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Abstract

A method for making semiconductor devices includes selectively simultaneously and momentarily irradiating a semiconductor substrate surface by a pulsed laser through a mask positioned between and spaced away from laser and substrate to briefly melt sub-regions of that surface. An optical beam reducer system is interposed between the relatively large separate mask and the substrate. An optical expander system is interposed between the laser and the mask to further increase the possible mask size and further reduce the radiation density at the mask. Wet photolithographic processing may be eliminated for selective diffusions of dopants, for selective epitaxy, for selectively converting polysilicon layers over silicon substrates to monocrystalline silicon layers and for selectively etching the substrate by a plasma induced by the patterned laser energy. Semiconductor device manufacture may thereby be greatly simplified.

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