Isolation in micromachined single crystal silicon using deep trench insulation

摘要

An electrical isolation method for silicon microelectromechanical systems provides trenches filled with insulation layers that support released silicon structures. The insulation layer that fills the trenches passes through the middle portion of the electrodes, anchors the electrodes to the silicon substrate and supports the electrode. The insulation layers do not attach the electrode to the sidewalls of the substrate, thereby forming an electrode having an "island" shape. Such an electrode is spaced far apart from the adjacent walls of the silicon substrate providing a small parasitic capacitance for the resulting structure. The isolation method is consistent with fabricating a complex structure or a structure with a complicated electrode arrangement. Furthermore, the structure and the electrode are separated from the silicon substrate in a single release step. Additionally, a metal layer is deposited on the surfaces of the structure and electrodes without using separate photolithography and etching steps.