Prospects for Terabit-scale nano electronic memories Venkata R.Malladi Instructor : Dr.Damian

Introduction Motivation What are Nano electronic memories? CMOS vs. NANO What is that it got to do with terabit-scale? What are hybrid memories? Is the present day architecture needed to be totally replaced for Nano scaled devices? Results

Motivation CMOS Memory “Complementary Metal Oxide Semiconductor” Traditional memory architecture Chipmakers won’t be able to shrink transistors much longer to fit more on a chip Need new ways to make memory chips more powerful and less expensive Solution: Nano-Scale Electronic Memories.

Nano-Scale Electronics Technology that manipulates physical structures at the molecular scale Can we, by moving to molecular scale electronics, buy a little bit more shrinkage? Is is possible? Is it economical? Example: nanowires

Nanowires Currently wires are made out of silicon and other materials that are ~ 15nm in diameter These are itsy bitsy wires enabling high density They have high resistance; hence limited speed Nanowires are only a few atoms wide; have been fabricated in many labs Two crossing nanowires form a switch; the switch is created only from a few molecules.

Nano Electronic memories Nano electronics is the technology where it pairs traditional silicon chips with manipulation of molecules themselves Advantages Greater density Lower power consumption High speed Field effect transistors with nanotube or nanowire conducting channels, as well as quantum dot-based single electron transistors, might serve in a limited capacity to enhance the performance of CMOS chips in a hybrid nano/microelectronic architecture Application : Toshiba Announces Availability of 32-Bit RISC Microcontroller with 2 Megabytes of Embedded NANO FLASH(TM) Memory

CMOS Vs NANO CMOS (Top –down Fabrication) Nano (Bottom-up fabrication) Eg : LithographyEg : Self fabrication Limited resolutionMolecular resolution Expensive & Arbitrary structures Potentially cheap & Regular structures ReliableHigher defect rates

Nano-Scale Circuits - Advantages Greater density Lower power consumption Higher speed

Nano-Scale Circuits - Disadvantages High defect rates is Due to number of bad nano devices The number of bad devices is around ~15% and it has to be reduced to ~2% to get and advantage in density. In order to achieve that we use 1. Repair most technique with hamming error code correction(Execution time scaling linearly with number of bits) 2. Exhaustive Search approach(exponentially large execution time)

Prospects for Terascale (2 40 ) Prospects for Terabit-scale nano memories?  Having Memory array configuration (Bad bit exclusion) using the following techniques:  Most repair techniques complemented with ECC (Error Correction Codes)  Using hybrid semiconductor/nano device circuits

Hybrid memories

Hybrid Memories Hybrid memories combine the advantages of Nano-scale components and reliability of CMOS circuits Hybrid memories use single-molecule single transistor in place of present day CMOS circuits The architectural challenges of Hybrid memories  Bad bit Nano devices  Limitation due to integration technique  Vulnerability due to Random charged effects Approach to address the above problem  Use Memory reconfiguration

Results The speed and Power and memory density if going to be the main advantages of Nano electronics. Potential development in future using Nano devices

Progress of technologies Capacity of magnetic hard disks: 1980’s: 30% growth per yearearly 1990’s: 60% growth per yearlate 1990’s: 130% growth per yeardisk capacity doubling every 9 months(twice the pace of Moore’s Law)

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