The present disclosure provides a method of manufacturing a semiconductor structure. The method includes forming a first mask on a substrate; defining a first doped region through an opening of the first mask; forming a second mask on the first mask and filling in the opening of the first mask with the second mask; defining a second doped region through an opening of the second mask; and stripping the first mask and the second mask from the substrate. The present disclosure provides a semiconductor structure, including a substrate having a top surface; a first doped region having a first surface; and a second doped region having a second surface. The first surface and the second surface are coplanar with the top surface of the substrate. Either of the doped regions has a monotonically decreasing doping profile from the top surface of the substrate to a bottom of the doped region.