Humidity control in the production of semiconductors is used to prevent the build-up of static electricity, prevent dimensional changes from occurring on the surface of the silicon wafer and cool the manufacturing environment.
Any uncontrolled electrical static discharge that occurs during production can damage the surface of the semiconductors and significantly lower production yields. The manufacturing process generates heat and this in-turn dries the air. As dry air promotes static build-up, humidifiers are used to control the atmosphere to around 55% relative humidity (%rH). This encourages the static to naturally dissipate removing the risk of damage to the surface of the semiconductor.
However, the printed surfaces of the silicon wafer are also very sensitive to moisture. The conductive tracts on the surface can distort during manufacturing if exposed to incorrect humidity levels. Extremely close control of humidity to ±0.1°C dew point over any 40 minute period is required. Any variation greater than this and the conductive tracts will be damaged and the semiconductor ruined.
Resistive seam humidifiers such as the Condair RS can provide this precise level of control while cold water humidifiers also offer the additional benefit of evaporative cooling. This helps lower the ambient temperature during manufacturing and reduces the required cooling, saving energy and lowering costs.
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