Provided are an image sensor and a method for manufacturing the same. The image sensor comprises a readout circuitry, an interconnection, an image sensing device, a first conductive-type ion implantation layer, and a via plug. The readout circuitry is formed in a first substrate. The interconnection is formed over the first substrate. The interconnection is electrically connected to the readout circuitry. Then image sensing device is formed over the interconnection. The image sensing device comprises a first conductive-type conductive layer and a second conductive-type conductive layer. The first conductive-type ion implantation layer is formed in a portion of the second conductive-type conductive layer of the image sensing device. The via plug penetrates through the first conductive-type ion implantation layer and the first conductive-type conductive layer to electrically connect the first conductive-type conductive layer to the interconnection.