Solid state imaging device and method for manufacturing same

A solid state imaging device, wherein

• a plurality of pixels are arranged in a matrix on a substrate,
• each of the plurality of pixels includes a photoelectric conversion region and an element separation region separating the photoelectric conversion region,
• the substrate includes a semiconductor substrate, a first epitaxial layer formed on the semiconductor substrate, and a second epitaxial layer formed on the first epitaxial layer,
• the photoelectric conversion region and the element separation region are formed over the first epitaxial layer and the second epitaxial layer, wherein an impurity concentration of a part of the photoelectric conversion region provided in the second epitaxial layer is equal to or higher than an impurity concentration of a part of the photoelectric conversion region provided in the first epitaxial layer
• the first epitaxial layer includes a drain part for discharging an excessive charge generated in the photoelectric conversion region,
• the drain part has a different conductivity type from the first epitaxial layer,
• the photoelectric conversion region is surrounded by the element separation region and the drain part, and
• a potential barrier of the drain part is lower than a potential barrier of the element separation region.