Patent ID: 7155977

Claim:
A capacitance type semiconductor dynamic quantity sensor comprising: a substrate having a support layer and a semiconductor layer mounted on the support layer; a weight portion displaceable in a predetermined direction; movable electrodes joined to the weight portion so as to be displaceable integrally with the weight portion; fixed electrodes disposed so as to confront the movable electrodes; and beam-shaped beam portions that are deformable elastically to displace the weight portion, wherein the weight portion, the movable electrodes, the fixed electrodes and the beam-shaped beam portions are formed by forming trenches in the semiconductor layer, wherein when a dynamic quantity is applied, the distance between each movable electrode and each fixed electrode is varied, and the applied dynamic quantity is detected based upon a capacitance variation between the fixed electrode and movable electrode caused by the variation of the distance, wherein the thickness h 2 of the beam portion is set to be larger than the thickness h 2 of the movable electrode.