An image sensor includes readout circuitry on a first substrate, a metal line electrically connected with the readout circuitry, a dielectric on the metal line, an image sensing device on the dielectric, including first and second conductivity type layers, a contact plug in a via hole penetrating the image sensing device to connect the first conductivity type layer with the metal line, and a sidewall dielectric in the via hole at a sidewall of the second conductivity type layer.