Semiconductor device and manufacturing method thereof

The invention provides a semiconductor device and a manufacturing method thereof. The manufacturing method of the semiconductor device comprises the following steps: providing a first wafer, wherein the first wafer is provided with a first surface and a second surface which face each other, the first wafer comprises a plurality of first device areas and a plurality of second device areas, and thefirst device areas and the second device areas are arranged at intervals; etching grooves in the positions, corresponding to the first device areas, of the first surface of the first wafer; forming isolation layers on the side walls of the grooves; growing epitaxial layers on the bottom walls of the grooves; preparing a device unit on each first device area and each second device area; and thinning the first wafer from the second surface so as to allow the isolation layers to be exposed from the second surface, wherein the adjacent device units are completely isolated by the isolation layers.Through the method, signal