ToF-SIMS analysis of antimony carboxylate EUV photoresists

Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is used to evaluate the composition of nonvolatile photoproducts created by EUV photolysis of antimony carboxylate photoresists [R₃Sb(O₂CR')₂]. Dozens of potential photoproduct ions were identified using exact mass and ¹²¹Sb/¹²³Sb isotopic ratios. Several oxygen-rich antimony ions were found to increase in abundance with exposure. Two methods were employed to identify photoproducts which create solubility contrast. First, samples were analyzed pre- and post-development to examine the effects of EUV exposure and developer solvent on secondary ion intensity. Secondly, changes in intensity of select ions were compared to dissolution contrast over a range of doses. Through these studies, ion intensities were found to correlate with dissolution contrast for several fragments, indicating their active role in creating negative-tone response.