Image sensor with decreased optical interference between adjacent pixels

US 8,030,723 B2
Filed: 08/20/2009
Issued: 10/04/2011
Est. Priority Date: 09/12/2005
Status: Active Grant

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First Claim

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1. An image sensor pixel comprising:

a microlens configured to receive an incident light and form a focused light;

a photodiode configured to receive the focused light from the microlens;

a first metal line;

a second metal line configured to connect the image sensor pixel to at least one of a logic circuit or a power line; and

a first dummy metal line positioned to block a light from an adjacent image sensor pixel from impinging on the photodiode.

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Abstract

An image sensor with decreased optical interference between adjacent pixels is provided. An image sensor, which is divided into a pixel region and a peripheral region, the image sensor including a photodiode formed in a substrate in the pixel region, first to Mth metal lines formed over the substrate in the pixel region, where M is a natural number greater than approximately 1, first to Nth metal lines formed over a substrate in the peripheral region, where N is a natural number greater than M, at least one layer of dummy metal lines formed over the Mth metal lines but formed not to overlap with the photodiode, and a microlens formed over the one layer of the dummy metal lines to overlap with the photodiode.

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20 Claims

1. An image sensor pixel comprising:
- a microlens configured to receive an incident light and form a focused light;
  
  a photodiode configured to receive the focused light from the microlens;
  
  a first metal line;
  
  a second metal line configured to connect the image sensor pixel to at least one of a logic circuit or a power line; and
  
  a first dummy metal line positioned to block a light from an adjacent image sensor pixel from impinging on the photodiode.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- - 2. The image sensor pixel of claim 1, wherein the image sensor pixel comprises a pixel region and a peripheral region, and wherein the pixel region includes the photodiode and the peripheral region includes a transistor.
  - 3. The image sensor pixel of claim 2, wherein:
    - the pixel region comprises the second metal line and the first dummy metal line;
      
      the peripheral region comprises a third metal line located in a third metal line layer; and
      
      the third metal line layer extends above the photodiode and comprises the first dummy metal line.
  - 4. The image sensor pixel of claim 1, further comprising an inter-layer dielectric layer between the second metal line and the first dummy metal line.
  - 5. The image sensor pixel of claim 4, wherein the second metal line, the inter-layer dielectric layer, and the first dummy metal line form a capacitor.
  - 6. The image sensor pixel of claim 1, wherein the image sensor pixel comprises a pixel region and a peripheral region, and wherein the first dummy metal line is located in the pixel region and corresponds to a via contact located in the peripheral region.
  - 7. The image sensor pixel of claim 1, further comprising a second dummy metal line located above the first dummy metal line and positioned to block the light from the adjacent image sensor pixel from impinging on the photodiode.
  - 8. The image sensor pixel of claim 7, wherein:
    - the first dummy metal line corresponds to a third metal line in a peripheral region; and
      
      the second dummy metal line corresponds to a via contact connecting the third metal line to a fourth metal line in the peripheral region.
  - 9. The image sensor pixel of claim 1, wherein the first dummy metal line comprises titanium nitride.
  - 10. The image sensor of pixel claim 1, wherein the first dummy metal line comprises a thickness of approximately 1,500 angstroms.

11. A method for detecting light in an image sensor pixel, the method comprising:
- receiving, at a microlens, an incident light;
  
  focusing the incident light to form a focused light;
  
  receiving, at a photodiode, the focused light;
  
  blocking, with a first dummy metal line, a light from an adjacent image sensor pixel from impinging on the photodiode.
- View Dependent Claims (12, 13)
- - 12. The method of claim 11, further comprising filtering the focused light with a color filter.
  - 13. The method of claim 11, further comprising blocking, with a second dummy metal line, the light from the adjacent image sensor pixel,wherein the first dummy metal line and the second dummy metal line are separated by an inter-layer dielectric layer.

14. A method of manufacturing an image sensor pixel, the method comprising:
- forming a photodiode;
  
  forming a first metal line in a layer above the photodiode; and
  
  forming a dummy metal line in a layer above the first metal line;
  
  wherein the photodiode is positioned to receive a focused light; and
  
  wherein the dummy metal line is positioned to block a light from an adjacent image sensor pixel from impinging on the photodiode.
- View Dependent Claims (15, 16, 17, 18, 19, 20)
- - 15. The method of claim 14, further comprising forming a second metal line in a layer between the first metal line and the dummy metal line.
  - 16. The method of claim 14, further comprising forming a color filter above the dummy metal line, wherein the color filter is configured to filter the focused light.
  - 17. The method of claim 14, wherein the dummy metal line comprises a thickness of approximately 1,500 angstroms.
  - 18. The method of claim 14, wherein said forming a dummy metal line comprises forming the dummy metal line substantially simultaneously with forming a second metal line in a peripheral region.
  - 19. The method of claim 14, wherein said forming a dummy metal line comprises forming a plurality of dummy metal lines in a corresponding plurality of image sensor pixels, and wherein the plurality of dummy metal lines is located at a junction of the plurality of image sensor pixels.
  - 20. The method of claim 14, further comprising forming a microlens configured to receive an incident light and form the focused light.

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Current Assignee
Intellectual Ventures II LLC (Intellectual Ventures LLC)
Original Assignee
Crosstek Capital LLC (Intellectual Ventures LLC)
Inventors
Lee, Won-Ho, Cho, Dong-Heon
Primary Examiner(s)
ZARNEKE, DAVID A

Application Number

US12/544,547
Publication Number

US 20090309010A1
Time in Patent Office

775 Days
Field of Search

257/431, 257/432, 257/435, 438/27
US Class Current

257/435
CPC Class Codes

H01L 27/14603   Special geometry or disposi...

H01L 27/14623   Optical shielding

H01L 27/14625   Optical elements or arrange...

H01L 27/14627   Microlenses

H01L 27/14629   Reflectors

H01L 27/14636   Interconnect structures

H01L 27/14643   Photodiode arrays; MOS imagers

Image sensor with decreased optical interference between adjacent pixels

First Claim

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Abstract

13 Citations

20 Claims

Specification

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Image sensor with decreased optical interference between adjacent pixels

First Claim

2 Assignments

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Litigations

0 Petitions

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Accused Products

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Abstract

13 Citations

20 Claims

Specification

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