Method of optimizing a mask and method of forming an integrated circuit

In some embodiments, a method may include improving a development process of a photoresist. The method may include simulating a negative-tone development process of a photoresist. The method may include determining a reaction of a developer with a soluble photoresist surface. Determining the reaction of the developer may include applying a reaction rate constant at a power of a reaction order to a blocked polymer concentration to yield a resist dissolution rate of soluble resist comprising the dissolution-limited regime of development. The method may include determining a flux of the developer into exposed and partially soluble resist. Determining the flux of the developer may include applying a vector valued diffusion coefficient of the developer dependent upon the blocked polymer concentration to a gradient of developer concentration to an expansion rate of insoluble resist comprising the expansion-controlled regime of development. The method may include optimizing an illumination source and a mask on a ful