The characteristics of the Electrolyzed D.I.water with chemicals and the outline of the supply system
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The characteristics of the Electrolyzed D.I.water with chemicals and the outline of the supply system Mitsuhiko Shirakashi*, Kenya Itoh*, Ichiro Katakabe*, Mamabu Tsujimura*, Takayuki Saitoh**, Kaoru Yamada**, Naoto Miyashita***, Masako Kodera***, Yoshitaka Matsui*** * Precision Machinery Group, Ebara Corporation 4-2-1,Honfujisawa, Fujisawa-shi, Kanagawa 251-8502, Japan ** Center of Technology Development, Ebara Research CO., Ltd. 4-2-1,Honfujisawa, Fujisawa-shi, Kanagawa 251-8502, Japan *** Manufacturing Engineering Center, Toshiba Corporation Semiconductor Company 8,Shinsugita-cho, Isogo-ku, Yokohama, Kanagawa 235-8522, Japan ABSTRACT In semiconductor device production, wafers are treated through many cleaning processes. Usually, several chemicals are used so as to match for several purposes like RCA cleaning method. As wafer size becomes larger, large amount of cleaning chemicals usage and waste are necessary, which becomes now a big problem. Considering the above, we developed the Electrolyzed D.I.water with chemicals supply system in order to minimize running cost of chemicals and waste treatment. It is feature that; 1) this system can generate the anode water of the acidity/high ORP (Oxidation-Reduction Potential) and the cathode water of the alkalinity/low ORP by electrolyzing D.I.water adding with a small quantity of chemicals; 2) this system can generate anode water and cathode water at the same time; 3) if necessary, the anode water can be diluted with D.I.water at the optional density, and it is possible with the cathode water that hydrogen peroxide is added. The anode water which shows acidity/high ORP has the effect of removing metal and organic contamination, and the cathode water which shows alkalinity/low ORP has the effect of particle removal. In this report, we explain the outline of this system and the basic characteristic of the Acid and Alkaline water made with this system and its performances.
INTRODUCTION RCA cleaning process using hydrochloric acid, ammonia, sulfuric acid, hydrofluoric acid etc. has been well adopted so far. However, in accordance with larger wafer size, it is very important to minimize chemical cost and waste treatment cost. Through above situation, in 90’s, new idea of chemical free or less has been highlighted as functioned water like gas-dissolved water. The Electrolyzed D.I.water with chemicals is developed in accordance with above requirement. The cleaning mechanisms are defined as follows. (1) Physical effects of removal foreign materials from cleaning surface using blush or jet. (2) Electrical potential is controlled by pH change. (3) Etch off of cleaning surface by chemical (4) Remove foreign materials by reacting with chemicals
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The anode water is effective for (4) and the cathode water is effective for (2) & (3). EXPERIMENTAL First of all, we explain the principle of generating the Electrolyzed D.I.water with chemicals on Figure 1. This cell has an ion exchange membrane, anode and cathode electrode and electrolyzes D.I. water adding chemicals. HCl is intr
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