Next, as shown in FIG. 7C, the filling insulating layer 227 is made to be substantially level with the first interlayer insulating layer 230 a by partially removing the filling insulating layer 227, the second conductive layer 355, and the first conductive layer 223 on the first interlayer insulating layer 230 a through a planarization process, for example using CMP. As shown in FIG. 7D, the secon