Abstract Airborne molecular contamination (AMC) effects reveal to be more and more prominent in clean room manufacturing areas, shrinking the dimensions of electronic circuits such as the last generation of flash memory devices (0.15–0.13 μm). This work enabled us to evaluate new resist stability to specific airborne contamination class in critical conditions; that is basic contamination of clean room environments (∼20 ppb), higher than a typical contamination status inside Deep UV equipment chambers (∼2 ppb). Formation of the so-called T-Topping (see Fig. 1) was observed, qualitatively discussed and quantitatively measured, facilitating comparison between experimental data on a time scale basis and a theoretical model developed for interpret contaminants adsorption on ultra clean surfaces; then we interpolated critical data between 1 and 5 min to gather information on process material characterization. The starting adsorption shift rate revealed to be 12 nm/min, showing that T-Topping is an almost instantaneous phenomena and that 2 min are sufficient to obtain CD values higher than specification limits in the experimental conditions. Finally, we calculated the resist characterization parameter (max shift rate per ppbV of airborne basis concentration) on a pure theoretical basis (0.637 nm/min/ppbV) resulting in a very good agreement with literature [D. Kinkead, W. Goodwin, K., MICRO 18(9) (2000) 71–84].