Suppression of micro-bubbles in photoresist coating by step dynamic coating

In recent years, micro-bubbles are seen in the photoresist film by advanced laser scan particle detector. These micro-bubbles have potential to cause fatal defects in IC products. Therefore, we need to suppress development of micro-bubbles as possible. First of all, we specified a photoresist process step which micro-bubbles develop. Then, we found a development mechanism of microbubbles that can be explained by considering the behavior of a viscous fluid on a rotating disk. From these experiments and mechanism, we suggest a new photoresist coating method "Step Dynamic Coating", which can suppress micro-bubbles drastically. Moreover, photoresist process trends show micro-bubbles will become more troublesome in the future. We do claim "Step Dynamic Coating" is one of the best solution to suppress microbubbles since this is based on our understanding of the micro-bubble development mechanism