Solid-state image sensor and imaging system

A solid-state image sensor including a semiconductor substrate containing a plurality of photoelectric conversion elements, the sensor comprising:

• a first insulating film arranged on the semiconductor substrate and having a plurality of openings, each of the plurality of openings being arranged on one of the plurality of photoelectric conversion elements;
• a plurality of insulator portions having a refractive index higher than a refractive index of the first insulating film, each of the plurality of insulator portions being arranged in one of the plurality openings;
• a second insulating film arranged on upper surfaces of the plurality of insulator portions and on an upper surface of the first insulating film;
• and
• a third insulating film having a refractive index lower than a refractive index of the second insulating film, the third insulating film being arranged on an upper surface of the second insulating film,
• wherein, letting λ represent a wavelength of light entering the plurality of insulator portions, n represent the refractive index of the second insulating film, and t represent a thickness of the second insulating film in at least part of a region on the upper surface of the first insulating film, a relation t<λ/n is satisfied, and
• wherein, letting t1 represent a thickness of the second insulating film in at least part of a region on the upper surfaces of the plurality of insulator portions, a relation t1>λ/n is further satisfied.