Semiconductor device and preparation method thereof

The invention provides a semiconductor device and a preparation method thereof, which can reduce the warping degree of an epitaxial layer comprising a first sacrificial layer and a channel layer, namely can reduce the defect density of the semiconductor device, and further improves the performance consistency of the semiconductor device. The semiconductor device may include a substrate, a plurality of first sacrificial layers, and a plurality of channel layers, the plurality of first sacrificial layers and the plurality of channel layers being alternately stacked on the substrate in a first direction. At least one first sacrificial layer in the multiple first sacrificial layers comprises silicon, germanium, an N-type doping element and a first element, and the first element comprises at least one of carbon, fluorine, sulfur and nitrogen.