Methods for sensitizing photoresist using flood exposures

A method for forming a pattern on a substrate, comprising:

• forming a chemically-amplified resist (CAR) layer on the substrate, wherein the CAR layer comprises a photo-acid generator (PAG), a photo-decomposable base (PDB), or both, and is free of addition of photosensitizer elements;
• defining a target resolution for the pattern to be formed in a target layer on the substrate;
• based on a reference dose and on a reference line width roughness for the pattern that results from a single patterning exposure using energy at a wavelength between 13 nm and 15 nm at the target resolution and reference dose, exposing the CAR layer to at least two exposures of radiative energy, the at least two exposures comprising:
• a patterning exposure comprising the energy at the wavelength between 13 nm and 15 nm and a dose selected to be at least 3 mJ/cm2 less than the reference dose and in a range of 20 mJ/cm2 and 75 mJ/cm2, and
• thereafter, a flood exposure comprising energy at a wavelength between 200 nm and 420 nm and a dose between 2 J/cm2 and 12 J/cm2;
• developing the CAR layer to form a mask pattern in the CAR layer;
• and
• etching the substrate using the mask pattern to form the pattern in the target layer on the substrate, the pattern comprising the target resolution and a line width roughness that is at least 0.1 nm less than the reference line width roughness and less than or equal to 5 nm.