3D Sensor

The first layer contains the sensor arrays, which are illuminated from the back. There are six different arrays, each with a different type of sensor cell. The two largest arrays each have over 9000 cells; these arrays are visible as the blue and yellow rectangles in this picture. The other four arrays are very small, and not easily distinguished here.
The second layer contains the sense amplifiers and other support circuitry. Each sensor cell in the first layer has a direct vertical connection to a sense-amp on this layer.
After stacking, the visible surface is the "back" of the sensor array layer. The small gold squares are probe points for testing. This finished device measures about 4 millimeters on a side.
In this photo, the sensor device is under the microscope, mounted in a test package. The device itself is barely visible in the center of the golden "window" on the test package.