Fine Lines in High Yield (Part CLXVIII)

摘要

DeForest's classic Photoresist book (Ref. 1) dates back to 1975, and the Introduction to Micro-lithography by L.E. Thompson, C.G. Willson, and M.J. Bowden (Ref. 2) dates back to 1983. My own Dry Film Photoresist Processing Technology book (Ref. 3), dated 2001, which contains a brief description of photolithography as it pertains to PWB fabrication, has collected a bit of dust as well. So I thought it might be of interest to take a fresh look at the topic and add some updates. "Negative" working resists form a polymeric resist structure in areas exposed to radiation. The label "negative" may be related to the fact that the phototool used in the exposure of negative working resists is the "negative" of the polymeric resist image, i.e. the clear areas in the phototool reproduce as the polymerized features of the resist.