Effect of pulse duration on scribing of ceramics and Si wafer with ultra-short pulsed laser

摘要

Nowadays, electronic products used for cellular phones etc. become smaller and more lightweighted, and thus the size of semiconductor boards for integrated circuits need to be reduced- In the case of the cutting process of a thin semiconductor wafer into single chips, conventional processing techniques tend to produce defects. Therefore, we aimed at the development of a new cutting processing technique, i.e. a method with less mechanical and thermal damages. In this study, we investigated the scribing of Al_2O_3 ceramics and of a Si wafer by a nanosecond-laser (Nd:YLF) and a femtosecond-laser (Ti:sapphire). For ceramics, better processing shape with high aspect ratio, no debris, no thermal effect and good processing efficiency were obtained by the femtosecond-laser rather than with the nanosecond-laser. Additionally, the pulse duration of the femtosecond-laser was changed between 30-600 fs at fixed processing conditions. When the pulse durations were changed in the femtosecond-range, the shape of the groove bottom and side varied. The processing efficiency was improved with increasing the pulse duration in the range of 30-600 fs, which was a finding contrary to results expected. The scribing of the Si wafer shows a similar tendency to that of the Al_2O_3 ceramics. We therefore conclude that the processing shape and the processing efficiency can be improved depending on the pulse duration.