Development of Dicing Technique for Thin Semiconductor Substrate by Using a Femtosecond Laser

Abstract

Recently, the semiconductor substrates for integrated circuits (ICs) have been required to become as thin as 50 μm, because the many electronic devices are strongly demanded to be miniaturized and light-weighted. It is very difficult for such a thin substrate fabricated with conventional dicing techniques. Therefore, we have proposed to process them using femtosecond laser ablation, expecting advantage of efficient processing without undesirable mechanical and thermal damages such as cracking and partial melting is expected. In this work, we have investigated the influence of the laser conditions such as pulse duration and fluence on the cutting depth and diameter in order to develop a new dicing technique for very thin ICs. Within the range of pulse energy used in the present experiments, the dependence of the pulse duration did not seem to be significant. It was also found that the lower energy of the laser pulses, the smaller and the deeper, i.e., the sharper holes were formed. The typical cutting depth and diameter for 200 μJ/pulse and 5 shots were 7 μm and 40 μm, respectively. These values are very promising for the practical dicing applications.