手塚智之・鶴我真紀子 Fabrication of permalloy nanostructure by Damascene technique ①Preparation of substrate: Spin-coating of ZEP resist with high etching resistance ②EB-exposition: Write patterns by EB ③Development: Formation of mask-pattern by development ④Etching ： By dry-etching process mask-pattern is transferred to the substrate ⑤Deposition of magnetic film: Deposition of magnetic films by sputter or evaporation ⑥Polishing: Obtain flat buried structure using chemicalmechanical polishing Process is simplified by abbreviation of lift-off and repeated spin-coating EB-patterning process Spin coating of resist EB exposure Development Si substrate 〔１〕Dot size 100nm×300nm rectangular dot with 300nmspacing 100nm square dot with 300nm-spacing 〔２〕Patterned area: 3mm×3mm 〔３〕EB-resist thickness: 300 nm ・・・by spin-coating with 5000 rpm rotation 〔４〕Baking 160℃ 20min Clean Room Laboratory • Electron beam lithography Dry etching process Etching 〔１〕Etching gas: Resist removal CF4 〔２〕Vacuum 3.0×10-3Pa 〔３〕Gas pressure 9.2Pa 〔４〕RF power: 400W 〔５〕Etching rate: 0.1μm/min 300nm 100nm Silicon surface after etching Dry-etching Embedding of permalloy 〔１〕material: permalloy（Ni80Fe20） 〔２〕Vacuum 3.0×10-6Torr 〔３〕Accelerating voltage 4kV Embedding of permalloy 〔４〕Deposition rate 1.0Å/sec film by electron beam deposition Chemical mechanical polishing 〔１〕Polishing chemicals: Si wafer flatting grain-size～20nm 〔２〕pH 11 〔３〕polishing rate: 60nm/min Laboratory EB deposition RF magnetron sputtering Buried permalloy dot array Ni80Fe20 約150nm Si 1μm Square dots 100nm 300nm 100nm 300nm 300nm 300nm 100nm 1μm Rectangular dots Circular dots Observation • ＡＦＭ/MFM FE-SEM 1m square dot array MFM AFM Square dots SEM observation 300nm×100nmsquare dot, 300 nm space Rectangular dots 3μm 0.6μm Cross sectional SEM observation 0.6μm 100nm Dot depth? Cross section SEM image of Line and space pattern (width =100nm) ０．３μm MFM observation of unpatterned permalloy film AFM and MFM observation of 300 nm x 100 nm dot array 1μm AFM Line scan ・・・Surface roughness~10nm MFM image ・・・magnetization axis along the longer side direction Comparison between two scans after magnetization in opposite direction 5kOe 5kOe MFM-image for different scanning direction Scan-direction dependence Pattern variation with scan direction 0° 15° 30° 45° 60° 75° 90° VSM measurement 0.0002 0.0004 0.0001 M(emu) M(emu) 0.0002 0 -0.0002 -0.0004 -2 Longer axis Shorter axis -1 0 H(kOe) In-plane 1 2 0 -0.0001 -4 -2 0 H(kOe) 2 Perpendicular 4 100nm circular dots with 300 nm spacing 0.5μm SEM AFM Surface roughness ~10nm VSM measurement of circular dot array 0.0002 M(emu) M(emu) 0.0002 0 0.0001 0 -0.0001 -0.0002 -0.0002 -0.4 -0.2 0 H(kOe) 0.2 Parallel to the plane 0.4 -4 -2 0 H(kOe) Perpendicul ar to the plane 2 4 MFM measurement of circular dots Demagnetized Magnetic field applied Perpendicular to the plane Influence of stray field from the MFM probe tip AFM sensing (23nmlevitation) MFM measurenment 80nm MFM probe A B Magnetization Recording by first scan A B Magnetization Reading by second scan Models to explain MFM images MFM image A B A C B Magnetization Magnetization MFM image MFM image Magnetization MFM image of 300nm x 100nm dot with a low-moment probe tip AFM MFM 300nm x 100nm dot （wide scan） with a low-moment probe tip AFM MFM Simulation by Nakatani Observation of dot-array structures using magnetically induced second harmonic generation (MSHG) MSHG Measureing System LD pump SHG laser Electromagnet l=532nm Filter Stage controller Ti: sapphire laser l=810nm Pulse=150fs P=600mW rep80MHz Mirror Berek compensator Mirror Sample Analyzer Lens Filter PMT Chopper lens polarizer Photon counting Photon counter Computer Laboratory • Nonlinear MO measurement system Sample 試料回転 w (810nm) Sample stage 45° Rotating analyzer Filter 2w (405nm) P-polarized or S-polarized light w (810nm) Analyzer Longitudinal Kerr configuration Polar Kerr configuration 磁場：面直 Electromagnet Rotating stage P sample B P S S Azimuthal angle dependence of SHG from unpatterned permalloy film 90 50000 PinPout 120 +H -H 60 (counts/10sec) 40000 30000 Longitudinal 30 150 20000 10000 0 180 0 10000 20000 30000 330 210 40000 50000 240 300 270 Unstructured permalloy film: H=±2.5kOe Azimuthal angle dependence of SHG from unpatterned Si wafer (counts/10sec) PinPout 6000 5000 4000 3000 2000 1000 0 1000 2000 3000 4000 5000 6000 90 120 Longitudinal 60 30 150 180 0 330 210 240 300 270 H=±2.5kOe Azimuthal angle dependence of SHG from GaAs wafer 90 10000000 8000000 150 6000000 4000000 2000000 0 180 2000000 4000000 6000000 210 8000000 10000000 120 60 30 0 330 240 270 300 Azimuthal angle dependence of MSHG from the square dot array 120 SHG強度(counts/10sec) +H -H 60 30 150 180 0 330 210 240 300 45000 40000 35000 30000 25000 20000 15000 10000 5000 0 5000 10000 15000 20000 25000 30000 35000 40000 45000 90 120 30 180 0 330 210 240 +H -H 60 30 150 180 0 330 210 240 300 270 300 270 90 120 +H -H 60 150 270 SinPout 180000 160000 140000 120000 100000 80000 60000 40000 20000 0 20000 40000 60000 80000 100000 120000 140000 160000 180000 PinSout 90 SHG強度(counts/10sec) 360000 320000 280000 240000 200000 160000 120000 80000 40000 0 40000 80000 120000 160000 200000 240000 280000 320000 360000 SinSout SHG強度(counts/10sec) SHG強度(counts/10sec) PinPout Londitudinal 80000 70000 60000 50000 40000 30000 20000 10000 0 10000 20000 30000 40000 50000 60000 70000 80000 90 120 +H -H 60 30 150 180 0 330 210 240 300 270 Azimuthal angle dependence of MSHG from 1m square dot array (counts/10sec) PinPout 360000 320000 280000 240000 200000 160000 120000 80000 40000 0 40000 80000 120000 160000 200000 240000 280000 320000 360000 90 120 +H -H 60 30 150 180 0 330 210 240 300 270 H=±4kOe Longitudinal Kerr configuration Nonlinear Kerr rotation In 1m square dots +H -H 6x105 5x105 5 4x10 5 3x10 5 2x10 5 1x10 0 -50 Nonlinear Kerr rotation 6.00 0 50 100 150 200 250 300 350 400 X axis title Analyzer angle(deg) 〈Pin〉 SHGカウント(counts/10sec) Y Axis Title SHGカウント(counts/10sec) Y Axis Title Nonlinear Kerr rotation 2.80 Longitudinal +H -H 3.5x105 5 3.0x10 5 2.5x10 2.0x105 1.5x105 5 1.0x10 4 5.0x10 0.0 -50 0 50 100 150 200 250 300 350 400 X axis title Analyzer angle(deg) 〈Sin〉 Azimuthal angle dependence of rectangular dots 90 120 30 150 180 0 330 210 240 SHG強度(counts/10sec) 300 25000 20000 15000 10000 5000 0 5000 10000 15000 20000 25000 90 +H -H 60 30 150 180 0 330 210 240 300 270 +H -H 60 30 150 180 0 330 210 240 300 270 90 120 longitudinal 120 270 SinPout 500000 400000 300000 200000 100000 0 100000 200000 300000 400000 500000 +H -H 60 SHG強度(counts/10sec) 500000 450000 400000 350000 300000 250000 200000 150000 100000 50000 0 50000 100000 150000 200000 250000 300000 350000 400000 450000 500000 PinSout SinSout 300000 SHG強度(counts/10sec) SHG強度(counts/10sec) PinPout 250000 200000 150000 100000 50000 0 50000 100000 150000 200000 250000 300000 90 120 +H -H 60 30 150 180 0 330 210 240 300 270 Azimuthal angle dependence of MSHG from 300nm x 100nm rectangular dot array (Longitudinal) (counts/10sec) PinPout 500000 450000 400000 350000 300000 250000 200000 150000 100000 50000 0 50000 100000 150000 200000 250000 300000 350000 400000 450000 500000 90 120 +H -H 60 30 150 180 0 330 210 240 300 270 H=±4kOe Azimuthal angle dependence of MSHG from 300nm x 100nm rectangular dot array (Polar) PinPout 90 (counts/10sec) 5 9x105 8x105 7x105 6x105 5x105 4x105 3x105 2x105 1x10 0 5 1x105 2x105 3x105 4x105 5x105 6x105 7x105 8x105 9x10 120 +H -H 60 30 150 180 0 330 210 240 300 270 H=±6kOe Nonlinear Kerr rotation in rectangular dot array longitudinal Y Axis Title SHGカウント(counts/10sec) Nonlinear Kerr rotation 0.25 60000 +H -H 50000 40000 30000 20000 10000 -50 0 50 100 150 200 250 X axis title Analyzer angle(deg) 〈Sin〉 300 350 400 Azimuthal angle dependence of MSHG in circular dots 600000 500000 400000 300000 200000 100000 0 100000 200000 300000 400000 500000 600000 PinSout 90 120 60 +H -H 30 150 180 0 330 210 240 300 SHG強度(counts/10sec) SHG強度(counts/10sec) PinPout 270 500000 400000 300000 200000 100000 0 100000 200000 300000 400000 500000 90 120 +H -H 60 30 150 180 0 330 210 240 300 270 40000 35000 30000 25000 20000 15000 10000 5000 0 5000 10000 15000 20000 25000 30000 35000 40000 90 120 +H -H 60 30 150 180 0 330 210 240 300 270 SinSout 100000 SHG強度(counts/10sec) SHG強度(counts/10sec) SinPout longitudinal 90 120 +H -H 60 80000 60000 30 150 40000 20000 0 180 0 20000 40000 60000 330 210 80000 100000 240 300 270 Summary • Square, rectangular and circular dot arrays of 0.1-1 m in dimension buried in Si wafer have been successfully obtained by Damascene technique using EB lithography • MFM observation in square dot clearly shows closure domain pattern. • MFM images of smaller dots show influence of magnetic field from the probe tip • MSHG reflects symmetry of dot-arrangements
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