Micromachined Sealed Cavities by Silicon Wafer Bonding for the Formation of Microstructures of Desired Thickness Using TMAH Etching

The present research report a fabrication process of suspended silicon microstructures of desired thickness over controlled depth micromachined cavities. The process is developed using direct wafer bonding to seal the micromachined cavities and wet anisotropic etching in pure and surfactant added tetramethyl ammonium hydroxide (TMAH) solutions. Wet anisotropic etching is used for the formation of cavities, thinning down the wafer for structural layer and releasing the structures. Non-ionic surfactant Triton-X-100 [C₁₄H₂₂O(C₂H₄O)_n] added TMAH is used to realize the microstructures with rounded concave and sharp convex corners.