Acceleration sensor element and acceleration sensor having same

A covered acceleration sensor element including a weight portion, a support frame portion surrounding the weight portion, a plurality of flexible beam portions for connecting the weight portion, to the support frame portion to support the weight portion, piezoresistance elements provided on the beam portions, and wirings for connecting them,

• the covered acceleration sensor element being configured such that an upper cover and a lower cover enclosing a periphery of the weight portion together with the support frame portion are joined to a face and a back of the support frame portion, and
• the covered acceleration sensor element being adapted to detect acceleration in a direction of a first axis as a thickness direction in which the upper cover, the support frame portion, and the lower cover are stacked, and acceleration in a direction of at least one of a second axis in a plane perpendicular to the first axis, and a third axis in the plane and perpendicular to the second axis, from changes in resistances of the piezoresistance elements,
• wherein the support frame portion is separated by separation grooves into an inner frame and an outer frame surrounding a periphery of the inner frame, the upper cover and the lower cover are joined to the outer frame, and the inner frame is connected to and held by the outer frame via a plurality of inner frame support portions having flexibility, and
• the beam portions are connected to both sides of the weight portion along at least one of the second axis and the third axis, and the inner frame support portions are connected to both sides of the inner frame after being rotated through a predetermined angle from the at least one of the second axis and the third axis in a direction in which an influence of deformation of the outer frame is minimally transmitted to the beam portions.