| abstract |
In some embodiments, a method is provided. The method includes forming a plurality of trenches in a semiconductor substrate, where the trenches extend into the semiconductor substrate from a rear side of the semiconductor substrate. An epitaxial layer comprising a dopant is formed on lower surfaces of the trenches, sidewalls of the trenches and the back of the semiconductor substrate, where the dopant has a first doping type. The dopant is driven into the semiconductor substrate to form a first doped region with the first doping type along the epitaxial layer, where the first doped region has a second doped region with a second doping type contrary to the first doping type from the side walls of the trenches and from the rear separates the semiconductor substrate. A dielectric layer is formed over the back of the semiconductor substrate where the dielectric layer fills the trenches to form deep backside trench isolation structures. |