Phase shift masks for an extreme ultraviolet lithography process includes a substrate, a reflection layer on the substrate, a capping layer on the reflection layer, and phase shift patterns on the capping layer. Each of the phase shift patterns may include a lower absorption pattern on the capping layer and an upper absorption pattern on the lower absorption pattern. A refractive index of the upper absorption pattern may be higher than a refractive index of the lower absorption pattern, and a thickness of the upper absorption pattern is smaller than a thickness of the lower absorption pattern.