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Megasonic Irradiation Induced Chemical Reaction in the Solution for Silicon Wafer Cleaning

Published online by Cambridge University Press:  10 February 2011

T. Ohmi ,
M. Toda ,
M. Katoh ,
K. Kawada  and
H. Morita
T. Ohmi
Affiliation:
Department of Electronics, Faculty of Engineering, Tohoku University Aza-aoba, Aramaki, Aoba-ku, Sendai 980-77, Japan
M. Toda
Affiliation:
Department of Material Science and Engineering, Faculty of Engineering, Yamagata University 3–16, Jonan 4 chome, Yonezawa City, Yamagata 992, Japan
M. Katoh
Affiliation:
Department of Material Science and Engineering, Faculty of Engineering, Yamagata University 3–16, Jonan 4 chome, Yonezawa City, Yamagata 992, Japan
K. Kawada
Affiliation:
Department of Electronics, Faculty of Engineering, Tohoku University Aza-aoba, Aramaki, Aoba-ku, Sendai 980-77, Japan
H. Morita
Affiliation:
Department of Electronics, Faculty of Engineering, Tohoku University Aza-aoba, Aramaki, Aoba-ku, Sendai 980-77, Japan
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Abstract

We have already proposed chemical vapor free and room temperature wet cleaning (UCT cleaning) for Si substrate surface, instead of conventional RCA cleaning, which consumes very little amount of chemicals and ultrapure water compared to that of RCA cleaning. This new wet cleaning has been developed by scientifically understanding contaminants removal mechanism as follows;

(1) Particles can be removed by simultaneously satisfying following two conditions,

(a) particles and substructure surface must have same polarity of zeta potential in the cleaning solution to exhibit repulsive electric coulomb force with each other.

(b) adhered particles must be lifted off from substrate surface by slight etching to make electric repulsive force greater than van der Waals force,

(2) Redox potential of the cleaning solution must be larger than a critical value to enable removal of electrons from adhered metals in order to dissolve them into the cleaning solution as positive ions and to decompose adhered organic molecules to CO2, H2O etc.

Megasonic irradiation is very essential in UCT cleaning, particularly to remove particles by lifting them off from substrate surface. In this study, chemical reaction in the cleaning solution induced by megasonic irradiation is mainly discussed. Irradiation of ultrasonic having frequencies higher than a few hundred KHz (Megasonic) to ultrapure water has been confirmed to be able to decompose H2O molecules to H radicals and OH radicals. Decomposition efficiency of H20 molecules is strongly dependent on remaining gas components and their volume in the ultrapure water. When the remaining gas volume is decreased to less than 0.2 ∼0.3ppm, H2O molecules decomposition to H radicals and OH radicals has not been observed. Generated OH radicals have been confirmed to produce H2O2, and NH4+, NO2−, NO3− ions by reacting. with remaining N2 gas. Thus the cleaning capability of the cleaning solutions can be controlled by irradiating megasonic.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 477 , 1997 , 3
Copyright
Copyright © Materials Research Society 1997

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References

REFERENCES

1. Kern, W. and Puotien, D. A., “Cleaning solutions based on hydrogen peroxide for use in silicon semiconductor technology, ” RCA Review, Vol.31, No.2, pp. 187–206, June 1970.Google Scholar
2. Itano, M., Miyashita, M. and Ohmi, T., “Particle deposition and removal on wafer surface in RCA cleaning process,” Proc. Microcontamination 91, San Jose, pp.521–542, October. 1991.Google Scholar
3. Ohmi, T., “Total room temperature wet cleaning for Si substrate surface”, Journal of Electrochemical Society, Vol.143, No.9, pp.2957–2964, September 1996.CrossRefGoogle Scholar
4. Ohmi, T., “Ultra clean technology contributing to the fast progress of asian semiconductor industries”, The Fifth International Symposium on Semiconductor Manufacturing, Proceeding of ISSM'96, pp.7, 377–388, < invited >, Tokyo, October 1996., Tokyo, October 1996.' href=https://scholar.google.com/scholar?q=Ohmi,+T.,+“Ultra+clean+technology+contributing+to+the+fast+progress+of+asian+semiconductor+industries”,+The+Fifth+International+Symposium+on+Semiconductor+Manufacturing,+Proceeding+of+ISSM'96,+pp.7,+377–388,+<+invited+>,+Tokyo,+October+1996.>Google Scholar
5. Toda, M., Kato, M. and Ohmi, T., “The effect of megasonic irradiation on ultra pure water”, Third International Symposium on Ultra Clean Processing of Silicon Surface, Antwerp, September 1996.Google Scholar
6. Kubo, K., Ojima, S., Sakata, Y., Kato, M., Toda, M. and Ohmi, T., “The impact of radical activated ultra pure water”, 1996 Semiconductor Pure Water and Chemicals Conference, UPW & Chemical Proceedings, Santa Clara, pp 196–214, March 1996.Google Scholar
7. Uri, N., “INORGANIC FREE RADICALS IN SOLUTION”, Chemical Reviews, 50, pp375–454, 1952.CrossRefGoogle Scholar
8. Tozuka, K., Kato, M., Toda, M. and Ohmi, T., “Evaluation of activated chemical species generated in RCA cleaning solution”, Technical Report of IEICE, Silicon Devices and Materials, SDM96–127, pp.71–78, Sendai, November 1996.Google Scholar
9. Kato, M., Ochiai, T., Toda, M. and Ohmi, T., “Effect of sonication on radical activation in wafer cleaning solution”, Technical Report of IEICE, Silicon Devices and Materials, SDM96–128, pp.79–86, Sendai, November 1996.Google Scholar