particulate control
**Particulate Contamination Control** encompasses clean room practices, filtration systems, and procedures designed to minimize particle deposition on semiconductor wafers.
## What Is Particulate Contamination Control?
- **Goal**: Keep particle counts below critical defect density
- **Methods**: HEPA/ULPA filtration, clean room protocols, equipment design
- **Metrics**: Particles per wafer, particles per ft³ of air
- **Standard**: ISO 14644 defines clean room classifications
## Why Particle Control Matters
At advanced nodes, particles >20nm can cause killer defects. A single particle on a critical layer fails multiple die.
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**Contamination Control Methods**:
| Source | Control Method |
|--------|----------------|
| Air | ULPA filters (99.9995% @ 0.12μm) |
| People | Gowning, airlocks, automation |
| Equipment | Pod-to-pod transfer, mini-environments |
| Process | Wet cleans, megasonic, HF dips |