| Summary: | 碩士 === 國立交通大學 === 機械工程系 === 88 === Recirculating air flow in a model lamp heated, rapid thermal, vertical single wafer processor for an eight-inch wafer is investigated experimentally by flow visualization. A copper plate is used to simulate the wafer for its better uniformity of the surface temperature and air is used to replace the inert gases in the present study. This study concentrates on how the inlet gas flow rate, temperature difference between the wafer and air jet, and chamber pressure affect the recirculating flow in the processing chamber resulting from the air jet impinging on the headed copper plate. The flow photos taken from the chamber side intend to unravel the vortex flow driven by the combining effects of the thermal buoyancy, jet inertia and jet impingement. The results show that typically the flow in the chamber is in the form of two-roll structure characterized by a circular vortex roll around the gas jet along with another circular roll near the side wall of the chamber. The rolls are generated by the deflection of the impinging jet flow along the wafer surface by the upward buoyancy due to the heated wafer. At low buoyancy and inertia the vortex rolls are steady and axisymmetric. At increasing buoyancy associated with the higher temperature difference and chamber pressure, the inner roll becomes slightly smaller and the outer roll becomes correspondingly bigger. Besides, the recirculating flow is stronger at high buoyancy. Moreover, at a higher gas flow rate the inner roll is substantially bigger. Based on the present data, a correlation equation is provided to predict the location where the two rolls contact each other, providing the approximate size of the rolls. Moreover, at high buoyancy and inertia, the flow becomes time dependent and does not evolve to a steady state. A flow regime map is given to delineate the temporal state of the induced flow.
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