Technological problems in forming Si waveguide lamellar diffraction gratings and 2D photonic crystals by plasma and wet etching of Si

A fabrication process (plasma and wet etching of Si, lift off technology) is developed for polycrystalline Si strip-like waveguides (220 nm thick), waveguide lamellar diffraction grating and 2D photonic crystal structures tuned to an electromagnetic wave with the wavelength 1.5 μm. The photonic crystals are composed of either Si pillars or pores in a Si waveguide which is situated on the surface of a SiO₂ (1 μm thick)/Si-wafer substrate. The measured attenuation coefficient of the polycrystalline Si waveguide is estimated to be 0.17 dB/mm at a wavelength of 1.5 μm.