CMOS image sensor and method for manufacturing the same
View Patent ↗A CMOS image sensor and a method for manufacturing the same are provided, in which a nitride layer for passivation is used as a microlens to reduce topology. The CMOS image sensor includes an upper metal layer partially deposited on a dielectric layer; a first nitride layer deposited on the upper metal layer; an undoped silicon glass layer deposited on the first nitride layer and polished by chemical-mechanical polishing; color filter array elements deposited and exposed on the undoped silicon glass layer and polished by the chemical-mechanical polishing; and a second nitride layer deposited on the first nitride layer and the color filter array elements and transfer-etched after forming a sacrificial microlens on the second nitride layer.
1. A method for manufacturing a CMOS image sensor, comprising:
partially depositing an upper metal layer on a dielectric layer;
depositing a first nitride layer on the upper metal layer;
patterning the upper metal layer and the first nitride layer;
forming patterns of an undoped silicate glass layer by depositing the undoped silicate glass layer on the patterned first nitride layer;
depositing color filter array elements between adjacent patterns of the undoped silicate glass layer and exposing the color filter array elements;
removing the undoped silicate glass layer deposited on the first nitride layer and portions of the color filter array elements higher than the first nitride layer by chemical-mechanical polishing;
depositing a second nitride layer after performing the chemical-mechanical polishing;
forming a sacrificial microlens on the second nitride layer; and
shaping the second nitride layer as the sacrificial microlens by a transfer etching that exposes portions of the first nitride layer.
2. The method of claim 1 , wherein depositing color filter array elements comprises:
depositing a first color filter array element between a first pair of adjacent patterns of the undoped silicate glass layer and exposing the first color filter array element;
depositing a second color filter array element between a second pair of adjacent patterns of the undoped silicate glass layer and exposing the second color filter array element; and
depositing a third color filter array element between a third pair of adjacent patterns of the undoped silicate glass layer and exposing the third color filter array element.
3. The method of claim 1 , wherein forming a sacrificial microlens comprises:
forming a sacrificial microlens layer on the second nitride layer;
removing the sacrificial microlens layer above the first nitride layer from the sacrificial microlens layer deposited on the second nitride layer; and
forming a sacrificial microlens from the sacrificial microlens layer remaining above the first nitride layer.
4. The method of claim 1 , wherein the transfer etching has an etching ratio of 1:1 between the sacrificial microlens and the second nitride layer.