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Electrolyzed Water as an Alternative for Environmentally Benign Semiconductor Cleaning

Published online by Cambridge University Press:  31 January 2011

Kunkul Ryoo
Affiliation:
Department of Advanced Materials Engineering, Soonchunhyang University, Shinchang, Asan, Choongchungnam-do, Korea
Byeongdoo Kang
Affiliation:
Department of Advanced Materials Engineering, Soonchunhyang University, Shinchang, Asan, Choongchungnam-do, Korea
Osao Sumita
Affiliation:
MicroBank, Paeksok, Ilsan, Koyang, Kyoungki-do, Korea
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Abstract

The present semiconductor cleaning technology is based upon RCA cleaning [W. Kern and D.A. Puotinen, Cleaning Solutions Based on Hydrogen Peroxide for use in Silicon Semiconductor Technology (RCA Rev., 1970) pp. 187–206], a high-temperature process that consumes vast amounts of chemicals and ultrapure water (UPW) [T. Futatsuki, T. Imaoka, Y. Yamashita, and K. Mitsumori, J. Electrochem. Soc., 142, 966 (1995)]. Therefore, this technology gives rise to many environmental issues, and some alternatives such as electrolyzed water (EW) are being studied. In this work, intentionally contaminated Si wafers were cleaned using electrolyzed water. The electrolyzed water was generated by an electrolysis system that consists of anode, cathode, and middle chambers. Oxidative water and reductive water were obtained in the anode and cathode chambers, respectively. When a NH4Cl electrolyte was supplied in the middle chamber, the oxidation–reduction potential and pH for anode water (AW) and cathode water (CW) were +1050 mV and 4.8, and −750 mV and 10.0, respectively. AW and CW deterioriated after electrolysis but maintained their characteristics for more than 40 min, which was sufficient for cleaning. Their deterioration was correlated with CO2 concentration changes dissolved from air. Contact angles of UPW, AW, and CW on DHF-treated Si wafer surfaces were 65.9°, 66.5°, and 56.8°, respectively, which characterizes clearly the electrolyzed water. To analyze the amount of metallic impurities on Si wafer surface, inductively coupled plasma, mass spectroscopy was introduced. AW was effective for Cu removal, while CW was more effective for Fe removal. To analyze the number of particles on Si wafer surfaces, we used the particle measurement Tencor 6220. The particle distributions after various particle removal processes maintained the same pattern. Overflow of EW during cleaning particles resulted in the same cleanness as that obtained with the RCA cleaning process. The roughness of patterned wafer surfaces after EW cleaning was similar to that of as-received wafers. Regardless of process sequence in this work, RCA consumed about 9 l of chemicals, while EW consumed only 400 ml HCl electrolyte or 600 ml NH4Cl electrolyte to clean 8-in. wafers. It was thus concluded that EW cleaning technology would be very effective for releasing environmental safety, and health issues in the next generation of semiconductor manufacturing.

Type
Articles
Copyright
Copyright © Materials Research Society 2002

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References

1.Kern, W. and Puotinen, D.A., Cleaning Solutions Based on Hydrogen Peroxide for Use in Silicon Semiconductor Technology (RCA Rev., 1970), pp. 187201.Google Scholar
2.Ohmi, T., Ultra Clean Technology 9, Suppl. 1, III19 (1997).Google Scholar
3.Futatsuki, T., Imaoka, T., Yamashita, Y., and Mitsumori, K., J. Electrochem. Soc. 142, 966 (1995).Google Scholar
4.Choi, B. and Sun, H., Korean J. Mater. Res. 8, 837 (1998).Google Scholar
5.ULSI Technology, edited by Chang, C.Y. and Eze, S.M. (McGraw-Hill International Editions, New York 1996), pp. 60104.Google Scholar
6.Morita, H., Ida, J., Ii, T., and Ohmi, T., Solid State Phenomena 65–66, 7 (1999).Google Scholar
7.Hattori, T., Osaka, T., Okamoto, A., Saga, K., and Kuniyasu, H., J. Electrochem. Soc. 145, 3278 (1998).CrossRefGoogle Scholar
8.Ojima, S., Kubo, K., Kato, M., Toda, M., Saga, T., and Kuniyasu, H., J. Electrochem. Soc. 144, 1482 (1997).CrossRefGoogle Scholar
9.Yamanaka, K., Imaoka, T., Futatsuki, T., Yamashita, Y., Mitsumori, K., Kasama, Y., Aoki, H., Yamasaki, S., and Aoto, N., Langmuir 15, 4165 (1999).CrossRefGoogle Scholar
10.Aoki, H., Yamasaki, S., Nakamori, M., Aoto, N., Yamanaka, K., Imaoka, T., and Futatsuki, T., in Science and Technology of Semiconductor Surface Preparation, edited by Higashi, G.S., Hirose, M., and Uerhaverbeke, S. (Mater. Res. Soc. Symp. Proc. 477, Warrendale, PA 1997), pp. 501512.Google Scholar
11.Shiramizu, Y., Watanabe, K., Tanaka, M., Aoki, H., and Kitajama, H., J. Electrochem. Soc. 143, 1632 (1996).CrossRefGoogle Scholar
12.Pourbaix, M., Atlas of Electrochemical Equilibria in Aqueous Solutions (NACE International Cebelcor, Texas 1974), pp. 158384.Google Scholar