Hydrodynamic Investigation of a Wafer Rinse Process Through Numerical Modeling and Flow Visualization Methods

In the current semiconductor industrial scenario, wafers are rinsed in an overflow rinsing tank while being mounted on several lifters prior to most of its manufacturing processes. However, a major drawback of this overflow rinsing methodology is that some of the processing fluid stagnates due to the generated vortices in the regions between the side and middle lifters which entrap some of the flushed particles that further adhere and deteriorate the surface of the wafers. In this work, the hydrodynamics of the flow field inside the wafer rinsing tank with this original lifter orientation setup was studied and compared through numerical simulation and flow visualization using particle image velocimetry (PIV) method, and a strong agreement was found between them in terms of velocity calculation. A new lifter orientation setup was initiated and it was evidenced by the numerical simulation that with this new setup, the generated vortices which are situated opposite to the lifters tilting direction can be displaced significantly in terms of magnitude and distribution. This work presents a new wafer cleaning concept which shows its great potentials in improvement and implementation to the current in-line wafer batch fabrication process without modifying the original design of the rinsing tank.