1.Introduction If the automobile had followed the same development cycle as the computer,a Rolls- Royce would today cost $100,get one million miles to the gallon and explode once a year Digital IC
Digital IC Introduction 1.Introduction If the automobile had followed the same development cycle as the computer, a RollsRoyce would today cost $100, get one million miles to the gallon and explode once a year
outline 。Course Introduction a brief history ·Design Metrics ·DIC characteristics Design partitioning/CMOS logic Semiconductor processing Digital IC 2
Digital IC outline • Course Introduction • a brief history • Design Metrics • DIC characteristics • Design partitioning/CMOS logic • Semiconductor processing 2
Semiconductor processing Semiconductor fabrication 。Layout fundamental o Semiconductor testing Semiconductor assembling Digital IC 3
Digital IC Semiconductor processing • Semiconductor fabrication • Layout fundamental • Semiconductor testing • Semiconductor assembling 3
CMOS Fabrication CMOS transistors are fabricated on silicon wafer photolithography process similar to printing press On each step,different materials are deposited or etched Easiest to understand by viewing both top and cross-section of wafer in a simplified process Note:photolithography from Greek photo(light),lithos(stone),and graphe(picture) means "carving pictures in stone using light Digital IC 4
Digital IC CMOS Fabrication • CMOS transistors are fabricated on silicon wafer • photolithography process similar to printing press • On each step, different materials are deposited or etched • Easiest to understand by viewing both top and cross-section of wafer in a simplified process • Note:photolithography from Greek photo(light),lithos(stone),and graphe(picture) means “carving pictures in stone using light” 4
Inverter Cross-section Typically use p-type substrate for nMOS transistors Requires n-well for body of pMOS transistors GND N SiO2 n+diffusion p+diffusion n+ n+ p+ p+ n well polysilicon p substrate metal1 nMOS transistor pMOS transistor Digital IC 5
Digital IC Inverter Cross-section • Typically use p-type substrate for nMOS transistors • Requires n-well for body of pMOS transistors n+ p substrate p+ n well A Y GND VDD n+ p+ SiO2 n+ diffusion p+ diffusion polysilicon metal1 nMOS transistor pMOS transistor 5
Well and Substrate Taps Substrate must be tied to GND and n-well to VDD Metal to lightly-doped semiconductor forms poor connection called Shottky Diode Use heavily doped well and substrate contacts taps GND n+ n+ p+ p+ n+ n well p substrate substrate tap well tap Digital IC 6
Digital IC Well and Substrate Taps • Substrate must be tied to GND and n-well to VDD • Metal to lightly-doped semiconductor forms poor connection called Shottky Diode • Use heavily doped well and substrate contacts / taps n+ p substrate p+ n well A Y GND VDD p+ n+ substrate tap well tap n+ p+ 6
Latchup External voltages can ring below GND or above VDD GND Dx ns n+ DA n+ p-substrate n-wel R (a) Substrate Tap Well Tap n well R n+ R (b) ut GND p substrate n+guard ring p+guard ring 7 (a) (b)
Digital IC Latchup External voltages can ring below GND or above VDD 7
Inverter Mask Set Transistors and wires are defined by masks Cross-section taken along dashed line GND nMOS transistor pMOS transistor substrate tap well tap Digital IC 8
Digital IC Inverter Mask Set • Transistors and wires are defined by masks • Cross-section taken along dashed line GND VDD Y A substrate tap well tap nMOS transistor pMOS transistor 8
Detailed Mask Views(Six masks) o n-well n well ·Polysilicon 图 Polysilicon 。n+diffusion n+Diffusion p+diffusion p+Diffusion Contact Contact 。Metal ☑ Metal Digital IC 9
Digital IC Detailed Mask Views(Six masks) • n-well • Polysilicon • n+ diffusion • p+ diffusion • Contact • Metal Metal Polysilicon Contact n+ Diffusion p+ Diffusion n well 9
Devices and Layers from a Silicon Chip Top protective layer Conductive layer Metal layer Insulation layers Recessed conductive layer Silicon substrate Silicon substrate Semiconductor Manufacturing Technology by Michael Quirk and Julian Serda Digital IC 10
Digital IC Devices and Layers from a Silicon Chip Silicon substrate drain Silicon substrate Top protective layer Metal layer Insulation layers Recessed conductive layer Conductive layer Semiconductor Manufacturing Technology by Michael Quirk and Julian Serda 10
