Explosion of poly-silicide links in laser programmable redundancy for VLSI memory repair

Laser programmable redundancy has been used in very large-scale memory devices to increase yields through the replacement of defective elements by spare rows or columns. The effect of scaling on the laser repair rate due to chip size and density increase in VLSI is discussed. The laser target link material systems that were used to implement redundancy in recent generations of DRAM and the laser pulse characteristics are described. Various laser explosion patterns in poly-silicide links are described, and the caused of their formation and their effects on repair rate are discussed. Several experiments of laser link explosion under various conditions were performed to compare the observed facts with a theoretical model. Good correlations have been obtained.>