Antimony photoresists for EUV lithography: mechanistic studies

We have developed a method to study the photomechanism of our antimony carboxylate platform R3Sb(COOR')(2). A series of mechanistic studies followed the production of reaction byproducts by mass spectrometer, as they left the film during exposure to EUV photons and 80 eV electrons. We identified several prominent outgassing fragments and their rates of production as a function of ligand structure. The degree of outgassing appears to be well-correlated with the bond dissociation energy of the carboxylate ligand R' group. Furthermore, a deuterium labeling study was conducted to determine from which ligand hydrogen is abstracted to form benzene and phenol during exposure. Benzene and phenol were found to abstract hydrogen from opposing sites within the film, and with greater than 95% isotopic purity. Using the results of the outgassing studies alongside established mechanisms for electron-induced reactions; a series of reaction pathways were proposed to generate the aforementioned outgassing species and a possible nonvolatile negative-tone photoproduct.