Semiconductor Process Technologies

ECE222

2http://www.porticus.org/bell/belllabs_transistor.html

First Transistor

1947 Bardeen Brattain and Shockley invented the first point-contact transistor.

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First Planar Transistor: Fairchild 2N1613

Jean Hoerni, Fairchild Semiconductor, 1959Silicon NPN Planar TransistorProtective oxide layer on top

http://semiconductormuseum.com/PhotoGallery/PhotoGallery_2N1613.htm

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First MOSFET

M.M. Atalla and Dawon Kahng, Bell Labs, 1959MOSFET Transistor

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First Integrated Circuit

Jack Kilby, Texas Instruments, 1958First IC: five resistors and capacitors on a germanium substrate

http://www.computerhistory.org/timeline/?category=cmpnt

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First Monolithic IC

Fairchild Semiconductor, 1961Resistor-transistor logic (RTL) flip-flop

http://www.computerhistory.org/timeline/?category=cmpnt

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From Transistor to Integrated Circuit

Vacuum tube

Point-contact transistor (1947)

Junction bipolar transistor (1951)

Diffused-base transistor (1955)

Integrated circuits (1961)

Dates in parenthesis are when the technology was invented.

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Modern VLSI

IBM Power5 Microprocessor Copper Interconnect

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MOSFET Device Structure

Polysilicon Aluminum

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MOSFET Device Structure: Cross Section

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Integrated Circuit Process Flow

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Crystal Growth

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Silicon Crystal Ingots

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Silicon Wafer

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Oxidation

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Oxidation

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Chemical-Vapor Deposition (CVD)

Used for deposition of• Silicon films: epitaxy layer, polysilicon• Dielectric Films: SiO2, Nitride, …• Metals: aluminum, tungsten, TiN, …

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Sputtering for Metallization

Ion beam

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Photolithography: Shadow Printing

UV Light

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Lithography: Projection Printing

(a) annual-field wafer scan (b) 1:1 step-and-repeat

(c) M:1 reduction step-and-repeat (d) M:1 reduction step-and-scan

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Pattern Transfer by Photolithography

PositiveResist

NegativeResist

A big advantage of silicon vs. GaAs is that SiO2 can be used as the mask for silicon in pattern transfer

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Liftoff Process

Used extensively for discrete devices such as power MOSFETs

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Wet Chemical Etching

H3PO4+…Al

HF or H3PO4Si3N4

HF (or NH4F)SiO2

HNO3+HFSi

EtchantMaterial

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Orientation-Dependent Etching of Single-Crystal Silicon

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Plasma-Assisted Dry Etching

Plasma Etching Mechanisim Reactive Ion Etching (RIE) Reactor

Silicon Trenches by Deep RIE

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Wet Etching vs. Dry Etching

Wet Etching: • Isotropic• Loss of resolution in pattern transfer

Dry Etching:• Anisotropic• High-fidelity transfer

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Chemical-Mechanical Polishing (CMP)

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Metal Patterning: Damascene Process

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Impurity Doping: Diffusion & Ion Implantation

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Diffusion

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Ion Implantation

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Packaging

Wirebond

Flip-ChipChip-Stack

Chip Package

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Further Reading

• Sedra & Smith, A.1• S.M. Sze, Semiconductor Devices: Physics and

Technology, 2nd ed., Wiley, 2002• International Technology Roadmap for

Semiconductors, http://public.itrs.net