| Summary: | 碩士 === 弘光科技大學 === 環境工程研究所 === 97 === Chemical mechanical polishing (CMP) wastewater of semiconductor industry by wafer surface planarization process is highly polluted. Because the CMP slurry contains nano particles and many kinds of organic or inorganic compounds, so the wastewater become complex and refractory. Thus, CMP wastewater needs to be treated properly to avoid the serious impact to the ecological environment. Initially, coagulation is the main CMP wastewater treatment method, which may remove the particles and reduce the turbidity effectively. However, the high operating cost and low recycling benefit make it unsuitable for the more advanced treatment requirement. Therefore, many innovative treatment technologies are developed recently. The objective of this research was to collect and analysis the literatures of CMP wastewater treatment technology from domestic semiconductor industries in this decade as well as the analysis for characteristics of CMP wastewater. In addition, the performance of each treatment technology was compared with four indexes such as technical feasibility, treatment efficiency, cost and operating difficulty.
From the results, the domestic semiconductor industry is water-consuming, which is dozens to hundreds of tons per day in CMP process. The water consumption quantities raising by the production increasing. One of the typical average consumption rate is 0.23 m3/pcs, which is about 7 % of all manufacturing process. The CMP wastewater contain many fine particles, and the characteristics such as narrow particle size distribution, higher Zeta potential, good suspension and stability. The CMP wastewater quality is extremely unstable which makes the treatment to be difficult. The major CMP wastewater treatment methods are coagulation, membrane filtration, electrochemistry, air bubble flotation and magnetic separation. Based on the technical feasibility index, coagulation is the best that magnetic separation is the worst; For the treatment efficiency, membrane filtration is superior that magnetic separation is least priority; The most economic benefit is magnetic separation that membrane filtration is the most expensive one; The membrane filtration is easiest to operate that coagulation and air bubble flotation are more difficult to operate. Therefore, the membrane filtration method is the best CMP wastewater treatment technology so far, though its cost is higher. The air bubble flotation or electrochemistry can be consider as the pretreatment to reduce the running cost and water recycle requirement at the same time. Besides, the magnetic separation is in the developing stage, that requires some technical improvement, so it’s not suitable at present. Finally, this research can provide the most suitable technology selection for a new semiconductor plant as well as provide the reference for optimum operation adjustment for a existing semiconductor plant.
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