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Department of Electronics

Advanced Information Storage 11. Atsufumi Hirohata. Department of Electronics. 16:00 11/November/2013 Monday (P/L 002). Quick Review over the Last Lecture. Bit patterned media (BPM) : **. Shingled write recording : *. Conventional recording. Discrete tracks : ***. Nano-holes.

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Department of Electronics

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  1. Advanced Information Storage 11 Atsufumi Hirohata Department of Electronics 16:00 11/November/2013 Monday (P/L 002)

  2. Quick Review over the Last Lecture Bit patterned media (BPM) : ** Shingled write recording : * Conventional recording Discrete tracks : *** Nano-holes Tracks Nano-holes * S. Matsuo, H. Uwazumi and N. Hara, FujidenkiGihou85, 316 (2012); Discrete tracks for BPM Conventional BPM ** http://news.cnet.com/2300-1008_3-6108692.html; *** http://www.tdk.co.jp/

  3. 11 Flash Memory • NOR flash • NAND flash • TSV • Multiple value • SONOS

  4. Performance Gap between HDD and DRAM * http://www.theregister.co.uk/2013/06/25/wd_shingles_hamr_roadmap/

  5. Flash Memory In 1980, Fujio Masuoka invented a NOR-type flash memory : • 1 byte high-speed read-out • Low writing speed • Difficult to integrate * http://rikunabi-next.yahoo.co.jp/tech/docs/ct_s03600.jsp?p=000500; ** http://www.wikipedia.org/

  6. NOR-Flash Writing and Erasing Operation Writing operation : Erasing operation : Negative potential voltage Positive potential voltage Control gate Insulating layer Floating gate Drain Source Open drain Ground Positive Positive * http://www.tdk.co.jp/techmag/knowledge/200705/index2.htm

  7. NAND Flash Memory In 1986, Fujio Masuoka invented a NAND-type flash memory : • No 1 byte high-speed read-out • High writing speed • Ideal for integration • Flash erase for a unit block ( 1 ~ 10 kbyte ) only ! * http://www.wikipedia.org/

  8. NAND-Flash Writing and Erasing Operation Writing operation : Erasing operation : Ground Positive potential voltage Control gate Insulating layer Floating gate Drain Source Ground Ground Positive Positive Positive Ground * http://www.tdk.co.jp/techmag/knowledge/200705/index2.htm

  9. Reading Operation “0” state : “1” state : * http://www.tdk.co.jp/techjournal_e/vol01_ssd/contents05.htm

  10. Cells, Pages and Blocks Flash memory blocks : * http://www.tdk.co.jp/techjournal_e/vol01_ssd/contents06.htm

  11. Flash Memory Integration NOR or NAND ? : * http://www.tdk.co.jp/techjournal_e/vol01_ssd/contents04.htm

  12. Solid State Drive with Flash Memory Solid state drive (SSD) started to replace HDD : pureSi introduced 2.5” 1-TB SDD in 2009 : • Data transfer speed at 300 MB/s • Slow write speed For example, a system with a units of 2kB for read / out and 256 kB for erase : in order to write 1 bit, the worst case scenario is • 128 times read-out • 1 time flash erase • 128 times re-write * http://www.tdk.co.jp/techjournal_e/vol01_ssd/contents02.htm

  13. HDD vs Flash Memory Demand for flash memories : Price of flash memories : * http://www.manifest-tech.com/ce_products/flash_revolution.htm

  14. Flash Memory Development Intel flash memories : • 130 nm (128 MB) in 2003 • 90 nm (512 MB) in 2005 • 50 nm (1 GB) in 2007 • 34 nm (4 GB) in 2009 • 25 nm (8GB) : http://www.pcper.com/reviews/Storage/Inside-Look-Intel-and-Micron-25nm-Flash-Memory-Production/Die-Shrinks-and-You

  15. For Higher Recording Density ... Through Silicon Vias　（TSV) : Stacked flash : Toshiba also demonstrated 16 GB flash. Samsung demonstrated 16 GB flash. * http://www.semiconductorjapan.net/serial/lesson/13.html; ** http://www.intechopen.com/books/advances-in-solid-state-circuit-technologies/dimension-increase-in-metal-oxide-semiconductor-memories-and-transistors

  16. Bit Cost vs Recording Capacity Simple memory stack and BiCS memory : Layers Bit cost [arb. unit] Simple memory stack Memory capacity [bit] BiCS flash memory * H. Aochi, R. Katsumata and Y. Fukuzumi, Toshiba Review66(9), 16 (2011).

  17. Bit Cost Scalable (BiCS) BiCS memory design : Bit line Upper selection gate Control gate Lower selection gate Source line String * H. Aochi, R. Katsumata and Y. Fukuzumi, Toshiba Review66(9), 16 (2011).

  18. Multiple-Valued Flash Memory Multiple electrons can be stored in the floating gate : Multiple-valued cells Conventional cells “1” “11” “10” Memory cell read-out threshold Memory cell read-out threshold “01” “0” “00” Cell distributions Cell distributions * http://www.semiconductorjapan.net/serial/lesson/13.html

  19. SONOS Si / SiO2 / SiN / SiO2 / poly-Si (SONOS) : By replacing the poly-Si floating gate with SiN, i.e., Si9N10, unbound dangling bonds can trap more electrons. * http://www.eetimes.com/document.asp?doc_id=1279116

  20. Flash Memory vs DRAM Comparisons between flash memory and DRAM : Flash memory Tunnel barrier Floating gate Principles Transistor Transistor Condenser Electron charges are stored in the On On Electrons are stored at the floating gate. condenser. Writing operation Leakage from the condenser. Electrons cannot tunnel through the barriers. Data volatility * http://pc.nikkeibp.co.jp/article/NPC/20061228/257976/

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