Pattern generator for avoiding stitching errors

An apparatus for creating a pattern on a workpiece, such as a photomask, a semiconductor wafer, an electronic interconnect device, a printed circuit board, a display panel, a microoptical device or a printing plate, whereby a pattern with less visible edges is created, comprising

• a source for emitting electromagnetic radiation with energy content in the wavelength range from EUV to IR,
• a spatial light modulator having multitude of modulating elements, illuminated by said radiation,
• a projection system creating an image of the modulator on the workpiece,
• an electronic data delivery system accepting a digital description of the pattern to be written, extracting a sequence of partial patterns from the digital pattern description, converting said partial patterns to modulator signals, and feeding said signals to the modulator,
• a precision mechanical system moving said workpiece relative to said projection system,
• an electronic control system coordinating the movement of the workpiece, the feeding of the signals to the modulator and the emitted radiation, so that a large pattern is stitched together from the partial images created by the sequence of partial patterns,
• where at least two adjacent images being stitched together are overlapping at the common boundary, each of said overlapping images having essentially the same pattern and a reduced exposure dose in the overlapping area.