The effect of humidity on water sorption in photoresist polymer thin films

A quartz crystal microbalance technique has been utilized to measure water sorption and desorption in three photoresist polymers: poly( p-hydroxystyrene), novolac, and bis-triflouromethyl carbinol substituted poly(norbornene). The humidity of the sample environment was varied to determine the rate and amount of water absorbed into the photoresist thin films as a function of local environmental conditions. At 100% absolute humidity, the polymers were found to absorb 9.8, 2–3, and 5–8 wt%, respectively. The sorption and diffusion of water into the polymer thin films was observed to initially follow Fickian behavior in the low fractional mass uptake regions ( M t / M ∞