Patent ID: 8339492

Claim:
An image sensor comprising: a readout circuitry at a first substrate; an interlayer dielectric on the first substrate; an interconnection in the interlayer dielectric, the interconnection being electrically connected to the readout circuitry; an image sensing device on the interconnection, the image sensing device comprising a first conductive type layer and a second conductive type layer; and a contact electrically connecting the first conductive type layer of the image sensing device and the interconnection, the contact passing through a first trench in the first conductive type layer and a second trench in the second conductive type layer; wherein a diameter of the second trench is larger than a diameter of the first trench, the second trench being formed by removing portions of the second conductive type layer of the image sensing device contacting the contact and exposing a portion of the first conductive type layer.