Study of optimization condition for spin coating of the photoresist film on rectangular substrate by Taguchi design of an experiment

There are four parameters concerning the spin coating of a positive photoresist film. This paper focuses on spin coating of the positive photoresist Clariantz AZ-P4620 on a 2x7 cm rectangular substrate. By ways of Taguchi L16 (44) method, the number of experiments can be reduced from 256 to 16. By analyzing the main impact plot of the signal to noise ratio, it is found that the most suitable values of the four parameters giving the desired thickness and uniformity is a photoresist dispense time of 13 seconds, then spin at a speed of 700 rpm for 5 seconds, and then accelerate at 2,000 rpm per seconds to 4,000 rpm. The speed is maintained at 4,000 rpm for 60 seconds with an exhaust pressure of 300 Pa. The substrate is later baked at 100 oCfor 90 seconds. The calculated thickness of the final film is 48,107.70±1,096 Angstroms. The analysis of the deviation showsthat no parameter has a significant on the thickness and uniformity of the final photoresist film with a confidence level of 95%. This DOE can be used in many applications in the micro and nano fabrication industry.