Image sensors and methods of forming the same
An image sensor includes a substrate including a light-receiving region and a light-shielding region, a device isolation pattern in the substrate of the light-receiving region to define active pixels, and a device isolation region in the substrate of the light-shielding region to define reference pixels. An isolation technique of the device isolation pattern is different from that of the device isolation region.
1. An image sensor comprising:
a substrate having a first surface and a second surface opposite to the first surface;
a plurality of photoelectric conversion parts between the first and second surfaces;
a plurality of interconnection structures on the first surface;
a light shielding pattern on the second surface of the substrate;
a first trench recessed from the second surface of the substrate overlapping the light shielding pattern;
a second trench recessed from the second surface of the substrate and not overlapping the light shielding pattern;
a first device isolation pattern in the first trench; and
a second device isolation pattern in the second trench,
wherein a length of the second device isolation pattern is different from a length of the first device isolation pattern.
2. The image sensor of claim 1 , further comprising a third trench between the first trench and the second trench, the third trench having a substantially same height with the second trench, and the third trench being positioned at or near a first end of the light shielding pattern.
3. The image sensor of claim 1 , further comprising a p-type doping region under the first surface of the substrate.
4. The image sensor of claim 3 , wherein the second trench contacts the p-type doping region.
5. The image sensor of claim 1 , further comprising an anti-reflection layer between the light shielding pattern and the second surface of the substrate.
6. The image sensor of claim 1 , the first and second device isolation patterns comprise insulating material.
7. The image sensor of claim 6 , wherein the insulating material has a refractive index lower than a refractive index of the substrate.
8. The image sensor of claim 1 , wherein the first trench is in a light shielding region, the second trench is formed in a light receiving region, and a third trench is formed in a dummy region, wherein each first, second, and third trench is between the plurality of photoelectric conversion parts.
9. The image sensor of claim 1 , wherein:
the light shielding pattern extends on more than one of the plurality of photoelectric conversion parts; and
the second trench does not overlap a light shielding material.
10. An image sensor comprising:
a substrate having a first surface and a second surface opposite to the first surface;
a plurality of photoelectric conversion parts between the first and second surfaces;
a plurality of interconnection structures on the first surface;
a light shielding pattern on the second surface of the substrate;
a first trench recessed from the second surface of the substrate overlapping the light shielding pattern;
a second trench recessed from the second surface of the substrate and not overlapping the light shielding pattern;
a first device isolation pattern in the first trench; and
a second device isolation pattern in the second trench,
wherein the light shielding pattern overlaps at least one of the photoelectric conversion parts in a plan view, and
wherein a bottom surface of the light shielding pattern is at a same or higher level than the second surface of the substrate.
11. The image sensor of claim 1 , wherein the first device isolation pattern is between at least two of the photoelectric conversion parts.
12. The image sensor of claim 1 , wherein the first device isolation pattern is configured to define reference pixels, and
wherein the second device isolation pattern is configured to define active pixels.