Nano-particles and nano-period ripples can be used to form some micro-nano-instruments in microelectronics. In this
paper a femtosecond (fs) pulse laser (148fs, 1KHz, center wavelength=775nm) is used to irradiate on metal surface, then
nano-particles and nano-period ripples can be obtained in the focal scale, the size of which is shorter than the center
wavelength. For describing the formation time and characteristic of nano-particles and nano-period ripples, we have
increased the laser fluence from the threshold of material to a higher value and increased the laser exposure time in fixed
laser fluence on different materials. Experimental results show that nano-particles occur earlier than nano-period ripples.
And as the fs laser pulse number being increased, the periodical nano-ripples is clearer and clearer and the depth of
ripples is deeper and deeper. Finally, permanent ablation will occur in the focal scale basing on the nano-ripples. After
surface plasmon polaritons theory is used, the period of nano-ripples can be explained exactly. This work is the basic
research for micro-nano-instruments by fs laser ablation technique on metal surface.
|