Photoelectric conversion element, method of manufacturing photoelectric conversion element, photoelectric conversion device, photodetection system, and movable object

A photoelectric conversion element, provided in a semiconductor layer having a first face and a second face opposed to the first face, comprising:

• a first semiconductor region of a first conductivity type provided in contact with the first face;
• a second semiconductor region of a second conductivity type provided closer to the second face than the first semiconductor region;
• a third semiconductor region provided closer to the second face than the second semiconductor region;
• a first impurity doped region to which an impurity of the first conductivity type is doped;
• a first electrode electrically connected to the first semiconductor region;
• and
• a second electrode electrically connected to the second semiconductor region,
• wherein the first semiconductor region and the second semiconductor region constitute an avalanche photodiode, and the avalanche photodiode is configured to multiply a signal charge generated in the third semiconductor region,
• wherein a width in a depth direction of a region having an effective impurity density of 1×1016 cm−3 or more of the second semiconductor region is 0.5 μm or less,
• wherein the first impurity doped region overlaps the second semiconductor region in a plan view and in the depth direction,
• wherein a depth at which a density of a first conductivity type impurity constituting the first impurity doped region has a peak is deeper than a depth at which a density of a second conductivity type impurity constituting the second semiconductor region has a peak,
• wherein an impurity density per unit area of the second conductivity type impurity constituting the second semiconductor region is 3×1012 cm−2 or more, and
• wherein an impurity density per unit area of the first conductivity type impurity constituting the first impurity doped region is not less than 5×1011 cm−2 and not more than ½ of an impurity density per unit area of the second conductivity type impurity constituting the second semiconductor region.