A reticle enclosure includes a base including a first surface, a cover including a second surface and coupled to the base with the first surface facing the second surface. The base and the cover form an internal space that includes a reticle. The reticle enclosure includes restraining mechanisms arranged in the internal space and for securing the reticle, and structures disposed adjacent the reticle in the internal space. The structures enclose the reticle at least partially, and limit passage of contaminants between the internal space and an external environment of the reticle enclosure. The structures include barriers disposed on the first and second surfaces. In other examples, a padding is installed in gaps between the barriers and the first and second surfaces. In other examples, the structures include wall structures disposed on the first and second surfaces and between the restraining mechanisms.