Photoelectric conversion apparatus, manufacturing method thereof, and image pickup system

A photoelectric conversion apparatus including a light-receiving element, the light-receiving element comprising:

• a first photoelectric conversion unit and a second photoelectric conversion unit;
• a separating portion located between the first photoelectric conversion unit and the second photoelectric conversion unit;
• and
• a light guide portion surrounded by an insulating film including at least one insulating layer, and provided to extend over the first photoelectric conversion unit and second photoelectric conversion unit,
• wherein
• when a direction in which the first photoelectric conversion unit and the second photoelectric conversion unit are arranged is defined as a first direction, and a direction in which the first photoelectric conversion unit and the second photoelectric conversion unit, and the light guide portion are arranged is defined as a second direction,
• the light guide portion includes a low refractive index portion and a high refractive index portion, the low refractive index portion having a refractive index equal to or lower than a refractive index of the insulating layer, and the high refractive index portion having a refractive index higher than a refractive index of the low refractive index portion, the low refractive index portion is located above the separating portion, and is sandwiched by the high refractive index portion in the first direction, and
• a width in the first direction of the low refractive index portion at a first position distant from the separating portion in the second direction is narrower than a width in the first direction of the low refractive index portion at a second position closer to the separating portion than the first position in the second direction.