A backside illuminated (BSI) image sensor device includes: a first substrate including a front side and a back side; a second substrate bonded with the first substrate on the front side; and a blocking layer between the first substrate and the second substrate. The first substrate includes an image sensor, and the image sensor is configured to collect incident light entering from the back side. The second substrate includes a circuit coupled with the image sensor. The blocking layer is configured to block radiation induced by the circuit.