METHODS FOR FORMING ANTI-REFLECTION STRUCTURES FOR CMOS IMAGE SENSORS

摘要

Protuberances (5), having vertical (h) and lateral (p) dimensions less than the wavelength range of lights detectable by a photodiode (8), are formed at an optical interface between two layers having different refractive indices. The protuberances may be formed by employing self-assembling block copolymers that form an array of sub lithographic features of a first polymeric block component (112) within a matrix of a second polymeric block component (111). The pattern of the polymeric block component is transferred into a first optical layer (4) to form an array of nanoscale protuberances. Alternately, conventional lithography may be employed to form protuberances having dimensions less than the wavelength of light. A second optical layer is formed directly on the protuberances of the first optical layer. The interface between the first and second optical layers has a graded refractive index, and provides high transmission of light with little reflection.