S1818 was hard baked at 125C for 2 hours and then put into RIE chamber. The recipe is SF6, 30mtorr, 45sccm, 3min. However, the color of the resist totally changed, as shown in the attachment. I totally don't understand what happened here. 3 min of SF6 etching won't peel the photoresist off. Is there anybody having any ideas?