Micro/nano scale amorphization of silicon by femtosecond laser irradiation.

This research aimed to investigate the feasibility of using direct amorphization of silicon induced by femtosecond laser irradiation for maskless lithography. A thin layer of amorphous silicon of predetermined pattern was first generated by irradiation by a femtosecond laser of Mega Hertz pulse frequency. The following KOH etching revealed that the amorphous silicon layer acted as an etch stop. Line width less than 1/67 the focused spot size was demonstrated and hence the proposed maskless lithography process has the potential of producing submicron and nanoscale features by employing a laser beam of shorter wavelength and a high NA focusing lens. Scanning Electron Microscope (SEM), a Micro-Raman and Energy Dispersive X-ray (EDX) spectroscopy analyses were used to evaluate the quality of amorphous layer and the etching process.