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Discover the diverse memory hierarchies in computer systems, from cache to NAND Flash. Learn about ideal memory characteristics – fast, reliable, low-cost, small, embeddable, low-power, and non-volatile. Dive into industry-reported cell sizes and the benefits of shrinking technology. Explore the operations of DRAM and NAND Flash memory, including programming and storage mechanisms. Uncover the significance of SSDs in computing, from improved performance and power efficiency to enhanced reliability. Stay informed about innovative memory research areas and Dean's humorous top 10 reasons to become an engineer. Be a "T" person - curious and knowledgeable about memory technology. Have any questions? Ask us!
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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!
