Absorption enhancement structure to increase quantum efficiency of image sensor
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsTsun-Kai Tsao, Cheng-Hsien Chou, Jiech-Fun Lu
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Abstract
Various embodiments of the present disclosure are directed towards an image sensor having a photodetector disposed within a substrate. The substrate has a front-side surface and a back-side surface. An absorption enhancement structure is disposed along the back-side surface of the substrate and overlies the photodetector. The absorption enhancement structure includes a plurality of protrusions that extend outwardly from the back-side surface of the substrate. Each protrusion comprises opposing curved sidewalls.
Claims20
A method of forming an image sensor, comprising:
- performing an ion implant process to form a photodetector within a substrate;
- depositing a dielectric layer over a back-side surface of the substrate;
- forming a masking layer over the dielectric layer, wherein the masking layer comprises a plurality of sidewalls defining a first plurality of openings that exposes an upper surface of the dielectric layer;
- performing a first patterning process on the dielectric layer and the substrate to form a plurality of recesses within the substrate;
- performing a second patterning process on the substrate, thereby expanding the recesses and forming an absorption enhancement structure along the back-side surface of the substrate, wherein the absorption enhancement structure comprises a plurality of protrusions that each comprise curved opposing sidewalls;
- and,
- performing a third patterning process on the plurality of protrusions, wherein the third patterning process expands the recesses.
A method for forming an integrated chip, comprising:
- forming a photodetector within a substrate;
- performing a first patterning process on a first surface of the substrate to from a plurality of recesses extending into the first surface;
- performing a second patterning process on the first surface to expand the plurality of recesses and form a plurality of protrusions in the first surface of the substrate that abut the plurality of recesses, wherein the first and second patterning processes respectively comprise a dry etch;
- and
- performing a third patterning process on the first surface to expand the plurality of recesses and remove portions of the protrusions, wherein the third patterning process comprises a wet etch, and wherein the protrusions respectively comprise curved sidewalls.
A method of forming an image sensor, comprising:
- performing an ion implant process to form a photodetector within a substrate;
- depositing a dielectric layer over a back-side surface of the substrate;
- forming a masking layer over the dielectric layer, wherein the masking layer comprises a plurality of sidewalls defining a first plurality of openings that exposes an upper surface of the dielectric layer;
- performing a first patterning process on the dielectric layer and the substrate to form a plurality of recesses within the substrate;
- performing a second patterning process on the substrate, thereby expanding the recesses and forming an absorption enhancement structure along the back-side surface of the substrate, wherein the absorption enhancement structure comprises a plurality of protrusions that each comprise curved opposing sidewalls;
- and
- performing a third patterning process on the back-side surface of the substrate, wherein the third patterning process is different from the first patterning process and the second patterning process.
Dependencies are inferred from the claim text.