The disclosure herein describes methods for Photosensitized Chemically Amplified Resist Chemicals (PS-CAR) to pattern light sensitive films (e.g., photoresist on anti-reflective coatings) on a semiconductor substrate. In one embodiment, a two-step exposure process may generate higher acid concentration regions within a photoresist layer. The PS-CAR chemicals may include photoacid generators (PAGs) and photosensitizer elements that enhance the decomposition of the PAGs into acid. The first exposure may be a patterned EUV or UV exposure that generates an initial amount of acid and photosensitizer. The second exposure may be a non-EUV flood exposure that excites the photosensitizer which increases the acid generation rate where the photosensitizer is located in the film stack. The distribution of energy during the exposures may be optimized by using certain characteristics (e.g., thickness, index of refraction, doping) of the photoresist layer, an underlying layer, and/or an overlying layer.