Field of Invention
This disclosure relates to an image sensor, and specifically to an image sensor having an extended spectral range.
Description of Related Technology
Image processing devices, such as digital cameras, smartphones or tablet computers, rely on image sensors to capture images. Image sensors receive light and convert that light into electrical signals. The image processing devices then transform these electrical signals into digital images.
Different types of image sensors are currently available. For example, image processing devices typically utilize either a frontside-illumination (FSI) image sensor or a backside-illumination (BSI) image sensor. An FSI image sensor is typically oriented such that light enters the top of the FSI image sensor and passes through a metal-interconnect layer before striking the light-sensing surface. In contrast, BSI image sensors are oriented to allow light to enter from the top of the BSI image sensor and to strike a light-sensing surface without passing through the metal/wiring layer of the BSI wafer. While each of the FSI and BSI image sensors have favorable imaging characteristics, they both may have limited spectral responses. Accordingly, there is a need for an image sensor having a greater spectral response than either a FSI or BSI image sensor.