LASER DIRECT WRITING OF METAL INTERCONNECTS.

Laser direct writing of metals offers the advantages of in-situ design and repair of ICs with a process that can be controlled and altered from chip to chip to meet the designer's needs. A summary of laser direct writing techniques for metal deposition--photolytic, pyrolytic, and photo-thermal--is presented, emphasizing the advantages of each technique. In particular, the authors have sought to produce high-quality metal interconnects suitable for VLSI dimensions of 2-3 mu m linewidths, yet with resistivities 3-5 times the bulk metal used. An important aspect of the study involved penetration of the native oxide layer that exists on evaporated Al metallizations in order to make low-resistivity interconnect lines.