Semiconductor Ultra Pure Water Treatment
Semiconductor water treatment is Ultra-Pure Water treatment aiming to reduce inorganics, organics, particulates (inorganic, organic and biological) and gases in water to the ppb range.
The most widely used requirements for UPW quality are documented by ASTM D5127 "Standard Guide for Ultra-Pure Water Used in the Electronics and Semiconductor Industries".
The technologies used are UF, RO, EDI, Mixed Bed Ion Exchange, Advanced Oxidation Processes (AOP's), UV, Active Carbon Filtration, combustion/heat and sometimes Membrane Contactors for degasification. All piping used must be semiconnductor grade to prevent particle and fiber shedding and leaching of any chemicals.
Chemicals used have to be semiconductor grade. Pumps used have to be of special design to minimize particle shedding. Some semiconductor grade ion exchange resins are sometimes used. UPW tanks are usually blanketed with Nitrogen to prevent the dissolution of gases such as O2 and CO2.
Production facilities in the semiconductor industry are CleanRoom type with HEPA fitted HVAC systems that filter out dust from the air. There are several classes of clean rooms depending on the size and number of dust particles per m3 of air. Workers in a semiconductor fab are normally fitted with "bunny suits" to prevent particle, bacteria and hair shedding from the body.
Impurities in semiconductor processing water have a negative impact on production yields due to defects caused by impurities in the production and lithographic process.
Monitoring these impurities requires specialized analytical instruments. From sampling and measuring to characterization and more, Air Liquide’s world-class analytical services are key in helping electronics manufacturers control, monitor and improve their Fab throughput, and assure the quality of electronics devices.
Waste water from the rinsing operations are normally high in some heavy metals like Copper. Clarifiers are one technology used for purification of this waste water as well as selective Ion Exchange and RO membranes. It is possible to recycle this water internally as it is still quite clean water.
Here is an interesting article from Hager El Sasser on this subject.
Here is an interesting article on waste water treatment for semiconductor industry.
Major suppliers of water treatment plants for the Semiconductor industry are:
GE Water aquired by SUEZ in 2017
Siemens Water now Evoqua
DOW has Special Semiconductor Grade RO membranes.
Compiled by Rami E. Kremesti M.Sc. , CSci, CWEM, CEnv
Last updated October 2, 2017