UPW (UltraPure Water) for semiconductor manufacturing
Water plays an important role in the semiconductor manufacturing process, particularly UltraPure Water (UPW). Semiconductor manufacturing facilities are typically located in areas with reliable water supplies, indicating the importance of water in semiconductor manufacturing. Throughout the entire semiconductor and microelectronics manufacturing process, this essential resource plays a key function.
The UPW ensures component purity and enhances productivity throughout the semiconductor manufacturing process, demonstrating its crucial responsibility in success and functionality.
When is water ultrapure?
The unit of measure most often used to assess water at such high purity is resistivity, expressed in Megohms centimetre (MΩ.cm). The higher the resistivity, the purer the water, owing to the lack of ionic contaminants present to conduct electrical charge. As a basic requirement, water is classed as ultrapure when it has a resistivity of 18.2 MΩ.cm (conductivity 0.055 µS/cm) and its organic and inorganic matter must be very low. The water’s TOC (total organic carbon) should only be 1 to 3 µg/L (ppb).
Water quality standards for UPW used in the semiconductor industry
| Test Parameter | Advanced Semiconductor UPW | Monitoring Method |
|---|---|---|
| Resistivity (25°C) | >18.18 MΩ.cm | Online resistivity meter |
| Total organic carbon (on-line for <10 ppb) | <1 μg/L | Online TOC meter |
| On-line dissolved oxygen | 10 μg/L | Online dissolved oxygen meter |
| On-line particles (>0.05 μm) | <200 particles/L | Online light scatter |
| Non-volatile residue | 100 ng/L | Particle counter and non-volatile residue monitor |
| Silica (total and dissolved) | 50 ng/L | GFAAS or inductively coupled plasma |
| 22 most common elements | <1–10 ng/L | (ICP/MS) |
| 7 major Anions and Ammonium | 50 ng/L | Ion chromatography or inductively coupled plasma |
| Bacteria | <1 CFU/100 mL | Microbial culture techniques or ATP testing |
The role of ‘ultrapure water’ in the semiconductor process
As a result of its exceptionally high purity levels, UltraPure Water (UPW) is used in a wide range of critical stages of the semiconductor manufacturing process, as well as various other applications. The following are some of the key areas where UPW is used:
Wafer cleaning:
UPW is a crucial component to the processing of semiconductor wafers to remove particles, residues, and contaminants that could negatively affect the manufacturing process and the final performance of the semiconductor device at the end of the process.
Etching:
In semiconductor wafer etching processes, UPW can be used to remove specific layers of material from semiconductor wafers precisely to achieve desired results. As part of this critical process, it is imperative that the water be pure to avoid introducing any impurities into the water supply.
Rinsing:
The semiconductor wafers need to be thoroughly rinsed after each process step to remove any remaining chemicals or contaminants that may have remained in the wafer. As a result, UPW is used in this process to ensure that the wafers are clean and free from residues that might affect the subsequent manufacturing steps in the process.
Chemical Mechanical Planarization (CMP):
As part of the CMP process, UPW is used to polish semiconductor wafers and to achieve the flatness and smoothness required for the fabrication of integrated circuits.
Photoresist Processing:
UPW is used as a preparation and development medium for photoresist layers, which are responsible for defining the patterns on semiconductor wafers during photolithography processes.
Dilution of chemicals:
There are several chemicals that are used in semiconductor manufacturing processes that need to be diluted to certain concentrations. As a diluent, UPW is used to ensure that chemical formulations are as accurate and precise as possible.
Cooling systems:
In addition to use in the cooling systems of semiconductor manufacturing equipment to maintain optimal operating temperatures and prevent overheating, UPW is also used in the cooling systems of other types of equipment.
UPW plays an important role in ensuring the quality, reliability, and performance of semiconductor devices through the provision of ultra-clean water to various manufacturing processes that are required to ensure the quality, reliability, and performance of semiconductor devices.
UltraPure Water and Purite
Production and maintenance of UltraPure Water (UPW) requires careful attention, but with the right system design, it is both achievable and sustainable. With over four decades’ experience purifying water for industrial and scientific purposes, Purite can help semiconductor and micro-electronics companies overcome the challenges associated with delivering reliable, cost-effective, and sustainable UPW solutions.
We provide comprehensive services including design, installation, and commissioning for facilities of all sizes, tailored to site-specific requirements. We remain committed to meeting semiconductor manufacturers’ ever-changing needs. Get in touch with us if you would like to learn more about our services.
