Abstract: A semiconductor device and manufacturing method thereof attaining higher capacitor capacitance and lower power consumption are provided. On an interlayer oxide film which is a BPTEOS film containing an impurity, an interlayer oxide film which is a TEOS film not containing any impurity is formed. Openings of approximately inverted frusto-conical shape of approximately the same size are formed in interlayer oxide films, respectively, providing a contact hole of such a shape that includes two inverted frusto-cones continued in the vertical direction as a whole is provided. Along the inner wall surface of the contact hole, a storage electrode, a dielectric film and a cell plate electrode constituting a capacitor are formed successively.