What s Hot in Heat Assisted Magnetic Recording (HAMR)

Transcription

1 What s Hot in Heat Assisted Magnetic Recording (HAMR) Mark Re Senior Vice President Seagate Research Some of this work was performed as part of the Information Storage Industry Consortium (INSIC) program in Heat Assisted Magnetic Recording (HAMR), with the support of the U. S. Department of Commerce, National Institute of Standards and Technology, Advanced Technology Program, Cooperative Agreement Number 70NANB1H3056

2 Outline Why HAMR? What is HAMR? Integrated HAMR Head Design & Challenges Optical Field Delivery Integration of Optical & Magnetic Field Deliveries Integrated HAMR Head Characterization Optical Microscopy Spin-Stand Future HAMR Prospects Conclusion

3 The Fundamental Problem Media SNR SNR~log 10 (N) Small Grains (V) Thermal Stability E B H KuV 1 H d 0 3/2 K u V = k B T H H 0 < Head Field Writability 2 Ku = α N M M 0 eff S S H d {

4 Writability with High Anisotropy Media With HAMR we can write on high anisotropy media maintain thermal stability with reduced grain size Coercivity Drive Temperature Store Here Cool Media Heat Media extend the areal density growth curve Available Head Field Write Here Temperature

5 HAMR System Suspension Grating Light Delivery Laser Module on E-block Waveguide Return Pole TGMR Element Lubricant/Overcoat Write Pole Near Field Transducer Write Coil Heatsink/SUL Magnetic Media

6 Recording Head - Optical Light Delivery Planar Solid Immersion Mirror W. Challener et al., published in Optics Express 09/05/05 Front View Coupling Grating Side View Cladding Cladding Core AlTiC Media

7 Completed Optical Heads Grating 200 μm Control SIM Near Field Transducer Channel Waveguide

8 Optical & Magnetic Integration PSIM in Gap of Asymmetric Ring Writer Optical Waveguide/PSIM ABS plane

9 HAMR Head Cross-section ABS (after lapping) Top Cladding Main Pole Back Via Write Location Return Pole Light intensity and direction Coils (x5) Core Bottom Cladding

10 Wafer Level HAMR Head Fabrication Standard Thin-film processes used s of heads per 6 wafer s of heads built into sliders & HGAs. PSIM Top Pole WG Core Return Pole WG Cladding Reader

11 Characterization: Witec SNOM Scanning Near-field Optical Microscopy (SNOM) to evaluate PSIM focusing. A hollow, metal coated SiO 2 tip is scanned over sample surface in contact mode. PSIM PMT Cantilever 200 µm Light 2 m by 2 m Silicon Wafer Front Face

12 Near-field Intensity SNOM scan over focal plane at ABS. At blue light (413 nm), FWHM focused spot size = 90 nm. Mode confinement 1 µm by 1 µm SIM Focusing Intensity (a. u.) Cross Track Position (nm)

13 Recording Temperature Challenges For areal density and low noise, we need high anisotropy For reliability, we need low T write K u (10 6 erg/cc) Head Disk Interface Constraint L1o L10 alloys alloys alloys RE-TM Multilayers Multilayers Multilayers Co-alloys Tc (K) Manufacturability

14 Anisotropy versus Curie Temperature FeNiPt Figure and data from J.- U. Thiele, K. R. Coffey, M. F. Toney, J. A. Hedstrom, and A. J. Kellock, Temperature Dependent Magnetic Properties of Highly Chemically Ordered Fe 55-x Ni x Pt 45 L1 0 Films, J. of Appl. Phys Vol. 91, pg 6595, Anisotropy (10^7 erg/cc) HDI Curie Temperature (K)

15 Fast Media Cooling Seagate HAMR Media Media thermal response times are extremely fast when properly designed Medium Temperature Heats and cools in ~ 150 ps Time (ps( ps)

16 HAMR Spinstand Demonstration Steering Mirror Reflecting Mirror Light source Spinstand recording performed with a fully integrated HAMR head and HAMR medium Time domain PRBS data

17 MFM of Non-HAMR & HAMR Tracks (Fully Integrated HAMR Head) Fully Integrated HAMR Head HAMR Unique Media High Anisotropy Proper Heatsinking Non-HAMR HAMR 120mA 70mA 70mA

18 Near Field Transducers NFT to reduce the optical spot size. Aperture, bowtie, ridge WG, beaked antenna, 500 nm 500 nm 200 nm 100 nm 0 nm nm Ridge Waveguide 37 nm Optical Field in Media 500 nm 500 nm nm 200 nm 100 nm 0 nm -100 nm -200 nm Nano-Holes L.Yin et al., APL 85 (3), pp (2004). E. Popov, et al., Appl. Opt. 44, pp (2005). Rectangular Aperture Shi, et al, Jap. J. Appl. Phys. 41 (2002). Bowtie R. Grober, et al, APL 70, pp (1997). Hitachi - Beaked Antenna T. Matsumoto, et al, ISOM/ODS 05, (2005). Sharp - Smash Head S. Miyanishi INTERMAG (2005). Sony - SIL + Single Pole Head N. Kojima, et al, INTERMAG (2007).

19 HAMR + Bit Patterned Media Cross-sectional View Non-Magnetic Filler Magnetic Nano-particle M M

20 Optical Switching with a Single Pulse Sweeping the pulsed laser beam at high speed across the sample GdFeCo Each domain is written with a single 40 fs laser pulse THz optical magnetic recording is possible! Rasing Group, Nijmegen October 2006

21 Summary / Conclusions HAMR is a candidate alternative technology to allow further HDD AD scaling. Conventional perpendicular recording may be limited to a 1 Tbpsi. HAMR allows high anisotropy materials to be recorded. The fully integrated HAMR heads were built & tested. Design uses conventional head processing technologies. MFM image shows HAMR is required for high Hk HAMR unique media. Demonstrated HAMR writing with fully integrated HAMR heads & HAMR media. Combining HAMR & BPM may further extend areal density.