An Innovative Tool for Fabricating Computer-Generated Holograms

Based on research at MIT, LumArray, Inc. has developed a maskless photolithography tool, the ZP-150, designed to cover an entire 15-cm substrate with a continuous, coherent high-resolution pattern, thereby avoiding the 'stitching problem' and making it ideal for fabricating computer-generated holograms (CGH). No mask is required, as data is transferred directly from a computer to a spatial-light modulator that adjusts the intensity of 1000 beamlets, and directs them to 1000 diffractive-optical lenses. Patterns of arbitrary geometry, with placement precision ∼1 nm, are written by scanning the stage in coordination with modulation of the beamlets by the spatial-light modulator. A fully automated proximity-effect-correction algorithm enables fine and large features to be written with equal ease, as well as the creation of 3-D structures. The ZP-150 uses stable, non-chemically amplified photoresists. Extension of resolution from the current 150 nm to the sub-100 nm domain is planned. In addition to providing rapid turn-around on designs, we envisage the ZP-150 being used in customized manufacturing of CGH's by virtue of its modest cost and low maintenance.