A comparative thermogravimetric study of polymers designed as dry-developing photoresists

We report a thermogravimetric study of the uncatalyzed and photo-acid-catalyzed decomposition of a series of polyformals and polycarbonates. Some of these polymers have previously been proposed as solventless photoresists. Such polymers should decompose at much lower temperatures when heated in the presence of strong acid than when heated in the absence of acid. In addition, decomposition should lead only to volatile break-down products. We found that most of these polymers underwent clean uncatalyzed thermal decomposition. When heated in the presence of acid, the onset of thermal decomposition occurred at much lower temperatures, as expected, but was accompanied by formation of significant amounts of non-volatile product. We also found that the extent of acid-catalyzed cross-linking (i.e., formation of non-volatile product) in the benzylic polyformals was greater than that for benzylic polycarbonates.