Methods and compositions for imaging acids in chemically amplified photoresists using pH-dependent fluorophores

The present invention relates to the field of lithography and more specifically relates to the use of chemically amplified photoresists in lithography. A method of imaging acids in chemically amplified photoresists involves exposing to radiation a chemically amplified photoresist comprising a pH-dependent fluorophore. Upon exposure to radiation, such as deep-UV radiation, the chemically amplified photoresist produces an acid, which is then visualized by the fluorescence of the pH-dependent fluorophore. An image is generated from the fluorescence of the pH-dependent fluorophore, thus providing a map of the location of the acid in the photoresist. The images are able to be visualized prior to a post-exposure bake of the resist composition. Chemically amplified photoresists comprising pH-dependent fluorophores are useful in the practice of the present invention. The method finds particular use in examining the efficiency of photoacid generators in chemically amplified photoresists, in that it allows the practitioner the ability to directly determine the amount of acid generated within the photoresist.