Photoelectric conversion apparatus

A photoelectric conversion apparatus having an avalanche photodiode, the apparatus comprising:

• a semiconductor layer having a first surface in which light is incident and a second surface;
• a first semiconductor region of a first conductivity type disposed at a first depth;
• a second semiconductor region of a second conductivity type disposed at a second depth that is greater than the first depth from the second surface, wherein the second semiconductor region forms the avalanche photodiode together with the first semiconductor region;
• a third semiconductor region of the first conductivity type provided in contact with an end portion of the first semiconductor region;
• an oxide film disposed on the second surface of the semiconductor layer;
• a protective film disposed on an opposite side of the oxide film from the semiconductor layer, wherein the protective film is made of a material that differs from a material used for the oxide film;
• an interlayer film disposed on an opposite side of the protective film from the oxide film;
• and
• a member provided between the oxide film and the protective film in cross-sectional view,
• wherein the member is disposed to overlap at least a boundary between the first semiconductor region and the third semiconductor region in plan view, and
• wherein an interface state density between the oxide film and the member is less than an interface state density between the oxide film and the protective film.

A photoelectric conversion apparatus including an avalanche photodiode, the apparatus comprising:

• a semiconductor layer having a first surface in which light is incident and a second surface;
• a first semiconductor region of a first conductivity type disposed at a first depth;
• a second semiconductor region of a second conductivity type disposed at a second depth that is greater than the first depth from the second surface, wherein the second semiconductor region forms the avalanche photodiode together with the first semiconductor region;
• a third semiconductor region of the first conductivity type provided in contact with an end portion of the first semiconductor region;
• an oxide film disposed on the second surface of the semiconductor layer;
• a member provided on an opposite side of the oxide film from the semiconductor layer in cross-sectional view;
• wiring;
• and
• a contact plug configured to connect the wiring to the second surface of the semiconductor layer,
• wherein the member is disposed to overlap at least a boundary between the first semiconductor region and the third semiconductor region in plan view,
• wherein the member is disposed between the wiring and the semiconductor layer, and
• wherein the member is made of second conductivity type polysilicon so that a potential gradient for signal charge is formed to urge the signal charge in a direction from the member toward the first surface.