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Showing papers on "Phase-shift mask published in 1978"


Patent
16 Jan 1978
TL;DR: An automatic photomask alignment system as discussed by the authors includes a monochromatic light source such as a laser, a series of diffraction patterns which are located on a semiconductor substrate and keys located on photomasks with which the substrate is to be aligned.
Abstract: An automatic photomask alignment system includes a monochromatic light source, such as a laser, a series of diffraction patterns which are located on a semiconductor substrate and keys which are located on photomasks with which the substrate is to be aligned. A light beam is directed through the key on a photomask onto the diffraction pattern to provide a pattern of light spots whose intensities at various locations are determined by the relative alignment of the mask and the diffraction grating. A feedback arrangement which employs photocells and means for moving the photomasks relative to the substrate provides the alignment of the photomasks with the substrate.

43 citations