Controlling chemical segregation in EUV resists by varying viscosity and evaporation rate during the spin coating process

Chemically amplified photoresists (CAR) are the leading photoresists used in Extreme Ultraviolet (EUV) lithography. Chemical stochastics are an issue for defectivity and roughness due to the distribution of the multiple components of the resist. It is believed that the non-random distribution of components occurs primarily during the spin coating process, as the resist dries, and the solvent concentration is reduced. Inhibiting the unwanted chemical segregation can be controlled by increasing the evaporation rate during the spin coating process. In addition to reducing the chemical segregation of the resist through the spin coating process, it is important to compare between different resist formulations for their risk of chemical segregation. We will show accelerated testing processes using solvent vapor annealing to help identify the relative risk of segregation between multiple commercial photoresists.