New laser pattern generator for DUV using a spatial light modulator
A new breed of pattern generators for photomasks using spatial light modulator (SLM) technology with many architectural similarities to that of a modern stepper is under development. The SLM, having an array of individually addressed micromirrors, is illuminated by an excimer DUV laser pulse and imaged onto the surface of a photomask. A stage moves the photomask to a new position and the SLM is reloaded with a new portion of the pattern, followed by a new exposure. The complete pattern is stitched together at a high rate. Analog modulation of each pixel provides an address grid satisfying the requirements of the industry roadmap without speed penalty. The new SLM technology has the resolution to rival that of e-beam pattern generators, yet provides the productivity of laser patterning due to the massive parallel exposure strategy.