To secure the rigidity of a thin wafer before it is divided into pieces of devices in the device manufacturing process of semiconductor chip and the like having a re-wiring layer on a backside, and preferably form the re-wiring layer on the backside of the chip on a stage of the wafer.

Only a region corresponding to a device formation region 4 where the semiconductor chip 3 is formed on the backside of the wafer 1 is thinned by polishing and etching to form a recess 11 on the backside. An annular salient 12 around the recess 11 allows the rigidity of the wafer 1 to be secured and handling of the wafer to be safely and easily performed at a time when the wafer is transferred to a process where a backside re-wiring layer 40 is formed.