Thin Film Application in Magnetic Recording - NCCAVS - User Groups
Thin Film Application in Magnetic Recording - NCCAVS - User Groups
Thin Film Application in Magnetic Recording - NCCAVS - User Groups
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<strong>Th<strong>in</strong></strong> <strong>Film</strong> <strong>Application</strong> <strong>in</strong><strong>Magnetic</strong> Record<strong>in</strong>gZheng Gao,Read Head Development teamHitachi Global Storage Technology© 2012 HGST, a Western Digital company HGST ConfidentialAVS North America Plasma <strong>Application</strong> 4-2013
Company of Vertical Drive IntegrationRecord<strong>in</strong>g Head/Media are Built on<strong>Th<strong>in</strong></strong> <strong>Film</strong> and Nano TechnologyMedia MFGHead Wafer MFG- San Jose/JPHead Slider MFGDrive AssemblyHDD Test<strong>in</strong>g and IntegrationServo/Channel© 2012 HGST, a Western Digital company HGST ConfidentialZ. Gao2
Perpendicular Record<strong>in</strong>g Head and MediaRead Sensor is Key Element <strong>in</strong> Read Head to Sense MediaSignal by Resistance Change.Read Sensor: Tunnel<strong>in</strong>g Magnetoresistive Sensor TMRRead HeadWrite Head<strong>Magnetic</strong> ShieldHead/Media InterfaceMedia- Perp. Magnetized© 2012 HGST, a Western Digital company HGST ConfidentialZ. Gao3
Read Head Structure and Wafer BuildBuild<strong>in</strong>g Read Head1. Deposit Multilayer Sensor Stack(15-22 PVD Layers <strong>in</strong> 4-80 Å Level)Top shield and lead2. 193 Photo Mask for Critical Dimension(25-50nm Track Width)3. Ion Mill or RIE Pattern Transfer4. ALD Isolation and Hard Bias StackBottom shield and lead5. Liftoff6. RIE Clean7. Top Contact8. Top Shield Plat<strong>in</strong>g© 2012 HGST, a Western Digital company HGST ConfidentialZ. Gao4
Read Head and Read SensorFujitsu Reader TEM Image250GB Earlier Generation Head;Sensor Total Thickness 35nm.Sensor/Junction/Isolation/HB/Shield© 2012 HGST, a Western Digital company HGST ConfidentialZ. Gao5
Read Head/TMR Sensor Work<strong>in</strong>g Pr<strong>in</strong>cipleReader <strong>Magnetic</strong> Config and SignalΔRa bcbacSignal OutputΔV=I*ΔRH appliedTMR (Tunnel<strong>in</strong>g Magnetoresistive) Field-Resistance SensorRmaxAlO TMRRm<strong>in</strong>NVE IEEE 2004© 2012 HGST, a Western Digital company HGST ConfidentialZ. Gao6
Read Sensor General Structure and FunctionS2Capp<strong>in</strong>g LayersFree FM LayersBarrier LayersRef. FM LayersAP Coupled LayersRef. FM LayersAFM P<strong>in</strong>n<strong>in</strong>g LayersSeed LayersS1Capp<strong>in</strong>g Layer: (10-50Å; 1-3 Layers)Free FM Layer: (30-80Å; 1-5 Layers)Barrier Layers: (~10Å; 1-4 Layers)Ref.+P<strong>in</strong>ned Layers: (~30-60Å; 2-10 Layers)AFM P<strong>in</strong>n<strong>in</strong>g Layer: (40-80Å; 1 Layer)Seed Layers: (> 20A, 2-5 Layers)All Layers (>20) are Deposited <strong>in</strong> PVD Cluster w/o Vacuum Break (BP 5E-09)© 2012 HGST, a Western Digital company HGST ConfidentialZ. Gao7
<strong>Th<strong>in</strong></strong> <strong>Film</strong> Plasma TreatmentFree FM LayersSpacer LayersRef. FM LayersLow Power Plasma TreatmentSmoothes <strong>Film</strong> w few Å RemovalHf Reduction and MR ratio Improvement:Ref Layer (~20Å) Roughness Reduction;High Quality Growth of Spacer layer;Improve Density and Resistivity of Ref FM Layer.US Patent 026470A1 2004 IBM© 2012 HGST, a Western Digital company HGST ConfidentialZ. Gao8
<strong>Th<strong>in</strong></strong> <strong>Film</strong> Oblique Deposition<strong>Magnetic</strong> Anisotropy is Important for Both Reader and Writer.Surface MorphologyOblique Deposition Stra<strong>in</strong> Anisotropy ⇒ Induced <strong>Magnetic</strong> AnisotropyMicrostructure/OrientationNiFe25nm/Ta25nmNiFe25nmUS Patent 6818961B1, Freescale, Filed 2003NiCo Oblique, CNRS France, J. Appl. Phys 1992Strong Anisotropy on Oblique Ta, NIST, J. Appl. Phys 2000© 2012 HGST, a Western Digital company HGST ConfidentialZ. Gao9
TMR Barrier from Year 2004Large MgO TMR Ratio Observeddue to Sp<strong>in</strong> Filter<strong>in</strong>g EffectCoFe 16 /MgO/CoFe 16(100) oriented crystall<strong>in</strong>e Co/MgO/Co-Crystall<strong>in</strong>e MgO barriersact as a sp<strong>in</strong> filter à LargeTMR (> 100%).- Low electron effectivemass à Low electricalresistanceW.Butler, Zheng et al2001/ 2004IBM S.Park<strong>in</strong> 2004Δ 1 state decays rapidly<strong>in</strong> antiparallel alignmentFe/MgO/FeΔ 2 and Δ 5 states are filteredout by barrierAIST Y. Yuasa 2004© 2012 HGST, a Western Digital company HGST ConfidentialZ. Gao10
<strong>Th<strong>in</strong></strong> <strong>Film</strong> Read <strong>Magnetic</strong> SensorMgO TMR Ratio Highly Sensitive toBarrier Process and Chamber Condition /Target QualitySputter Condition Anneal<strong>in</strong>g Condition Surface RoughnessStack:Sub/Ta5/UL50/Ta5/NiFe5/IrMn8/CoFe2/Ru8/CoFeB3/MgO/CoFeB30/Ta5/Ru15 (nm)Tohoku Univ. and Hitachi Ltd.© 2012 HGST, a Western Digital company HGST ConfidentialZ. Gao11
<strong>Th<strong>in</strong></strong> <strong>Film</strong> Read <strong>Magnetic</strong> SensorMgO RA MR Ratio are Highly Sensitive toInterface Material and Structure <strong>in</strong> Atomic LevelIntermag Jan 2013 Anelva© 2012 HGST, a Western Digital company HGST ConfidentialZ. Gao12
PVD Tools for <strong>Magnetic</strong> SensorAnelva 7100Ulvac ENTRON-EXMultiple DC/RF CathodeUltra High Vacuum (-9 to -10 Torr)Angstrom level of control with uniformityS<strong>in</strong>gulus TIMARISWafer Size 150mm to 300mm© 2012 HGST, a Western Digital company HGST ConfidentialZ. Gao13
SummaryHDD is Abundant with Every Eng<strong>in</strong>eer<strong>in</strong>g Discipl<strong>in</strong>e<strong>Th<strong>in</strong></strong> <strong>Film</strong> <strong>Magnetic</strong>s and Micro FabricationProcess Play Important Role <strong>in</strong> Record<strong>in</strong>gHead Build and Head PerformanceThank You© 2012 HGST, a Western Digital company HGST ConfidentialZ. Gao14
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