CMOS structure and forming method thereof

The technical scheme of the invention provides a CMOS (Complementary Metal Oxide Semiconductor) structure and a forming method thereof, and the forming method comprises the steps: providing a semiconductor substrate, and forming PMOS (P-channel Metal Oxide Semiconductor) channel layers which are alternately distributed and NMOS (N-channel Metal Oxide Semiconductor) grooves which penetrate through the PMOS channel layers on the surface of the semiconductor substrate; forming an NMOS channel material layer on the surface of the PMOS channel layer and in the NMOS groove, wherein the surface of the NMOS channel material layer is provided with a recess; filling the recess with a sacrificial layer, wherein the sacrificial layer and the surface of the NMOS channel material layer are coplanar; and removing the sacrificial layer and a part of the NMOS channel material layer, forming a protection layer on the surface of the PMOS channel layer, forming an NMOS channel layer in the NMOS groove, and enabling the protectio