Frontside illuminated image sensor and manufacturing method thereof
Disclosed are a frontside illuminated image sensor and a method of manufacturing the same. More particularly, a frontside illuminated image sensor and a method of manufacturing the frontside illuminated image sensor include a light scattering portion in a substrate, configured to increase a path of incident light, thereby preventing cross-talk between adjacent pixels and increasing light sensitivity.
1 . A frontside illuminated image sensor comprising:
a substrate having a front surface and a back surface;
a photoelectric conversion structure in the substrate, in a unit pixel of the image sensor;
a wiring region comprising an interlayer insulation film on the front surface of the substrate, and a metal wiring layer in the interlayer insulation film;
a color filter on the wiring region;
a planarization layer on the color filter;
a lens on the planarization layer; and
a light scattering portion having an upper surface at the front surface of the substrate, the light scattering portion having a lower surface in the substrate, wherein the light scattering portion comprises:
a center section having a first depth at a center of the unit pixel, wherein the center section does not contact the photoelectric conversion structure; and
a plurality of side sections spaced apart from the center section along a lateral direction in the unit pixel, each of the plurality of the side sections having a second depth greater than the first depth and a lowermost surface that contacts the photoelectric conversion structure.
2 . The frontside illuminated image sensor of claim 1 , wherein the light scattering portion comprises a first plurality of side sections along a first lateral direction from the center section.
3 . The frontside illuminated image sensor of claim 2 , wherein a first one of the side sections adjacent to the center section has a depth greater than a depth of a second one of the side sections farther from the center section.
4 . The frontside illuminated image sensor of claim 3 , wherein a first one of the side sections adjacent to the center section has a depth shallower than a depth of a second one of the side sections farther from the center section.
5 . The frontside illuminated image sensor of claim 2 , wherein the first one of the side sections has a planar shape or a width smaller than a width of the second one of the side sections.
6 . The frontside illuminated image sensor of claim 2 , wherein at least one of the plurality of side sections contacts the photoelectric conversion structure.
7 . The backside illuminated image sensor of claim 2 , wherein each of the first and second pluralities of side sections comprises a first, outermost side section and a second, inner side section between the first, outermost side section and the center section along a corresponding one of the first and second lateral directions.
8 . The backside illuminated image sensor of claim 7 , wherein each first, outermost side section is within an area of the photoelectric conversion structure and has a depth greater than that of the second, inner side section.
9 . The backside illuminated image sensor of claim 8 , wherein each first, outermost side section is adjacent to an outermost peripheral border of the photoelectric conversion structure.
10 . The backside illuminated image sensor of claim 8 , wherein each of the second, inner side sections has a lowermost surface that contacts the photoelectric conversion structure.
11 . The frontside illuminated image sensor of claim 1 , wherein at least a first side of the side section has a planar shape or a width larger than a width of the center section.
12 . The frontside illuminated image sensor of claim 1 , comprising different unit pixels for different wavelengths of light, wherein the light scattering portion has different light path distances and different depths for respective ones of the different unit pixels.
13 . The frontside illuminated image sensor of claim 12 , wherein the different unit pixels comprise red unit pixels, green unit pixels, and blue unit pixels.
14 . The frontside illuminated image sensor of claim 1 , wherein the light scattering portion comprises an oxide, a nitride, a multilayered film thereof, a single elemental metal or an alloy including at least two types of metals, or polysilicon.
15 . The frontside illuminated image sensor of claim 14 , wherein the light scattering portion comprises silicon dioxide and/or silicon nitride.
16 . The frontside illuminated image sensor of claim 1 , wherein the unit pixel further comprises a boundary region comprising a deep trench isolation structure in the substrate, wherein the photoelectric conversion structure is completely inside the deep trench isolation structure.
17 . The backside illuminated image sensor of claim 16 , wherein the light scattering portion comprises a same material as the deep trench isolation structure.
18 . The backside illuminated image sensor of claim 16 , wherein the deep trench isolation structure has a third depth greater than the second depth of each of the plurality of the side sections.
19 . The backside illuminated image sensor of claim 1 , wherein each of the plurality of side sections is within and adjacent to an outermost peripheral border of the photoelectric conversion structure.