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Development of dicing technique for thin semiconductor substrates with femtosecond laser ablation

Recently, the semiconductor substrates for integrated circuits have been required to become as thin as 50 micrometers , because the many electronics devices are strongly demanded to be miniaturized and light-weighted. Machining of such thin substrates with conventional dicing techniques is very difficult. Therefore, we have proposed to process them using femtosecond laser ablation, expecting advantage of efficient etching without undesirable mechanical and thermal damages such as cracking and 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 photo-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 0.20 mJ/pulse and 5 shots were 17 micrometers and 40 micrometers , respectively. These values are very promising for the practical dicing applications.