A method for fabricating a photomask is provided. The method includes several operations. A photomask substrate, having a chip region and a peripheral region adjacent to the chip region, is received. A reference pattern is formed by emitting one first radiation shot and a first beta pattern is formed by emitting a plurality of second radiation shots in the peripheral region. The plurality of second radiation shots are emitted along a first direction. A roughness of a boundary of the first beta pattern along the first direction is compared to a roughness of a boundary of the reference pattern along the first direction from a top view perspective. An alignment of the plurality of second radiation shots is adjusted if a result of the comparison exceeds a tolerance, or the photomask is formed. A photomask structure thereof and a method for manufacturing a semiconductor are also provided.