Abstract: An apparatus comprising a mask having an active device area and a moat. The moat substantially surrounds the mask active device area and has a width greater than a plasma specie diffusional length. A method comprising depositing a layer of resist on a mask substrate having transparent and opaque layers; and exposing the resist layer to radiation. The radiation is patterned to produce features within an active device area. The radiation is also patterned to produce a moat substantially surrounding the active device area having a width greater than a plasma specie diffusional length.