Chip Manufacturing · Topic 10 of 16
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Chip ManufacturingLesson 10 of 16
CMP
Chemical-mechanical planarisation — polishing each layer flat before the next.
What you’ll learn
- Why planarity is essential
- How CMP works
- Where CMP is used
Why it matters
Without flat surfaces between layers, lithography can't stay in focus and wiring fails.
Explanation
CMP presses the wafer against a rotating pad with an abrasive, chemically active slurry, removing high spots to leave a flat surface. It is used many times through the process.
Flatness (planarity) keeps each new lithography layer sharp and lets many metal layers stack reliably.
Visual explanation
Key terminology
- Planarisation
- Making a surface flat.
- Slurry
- The abrasive, reactive polishing fluid.
Example
After depositing metal into trenches, CMP polishes back the excess to leave flat, isolated wires.
Common mistakes
Watch out for:
- Thinking CMP is a one-time step — it recurs at nearly every layer.
Real-world application
Copper interconnect (the damascene process) depends entirely on CMP.
Explore related concepts
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CMP
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Metallization
Chip Manufacturing
Wiring the transistors together with layers of metal interconnect.
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