Individual devices have been saw-cut (“singulated”) from wafers since the invention of the integrated circuit. As circuits get smaller and wafers get thinner, however, the limitations of mechanical processes begin to interfere with productivity. Saws tend to chip thin wafers. Newer, more porous “low-k” dielectrics also are prone to chipping when mechanically cut.
At this time, 355nm diode-pumped solid-state lasers are have advantages over mechanical saws when cutting silicon less than 200 microns thick. We have been examining methods of improving laser cutting speed and edge quality to increase the laser’s effective cutting capacity. A significant improvement in process rate can be achieved by shaping the focused beam. The fracture strength of the edges, as measured by bend testing, was maintained.