Chip Manufacturing · Topic 6 of 16
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Photoresist
A light-sensitive coating that records the pattern to be etched.
What you’ll learn
- What photoresist does
- Positive vs negative resist
- The coat–expose–develop cycle
Why it matters
Photoresist is the recording medium that turns light into a physical pattern.
Explanation
A liquid photoresist is spun onto the wafer as a thin, even film. Where light hits it (through a mask), its solubility changes. Positive resist becomes soluble where exposed; negative resist becomes insoluble where exposed.
After exposure, a developer washes away the soluble regions, leaving a patterned mask for etching or implantation.
Visual explanation
Key terminology
- Photoresist
- A light-sensitive polymer coating.
- Positive/negative resist
- Whether exposed regions become soluble or insoluble.
- Spin coating
- Applying an even film by spinning the wafer.
Example
Common mistakes
Watch out for:
- Confusing which regions remain for positive vs negative resist.
Real-world application
EUV lithography needs specially engineered resists sensitive to 13.5 nm light.
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Photoresist
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Photolithography
Chip Manufacturing
Printing each layer's pattern onto the wafer with light — the step that decides how small a chip's features can be.
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