Enabling Areal Density Growth

Transcription

1 Shrinking the Magnetic Spacing for Advanced PMR Heads Diskcon Asia 2007 Enabling Areal Density Growth Shrinking the magnetic spacing remains one of the biggest levers for areal density growth! Areal Density (Gb/in 2 ) Height Control σ (nm) PTR / PTP σ (nm) Overcoat σ (nm) Elements of Magnetic Spacing Thin Film Head Pole tip recession (PTR) ABS shape & parallelism Slider overcoat Fly-height characteristics Media Lube & overcoat Non-magnetic spacers Other Thermal fly-height control Processes must achieve sub-nm accuracy & repeatability 1

2 Magnetic Spacing: A Process Viewpoint Magnetic Spacing PTR Crown & camber Rough & Fine Lap Kiss Lap DLC Virtually every process step impacts some aspect of Magnetic Spacing Magnetic Spacing Ultra Ultra-thin thin defect-free free coating Flyheight Control Triple cavity etch Cavity shape CD & depth ABS Pattern & Etch Head Performance Stripe height Throat height PTR Sensor smearing Slice Shape Control Straightness Perpendicularity Rowbar bow Pullouts Dice Defects Pressure ridges Debris Pullouts Processing & Metrology Overview Slider Processing Dual-pass dice Pulsed FCA for minimizes Pressure Ultra-thin, thin, defect- Ridges, Sidewall free overcoat Roughness & Debris IBE provides precise depth & shape control Low lapping pressure improves Flatness, Surface Finish and PTR Wedge angle control minimizes Reader/Writer Offset Slider Metrology Lapping Flatness, sensor & throat height, PTR Overcoat Thickness & PTR ABS Etch Etch depth, cavity shape, roughness & fencing / debris Dicing Ridges, sidewall roughness, cracks & debris ELG feedback provides Height Control Backside grind sets Reference Plane for lapping 2

3 Shrinking the Magnetic Spacing Grind & Slice for Shape Control µm µm EDGE GRIND WHEEL 90 ±0.1 Thin blade deflects during slicing Solution: Edge grind backside of rowbar for perpendicularity Establishes reference for subsequent processing 3

4 Stripe & Throat Height Control for PMR Row Tool Slider Glue Line Row Tool Slider ROW IS MICRO-ADJUSTED BY ELG LAPPER UNTIL ABS IS PARALLEL WITH ROW TOOL Plate Variable Plate Run-out, Shape, Arm Square Gb/in Stripe Height (nm) 150 Stripe Height 1σ (nm) 7.5 Throat Height 1σ (nm) 20 Perpendi- cularity ±0.375 o ±0.15 o Reader & writer ELG feedback for height control Wedge angle control for parallelism Low pressure for controlled PTR Overcoat Thickness Reduction Reduce Variability Carbon and Si WIW Å RTR Å Pre-clean Uniform etching Improve pre-clean process Reduce sensor recession 1.5 nm < 1 nm Reduce Si/Carbon Thickness 10 Å Si/10 Å C 13 Å total = -4 Å Improved in-situ thickness monitoring Pulsed FCA source Long-throw PVD Silicon = - 5 to 10 Å Tunable Low Energy ion source Interface Control Module = -5 to 8 Å Dual Source FCA in HMS -15 Å 4

5 Low Energy Ion Beam Etching Etch Depth [A] Etch Profile for Different Tilt Angles Ub=100V, Ib=150mA, Us=700V -75 deg (1.8%) -55 deg (1.5%) -35 deg (2.1%) 0 deg (1.9%) R, inch CPP sensor smear removal & ABS smoothening with controlled PTR & uniformity Pulsed FCA ta-c Film Properties Precise control of film thickness Linearly dependent on number of pulses Film density ~ g/cm 3 Higher than DC FCA ~ 2.8 g/cm3 Optical properties (n, k) are similar to DC FCA Films have the same microstructure Film stress -4 to -6 GPa (~ 25 nm DLC) Similar to DC FCA Particulate levels are similar to DC FCA Uniformity < 5% 3σ Shape the plume with focusing / deflection coils 5

6 PFCA Uniformity: ~2A Range PFCA Thickness Profiles. Runs # Thickness [A] WIW Uniformity Range: ~2A Radius [inch] Avg. Tx [A] PFCA FilmsTx Repeatability, Runs # RTR Uniformity Range: ~0.5A Run # PTR Metrology 6

7 Process Control Metrology Atomic Force Microscopy (AFM) Highly accurate; industry baseline Profile entire slider High CoO driven by throughput Optical Profilers High throughput with low CoO Limited lateral resolution sees only large structures Material properties effect overall accuracy Production Readiness Requirements Environmental vibration Device fixturing Veeco Vx200-PTR (AFM) Veeco HD8100 (Optical) PTR Process Monitor Trends Gauge Repeatability & Reproducibility (GR&R) once drove metrology qualifications Today Accuracy and CoO are major Drivers Historical Noise must now be compensated Throughput & consumables are primary factors in CoO Error Factors Phase Shift Contamination Environmental Vibration Roughness Phase Shift 7

8 AFM for PTR Monitoring Advantages True material mapping High resolution imaging Excellent physical measurement accuracy Development Trends Improve throughput 10 min/slider < 30 sec/slider AFM tip replacement Automated Replacement Eliminate Operator Errors Extended tip lifetime 500 sliders sliders Improved AFM Matching PTR (nm) Typical AFM PTR Image PTR Tool Repeatabilty AFM Self Correlation y = x R 2 = PTR (nm) AFM Trends Reduction of CoO Increased Throughput Single Scan increases throughput by 40% Increasing Scan Rates Tip Lifetime Improvements Materials and Coatings COO ($/Slider) $3.50 $3.00 $2.50 $2.00 $1.50 $1.00 Today's Performance Throughput (Sliders/Week) $ $- "COO ($/Slider)" Throughput per Week Test Time (Minutes / Slider) Sampling Capability Increases Past Year Increased 55% to 160 sliders/day Flat Scan XY Eliminates 2 nd Scan Requirements 100 µm range scan with < 2nm Out of Plane Motion Trend towards 500 Sliders/Day 3X Today s Capabilities 8

9 AFM Performance Trends for PTR Intelligent Scanning Improvement throughput Advanced pattern identification Only scan areas of interest Less time for data acquisition Higher Sampling Density Higher resolution 78 nm PTR Scan Resolution to 2.5nm resolution improvement Improves algorithmic performance Result Verification Auto-rescan of out-of-spec parts PTR Algorithm Advanced analysis for improved repeatability & robustness Reference scan #1 Reference scan #2 High resolution data scan Optical Profilers for PTR Monitoring Advantages Fast (seconds/measurement) Low CoO Wide scanning / imaging area Development Trends Optically limited lateral resolution ( ~ 500 nm) Optical properties of dissimilar materials Noise suppression seismic and acoustic Optical Compensation of Material Properties Significantly improved matching to AFM Maintains low COO with improved performance 9

10 Optical PTR Technology Improvement Optical Process Variation Range of total Population AFM Gauge GR&R Std Optical Actual PTR Today s Optical PTR is Highly repeatable but limited accuracy due to Material Properties Optical PTR Technology Improvement Dual AccuPhase Compensated Process Variation of Population AFM Gauge Actual PTR GR&R Dual AccuPhase Advances in Dissimilar Material Compensation significantly improves Optical Accuracy 10

11 Pole Recession Improvements P1P Rec ession Mean(nm ) St d Dev(nm ) AFM Opt ic al Delt a A 0.19 nm Pole Recession Improvements P1P Rec ession Mean(nm ) St d Dev(nm ) AFM Opt ic al Dual Ac c uphase Delt a < 3 A 0 nm STD ERROR 0.35 vs nm 34% Improvement 11

12 PTR Rowbar Comparison Dissimilar Material Compensation AlTiC; Poles, DLC Optical Enhancements enable matching to AFM DC Compensation driven by physical material properties 0 Before Compensation 0 After Dual AccuPhase -2-2 PTR (nm) AFM PTR Optical PTR PTR (nm) AFM PTR Dual AccuPhase PTR 0 y = x R 2 = Rowbar Location -12 Standard Error No -14 Compensation: 0.47 nm Dual AccuPhase: 0.37 nm % Better AFM PTR (nm) PTR (nm) Rowbar Location Production Trends Device Fixturing Improves Accuracy and GR&R Stability and true device monitoring Sample Handling Controlling contamination improves accuracy Production Environment Conditions Reduced susceptibility to acoustic and seismic vibrations improves Accuracy and GR&R HD9800 (2007) -Vibration Immunity - Extended Performance - Tool-Tool Correlation - Next Gen Camera/Illum. HD8100 (2003) - 1 st ESD Compliant - Enhanced Performance - Correlation Improvement Calibration and PM processes Enhances integrity of metrology results RST (Circa 1990) -First Optical Profiler PTR 2000 (1996) -First Automated Profiler -Integrated Analysis HD3300 (1999) - Advanced Analysis - Improved Throughput 12

13 PTR Metrology Trends Optical and AFM profilometry on shared platform Optical Throughput with AFM Verification Common PTR analysis techniques and matched results Enables cross calibration In-line and integrated metrology Feed forward of equipment parameters to metrology Improves metrology accuracy Speeds up process control loop PTR Feedback PTR Feed Forward PTR Feedback Lap Optical PTR DLC AFM/Optical PTR ABS Etch Final PTR PTR, Cavity, Step AFM/Optical PTR Dice AFM/Optical PTR Summary Slider processes approaching sub-nm capabilities Closed loop low pressure lapping Pulsed FCA for ultra-thin overcoats Dual pass dicing Metrology Technology keeping pace with process control requirements Atomic Force Microscopy Optical with Dual AccuPhase Compensation Trend continues towards sub-nm process control capabilities across multiple steps of process flow 13

14 Acknowledgments Adrian Devasahayam Meng Lee Bill Abeyta John Wissinger Michael Peters Thanks for your attention! 14