Semiconductor fabrication treats compressed air as a process gas. Clean Dry Air (CDA) drives wafer handling, lithography tools, testing and valve actuation, and any particle, moisture or oil contamination can ruin entire wafers.
The CDA specification
CDA systems typically demand ISO 8573-1 Class 1:1:1 with Class 0 oil, and a pressure dew point of -40°C to -70°C or lower. The air is filtered to sub-micron levels and continuously monitored, because the cost of contamination far exceeds the cost of treatment.
System architecture
- Oil-free compressor, usually with variable speed for tool demand swings
- Heatless or heated desiccant dryers in redundant pairs
- Coalescing and particle filtration plus activated-carbon stages
- Stainless or specially treated pipework to prevent shedding
Operational discipline
Build in N+1 redundancy so maintenance never interrupts supply. Monitor dew point, particle count and pressure at the point of use, and log the data for audit. Even short excursions outside specification can justify scrapping product, so the system is designed to fail safe rather than fail cheap.