Abstract: Laser interference structuring is a relatively efficient and cost-effective technique for fabricating periodical micro-nano structures. The direct fabrication of sub-micron sized dot array on silicon is performed by four interfering nanosecond laser beams with diffractive beam splitter. It is found that the obtained conical dot array has a negative shape of the interference pattern of four laser beams. And the height at the hotter regions is a litter higher than the root of the conical dots due to the liquid-solid expansion. In addition, the influence of laser pulse number on the dot shape is studied. Beams at the top of dots can be induced for a large number of pulses. The dot height is found to grow with the increase of laser pulse number, but the saturation can be observed when the pulse number is large enough.

Key words: Interference, Microstructure, Nanosecond laser, Silicon