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실리카 활성화제를 이용한 부유 실리카의 응집

The Flocculation of Colloidal Silica Particles by Using Silica Activators

정소연 조영상^† 김주희 김우식¹ 조철형² 김영일²

So-youn Jung Young-sang Cho^† Ju-hee Kim Woo-sik Kim¹ Chul-hyung Cho² Young-il Kim²

한국과학기술연구원 청정기술연구센터, 서울 136-791 ¹경희대학교 화학공학과, 용인 449-701 ²(주)하이닉스반도체, 서울 136-791

Clean Technology Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea ¹Department of Chemical Engineering, Kyunghee University, Yongin 449-701, Korea ²Hynix Semiconduct. Co. Ltd., Seoul 136-791, Korea

HWAHAK KONGHAK, December 2001, 39(6), 770-776(7), NONE

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Abstract

본 연구에서는 반도체 제조 과정중 화학적 기계 연마(CMP) 폐수 중의 부유 실리카 문제를 해결하는 방법의 하나로 전통적인 응집 방법에 더하여 황산, 질산, 염산 등의 실리카 활성화제를 추가적으로 사용하는 경우 효과가 있음을 발견하고 이들 실리카 활성화제가 응집에 미치는 영향에 대하여 조사하였다. 실험결과 부유 실리카 수용액에 실리카 활성화제를 첨가하면 실리카의 입경이 증대되고 입자 표면의 음전하의 세기도 동시에 증가함을 알 수 있었다. 또한 실리카 활성화제, 음이온 폴리머 응집제와 Ca(OH)₂ 응집제를 순차적으로 투입하는 방법에 의해 형성되는 실리카 최종 응집체의 크기와 밀도도 모두 크게 증대되었으며 결과적으로 최종 응집체의 침전 특성이 개선됨을 알 수 있었다. 실리카 활성화제로는 황산이 가장 우수한 결과를 주는 것으로 관찰되었으며 적절한 양의 실리카 활성화제와 응집제를 투입하는 경우 입경 15 mm의 초대형 고밀도 응집체의 형성이 가능함을 알 수 있었다.

In this study the use of silica activators such as sulfuric acid, nitric acid and chloric acid, in addition to the conventional coagulants and flocculants, was found to give much better results in flocculating and sedimenting the colloidal silica particles from CMP process which is now generally used in semiconductor industry for the purpose of planarizing the surface of the silicon dioxide. Experimental results show that both the diameter of the silica particles and the negative charge build-up on the surface on the silica particles are increased when the silicon activator is added into the colloidal silica solution. It was also found that the final silica floc formed by using a silica activator, and anion polymer flocculant and Ca(OH)₂ has a higher density and a larger size than the floc made by using only the polymer flocculant and Ca(OH)₂. Among silica activators sulfuric acid was found to yield the best flocculation results from the stand point of the floc size and density. It was even possible to form a dense silica floc having a diameter of 15mm if proper quantities of a silica activator, an anionic polymer flocculant and Ca(OH)₂ are added into the colloidal silica solution.

Keywords

Silica Activator Flocculation of Colloidal Silica Particles Waste Water Treatment

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