| 摘要 |
PURPOSE:To prevent the trouble of an exhaust system due to a foreign matter contained in exhaust gas by arranging a foreign matter trap device in the front stage of an exhaust system. CONSTITUTION:Low pressure CVD processing is carried out by feeding source gas 2 into a reaction tube 1 and exhaust gas is discharged from an exhaust tube 3. In the input stage of the exhaust tube 3, a vacuum sensor 4 and a foreign matter trap device 5 for catching foreign matters are installed. This foreign matter trap device 5 is composed of a main pipe 6 connected to the exhaust tube 3 and a cylindrical cover 7 surrounding the main pipe 6 and a cooling space 8 is provided between the cover 7 and main pipe 6. A cooling medium supply pipe 9 for supplying cooling medium such as cooling water, liquid nitrogen, etc. and a discharge pipe 10 are connected to the cover 7, and arranged so that the main pipe 6 is cooled, in other words, exhaust gas passing through the main pipe 6 is cooled and foreign matters are caused to adhere to the internal wall of the main pipe 6. This foreign matter trap device 5 is compact and can be easily removed. In a CVD device like this, the main pipe 6 of the foreign matter trap device 5 becomes low temperature, therefore, foreign matters in exhaust gas adhere to the internal wall. As a result of this, the adhesion of foreign matters to the exhaust system after the foreign matter trap device 5 will not take place, and troubles of devices including valves, pumps can be prevented. |
