520.216 Introduction to VLSI Systems 1

520.216Introduction to VLSI Systems

Lecture 3

Integrated Circuits Fabricationand

Very Large Scale Integration

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Charges and Their Movement (I)

• Electrons• Ions

SuperconductorsConductorsSemiconductorsInsulators

SolidsLiquidsGases

and

INTERFACES

Where? How Well?

How?

Drift / Diffusion (Classical)Tunneling (Quantum Mechanical)

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Charges and Their Movement (II)

FUNCTIONAL STRUCTURAL

• Electrical conduits(1D, 2D, 3D)• Transistors• Switches

• Etching• Film deposition(electroplating)

REDOX

We now consider transport in the solid-state and more specifically in the semiconductor Silicon

the microelectronics world does not use SI units! distance will be measured in cm and not meters.

for example: conductivity has units of ohm-cm

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Silicon!

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SiliconSisemiconductor

P.D. Neillist, "Incoherent Transmission Electron Microscopy" Phys. Rev. Lett. 81, 4156 ( 9 Nov. 1998)

Silicon molecule 5 silicon atoms in a unit cellDiamond latticeCovalent bonds

14 electrons4 valence electrons

Silicon molecules: http://www.eere.energy.gov/pv/simolecule.html

0.543 nm0.235 nm

Si Si Si

Si Si Si

Si Si Si

electronsholes

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Doped Silicon

N- doped P- doped

Silicon molecules: http://www.eere.energy.gov/pv/simolecule.html

Si Si Si

Si P Si

Si Si Si

free electrons and holes

Si Si Si

Si B Si

Si Si Si

bound electrons

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Equilibrium Carrier Densities

2i

o D oD

nn N and p n typeN

= = −

2i

o A oA

np N and n p typeN

= = −

where no is electron and po hole carrier concentrations

in most cases of interest the donor doping ND or acceptor NA doping concentration is much larger than the intrinsic concentration ni so that

2 20 310 cmn o in p n −= =

by convention, donor or acceptor concentrations as well as electron and hole concentrations are given as a number per cm3

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Integrated Circuit Fabrication

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Where is it done?

UMC 300mm wafers

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Basic CMOS components

• Conductors• Switches (MOS transistors)• Capacitors (MOS capacitors)• Inductors• Resistors

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Bulk CMOS Technology (I)

p-substrate

n-well

n++p++

Polysilicon 1

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polysilicon 2

contact metal 1

Bulk CMOS Technology (II)

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vias metal 2

metal 3

Bulk CMOS Technology (III)

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CMOS Inverter

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Metallization Details

IBM PowerPC 500nm

UMC CMOS 90nm