Rinsing processes for the production of silicon solar cells: A numerical and experimental investigation

Potential improvements for the rinsing process of Si wafers are identified by numerical simulations. A model was developed which describes the concentration distribution near the wafer surface of potassium hydroxide (KOH) as a function of time, temperature, volume flow, wafer size and gap distance between the wafers. It was found that the rinsing process can be divided into two phases: The diffusion of the chemicals from the surface in the flow field and the transport of the chemicals by the rinsing water. In contrast to constant low-flow rinsing, the combination of a phase without flow and subsequent high flow saved 35 seconds of process time. The simulation results were transferred to experimental rinse recipes. With regards to the flow conditions two different inlet pipes, an industrial standard and an optimized pipe are compared using three different recipes.