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
An image sensor, comprising:
- a substrate comprising a front-side surface and a back-side surface;
- a photodetector disposed within the substrate;
- and
- an absorption enhancement structure disposed along the back-side surface of the substrate and overlying the photodetector, wherein the absorption enhancement structure comprises a plurality of protrusions extending outwardly from the back-side surface of the substrate, and wherein each protrusion comprises slanted straight sidewalls overlying opposing curved sidewalls.
An integrated chip, comprising:
- a substrate comprising a front-side surface and a back-side surface;
- an interconnect structure disposed along the front-side surface of the substrate;
- a photodetector disposed within the substrate;
- an absorption enhancement structure disposed along the back-side surface of the substrate, wherein the absorption enhancement structure comprises a plurality of first protrusions and a corresponding plurality of recesses in the back-side surface that engagedly meet the first protrusions, wherein each first protrusion comprises slanted straight opposing sidewalls overlying opposing curved sidewalls;
- and
- an upper dielectric structure overlying the back-side surface of the substrate, wherein the upper dielectric structure comprises a plurality of second protrusions disposed along a lower surface of the upper dielectric structure, wherein each second protrusion comprises a convex lower surface and fills a corresponding recess in the plurality of recesses, wherein an index of refraction of the upper dielectric structure is less than an index of refraction of the substrate.
An integrated chip, comprising:
- a substrate having a front-side surface opposite a back-side surface;
- a photodetector disposed within the substrate;
- an isolation structure extending into the back-side surface of the substrate, wherein the photodetector is spaced between opposing sidewalls of the isolation structure;
- and
- an upper dielectric structure disposed over the substrate, wherein the upper dielectric structure comprises a plurality of first protrusions that extends into the back-side surface of the substrate, wherein the first protrusions are spaced laterally between the opposing sidewalls of the isolation structure, wherein the first protrusions respectively comprise a curved lower surface that is disposed below the back-side surface of the substrate, wherein a top surface of the upper dielectric structure is substantially flat.
Dependencies are inferred from the claim text.