Method for forming micro cavity

Abstract

A method for forming a micro cavity is disclosed. In the method for forming the cavity, a first layer is formed on a silicon layer and a trench is formed in the silicon layer by selectively etching the silicon layer. A second and a third layers are formed on the trench and on the silicon layer. Etching holes are formed through the third layer by partially etching the third layer. A cavity is formed between the silicon layer and the third layer after the second layer is removed through the etching holes. Therefore, the cavity having a large size can be easily formed and sealed in the silicon layer by utilizing the volume expansion of the silicon or the poly silicon layer. Also, a vacuum micro cavity can be formed according as a low vacuum CVD oxide layer or a nitride layer formed on the etching holes which are partially opened after the thermal oxidation process by controlling the size of the etching holes concerning the other portion of the poly silicon layer.

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