METHOD OF FORMING AN INFRARED FILTER ASSOCIATED WITH AN IMAGE SENSOR

摘要

An image sensor having a portion including interconnection levels formed on a semiconductor substrate covered with a first layer of a dielectric material, including conductive tracks separated from one another by insulating layers interconnected by vias crossing the insulating layers, and an infrared bandpass filter comprising filter levels adjacent to the interconnection levels formed by an alternation of second layers of the dielectric material and of silicon layers, the refraction index of the dielectric material being smaller than 2.5 at the maximum transmission wavelength of the filter, one of the second dielectric layers of each filter level being identical to the insulating layer of the adjacent interconnection level.

主权项

1. A method of simultaneously forming an infrared bandpass filter infrared on a filter side and interconnection levels on an interconnect side of an image sensor, comprising the steps of:
a) forming a first layer of a dielectric material having a refraction index smaller than 2.5 at the maximum transmission wavelength of the filter on a semiconductor substrate; b) depositing an etch stop layer; c) depositing at least one silicon layer having a first thickness; d) removing, on the interconnect side, said at least one silicon layer; e) depositing a second layer of the dielectric material having a second thickness greater than the first thickness; f) forming in the second layer metal tracks and interconnection vias, on the interconnect side; g) planarizing the surface to a level corresponding to the level of the surface of the second layer, where the second layer does not cover said at least one silicon layer; and h) repeating steps b) to g) at least once, the values of the first and second thicknesses being selected from one repetition to another, according to calculations implying a simulation step and/or according to the desired electric performances.