Argon ion sputtering is one of the most accepted techniques for depth profiling in practical X-ray photoelectron spectroscopy (XPS) analysis, while this technique is known to cause severe degradation especially with organic materials. Sputtering system using buckminsterfullerene (C₆₀) ion beam has recently been introduced to XPS apparatus as a new sputtering tool for depth profiling. It enables the XPS depth analysis of organic materials such as photoresists without chemical damages. In this paper, the XPS analysis using the C₆₀ ion sputtering was applied to examine the depth distributions of a fluoropolymer in ArF immersion resists to clarify the mechanism of the water-repellency change between the co-polymer and blend polymer. In addition, the depth profiling of the resist is compared to those observed with other techniques such as angle resolved XPS analysis and XPS analysis on the gradient shaved surfaces.