Abstract: A semiconductor structure and a method for forming the semiconductor structure are provided. The method for forming a semiconductor structure of the present invention may include the following steps. First, a substrate is provided, wherein a gate is formed over the substrate, and a plurality of offspacers are formed over a sidewall of the gate. Then, a source/drain trench is formed in the substrate at two sides of the gate respectively. Next, an outermost offspacer of the offspacers is removed to expose a flat surface on a surface of the substrate. Thereafter, the source/drain trenches are filled to form a source/drain region. Then, a lightly doped drain (LDD) region is formed in a portion of the substrate under the flat surface.