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Etching characteristics of hexagonal and triangular cavities on a ⟨1 1 1⟩-oriented silicon wafer in the etchant of ethylene diamine, pyrocatechol and water (EDP/EPW) were investigated. The patterns are aligned to keep the sides perpendicular to ⟨1 1 0⟩ crystal orientations, in order that the sidewalls of cavities are parallel to {1 1 0} crystalline planes. RIE-ICP etching is used to define the depth of the triangular and hexagonal cavities, and EDP etching is followed for different etching times. The final self-etch-stop profiles of cavities are determined by the dimension of mask patterns and the depth of cavities in the wafer. The etching process of the hexagon and triangle cavities is modeled, based on the crystal structure and wet etching principle. The results of etched cavities confirm the condition to determine the final etching profiles.

We report small reflecting mirrors with high reflectance, which are fabricated by using square quartz chips. These quartz mirrors are going to be used in the construction of a miniaturized Fabry Perot Interferometer (FPI) with a commercial ring type PZT from Fuji Ceramic Company. The dimension of quartz substrates is 10×10mm with a thickness of 1mm. The high reflectance of mirrors is obtained by depositing multi-layer thin films on quartz substrates. Magnetron RF sputtering machine is used to ensure that the thickness of dielectric coatings can be precisely controlled. These mirrors are measured by SEM and AFM and the reflectance is detected by a visible light spectrometer. The maximum reflectance of these mirrors is about 99.4% on the designed wavelength 553nm. A small FPI set up by this kind of mirror can have a theoretical finesse of 522, and if a PZT resonator with a length of 7.22mm is used, the resolution of this small interferometer can reach 4.06×10 -5 nm, in another word, the resolving power is 1.36×10 7 .

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