The need for ultra-pure water in semiconductor fabrication arises from the fact that even minute impurities can have a significant impact on the performance and reliability of semiconductor devices. Contaminants such as ions, particles, organic materials, and bacteria can interfere with the manufacturing processes, leading to defects in the final products.
Ultra-pure water is used in several critical steps of semiconductor fabrication, including:
- Cleaning: UPW is used for cleaning semiconductor wafers at various stages of the manufacturing process. Any residue or impurities on the surface of the wafers can lead to defects, affecting the functionality of the integrated circuits.
- Rinsing: After each chemical process, the wafers need to be thoroughly rinsed to remove any remaining chemicals. UPW is used in this rinsing step to ensure complete removal of contaminants.
- Dilution of Chemicals: Many chemicals used in semiconductor manufacturing processes need to be mixed or diluted with ultra-pure water. This ensures that the chemicals are not introducing additional impurities into the fabrication process.
- Cooling: UPW is used as a coolant in various tools and equipment used in semiconductor fabrication. Using ultra-pure water helps maintain stable temperatures without introducing contaminants that could affect the semiconductor manufacturing process.
The production of ultra-pure water involves multiple purification techniques, including distillation, deionization, and filtration. The water quality is monitored rigorously to maintain specific standards, typically measured in parts per billion (ppb) or even parts per trillion (ppt) for certain critical applications.
In summary, ultra-pure water is a critical component in semiconductor fabrication because it provides a clean and controlled environment, free from contaminants, ensuring the reliability and performance of the semiconductor devices produced.