A method for reducing a photoresist critical dimension, the method comprising depositing a photoresist film on a substrate, wherein the photoresist film includes a thermal base generator; patterning the photoresist film to form a first patterned film possessing a first critical dimension; depositing a crosslinkable film over the first patterned film; heat-activating the first patterned film, either before or after depositing the crosslinkable film, to release a base in the first patterned film and cause crosslinking in the crosslinkable film in contact with the first patterned film; and developing the crosslinkable film to remove non-crosslinked soluble portions therein to form a second patterned film possessing a reduced critical dimension compared to the first critical dimension.