Dicing Process for Thin Silicon Wafer by Using Femtosecond-laser

Abstract

Thin semiconductor wafer is more required for portable devices due to its mechanical flexibility or space gain. In dicing process for this thin wafer, suppression of micro-cracks is indispensable, which result in starting point of substrate breakage. In this research, laser cutting was performed for thin silicon wafer as a new dicing technique to conventional diamond blade dicing. Nano-, pico- and femtosecond laser were used to cut substrates in order to investigate the dependence of the flexural strength on the pulse width and the irradiated laser energy. As a result of that, the average strength of the diced wafer with the femtosecond laser was about three times larger than that with the nanosecond laser. In the case using the femtosecond laser, moreover, the minimum strength was about three times as large as that of the conventional blade dicer.