Photoelectric conversion apparatus and imaging system having revision with multiple impurity densities

A photoelectric conversion apparatus comprising:

• a plurality of P-type charge accumulating areas disposed in a semiconductor substrate, each of the plurality of P-type charge accumulating areas containing P-type impurities;
• an N-type well portion arranged in the semiconductor substrate and under the plurality of P-type charge accumulating areas, extending across the plurality of P-type charge accumulating areas, each of the plurality of P-type charge accumulating areas configuring a photoelectric converter together with the N-type well portion, wherein the well portion includes:
• an N-type first semiconductor region extending across the plurality of P-type charge accumulating areas and containing arsenic at a first density,
• an N-type second semiconductor region disposed below the first semiconductor region so as to extend across the plurality of P-type charge accumulating areas and containing arsenic at a second density that is lower than the first density, and
• an N-type third semiconductor region disposed below the second semiconductor region so as to extend across the plurality of P-type charge accumulating areas and containing N-type impurities at a third density that is higher than the first density;
• a device isolation area disposed in the semiconductor substrate;
• and
• a potential barrier disposed between the device isolation area and the N-type first semiconductor region of the well portion so as to isolate the plurality of P-type charge accumulating areas from each other, wherein the potential barrier includes:
• an N-type fourth semiconductor region disposed below the device isolation area and containing N-type impurities at a fourth density that is higher than the second density;
• and
• an N-type fifth semiconductor region disposed below the fourth semiconductor region and containing N-type impurities at a fifth density that is higher than the second density.