Shielding Layer outside the Pixel Regions of Optical Device and Method for Making the Same
A shielding layer outside a sensing region I of a CMOS image sensor includes a stack of a first monochromatic color filter layer and a second monochromatic color filter layer. Such a two-layered monochromatic color filter acts as a shielding layer, and the amount of black photoresist needed is decreased. Therefore, a process of CMOS image sensor fabrication is simplified and the cost of fabrication is decreased. The black pigment is prevented from remaining and causing contamination.
1 . A method for making an optical device, which is deposited on a substrate, which comprising an optically active region and a peripheral circuit region, the method comprising:
forming a first monochromatic color filter layer in the a peripheral circuit region while forming another first monochromatic color filter layer in the optically active region; and
forming a second monochromatic color filter layer on the first monochromatic color filter in the a peripheral circuit region to form a shielding layer, while forming another second monochromatic color filter layer in the optically active region.
2 . A method according to claim 1 , wherein the optically active region is a sensing region, and the optical device is a complementary metal-oxide semiconductor image sensor.
3 . A method according to claim 1 , wherein the optical active region comprises a plurality of photodiodes, a plurality of insulators deposited between the photodiodes, and a monochromatic color filter array.
4 . A method according to claim 3 , wherein the monochromatic color filter array comprises a plurality of monochromatic color filters disposed in a predetermined arrangement, the monochromatic color filters corresponding to the photodiodes respectively.
5 . A method according to claim 4 , wherein the predetermined arrangement comprises a grid arrangement or honeycomb arrangement.
6 . A method according to claim 3 , wherein the monochromatic color filter array comprises a blue monochromatic color filter layer, a green monochromatic color filter layer and a red monochromatic color filter layer.
7 . A method according to claim 3 , wherein the first monochromatic color filter layer and the second monochromatic color filter layer in the optically active region is used to form the monochromatic color filter array.
8 . A method according to claim 1 further comprises forming a third monochromatic color filter layer on the second monochromatic color filter in the a peripheral circuit region to form a shielding layer, while forming another third monochromatic color filter layer in the optically active region.