Institut für Technische Informatik Chair for Embedded Systems - Prof. Dr. J. Henkel Vorlesung im SS 2010 Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design A. Grudnitsky, L. Bauer, J. Henkel
Carbon Nanotube Based Architectures eFPGAs References Outline Carbon Nanotube Based Architectures 1 Carbon Nanotubes A Field Programmable Carbon Nanotube Array 3D nFPGA2 eFPGA - Embedded FPGA 2 eFPGA Basics ASIP-eFPGA Architecture for Navigation Systems Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 2
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary State of Semiconductor Fabrication Higher integration requires smaller feature size → CMOS scaling Current feature size: 45nm - 32nm International Technology Roadmap for Semiconductors assesses developments in Semiconductor production and projects targets for future fabrication processes Next technology nodes: 22nm (ITRS: 2015, Intel announced for 2011) 16nm (ITRS: 2018) Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 3
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary Problems With CMOS Scaling Smaller feature size → more complex fabrication process Low yield Non-visual defects cause electric failure, leave no physical remnant → very hard to test for Process variation Increasing device failure probability during its lifetime (e.g. Electromigration) Size limit - transistors already only a few atoms thick - can’t scale down much further High manufacturing costs Expensive equipment (e.g. Steppers) Clean room requirements One solution: use new materials. Here: Carbon Nanotubes Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 4
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary The Carbon Nanotube (CNT) [src: LBL07] [src: Ausman] Graphene (deutsch: “Graphen”) - planar sheet of carbon atoms, bonded in a hexagonal lattice Carbon Nanotube: sheet of graphene wrapped into a tube Few nm thick, up to several cm long Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 5
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary Types of CNTs TEM micrographs of SW and MW CNTs [src: Zettl] Single-Walled CNTs (wall thickness 0.7nm - 2nm) can be either metallic or semiconducting Multi-Walled CNTs (wall thickness 10nm - 20nm, multiple concentric wall layers) metallic In this lecture: only Single Walled Carbon Nanotubes (SWCNT) (unique electric properties) Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 6
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary Types of CNTs TEM micrograph of MWCNT produced using Laser assisted chemical vapor deposition [src: Bondi] Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 7
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary Properties of CNTs Electrical Depending on the chirality of the CNT (“angle under which the graphene sheet is rolled up”) a CNT is either metallic or semiconducting Resistant to Electromigration Thermal High thermal conductivity along the tube Thermal insulation across the tube High contact resistance for individual CNTs use bundles of CNTs for interconnect Other properties: Very high mechanical strength Can be used for field emission - electron beam source Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 8
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary CNT Manufacturing Methods Catalyst enhanced Chemical Vapor Deposition (CCVD) place catalyst particle on substrate pass carbon gas over wafer CNT grows Arc discharge - arc induced between two rods and vaporizes one carbon rod. Vaporized carbon reforms into CNTs Laser ablation - similar principle as arc discharge - use laser to vaporize rod Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 9
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary CNT Manufacturing Methods Problem: stochastic process, can only bias towards a certain type of CNT (metallic or semiconducting) Recent (end 2009) research has presented techniques to increase bias at up to > 90 % towards the desired type of CNT Techniques to separate metallic from semiconducting CNTs exist Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 10
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary CNT Field Effect Transistor CNT FET [src: HH2009] Same operation principle as silicon-based transistors Only the conducting channel is CNT based. Source, Drain, Gate can be produced with standard fabrication techniques Under ideal conditions: CNT FET can be up to > 10 x faster, but : imperfections, parasitic capacitances, etc. Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 11
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary CNT NRAM [src: HH2009] Trench with base electrode at bottom CNT suspended over trench off : CNT hangs over trench, no contact to base electrode → very high junction resistance (no contact) on : CNT is bent into trench, contact with electrode → low junction resistance (contact) Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 12
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary CNT NRAM but: does on state consume power to overcome elastic strain of CNT? No , van-der-Waals forces between CNT and electrode molecules keep CNT bent into trench Only state changes require energy Other properties: No mechanical fatigue Naturally radiation hardened Resistant to mechanical shock, vibration Work in a wide temperature range (below room temp to 200 ◦ C) Switching speed: 2GHz for 180nm process, expected to be much higher for smaller feature size Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 13
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary CNT NRAM but: does on state consume power to overcome elastic strain of CNT? No , van-der-Waals forces between CNT and electrode molecules keep CNT bent into trench Only state changes require energy Other properties: No mechanical fatigue Naturally radiation hardened Resistant to mechanical shock, vibration Work in a wide temperature range (below room temp to 200 ◦ C) Switching speed: 2GHz for 180nm process, expected to be much higher for smaller feature size Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 13
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary CNT NRAM Nanotube fabric suspended over embedded electrode. Bond pads on each side. [src: Ward] Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 14
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary CNT Bundle Interconnect Bundle of SWCNTs produced using laser ablation [src: Maser] Current material for interconnect: Cu Problems: Electromigration, grain-boundary scattering Single CNTs have large contact resistance → use bundles of CNTs Performance can be higher than Cu interconnect, esp. for longer distances Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 15
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary Solid-Electrolyte Nanoswitch [src: CDC2009] [src: Kaeriyama] Not CNT based, but still a nano-scale device Solid Electrolyte (Cu 2 S) used as bridge between two metal layers Depending on voltage between metal layers, nanometer-scale metal bridge is grown (switch on ) or shrunk (switch off ) . Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 16
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary Solid-Electrolyte Nanoswitch TEM micrograph of a 4x4 crossbar made of solid-electrolyte switches [src: CDC2009] Properties: Switches can be stacked vertically very low resistance in on state (50 Ω ) Cu based → better compatibility with current CMOS technology than nanowire switches Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 17
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary CNT Thermal Via CNTs have very high thermal conductance along their axis Use CNT bundles as thermal vias to transfer heat from chip interior to heat sink Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 18
CNT Carbon Nanotube Based Architectures FPCNA eFPGAs 3D nFPGA2 References Summary A Field Programmable Carbon Nanotube Array (FPCNA) Designed at University of Illinois at Urbana-Champaign Recent papers from: Chen, Chilstedt, Dong Concept and evaluation, no prototype but: built upon existing base components 2D Design and architecture similar to traditional FPGAs, but uses CNT-based building blocks Reconfigurable and Adaptive Systems (RAS) New Directions in FPGA Design 19
Recommend
More recommend
