Without being restricted to solder bumps, the bumps may beelectrically conductive bumps including metals, such as gold bumps, nickel bumps, copper bumps, and electrically conductive resin bumps.Here, since the n.sup.+-type diffusion layer 209 constituting the projections 213 between photodiodes has an n-type impurity concentration higher than that in the n-type substrate, carriers are generated wh