Taiwan Semiconductor Manufacturing Company Limited
OPTICAL BLOCKING STRUCTURES FOR BLACK LEVEL CORRECTION PIXELS IN AN IMAGE SENSOR

Abstract:

An image sensor includes an array of image pixels and black level correction (BLC) pixels. Each BLC pixel includes a BLC pixel photodetector, a BLC pixel sensing circuit, and a BLC pixel optics assembly configured to block light that impinges onto the BLC pixel photodetector. Each BLC pixel optics assembly may include a first portion of a layer stack including a vertically alternating sequence of first material layers having a first refractive index and second material layers having a second refractive index. Additionally or alternatively, each BLC pixel optics assembly may include a first portion of a layer stack including at least two metal layers, each having a respective wavelength sub-range having a greater reflectivity than another metal layer. Alternatively or additionally, each BLC pixel optics assembly may include an infrared blocking material layer that provides a higher absorption coefficient than color filter materials within image pixel optics assemblies.