BACKGROUND

Backside illuminated (BSI) sensors are a type of digital image sensor. The BSI sensor may include the same elements as a front-side illuminated sensor, but arranges the wiring behind the photocathode layer by flipping the silicon wafer during manufacturing and then thinning its reverse side so that light can strike the photocathode layer without passing through the wiring layer. The BSI sensor can increase the amount of light that is captured and, thus, improve low-light performance.

The BSI sensors are formed on silicon substrates of a wafer, followed by the formation of an interconnect structure on a front side of the silicon chip. The BSI sensors may generate electrical signals in response to the stimulation of photons. The magnitudes of the electrical signals may depend on the intensity of the incident light received by the respective image sensors.

