Electrical capacitance pressure sensor having electrode with fixed area and manufacturing method thereof

An electrical capacitance pressure sensor comprising:

• a substrate having first and second surfaces;
• a lower electrode formed on the first surface of the substrate;
• a movable electrode formed on the lower electrode and separated by a predetermined distance from the lower electrode, for forming a diaphragm;
• an upper electrode formed on the movable electrode and separated by a predetermined distance from the movable electrode,
• a first cavity portion formed between the lower electrode and the movable electrode to form an electrical capacitance that is to be changed to a first capacitance value when the movable electrode deforms based on a pressure difference between both sides thereof;
• and
• a second cavity portion formed between the upper electrode and the movable electrode to form an electrical capacitance that is to be changed to a second capacitance value thereof when the movable electrode deforms based on the pressure difference between both sides thereof;
• wherein the substrate has an opening portion that penetrates the substrate from the first surface to the second surface thereof,
• the lower electrode has at least one first window portion that penetrates the lower electrode from the side of the substrate to the side of the first cavity portion and communicates the cavity portion to the opening portion of the substrate, and
• the upper electrode has at least one second window portion that penetrates the upper electrode from the side of the cavity portion to the outside thereof to communicate the cavity portion to an outside environment.

A method for manufacturing an electrical capacitance pressure sensor comprising:

• preparing a substrate having first and second surfaces;
• forming a lower electrode on the first surface of the substrate;
• forming a sacrificial layer on the lower electrode;
• forming a movable electrode on the sacrifice layer;
• etching the substrate from the second surface to form an opening portion;
• forming at least one window portion to penetrate a part of the lower electrode that is exposed from the opening portion of the substrate;
• etching the sacrificial layer to form a cavity portion and a diaphragm by the movable electrode through the opening portion of the substrate and the at least one window portion of the lower electrode;
• and
• forming a cover member on the lower electrode on a side of the opening portion of the substrate to cover the at least one window portion and to form a reference pressure chamber in the cavity portion.

A method for manufacturing an electrical capacitance pressure sensor comprising:

• preparing a substrate having a first and a second surface;
• forming a lower electrode on the first surface of the substrate;
• forming a first sacrificial layer on the lower electrode;
• forming a movable electrode on the first sacrificial layer;
• forming a second sacrifice layer on the movable electrode;
• forming an upper electrode on the second sacrificial layer;
• etching the substrate from the second surface to form an opening portion;
• forming at least one first window portion to penetrate a part of the lower electrode that is exposed from the opening portion of the substrate;
• forming at least one second window portion to penetrate a part of the upper electrode;
• and
• etching the first and second sacrificial layers to form a first cavity portion, a second cavity portion and a diaphragm by the movable electrode through the opening portion of the substrate, the at least one first window portion of the lower electrode and the at least one first window portion of the upper electrode.