cleanroom
**Cleanroom** — an environmentally controlled manufacturing space with extremely low levels of airborne particles, essential for semiconductor fabrication.
**Classification (ISO 14644-1)**
- **Class 1 (ISO 3)**: ≤10 particles/m$^3$ at 0.1um. Leading-edge fabs
- **Class 10 (ISO 4)**: ≤100 particles/m$^3$. Standard for lithography areas
- **Class 100 (ISO 5)**: ≤3,520 particles/m$^3$ at 0.1um. General fab areas
- **Class 1000 (ISO 6)**: Less critical process areas
**For comparison**: Outdoor air has ~35 million particles/m$^3$
**How It Works**
- HEPA/ULPA filters remove 99.999%+ of particles
- Laminar airflow pushes particles downward
- Positive pressure prevents outside air infiltration
- Temperature: 21±0.5C, humidity: 43±5% RH
**Personnel Protocols**
- Gowning: Bunny suit, hood, gloves, booties, face mask
- Humans shed ~600,000 particles/minute — the biggest contamination source
- Air showers before entry
**Why It Matters**: A single 50nm particle on a wafer can kill a transistor. Modern chips have features smaller than most airborne particles.