Backside illuminated image sensor and manufacturing method thereof
Disclosed are a backside illuminated image sensor and a method of manufacturing the same. More particularly, a backside illuminated image sensor and a method of manufacturing the backside illuminated image sensor include a light scattering portion in a substrate configured to converge a path of incident light to a photoelectric conversion structure, thereby preventing cross-talk between adjacent pixels and increasing light sensitivity.
1 . A backside 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 backside illuminated 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;
an insulation film on the back surface of the substrate;
a color filter on the insulation film;
a planarization layer on the color filter;
a lens on the planarization layer; and
a light scattering portion having an upper surface at the back surface of 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 side sections having a second depth greater than the first depth and a lowermost surface that contacts the photoelectric conversion structure.
2 . The backside 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 and a second plurality of side sections along a second lateral direction from the center section, the second lateral direction being opposite from the first lateral direction.
3 . The backside illuminated image sensor of claim 1 , wherein the plurality of side sections comprises a first number of side sections along a first lateral direction from the center section, and a second number of side sections along a second lateral direction from the center section, the second number being different from the first number, and the second lateral direction being opposite from the first lateral direction.
4 . The backside illuminated image sensor of claim 1 , wherein each of the plurality of side sections has a width larger than a width of the center section.
5 . The backside illuminated image sensor of claim 1 , wherein the light scattering portion comprises silicon dioxide, silicon nitride, a single elemental metal, an alloy including at least two types of metals, polysilicon, or a refractory metal nitride.
6 . The backside illuminated image sensor of claim 5 , wherein a boundary region comprises a same material as the light scattering portion.
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.
9 . The backside illuminated image sensor of claim 7 , wherein the second, inner side section has a depth less than the first, outermost side section.
10 . The backside illuminated image sensor of claim 7 , wherein each of the first and second pluralities of side sections has a width larger than a width of the center section, and the second, inner side section has a width smaller than a width of the first, outermost side section.
11 . The backside illuminated image sensor of claim 8 , wherein each first, outermost side section is adjacent to an outermost peripheral border of the area of the photoelectric conversion structure.
12 . The backside illuminated image sensor of claim 7 , wherein each of the second, inner side sections has a lowermost surface that contacts the photoelectric conversion structure.
13 . 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.