1. Filtration
2. Reverse osmosis
3. Oxidation
4. UV
5. Degassing
6. Electrodeionization
7. Ion exchange
8. Ultrafiltration
The specifications for ultrapure water and analytical measurement capabilities have evolved to meet the demanding needs of manufacturers of microprocessors, semiconductors, and other silicon-based devices. Ultrapure water is generally considered to have a resistivity >18.2 MΩ-cm at 25 °C and to contain low concentrations of metals in parts per billion (ppt), less than 50 ppt of inorganic anions and ammonia, less than 0.2 parts per billion (ppb) of organic anions, and less than 1 ppb of total organic carbon (TOC) and silica (dissolved and colloidal).
Ion exchange resins play a vital role in the ultrapure water production process. Dow Water & Process Solutions offers specially designed ion exchange resins that provide extended service life and high-purity water clarification capabilities for specialized electronics applications, such as the fabrication of lower-density display devices and integrated circuit (IC) chips, or wafer slicing and chip-termination assembly operations. Consider, for example, DOW AMBERJET UP4000, a strong-base, uniform anion exchange resin specifically developed for ultrapure water production for the semiconductor industry. It can be used in single vessels or in mixed-bed units in conjunction with DOW AMBERJET™ UP1400 for the removal of ionized organic matter from water.
However, ion exchange processes typically do not remove non-ionized organic matter, including many man-made organic compounds, thus requiring other types of membrane treatments. DOW FILMTEC™ SG reverse osmosis elements (for use with semiconductors) have been specifically designed and manufactured to achieve the ultrapure water quality required for manufacturing electronic components, such as microprocessor chips. These electronic elements include a membrane that offers high filtration capacity for low molecular weight organic compounds and silica, as well as an accelerated TOC washout profile—important characteristics for the electronics manufacturing industry.
