PART 2 • CLEANROOM FUNDAMENTALS

Why do we need cleanrooms?

Microfabrication works with extremely small structures, so contamination that seems tiny to us can become a major fabrication defect.

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Dust, fibers, skin particles, oils, chemical residue, and other contaminants can interfere with processes such as lithography, deposition, etching, and bonding.

Key idea: As device features become smaller, contamination control becomes more important.

CONTAMINATION

Where does contamination come from?

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People

Skin particles, hair, clothing fibers, oils, and salts.

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Airborne Particles

Dust and other particles can settle onto wafer surfaces.

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Process Residue

Chemicals, photoresist, metals, and previous process materials.

A clean wafer can easily become contaminated again if it is handled improperly.

WAFER CLEANING

Start with a clean surface.

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Before important fabrication steps, wafers are cleaned to remove contamination from their surfaces.

Cleaning can target particles, organic residue, and metallic contamination.

One established semiconductor cleaning method is known as RCA cleaning.

A contaminated starting surface can create defects that remain through later processing.

UNIT 4 STUDY COMPLETE

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Ready for the Fab Challenges?

You've covered Cleanroom Basics & Wafer Cleaning.