US Patent 8213085 Image sensor device with high photosensitivity

An anti-reflection structure for transmitting a light source is disclosed. The anti-reflection structure comprises a first dielectric layer of a first refractive index and a second dielectric layer of a second refractive index different from the first refractive index. The first dielectric layer has a plurality of protrusions randomly arranged on a top surface thereof, in which the plurality of protrusions and the intervals therebetween has an average size smaller than the wavelength of the light source. The second dielectric layer has a bottom surface conformally attached to the top surface of the first dielectric layer. The invention also discloses an image sensor device having the anti-reflection structure.