An image sensor and a method for manufacturing the same are provided. An image sensor comprises a readout circuitry, an interlayer dielectric, an interconnection, an image sensing device, and a contact. The readout circuitry is formed at a first substrate. The interlayer dielectric is formed on the first substrate. The interconnection is formed in the interlayer dielectric. The interconnection is electrically connected to the readout circuitry. The image sensing device is formed on the interconnection. The image sensing device comprises a first conductive type layer and a second conductive type layer. The contact connects the first conductive type layer of the image sensing device and the interconnection electrically. The contact is isolated from the second conductive type layer by a trench formed in the second conductive layer around the contact.