Abstract

Lasers have been used to pattern thin metal films in air,^1,2 a wet chemical solution,³ and gas.⁴ Our interest is in maskless processing of the top layer of metal in an integrated circuit chip for quick turnaround. We, therefore, want to be able to break metal links on a chip to customize It in a manner similar to the laser restructuring of a gate array previously reported.⁵ For this we require a technique to cut aluminum lines with high resolution (<2 μm), speed (>100 links/s), and without damage to active MOS devices in the layers beneath. A tightly focused pulsed UV laser system has the advantage of a small diffraction-limited beam spot combined with a short (~10-ns) puise to minimize heat transfer and keep damage local to the spot. We report results of using such a laser system to etch fine patterned aluminum lines on a silicon chip. The laser was used to enhance the etch rate of a solution⁵ and also to cut links ablatively in air.

© 1986 Optical Society of America