Silicon three-dimensional structures fabricated by femtosecond laser modification with dry etching.

Abstract

In this paper, a maskless, high efficiency, and flexible technology is developed to fabricate three-dimensional (3D) microstructures on a silicon wafer, which is based on the combination of femtosecond laser modification and subsequent dry etching. The silicon atoms in 2D patterned areas were insufficiently oxidized after femtosecond laser irradiation. Complex 3D structures can be fabricated on the silicon wafer after etching, such as micro gears, comb drive actuators, and micro cantilevers applied in microelectromechanical systems (MEMS) and micro Fresnel zone plates applied in micro optics. What is more, surface roughness of the laser structured wafer can be improved with increased etching time in the dry etching process. This technology shows its unique capacity to fabricate various 3D microstructures for applications in MEMS and micro optics.