EE1411EE1411EECS141EE141EE141--Fall 2006Fall 2006Digital Integrated Digital Integrated CircuitsCircuitsLecture 11Lecture 11Wire modelingWire modelingCMOS logicCMOS logicEE1412EECS141AnnouncementsAnnouncements No lab this week Lab 4 reports due next week Hardware lab next week Homework #5 due today No new homework this week Midterm 1 on Thursday, 6:30-8pm, 105 North G. Material until last lecture, homework 5, lab 4 Review session tonight 6-7:30pm, 60 Evans Check the web page for extra office hours There is a lecture on Th No lecture on October 24EE1412EE1413EECS141Class MaterialClass Material Last lecture Scaling Wires Today’s lecture Wire models CMOS logic gates Reading (Chapters 4, 6)EE1414EECS141EE1413EE1415EECS141INTERCONNECTINTERCONNECTEE1416EECS141Wire Resistance Wire Resistance WLHR = ρH WLSheet ResistanceRoR1R2EE1414EE1417EECS141Interconnect Resistance Interconnect Resistance EE1418EECS141Dealing with ResistanceDealing with Resistance Selective Technology Scaling Use Better Interconnect Materials reduce average wire-length e.g. copper, silicides More Interconnect Layers reduce average wire-lengthEE1415EE1419EECS141EE14110EECS141EE1416EE14111EECS141PolycidePolycideGate MOSFETGate MOSFETn+n+SiO2PolySiliconSilicidepSilicides: WSi2, TiSi2, PtSi2and TaSiConductivity: 8-10 times better than PolyEE14112EECS141Sheet ResistanceSheet ResistanceEE1417EE14113EECS141Modern InterconnectModern InterconnectEE14114EECS141Example: Intel 0.25 micron ProcessExample: Intel 0.25 micron Process5 metal layersTi/Al - Cu/Ti/TiNPolysilicon dielectricEE1418EE14115EECS141Modern InterconnectModern Interconnect 90nm process EE14116EECS141INTERCONNECTINTERCONNECTEE1419EE14117EECS141InterconnectInterconnectModelingModelingEE14118EECS141The Lumped ModelThe Lumped ModelVoutDrivercwireVinClum pedRdriverVoutEE14110EE14119EECS141EE14120EECS141The Elmore DelayThe Elmore DelayRC ChainRC ChainEE14111EE14121EECS141Wire ModelWire ModelAssume: Wire modeled by N equal-length segments For large values of N:EE14122EECS141The Lumped RCThe Lumped RC--ModelModelThe Elmore DelayThe Elmore DelayEE14112EE14123EECS141The Distributed RCThe Distributed RC--linelineEE14124EECS141StepStep--response of RC wire as a response of RC wire as a function of time and spacefunction of time and space0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 500.511.522.5time (nsec)voltage (V)x= L/10 x = L/4 x = L/2 x= LEE14113EE14125EECS141Driving an RCDriving an
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