Development of a polymer etch rate monitor: design, characterization, and application

A polymer etch rate monitor (PERM) was designed to quantify rates of base-soluble polymeric materials by measuring electric signals. The thickness of a thin film was demonstrated to be proportional to the electric resistance of the polymer coating. The applicability of the electric cell design for characterizing the dissolution of polymer coatings was demonstrated. Characterization of the electric signal versus the developing process revealed distinctive steps and mechanisms of the dissolution process. Scanning electron microscopy provided some insight into the dissolution process and the interaction between polymeric coatings and base. The correlation between dissolution rate and the concentration of base was investigated. Also investigated was the relationship between dissolution rate of polymeric coating and its thermal curing parameter. This monitor is able to provide instant information about the dissolution process as well as the etch rate in the base solution. Not only can the overall dissolution rate be measured, but the dissolution behavior and interaction can also be interpreted by analyzing the dissolving curve. This instrument has been used successfully for quality control purposes. Currently, the applicability of this device for photosensitive polymeric coatings is being evaluated.