Image sensor and method of forming the same

Abstract

The various embodiments disclosed herein pertain to an image sensor. The image sensor includes a plurality of pixel regions, each including a photodetector in a substrate. A floating diffusion node is located in the substrate and disposed between a first pixel region and a second pixel region within the plurality of pixel regions. An isolation structure is located in the substrate and disposed between adjacent pixel regions within the plurality of pixel regions. The isolation structure includes a first portion of depth isolation members aligned with the floating diffusion node and one or more deep isolation members disposed between the plurality of pixel regions. A plurality of vertical well regions are located in the substrate and laterally spaced between corresponding sidewalls of the first portion of depth isolation members and one or more deep isolation members.

Claims

1. An image sensor, comprising: A plurality of pixel regions, each including a photodetector in the substrate; a floating diffusion node in the substrate and disposed between a first pixel region and a second pixel region in the plurality of pixel regions; an isolation structure in the substrate and disposed between adjacent pixel regions in the plurality of pixel regions, wherein the isolation structure includes a first portion of depth isolation member aligned with the floating diffusion node and one or more deep isolation members disposed between the plurality of pixel regions; and a plurality of vertical well regions in the substrate and laterally spaced between corresponding sidewalls of the first portion of depth isolation member and the one or more deep isolation members.

2. The image sensor as claimed in claim 1, wherein a first pair of vertical well regions in the plurality of vertical well regions are configured along a first pair of outer sidewalls of the first portion depth isolation member.

3. The image sensor as claimed in claim 1, wherein the lateral distance between the first sidewall of the first portion of the depth isolation member and the directly adjacent deep isolation member among the one or more deep isolation members is equal to the width of the first vertical well region along the first sidewall in the plurality of vertical well regions.

4. The image sensor as claimed in claim 1, wherein the one or more deep isolation components and the plurality of vertical well regions have a first height, and the first portion of the deep isolation components has a second height less than the first height.

5. The image sensor as claimed in claim 1, further comprising: A plurality of peripheral well regions located at the corners of the plurality of pixel regions within the substrate; and wherein the isolation structure further includes a plurality of peripheral partial depth isolation members aligned with the plurality of peripheral well regions, wherein the peripheral vertical well regions of the plurality of vertical well regions are spaced between the plurality of peripheral partial depth isolation members and the one or more deep isolation members.

6. The image sensor as claimed in claim 1, wherein the width of the first portion of the depth isolation member is greater than the width of an individual vertical well region among the plurality of vertical well regions, and wherein the height of the first portion of the depth isolation member is less than the height of the individual vertical well region.

7. A method for forming an image sensor, comprising: A plurality of photodetectors are formed within a substrate, wherein the photodetectors are respectively disposed within a plurality of pixel regions, wherein the substrate includes a first surface and a second surface, and wherein the first surface and the second surface are perpendicularly offset; the substrate is doped to form floating diffusion nodes at the intersections of the plurality of pixel regions; the substrate is doped to form a plurality of vertical well regions in the substrate, wherein the plurality of vertical well regions extend into the first surface of the substrate, wherein a pair of vertical well regions are disposed on opposite sides of the floating diffusion nodes; an etching process is performed on the second surface of the substrate to form a plurality of trenches in the substrate and between the plurality of pixel regions, wherein the plurality of trenches include one or more first trenches on opposite sides of the pair of vertical well regions and a second trench between the pair of vertical well regions, wherein the pair of vertical well regions laterally space the second trench from the one or more first trenches; and an isolation structure is formed in the plurality of trenches and along the plurality of vertical well regions.

8. The method of claim 7, wherein the one or more first trenches have a first depth and the second trenches have a second depth less than the first depth, wherein the second depth is less than the height of the plurality of vertical well regions.

9. A method for forming an image sensor, comprising: A plurality of photodetectors are formed within a substrate, wherein the substrate includes a first surface and a second surface, and wherein the first surface and the second surface are perpendicularly offset. A plurality of peripheral well regions having a first doping type are formed at the corners of the plurality of photodetectors; a floating diffusion node having a second doping type opposite to the first doping type is formed at the intersection of the plurality of photodetectors; a plurality of vertical well regions are formed, the plurality of vertical well regions being configured at least partially around the floating diffusion node and the plurality of peripheral well regions, wherein the plurality of vertical well regions include the first doping type and extend from the first surface of the substrate toward the second surface; a thinning process is performed on the second surface of the substrate, wherein the thinning process exposes the tops of the plurality of vertical well regions; An etching process is performed on the substrate to form a plurality of trenches in the substrate; and an isolation structure is formed in the plurality of trenches, wherein the isolation structure includes a plurality of deep isolation components, a first portion of deep isolation components aligned with the floating diffusion node, and a plurality of peripheral portion deep isolation components aligned with the plurality of peripheral well regions, wherein the first portion of deep isolation components and the plurality of peripheral portion deep isolation components are laterally offset from their corresponding directly adjacent deep isolation components among the plurality of deep isolation components.

10. The method of claim 9, wherein the plurality of vertical well regions are formed after the plurality of photodetectors are formed and before the thinning process is performed.

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