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[4] Lin JS, Tsai CJ. Thermophoretic deposition efficiency in a cylindrical tube taking into ac-count developing flow at the entrance region. J Aerosol Sci 2003; 34: 569-83.
[5] Tsai CJ, Lin JS, Aggarwal SG, Chen DR. Thermophoretic deposition of particles in laminar and turbulent tube flows. Aerosol Sci technol 2004; 38: 131-39.
[6] Jyh-Shyan Lin, Chuen-Jinn Tsai and Cheng-Ping Chang. “Suppression of particle deposition in tube flow by thermophoresis”, Journal of Aerosol Sci. 2004; 35: 1235-50.
[9] Pich J. Theory of gravitational deposition of particles from laminar flows in channels. J Aerosol Sci 1972; 3: 351-61.
[10] Cheng YS, Wang CS. Motion of particles in
bends of circular pipes. Atmos Environ 1981; 15:301-6.
[11] Ye Y, Tsai C J, Pui DYH. Particle transmission characteristics of an annular denuder ambient sampling system. Aerosol Sci Technol 1991; 14: 102-11.
[12] Forsyth BR, Liu BYH. Exhaust aerosol of a plasma enhanced CVD system: II. electric charging and transport. Aerosol Sci Technol 2002; 36: 526-35.
[13] Cohen BS, Xiong JQ, Asgharian B, Ayres L. Deposition of inhaled charged ultrafine parti-cles in a simple tracheal model. J Aerosol Sci 1995; 26: 1149-60.
[14] Pich J. Comments on the paper: C. P. Yu’s pre-cipitation of unipolarly charged particles in cylindrical and spherical vessels. J Aerosol Sci 1978; 9: 275-8.
[15] Messerer A, Niessner R, Pöschl U. Miniature pipe bundle heat exchanger for thermophoretic deposition of ultrafine soot aerosol particles at high flow velocities. Aerosol Sci Technol 2004; 38: 456-66.
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Journal of Occupational Safety and Health 13: 257-264�2005�
Field Study on Particle Deposition in the Exhaust Pipeline of Semiconductor Manufacturing Process2
1 Institute of Environmental Engineering, National Chiao Tung University 2 Department of Industrial Safety and Risk Management College of Engineering, National Chiao
Tung University 3 Institute of Occupational Safety and Health, Council of Labor Affairs
Abstract
The objective of this study is to verify the effectiveness of heating the exhaust pipe to prevent particles deposition in the pipe of a semiconductor dry etching process. The effects of thermophoretic deposition, Brownian diffusion, gravitational setting and bend loss of aerosols particle on deposition efficiency are in-vestigated. The experiment was performed in a horizontal stainless-steel straight pipe (ID= 5.72cm) of 120 cm in length including a 90-degree bend with the bend radius of 20 cm. The pipe is the exhaust of a vacuum pump of a dry etcher in a semiconductor factory. The exhaust gas temperature from the vacuum pump was 80 oC. To heat up the wall temperature, the stainless-steel pipe was covered with a heating tape, and the pipe wall temperature was heated to the temperatures of 100 oC, 80 oC, 60 oC, 40 oC and 25 oC (no heating case). The results show that the deposition efficiency of aerosol particles (aerodynamic diameter ranges from 0.04 µm to 23.24 µm) is 43~56% when the pipe was not heated and the wall tem-perature, 25 oC, remained the same as the ambient temperature. When the pipe was heated up to 100 oC,80 oC, 60 oC and 40 oC, the deposition efficiency of aerosol particles (diameter from 0.04 µm to 23.24 µm)is about 11~19%, 19~42%, 27~50% and 39~58%, respectively. The experimental results show that the higher the temperature of pipe wall, the lower the particle deposition efficiency and hence the less frequent cleaning of the pipe is needed. When the pipe wall is heated to a temperature, 100 oC, which is higher than the inlet gas temperature, 80 oC, the particle deposition efficiency for particles less than 1 µm can be reduced substantially. However, complete elimination of particle deposition isn’t available due to the deposition of charged particles and the settling of coagulating particles.
Keywords: Thermophoresis, Particle deposition, Particle control technology
Accepted 17 August 2005 * Correspondence to: Chuen-Jinn Tsai, Institute of Environmental Engineering, National Chiao Tung University.