Abstract: A semiconductor structure includes a substrate, a gate structure, a first oxide layer, and a second oxide layer. The substrate has a trench. An inclined surface and a bottom surface of the trench have an obtuse angle therebetween. The gate structure is located in the trench. A width of a bottom surface of the gate structure is less than a width of a top surface of the gate structure. A cross-sectional profile of the gate structure is inverted trapezoid. The first oxide layer is located between the gate structure and the substrate. The second oxide layer is located on the top surface of the gate structure.

Abstract: A method of forming a semiconductor structure includes the following operations. A semiconductor epitaxial layer is formed on a first semiconductor substrate. A first side of the semiconductor epitaxial layer is adhered to a transfer substrate by an adhesive layer covering the first side of the semiconductor epitaxial layer. The semiconductor epitaxial layer and the first semiconductor substrate are turned over by the transfer substrate. The first semiconductor substrate is removed to expose a second side of the semiconductor epitaxial layer opposite to the first side. A first semiconductor doped region is formed on the second side of the semiconductor epitaxial layer. After the first semiconductor doped region is formed, the adhesive layer and the transfer substrate are removed.