SUBSTRATE PROCESSING METHOD

A substrate processing method includes forming a layer of an inorganic photoresist composition on a substrate, irradiating the layer of the inorganic photoresist composition with extreme ultraviolet (EUV) light using an exposure mask, baking the layer of the inorganic photoresist composition, which is irradiated with EUV light, developing the layer of the inorganic photoresist composition using a developer to form a first inorganic photoresist pattern, performing plasma treatment on the first inorganic photoresist pattern to form a second inorganic photoresist pattern, and processing the substrate using the second inorganic photoresist pattern as a process mask, wherein the plasma treatment uses plasma of a process gas capable of generating hydrogen ions and fluorine ions.