A method and a structure are provided for preventing lift-off of a semiconductor monitor pattern from a substrate. A semiconductor structure and a semiconductor monitor structure are formed on a substrate. A material layer is formed covering the semiconductor monitor structure. A part of the semiconductor structure is removed without removing the semiconductor monitor structure, by using the material layer as an etch protection layer. A mask for the method is also provided. The mask includes a clear area and a dark area. The dark area prevents a semiconductor monitor structure from being subjected to exposure so as to form a material layer covering the semiconductor monitor structure and prevent removal of the semiconductor monitor structure from the substrate while a part of a semiconductor structure is removed.