US Patent 8715919 Surface switchable photoresist

Lithography methods on a semiconductor substrate are described. The methods include coating a resist layer on the substrate, wherein the resist layer comprises a resist polymer configured to turn soluble to a base solution in response to reaction with an acid, and a switchable polymer that includes a base soluble polymer having a carboxylic acid, hydroxyl, lactone, or anhydride functional group, performing a pre-exposure bake on the resist layer, exposing the resist-coated substrate, and developing the exposed substrate with a developing solution.