Don’t Forget the Memory…

Don’t Forget the Memory…Dean Klein, VP Memory System DevelopmentMicron Technology, Inc.

©2007 Micron Technology, Inc. All rights reserved.

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Memory is Everywhere


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One size DOES NOT fit all…


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Question:

• How many different memories does your computer use?


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The Evolving Memory Hierarchy

Level 1 Cache

Level 2 Cache

Main Memory

Disk Boot ROM


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Question:

• How many different memories does your cell phone use?


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The Cell Phone Memory Hierarchy

Instruction Cache

Data Cache

Boot ROM

uSD Card NAND

NAND Flash

PSRAM or LPDRAM

MCP


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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


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Industry Reported Cell SizesCell Size (u2) Tech Node (nm) Cell size (F2) Endurance

IBM/Infineon MRAM0.74 130 44 Excellent

Freescale 6T-SRAM0.69 65 163 Excellent

Intel 45nm 6T-SRAM0.27 45 135 Excellent

Freescale TFS: Nanocrystaline0.13 90 16 Unknown

Freescale eDRAM0.12 65 28 Excellent

Samsung 512Mbit PRAM Device0.050 95 5.5 1E7??

Micron 40-series DRAM0.037 78 6 Excellent

Micron 60-series NAND0.0046 34 4 Good


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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.


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DRAM Operation


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NAND Flash Memory

• The “ideal” memory?• Non-volatile• Small cells – Under 6F2

• Low cost process• Scaleable?• Wear issues?• Slow writes• Ideal for some applications


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NAND Operation

• Control Gate traps electrons injected by Fowler-Nordheim tunneling.

• Voltages of up to 20V exist during cell programming. p-sub

N-well

p-wellN+ N+

Source Drain

ControlGate


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NAND Programming Operation



N-well

p-wellN+ N+

SourceOpen

Drain0V

ControlGate20V

0V0V0V

Cell is programmed to “0”


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NAND Storage Operation



N-well

p-wellN+ N+

Source Drain

ControlGate

Cell retains its “0” state


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NAND Read Operation



N-well

p-wellN+ N+

SourceReads

0V

Drain4.5V

ControlGate

0V

0V0V0V

Cell read in “0” state


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NAND Read Operation



N-well

p-wellN+ N+

SourceReads >0V

Drain4.5V

ControlGate

0V

0V0V0V

Cell read in “1” state


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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?


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Questions:

1. How fast is the speed of light?

2. How far can light travel in the single “tick” of a 3GHz processor clock?


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Question:

• How many ticks of the 3GHz processor clock does it take to access the average piece of data on a 7200RPM hard drive?


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Why SSD’s?

• Performance


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SSDs in Computing

1 L1 Cache 1,800

2.5 L2 Cache 1,400

1,200 DRAM 10

RelativeLatency

RelativeCost/bit

CPU

NAND Flash Closes the Latency GapCost/bit Data as of November 2007

25,000,000 HDD 1NAND 25,000 SSD 3


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Why SSD’s?

• Performance• Power


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Notebooks: SSD’s Can Improve Battery Life

Power consumption decreases when solid state drives are used in today’s notebook computers.

HDD SSD

Power


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SSD: Power and Performance

SSDs do more with less power


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Why SSD’s?

• Performance• Power• Reliability


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HDD & SSD in the Enterprise Server Market


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Why SSD’s?

• Performance• Power• Reliability• New Form Factors


Innovative Platforms

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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)


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Top 10 Reasons You Want to Be an Engineer

1. For the great memories!2. It rationalizes why you always took things apart as a

kid3. You always were fascinated by trains4. It sure beats flippin’ burgers!5. You love calculus, differential equations, numerical

analysis…6. At least your computer listens to you7. You would have been a doctor or a lawyer, but

where’s the challenge?8. You believe anything is possible9. You’re going to get rich off that cold fusion project

you have going in your bathtub10.It’s logical


Final Advice:

Be a “T” person!

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Questions?

Documents

Don’t Forget the Memory…