SEMICONDUCTOR DEVICE AND MANUFACTURING METHOD OF THE SAME

PROBLEM TO BE SOLVED: To achieve downsizing of a semiconductor device in which a cap wafer is bonded to a device wafer.SOLUTION: A semiconductor device manufacturing method comprises: forming an oxide film 64 on one surface 61 of a semiconductor substrate 63 before forming a cavity 66; and forming the cavity 66 by etching the semiconductor substrate 63 from the one surface 61 after removing the oxide film 64 by using a mask 81. This can make the oxide film 64 have a uniform film thickness and since thermal oxidation when forming the oxide film 64 is unaffected by the cavity 66, the one surface 61 becomes a flat surface around an end 61a which forms a boundary with the cavity 66. Further, a surface of the oxide film 64 does not have a protruding shape but has a flat surface. For this reason, the oxide film 64 can be bonded to a device wafer 10 from the end 61a, does not have an unbonded area as in conventional techniques but a whole area can be a bonded area. Accordingly, a broad area is not required for a bonding margin thereby to achieve downsizing of the semiconductor device.