Method of manufacturing semiconductor devices by dividing wafer into chips and such semiconductor devices

A plurality of chips divided from a semiconductor wafer having a plurality of semiconductor integrated circuits formed on a front surface of the wafer, are prepared, front surfaces of the chips being bonded to a first wafer sheet. The back and side surfaces of each chip bonded to the first wafer sheet are covered with a reinforcing thin film. Each of the plurality of chips is removed from the first wafer sheet. The flexural strength of a chip can be suppressed from being lowered by chipping and chip cracks.