A mask for producing an image feature on an image surface during a semiconductor fabrication process is provided, the mask comprising a main feature having opaque areas and transmissive areas arranged in the form of the image feature, wherein each end of the main feature includes at least one of an opaque edge and a transmissive edge, wherein the opaque edge includes a set of transmissive assist features arranged therein such that the set of transmissive assist features align alternately with the transmissive areas of the main feature, and the transmissive edge includes a set of opaque assist features arranged therein such that the set of opaque assist features align alternately with the opaque areas of the main feature.