Wafertrac processing was used to optimize the photolithographic process of Shipley 812 positive photoresist. For two, three, four, and five micron lines, it was found that optimum conditions are 30-40 seconds development time in MF-3 19 and about 72 mj/cm2 exposure dose. These optimum conditions maximize the control over the size of the image being replicated into the resist from the mask. Hardbaking of the resist resulted in a 300-400 micron thickness loss as well as a rounding of the resist profile. Contrast varied from 1.42 to 1.76 with the highest contrast being in the optimum development time range of 30-40 seconds. Thickness versus spin speed was close to the manufacturers data and uniformity of thickness was good.
Taylor, David H.
"Characterization, Optimization, and Qualification of Shipley 812 Photoresist for Wafertrac Processing,"
Journal of the Microelectronic Engineering Conference: Vol. 5
, Article 23.
Available at: http://scholarworks.rit.edu/ritamec/vol5/iss1/23