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Carbon Nanotube Memory. Ricky Taing. Outline . Motivation for NRAM Comparison of Memory NRAM Technology Carbon Nanotubes Device Operation Evaluation Current State of NRAM Fabrication Conclusions. Motivations and Goals . Physical limitations of current memory
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Carbon Nanotube Memory Ricky Taing
Outline • Motivation for NRAM • Comparison of Memory • NRAM Technology • Carbon Nanotubes • Device Operation • Evaluation • Current State of NRAM • Fabrication • Conclusions
Motivations and Goals • Physical limitations of current memory • Threshold voltage scaling, soft error • Low power for mobile devices • Universal memory • Fast, dense, non-volatile, low energy
Comparison - Current Tech • Size compared to DRAM • Speed compared to SRAM • Energy compared to Flash • limited lifetime for flash
Comparison - Future Tech • MRAM (Magnetic Memory) • Insulator separated magnetic plates • Changing polarity causes high or low resistance across insulator • size limit being reached, larger than flash • FRAM (Ferroelectric Memory) • replace capacitor with Ferroelectric crystal • in use • unlimited writes • smallest possible size larger than NRAM • Josephson based
NRAM Technology • Carbon Nanotubes • cylindrical carbon molecules • extremely strong (52x carbon steel) • SWNT • conductors • composite fibers: 600 J/g to break • 4x spider silk, 18x Kevlar fiber • “Gecko strength” • 200x as sticky
NRAM Technology • Device Overview
NRAM Technology • On/Off States • Potential Energy • Van der Waals interactions • Keeps state w/o current • Threshold: 4.5V(on) and 20V(off)
NRAM Technology • Data Access • OFF: high resistance • ON: low resistance • 100GHz operations for 10nm element
NRAM Technology • Calculations • Stable at room temperature • States hold for a variety of sizes • Measurable resistance difference • Bending force will not strain strain SWNT • Small voltages • Localized interactions
NRAM Technology • Density • 10^12 elements/cm^2 • Speed • current: 10x flash
Fabrication • Work with fabrication companies • Current tech • Deposit nanotubes on chips • Remove wrongly placed ones
Current State • Nantero • “Made ground in the manufacturing process” • Density • 13 cm circular wafers - 10GB • Future • Space memory / BAE • Problems? • fabrication
Conclusion • Stable, unlimited lifetime, instant on/standby, scalable • “Universal” • NRAM prototype devices in 2006