Preparation of all silicon dielectric metasurface by femtosecond laser modification combined with wet etching, achieving ideal compatibility with complementary metal oxide semiconductor technology

The fully dielectric element surface has the characteristics of low material loss and strong field localization, making it very suitable for manipulating electromagnetic waves at the nanoscale. Especially the surface of all silicon dielectric elements can achieve ideal compatibility with complementary metal oxide semiconductor technology, making it an ideal choice for large-scale monolithic integration of photonic chips. However, in traditional silicon micro processing, the combination of mask lithography and active ion etching involves multiple preprocessing stages, resulting in increased costs and processing time.

This article proposes a femtosecond laser direct writing method, which uses femtosecond laser to process silicon below the ablation threshold and wet chemical etching to achieve the surface of all silicon dielectric resonant elements. This method utilizes different etching rates between laser modified and untreated regions to achieve the manufacturing of large-scale patterned silicon surfaces in a simple and economical manufacturing method.

The Ioanna Sakellari team from Greece utilized ultrafast laser modification and wet chemical etching to form a two-dimensional micro nano circular array structure on silicon surface. By adjusting the size of micro nano stage units on the silicon surface and changing the surface diameter of the stage, the resonance frequency of the metasurface can be effectively controlled. The Fourier transform infrared spectra of linearly polarized incident light with different silicon based nano cone array structures were experimentally measured, and the scale of 200 was characterized μ M × two hundred μ The infrared light transmittance of different nano cone array structures of m, with a cone height of approximately 0.95 μ m. The period of the array in both the x and y directions is 2.42 μ m. The surface diameters on the circular platform are 220nm (green), 380nm (blue), and 740nm (red), respectively. The electron microscope images of different nano cone array structures prepared are shown in the following figure:

Figure 1. Structure of a two-dimensional micro nano cone array on silicon surface

Source: Sohu