Influence of laser wavelength and pulse duration on processing of crystalline silicon

The paper discusses the fundamental interaction between laser light and crystalline silicon within a broad range of laser parameters, especially the pulse duration, with relevance for cutting and drilling. For laser processing of silicon the absorption at the laser wavelength and the sensitivity of the material to thermal stresses are dominant. Using laser sources with wavelengths near the indirect band-gap and with rising temperatures the optical behaviour of silicon changes significantly. A comparison of processing with different pulse durations at the same wavelength from ultra-short picosecond pulses up to microsecond pulses is presented. The material removal processes such as melt ejection and vaporization are studied. The influence of the laser radiation wavelength on the processing is briefly discussed. The relevance of this work for some applications, like wafer dicing in the electronics industry and photovoltaic applications will be discussed as well.