Fabrication of high Q microtoroid cavity on a silicon wafer by wet etching

The miniaturization of optical devices is the development trend of optical products in the future. The WGM microcavity has been studied extensively in recent decades. We demonstrated a method of fabrication of high Q microtoroid cavity on a silicon wafer by the wet-etching without the dry-etching of poisonous XeF2. A 2.5 μm SiO₂ layer was fabricated by wet oxidation on the silicon wafer with a <100<. The main procedure was as follows: the standard photolithography technology was used to form disk on a <100< silicon wafer; tetramethylammonium hydroxide was used to corrode silicon; and the CO₂ laser was used to melt the disk and then obtained a microtoroid cavity with a microchip on the silicon wafer. We measured the transmission morphology characterization spectra of the microtoroid, and calculated the Q value.