­^¤åºK­n In the wet wafer cleaning process, the wafer surfaces are washed with toxic solutions such as ammonia and sulfuric acid which was not to allow to enter the surroundings i.e. clean room. Therefore, common practice is to reduce the pressure differential between the wet bench and the surroundings to a very low pressure difference level while maintaining a high exhaust flow rate for toxic fumes. In such a case, the isolation of process area from the surrounding area may be compromised i.e. there is a danger that the surrounding air was suctioned to the process area. Conceptually, this dilemma can be solved by creating an air buffer between the wafer process area and the surrounding area. This study aims to determine/prove-in the optimal operational conditions and geometries of such design by both CFD analysis and experimental verification. This thesis includes three parts. First, the detailed experimental data to a bio-clean bench installed with the guide-vane design are conducted. The data are then used to verify the feasibility/accuracy of the CFD model. Second, the optimal operational conditions and geometries of a full-scale isothermal wet bench with the guide-vane design are determined by CFD simulation that takes most influential factors into account. These influential factors include exhaust pressures, length of the guide- vane, guide-vane angle and downward face velocity of the filter etc. The results show that the air curtain created by the guide-vane is able to isolate the process area from surrounding area, and vise-versa. Third, the thermal effect of ammonia solution on the distribution of ammonia vapor are examined. The shape of the thermal plume that encounters the downward air stream of the filter is discussed intensively. In general, this thesis provides significant information in improving the isolation effect of wet benches by the air-curtain design.