Nanoscale molecular analysis of photoresist films with massive cluster secondary-ion mass spectrometry
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2019 Society of Photo-Optical Instrumentation Engineers (SPIE). We describe a methodology for nanoscale molecular analysis and present its capabilities. The analysis method is based on secondary-ion mass spectrometry with gold nanoparticles (e.g., Au4004+). The methodology presented has unique features that enable nanoscale molecular analysis, namely the method of acquiring the mass spectrum and the nature of the impacting projectile. In the method, a sequence of individual gold nanoparticles (Au4004+) is used to bombard the sample; each impact results in ion emission from an area 10-20 nm in diameter. For each of impact of Au4004+, the emitted ions are mass analyzed by time-of-flight mass spectrometry, detected and stored together in one mass spectrum prior to the arrival of the subsequent projectile. Each mass spectrum contains elements and molecules, which are colocalized within 10 to 20 nm of one another. Examination of the coemitted ions allows us to test the molecular homogeneity and chemical composition at the nanoscale. We applied this method to a chemically amplified resist before and after exposure and development. After development the method was used to chemically characterize defect sites that were not removed by the developing solution.