A study on the Separation of Acetic Acid, Nitric Acid and Hydrofluoric Acid from Waste Etching Solution of Si Wafer Manufacturing Process

Silicon wafer 에칭공정시 발생(發生)되는 폐(廢)에칭액 으로부터 초산(醋酸), 질산(窒酸) 및 불산(弗酸)의 분리.회수(分離.回收)에 관한 연구(硏究)

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  • 안재우 (대진대학교 신소재공학과)
  • Published : 2007.02.27

Abstract

Recovery of acids from the waste etching solution of containing acetic, nitric and hydrofluoric acid discharged from silicon wafer manufacturing process has been attempted by using solvent extraction method. EHA(2-Ethylhexlalcohol) for acetic acid and TBP(Tri-butly Phosphate) for nitric and hydrofluoric acid as a extraction agent was used to the experiment to obtain the process design data in separation procedure. From the experimental data and McCabe-Thiele diagram analysis, we obtained the optimum conditions of phase ratio(O/A) and stages to separate each acid sequently from the mixed acids. The recovery yield was obtained above 90% for acetic acid from the acid mixtures, 90% for nitric acid from acetic acid extraction raffinate and then above 67% for hydrofluoric acid from final extraction raffinate.

실리콘 웨이퍼 제조공정 중 발생되는 초산, 질산 및 불산을 함유한 3성분계 폐혼산으로부터 개별산으로 분리하여 재활용할 목적으로 용매추출법을 적용하였다. 각 산의 분리를 위해 사용한 추출제로는 초산의 경우는 EHA(2-Ethylhexlalcohol)를 사용하였고, 질산과 불산의 경우에는 TBP(Tri-butylphosphate)를 사용하여 각 산의 분리과정에 대한 공정설계를 위한 기초 data를 얻고자 하였다. 3성분계 폐혼산에서 초산을 추출 분리하고 이후 추출여액 중 질산 및 불산을 순차적으로 추출 분리 할 수 있는 연속공정개발을 위하여 기초 실험 자료와 McCabe-Thiele해석을 통해 최적 투입유량비(O/A), 소요단수(Stage) 등을 결정하였다. 분석 결과 혼산으로부터 초산의 회수율은 90%이상 이었으며 초산 추출여액에서 질산의 회수율은 90%, 최종 추출잔류액에서 불산의 회수율은 67%이상 이었다.

Keywords

References

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