Abstract: A multilayered wafer with a thick sacrificial layer, which is obtained by forming a sacrificial layer of oxidized porous silicon or porous silicon and growing an epitaxial polysilicon layer on the sacrificial layer, and a fabrication method thereof are provided. The multilayered wafer with a thick sacrificial layer adopts a porous silicon layer or an oxidized porous silicon layer as a sacrificial layer such that a sufficient gap can be obtained between a substrate and a suspension structure upon the manufacture of the suspension structure of a semiconductor actuator or a semiconductor inertia sensor. Also, in a fabrication method of the wafer according to the present invention, a p+-type or n+-type wafer doped at a high concentration is prepared for, and then a thick porous silicon layer can be obtained simply by anodic-bonding the surface of the wafer. Also, when polysilicon is grown on a porous silicon layer by an epitaxial process, it is grown faster than when single crystal silicon is grown.