Image sensor wherein the transfer gate contacts a first refractive layer that is coplanar with a second refractive layer

Abstract

An image sensor includes a first structure, a second structure, and a third structure that are sequentially stacked in a vertical direction. The first structure includes a first substrate and at least one first transistor disposed on the first substrate. The second structure includes a second substrate and at least one second transistor disposed on the second substrate. The third structure includes a third substrate that includes an upper surface on which light is incident and a lower surface that is opposite to the upper surface, a photoelectric conversion region disposed in the third substrate, a transfer gate disposed on the lower surface of the third substrate, and a reflective structure disposed on the lower surface of the third substrate and on a lower surface and side surface of the transfer gate.