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Don’t Forget the Memory…. Dean Klein, VP Memory System Development Micron Technology, Inc. Memory is Everywhere. One size DOES NOT fit all…. Question:. How many different memories does your computer use?. At least 5. The Evolving Memory Hierarchy. Level 1 Cache. Level 3 Cache.
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Don’t Forget the Memory… Dean Klein, VP Memory System Development Micron Technology, Inc.
Question: • How many different memories does your computer use? At least 5
The Evolving Memory Hierarchy Level 1 Cache Level 3 Cache Level 2 Cache Main Memory Disk NAND Flash Boot ROM
Question: • How many different memories does your cell phone use? At least 4
The Cell Phone Memory Hierarchy Instruction Cache Data Cache PSRAM or LPDRAM uSD Card NAND Boot ROM MCP NAND Flash
What is the Ideal Memory? • Fast – to keep pace with processors • Reliable – not susceptible to corruption • Low cost – pennies per mm2 • Small – helps with low cost, but also for new platforms • Embeddable – ability to be integrated with logic • Low power – for dense systems and un-tethered systems • Non-volatile – no power required to retain data
Benefit of Shrinking • The ability to fit more bits on a wafer, thereby reducing the cost of those bits. • The ability to add features to a product, thereby increasing performance. • The ability to lower the power of the device.
NAND Flash Memory • The “ideal” memory? • Non-volatile • Small cells – Under 6F2 • Low cost process • Scaleable? • Wear issues? • Slow writes • Ideal for some applications
NAND Operation • Control Gate traps electrons injected by Fowler-Nordheim tunneling. • Voltages of up to 20V exist during cell programming. ControlGate Source Drain p-well N-well p-sub
NAND Programming Operation ControlGate 20V • Control Gate traps electrons injected by Fowler-Nordheim tunneling. • Voltages of up to 20V exist during cell programming. Source Open Drain 0V p-well 0V 0V 0V N-well p-sub Cell is programmed to “0”
NAND Storage Operation ControlGate • Control Gate traps electrons injected by Fowler-Nordheim tunneling. • Voltages of up to 20V exist during cell programming. Source Drain p-well N-well p-sub Cell retains its “0” state
NAND Read Operation ControlGate 0V • Control Gate traps electrons injected by Fowler-Nordheim tunneling. • Voltages of up to 20V exist during cell programming. Source Reads 0V Drain 4.5V p-well 0V 0V 0V N-well p-sub Cell read in “0” state
NAND Read Operation ControlGate 0V • Control Gate traps electrons injected by Fowler-Nordheim tunneling. • Voltages of up to 20V exist during cell programming. Source Reads >0V Drain 4.5V p-well 0V 0V 0V N-well p-sub Cell read in “1” state
Questions: • In 1982, as the personal computer became successful, how many memory bits were there in a standard memory chip? • In 2010 how many memory bits are in a leading edge standard NAND Flash memory chip? 64K bits 64 Billion bits
Questions: • How fast is the speed of light? • How far can light travel in the single “tick” of a 3GHz processor clock? About 186,200 miles/second About 4 inches
Question: • How many ticks of the 3GHz processor clock does it take to access the average piece of data on a 7200RPM hard drive? About 25 million!
Why SSD’s? • Performance
SSDs in Computing NAND CPU RelativeLatency RelativeCost/bit NAND Flash Closes the Latency Gap Cost/bit Data as of November 2007
Why SSD’s? • Performance • Power
Notebooks: SSD’s Can Improve Battery Life Power consumption decreases when solid state drives are used in today’s notebook computers. Power HDD SSD
SSD: Power and Performance SSDs do more with less power
Why SSD’s? • Performance • Power • Reliability
Why SSD’s? • Performance • Power • Reliability • New Form Factors
Memory Research Areas • DRAM: • New materials, High-K gates, Low-K dielectrics • New structures: 3D transistors, lattices • New features: Ultra-high bandwidth, lower power • New types: • MRAM • FeRAM • Polymer • Programmable conductor • Phase Change memory • ‘Nano’ (?) • Micromechanical/nano (Millipede)
Top 10 Reasons You Want to Be an Engineer • For the great memories! • It rationalizes why you always took things apart as a kid • You always were fascinated by trains • It sure beats flippin’ burgers! • You love calculus, differential equations, numerical analysis… • At least your computer listens to you • You would have been a doctor or a lawyer, but where’s the challenge? • You believe anything is possible • You’re going to get rich off that cold fusion project you have going in your bathtub • It’s logical
Final Advice: Be a “T” person!