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[05]
MECS's. Veolia currently regenerates spent semiconductor two distillation columns. One is used to remove water from the
sulfuric acid in Linden, New Jersey and El Paso, Texas in the IPA and the other is used to recover the third solvent. However,
United States but its impurities of the final product are at ppb this method has a problem in that the risk of contamination
level as well. In sum, no current process licensers claim they due to the use of a solvent increases, and management costs
can meet with the semiconductor grade H 2 SO 4 quality. and equipment costs are high. In addition, a third solvent may
act as another impurity to contaminate the IPA. If such a third
2.2 Waste IPA Regeneration Technology
pollution occurs, there is a problem that the purification by
Isopropanol(IPA) is widely used as a drying solvent installing another distillation column. The best achievement is
and cleaning agent in the semiconductor, electronics, at ppb level of impurities, suitable only for LCD grade.
pharmaceutical, and fine machine parts industries. A In sum, no current process licensers claim they can meet
conceptual study of distillation, extraction, reactive distillation, with the semiconductor grade of IPA quality.
adsorption, and membrane-based processes was performed
2.3 Waste NH 3 Regeneration Technology
for the purification and recovery of isopropanol(IPA) from waste
streams. Through use of computer simulation and literature/ RCA standard clean solution(ammonia+hydrogen
design methodologies, traditional methods were shown to be peroxide) is widely used in wafer clean process to removes
unable to obtain semiconductor grade IPA purities with the the particulate pollutants from the wafer surface, resulting in
available equipment. [06] high concentrations of ammonia in the discharged wastewater.
Typically, the IPA solution cannot be used when the Ammonia-nitrogen wastewater causes environmental
water content exceeds about 15 to 20 wt% water. The simple problems of optimizing water quality and nourishment. Since
regeneration of the IPA by distillation is not possible due to the the amount of the ammonia-nitrogen wastewater is quite
[07]
water-IPA azeotrope at 85 wt% IPA. large, the treatment method using breakpoint chlorination
An integrated method consisting of air stripping in generally requires a relatively high cost ; while the biological
conjunction with condensation and packed activated carbon treatment method has a lower processing cost, it requires a
fiber(ACF) adsorption for dealing with this waste solvent. The larger processing space and a longer processing time.
air stripping with proper stripping temperature control was In addition, some semiconductor factories use
employed to remove IPA from the waste solvent and the membrane distillation, which uses a hydrophobic hollow fiber
IPA vapor in the gas mixture was condensed out in a side gas permeable membrane inside and a shell side to pass
condenser. The air stripping with condensation was able to ammonia-containing wastewater and an acidic absorbent(such
recover up to 93% of total IPA in the initial waste solvent. The as dilute sulfuric acid) in a reverse flow manner to produce
[14]
recovered IPA was found to be of high purity and could be ammonium sulfate solution. Then, the water vapor is directly
only considered for reuse as industrial grade. [08][09] sprayed from the bottom of the stripping tower into contact
Another IPA purification method is the removal of water with ammonium sulfate solution, ammonia is taken out from
from the IPA using a pervaporation membrane up to a the top of the tower, and then condensed to obtain high-
concentration of 300-500ppm. However, it is difficult to remove concentration and high-purity ammonia water, and then
water below 100ppm and is not suitable for medium to large vacuum-atomizes the ammonia to pressurize the liquid
scale industries, which are practical operating conditions. That ammonia purification system to obtain semiconductor grade
is, it is necessary to lower the pressure on the side where the liquified ammonia. [15]
product of the membrane is produced by using the vacuum
equipment to give pressure difference on both sides of the 3. Overview of Tai-Chung Zero Waste Manufacturing Project
membrane. [10][11]
3.1 Project Goals
Another IPA purification method involves mixing a third
solvent with water and an IPA mixture to remove the water Firstly TSMC targets to develop the world's first state
from the IPA by allowing the water and the third solvent to of art electronic-grade material regeneration technologies.
form an azeotrope at a lower temperature instead of forming The quality meets the TSMC electronic grade raw material
an azeotrope with the IPA and water. [12][13] The method requires specifications, and the objective is to reduce the fresh raw

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