| 摘要 |
PURPOSE:To provide the superposition of semiconductor device with high precision while making resist coating shapes at both sides of a basic pattern symmetrical by a method wherein once coated resist is forced to resume flowing. CONSTITUTION:Phenol novolak base positive type photo resist 4 is dripped on a wafer 1 to be turned at around 5,000rpm for 3sec for coating the wafer 1. After a spinner stops turning, the resist 4 resumes flowing to be formed into symmetrical shapes at both sides of pattern. In such a status, the resist 4 is continuously prebaked to thoroughly remove any residual solvent. The interval between the coating and prebaking processes may be within 20sec. Through these procedures, the resist film thickness at both sides of basic alignment pattern 2 may be equalized to make the actual mark center C0 and the apparent pattern center C' correspond with each other providing superposition of semiconductors with high precision. The coating time may be recommended for 2-5sec. Besides, any resist film exceeding 2mum thick will not be practical in terms of the signal intensity level of chip alignment. |
