Membrane Structure and Method for Manufacturing the Same

A manufacturing method of a membrane structure comprising the steps of;

• forming a mask having an opening on a first layer of a substrate comprising at least the first layer, a second layer formed so as to cover one of principal faces of the first layer, and a third layer formed between the first and second layers;
• forming a first opening having a side face in virtually vertical which passes through the first layer and by dry etching through the opening of the mask;
• smoothing an inner peripheral face of the first opening of the first layer by wet etching such that a specific crystal face appears at least on an end of the second layer side of the first opening;
• and
• forming a second opening on the third layer by etching through the opening of the first layer;
• wherein the step of forming the second opening is to form the second opening such that an amount of setback of the opening of the second opening from the opening of the first layer at a boundary face of the first layer and the third layer is larger than 0, and about the same as the film thickness of the third layer or smaller than the film thickness;
• and
• the steps of forming the first and second openings are to form the first and second opening so as to provide a predetermined deflection proximity to the opening depending on the difference in pressure applied to one principal face and another principal face.