In order to understand the mechanism of line width roughness (LWR) generation and to find control knobs for improving photoresist design, we established PAG activity analysis methods by utilizing Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and Transmission Electron Microscopy (TEM). TOF-SIMS depth profiling using Gas Cluster Ion Beam (GCIB) allowed the ability to clearly identify photoresist ingredient distribution in the photoresist films from the surface to the bottom of the resist films. TEM provided distribution information of photoresist ingredients in nanometer scale. As a result, PAG function and polymer reaction mechanism can be monitored by these methods. The TOFSIMS outputs during coating, exposure, and post-exposure bake (PEB) steps provide indications of distribution change of PAGs, quenching reaction derivatives, and remaining protecting group, which correspond to acid generation distribution, acid diffusion, and diffusion of deprotection reaction in photoresist film respectively during each consecutive lithographic patterning step. The difference in activity of PAGs can also be observed. These novel analytical methods can provide remarkably helpful information about identifying proper control knobs for lithographic performance of photoresist and for next generation lithography (NGL), especially extreme ultra violet lithography (EUVL) materials, where exposure tool time is very limited.