In this study, we evaluated the influence of photoresist-water contact time on the quantity of the photoacid generator (PAG) leached from photoresists into pure water and alteration of the photoresist composition using LC-MS, XPS, and TOF-SIMS, by employing exposed and unexposed photoresists. As a result, the quantity of PAG leached into pure water increased as the contact time elapsed. Then, it was observed by TOF-SIMS that the quantity of the PAG on the photoresist surface decreased as the contact time elapsed. Regarding the ratio of the functional groups on the photoresist surface, the methyladamantyl group decreased but the carboxyl group increased because of exposure, respectively. On the exposed photoresist surface, the methyladamantyl group increased as the contact time elapsed. This was strongly related to the phenomenon that the quantity of methyladamantyl group was different between the inside and surface of photoresist. (C) 2008 Elsevier B. V. All rights reserved.