An image sensor includes a first semiconductor chip including first and second surfaces a second semiconductor chip including first and second surfaces and a first adhesive layer between the second surface of the first semiconductor chip and the second surface of the second semiconductor chip, the first semiconductor chip being stacked on the second semiconductor chip via the first adhesive layer such that a footprint of the first semiconductor chip is larger than a footprint of the second semiconductor chip with respect to a plan view of the image sensor, the first semiconductor chip including an array of unit pixels configured to capture light corresponding to an image and to generate image signals based on the captured light, the second semiconductor chip including first peripheral circuits configured to control the array of unit pixels and receive the generated image signals.
