METHOD OF FORMING A CAVITY BY TWO-STEP ETCHING AND METHOD OF REDUCING DIMENSION OF A MEMS DEVICE

摘要

A method for reducing dimension of an MEMS device. A single crystalline substrate having a diaphragm is provided. A first-step anisotropic dry etching process is performed to form an opening corresponding to the diaphragm in the back surface, the anisotropic dry etching stopping on a specific lattice plane extending from the edge of the diaphragm. A second-step anisotropic wet etching process is performed to etch the single crystalline substrate along the specific lattice plane until the diaphragm is exposed to form a cavity having a diamond-like shape.