An integrated circuit is formed in each region of a front surface of a semiconductor device. The semiconductor device is mechanically ground so as to be left having a thickness enough to prevent a defect on the back surface from reaching its opposed front surface. Thereafter, the back surface of the semiconductor device is subjected to etching in mainly chemical reaction to thereby smoothe concaves and convexes caused on the back surface of the semiconductor device in mechanical grinding, so that the semiconductor device is made thinner by the amount corresponding to a concave/convex difference. When the back surface of the semiconductor device is smoothed as described above, stress will not concentrate at the concaves and convexes on the back surface of the semiconductor substrate at a later processing stage where a lower supporting base is fixedly formed on the back surface of the semiconductor substrate via an insulating resin layer, whereby a laminated body is formed on the back surface of the semiconductor substrate. This arrangement enhances the reliability of the resulting semiconductor devices.