Patent ID: 7107847

Claim:
A semiconductor acceleration sensor formed of a semiconductor substrate, and comprising: a rectangular frame having sides and an opening inside thereof, and further having corner portions each being of each two neighboring sides of the frame; plural flexible beams extending from the frame to the inside of the opening of the frame, and having an intersection portion at an intersection therebetween; a weight being suspended from and supported by the intersection portion of the beams, and being positioned in the opening as seen in plan view so as to be freely movable, and having corner portions facing the corner portions of the frame, respectively; and piezoresistors being mounted on the beams and varying the resistance values with distortions generated in the beams due to displacement of the weight, wherein the frame comprises damper plate portions provided at the corner portions of the frame, respectively, for limiting displacements of the corner portions of the weight, respectively, beyond a predetermined amount, wherein each of the damper plate portions covers a part of the opening, which part spans from each of the corner portions of the frame to the inside of the opening, and wherein each of the corner portions of the weight is chamfered to have a shape of arc or a polygonal line consisting of at least three sides as seen in plan view.