TOF-SIMS analysis of chemical state changes in cresol–novolak photoresist surface caused by O2 plasma downstream

Abstract The chemical state changes on cresol–novolak photoresist surfaces caused by O 2 plasma exposure were investigated using time-of-flight secondary ion mass spectrometry (TOF-SIMS). TOF-SIMS spectra were measured at the surface of the photoresist samples which were exposed to the O 2 plasma downstream for various exposure times and the spectral intensity changes of characteristic secondary ion species with respect to O 2 plasma conditions were quantitatively evaluated. Oxidation and decomposition of the polymer were observed from analysis of the changes in the peaks originating from the chemical structure of the polymer, both in positive and negative mass spectra. It was clarified that oxidation and vaporization attain a balance within a thin altered layer. In addition, depletion of photosensitive additive at the surface was confirmed and the usefulness of TOF-SIMS for predicting the reaction occurring on photoresist surfaces was successfully demonstrated.