Composite etch stop layers for sensor devices
A device and method for fabricating the same is disclosed. For example, the device includes a sensor having a front side and a back side, a metal interconnect layer formed on the front side of the sensor, an anti-reflective coating formed on the back side of the sensor, a composite etch stop mask layer formed on the anti-reflective coating. wherein the composite etch stop mask layer includes a silicon nitride layer and a stressed layer. A percentage of Si—H bonds in the silicon nitride layer is greater than a percentage of Si—H bonds in the stressed layer.
1. An image sensor, comprising:
a substrate having a plurality of pixel regions;
an grid structure over the substrate; and
a silicon nitride layer between the grid structure and the substrate; and
a stressed layer between the silicon nitride layer and the grid structure, wherein a percentage of Si—H bonds in the silicon nitride layer is greater than a percentage of Si—H bonds in the stressed layer.
2. The image sensor of claim 1 , wherein the stressed layer comprises silicon nitride.
3. The image sensor of claim 1 , wherein the stressed layer has a compressive stress.
4. The image sensor of claim 1 , wherein the silicon nitride layer has a different type of stress than the stressed layer.
5. The image sensor of claim 4 , wherein the silicon nitride layer has a tensile stress.
6. The image sensor of claim 1 , wherein the stressed layer has a first thickness at a region overlapping the grid structure and a second thickness at a region non-overlapping the grid structure, and the first thickness is greater than the second thickness.
7. The image sensor of claim 1 , further comprising:
an interconnect structure over a first side of the substrate, wherein the grid structure is over a second side of the substrate opposite the first side of the substrate.
8. The image sensor of claim 1 , further comprising:
a conductive layer between the silicon nitride layer and the substrate.
9. An image sensor, comprising:
a plurality of sensing pixels in a substrate;
a hydrogen-containing layer over the plurality of sensing pixels;
a stressed layer over the hydrogen-containing layer, wherein a stress in the stressed layer is greater than a stress in the hydrogen-containing layer; and
a grid structure spaced apart from the hydrogen-containing layer by the stressed layer.
10. The image sensor of claim 9 , wherein the stress in the stressed layer is a compressive stress.
11. The image sensor of claim 9 , wherein the stress in the hydrogen-containing layer is a tensile stress.
12. The image sensor of claim 9 , wherein the hydrogen-containing layer comprises silicon nitride.
13. The image sensor of claim 9 , wherein the stressed layer comprises silicon nitride.
14. The image sensor of claim 9 , wherein an atom percent of Si—H bonds in the hydrogen-containing layer is greater than an atom percent of Si—H bonds in the stressed layer.
15. The image sensor of claim 9 , wherein the hydrogen-containing layer comprises greater than 12 atom percent of Si—H bonds.
16. The image sensor of claim 9 , wherein the hydrogen-containing layer is over a backside of the substrate.
17. An image sensor, comprising:
a substrate comprising a photo sensing region;
a multi-layered nitride film over the substrate, the multi-layered nitride film comprising a first nitride layer over the substrate and a second nitride layer over the first nitride layer, the first nitride layer having a first stress, and the second nitride layer having a second stress, the first stress and the second stress being of different types of stress; and
a grid structure over the multi-layered nitride-containing film.
18. The image sensor of claim 17 , wherein the first stress of the first nitride layer is a tensile stress.
19. The image sensor of claim 17 , wherein the second stress of the second nitride layer is a compressive stress.
20. The image sensor of claim 17 , wherein a value of the first stress of the first nitride layer is less than a value of the second stress of the second nitride layer.