Selected implications of photoresist processing in 300-mm manufacturing

We discuss implications currently relevant to 300-mm resist processing in lithography. The large size of the wafers, and therefore the large volume of machine modules and media within these modules, demand tighter specifications and a careful reconsideration of design. We investigate a novel resist development process based on a new developer dispense nozzle. The critical dimension (CD) uniformity across the 300-mm wafer thus achieved is compared to a common process. Based on this, we are able to make a preliminary recommendation for the photoresist development technology required for future, high-end semiconductor device manufacturing. Resist thickness fluctuations around the edge area of a silicon wafer typically occur if high spin speeds are applied during the photoresist coating process. The 300-mm coating processes are particularly prone to the occurrence of such spin marks because the operating range of applicable spin speeds is lower in comparison to processes applied to wafers of lower diameters. In our example, we show how such local resist thickness fluctuations impact the product yield. Finally, a special type of micromasking defect is found to be particularly relevant to 300-mm lithography layers. This "doughnut-type" defect detracts the yield of the semiconductor product. The defect has a distinct physical appearance and is precipitated onto the wafer as a hollow resin sphere. This defect is not yet observed in our 200-mm reference process. The occurrence of the defect directly depends on the matching of the air flows entering and leaving the 300-mm coater cup. The mechanism of formation involves the presence of a photoresist-solvent aerosol.