Thin silicon wafer dicing with a dual-focused laser beam

Abstract

Driven by the ever-growing desire for more compact electronic devices, the semiconductor industry has moved toward thinner silicon wafers. Simultaneously, the semiconductor industry has introduced new and better materials to facilitate the size shrinking. These factors introduce serious limitation in current saw blade semiconductor wafer dicing technology and needs new processing tools. Although nanosecond laser dicing overcomes most of the issues related to saw blade dicing, the dicing throughput remains below the current industrial requirement. In this paper a novel dual focus mechanism is introduced to increase the throughput of laser wafer dicing. Experimental results proved that dual focus increases the dicing speed, reduces the kerf width, eliminates the debris and enhances the die fracture strength. Cutting strategy and laser parameters, such as back focus power, repetition rate and wavelength, that influence the machining efficiency and quality, were studied in detail. The industrial implement of laser singulation is discussed.