1、A High Density Carbon Nanotube Capacitor for Decoupling Applications,Mark M. Budnik, Arijit Raychowdhury, Aditya Bansal, Kaushik Roy July 27, 2006,A High Density Carbon Nanotube Capacitor,Introduction to Decoupling Capacitors Carbon Nanotube Capacitor Physical Structure Carbon Nanotube Electrical Mo
2、del Carbon Nanotube vs. Conventional Capacitors Capacitance per Unit Area Leakage per Unit Area Conclusions,Introduction to Decoupling Capacitors,Decoupling capacitors are used to reduce supply voltage variations in advanced processors,i (t),Input Voltage,+,-,Integrated Decoupling Capacitor Structur
3、e,t,A,A,Traditional Decoupling Capacitors,Problems Parallel plate topology - low capacitance / unit area Expensive die area High leakage current Algorithm placementImprovements? Improve dielectric material - limited Increase area - more expensive, more leakage Decrease dielectric thickness - more le
4、akage Increase number of layers - unproven,Carbon Nanotube Capacitor Alternative,Metallic, single wall carbon nanotubes Offer large surface area to volume ratio, 1nm, 1nm, 1m,Carbon Nanotube Capacitor (CNCAP),C,C,C,C,C,C,C,C,A,A,A,A,A,A,A,A,C = CathodeA = Anode,CNCAP Electrical Model,Parallel CNTs,C
5、NCAP Model,Front,End,R/2,L/2,L/2,R/2,CQ,CG,Front,End,R/2,L/2,L/2,R/2,CQ,CG,CQ,CQ,CC,Cathode,Anode,L,R,CT,Capacitance Per Unit Area,Separation 2 nm 3 nm 4 nm,CC 22.8 aF / m 18.1 aF / m 15.6 aF / m,CT 20.4 aF / m 16.6 aF / m 14.4 aF / m,4xCT 81.6 aF / m 66.4 aF / m 57.6 aF / m,Capacitor Technology 201
6、8 MOS CNCAP, s=2nm CNCAP, s=3nm CNCAP, s=4nm,ITRS Capacitance ( fF / m2 ) 11 - - - - - - - - -,200 CNT Layers Capacitance ( fF / m2 ) - - - 2,710 1,660 1,160,Capacitance Leakage Per Unit Area,Capacitor Technology 2018 MOS CNCAP, s=2nm CNCAP, s=3nm CNCAP, s=4nm,Capacitance ( fF / m2 ) 11 2,710 1,660
7、1,160,Leakage Current ( / m2 ) 20 fA 1.83 A 27.5 pA 0.586 fA,ILEAK,Conclusions,Traditional MOS parallel plate capacitors Limited in ability to serve as decoupling capacitors Limited improvements for the forseeable future Metallic, single wall carbon nanotubes High surface area to volume ratio Small
8、inter-tube spacing can result in appreciable capacitance per unit length May be placed in multiple layer bundles 3-D carbon nanotube capacitor structure High capacitance per unit area ( 11fF / m2 as a function of the number of layers) Low leakage current per unit area ( 1fA / m2 for inter-tube spacing of 4nm),
