Shp13 4 1

1) The study investigated particle deposition in the exhaust pipe of a semiconductor manufacturing process by heating the pipe wall to different temperatures. 2) Without heating, deposition efficiency was 43-56% for particles 0.04-23.24 microns, but efficiency decreased to 11-19%, 19-42%, 27-50%, and 39-58% for pipe wall temperatures of 100°C, 80°C, 60°C, and 40°C respectively. 3) Heating the pipe wall above the inlet gas temperature of 80°C (e.g. to 100°C) substantially reduced deposition of particles less than 1 micron due to increased thermophoretic effects, though complete prevention of deposition