Microstructures with Protected Convex Corners in Modified KOH Solution Exhibiting High-Speed Silicon Etching

Abstract

In wet anisotropic etching based silicon bulk micromachining, undercutting, which has both advantage and disadvantage, takes place at the convex corners of microstructures. In order to retain the desired shape of fabricated structure, corner compensation method is most commonly used to protect the convex corners. The design and shape of the compensation geometry depend on the type of etchant. In this work, various types of corner compensating structures to protect convex corners on Si{110} and Si{110} are studied in potassium hydroxide (KOH) modified by adding NH 2 OH solution. Silicon etch rate in NH 2 OH-added KOH is 3–4 times more than that in pure KOH solution, which is very useful for industrial application to improve productivity. Mesa shape structures are fabricated using different shapes corner compensating geometry to optimize the design to obtain best shape convex corner. Triangular shape and beam shape geometries are found most appropriate structures to obtain well-shaped convex corner on Si{100} and Si{110}, respectively.