Formation method of semiconductor structure

According to the forming method of the semiconductor structure, sacrificial layers in a channel lamination layer comprise two first sacrificial layers and a second sacrificial layer clamped between the two first sacrificial layers, annealing treatment is carried out on the channel lamination layer in a transistor region, and the uniformity of the diffusion degree between materials of the adjacent first sacrificial layer and the second sacrificial layer is improved; therefore, the transverse depth uniformity of the inner groove is improved; the second sacrificial layer and the first sacrificial layer have an etching selection ratio, the first sacrificial layer plays a role in protecting the channel layer in the process of transversely etching the second sacrificial layer, and the flatness of the end parts of the second sacrificial layer and the mixed layer exposed out of the initial inner groove is improved while the depth of the initial inner groove meets the requirement; besides, the diffusion capability bet