PRESSURE SENSOR OF ELECTROSTATIC CAPACITANCE TYPE

摘要

To provide a capacitive sensor which produces a sensor output excellent in linearity. The capacitive sensor 1 comprises a semiconductor substrate 2 and a substrate 3. The semiconductor substrate 2 is formed with a frame portion 21 and a diaphragm portion 22 serving as a movable electrode, and bonded with the substrate 3 at the upper surface of the frame portion 21 by anodic bonding. The substrate 3 is provided with a fixed electrode 31 on a surface facing the diaphragm portion 22. A fixing projection 24 is provided on a center of the diaphragm portion 22 and is fixed to the substrate 3 through a hole of the fixed electrode 31. When external force is applied to the sensor, the diaphragm portion 22 displaces upward and/or downward. The external force is detected based on change of electrostatic capacitance. Since the center of the diaphragm portion 22 is fixed by the fixing projection 24, the maximum displacement region of the diaphragm portion 22 forms a ring, resulting in enhancement of linearity of the sensor output.