Study on micro-bubble defect induced by RRC coating

RRC (Reducing resist consumption) coating is widely used to reduce photo resist consumption. By using solvent to pre-wet the wafer surface, photo resist can be coated on wafer easier than normal coating method. But it also can be the source of defects. In this study, we found that RRC solvent will induce micro-bubble and cause defects. Different methods had been tried to solve this kind of micro-bubble defects. Results showed that micro-bubble defects can be found when the wafer is static during RRC solvent dispense. And the defect map was a ring shape. The diameter of the rings depended on the RRC solvent dispense amount. Non micro-bubble defect was found, if wafer was spinning during RRC solvent dispense.