Semiconductor structure and method of manufacturing the same

A method of manufacturing a semiconductor structure, comprising:

• forming a trench in a substrate;
• forming a dielectric layer over a first surface of the substrate and on a sidewall of the trench, wherein the dielectric layer extends to a first depth from the first surface of the substrate;
• reducing a thickness of the dielectric layer to reduce the first depth of the dielectric layer to a second depth from the first surface of the substrate, wherein the second depth is less than the first depth, and the first depth and the second depth are measured from the first surface of the substrate toward a bottom of the trench along a vertical direction;
• and
• forming a diffusion region in the substrate to wrap around the sidewall of the trench separated from the dielectric layer.

A semiconductor structure, comprising:

• a semiconductor substrate, including a first surface;
• an deep trench isolation (DTI) structure, comprising a filling material and a doped epitaxial layer, and disposed in the semiconductor substrate extending from the first surface and stopped inside the semiconductor substrate, wherein the filling material includes a first portion and a second portion disposed below the first portion and separated from the first surface, and the second portion is thicker than the first portion, and the second portion of the filling material is surrounded by the doped epitaxial layer;
• and
• a doping region, disposed in the substrate and surrounding the doped epitaxial layer of the DTI structure, wherein the doping region is separated from the first portion the filling material.