IMAGE SENSOR WITH DECREASED OPTICAL INTERFERENCE BETWEEN ADJACENT PIXELS

• US 20090309010A1
• Filed: 08/20/2009
• Published: 12/17/2009
• Est. Priority Date: 09/12/2005
• Status: Active Grant

• Current Assignee: Intellectual Ventures II LLC (Intellectual Ventures LLC)
• Original Assignee: Crosstek Capital LLC (Intellectual Ventures LLC)
• Inventors: Lee, Won-Ho, Cho, Dong-Heon
• Granted Patent: US 8,030,723 B2
• Time in Patent Office: Days
• US Class Current: 250/216
• CPC Class Codes: H01L 27/14603 Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
• CPC Class Codes: H01L 27/14623 Optical shielding
• CPC Class Codes: H01L 27/14625 Optical elements or arrangements associated with the device
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H01L 27/14629 Reflectors
• CPC Class Codes: H01L 27/14636 Interconnect structures
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers

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.

Claims

1. An image sensor, comprising:

a photodiode in a pixel region;

a plurality of first metal lines in the pixel region;

a plurality of second metal lines in a peripheral region non-overlapping with the pixel region in a light receiving direction;

a first layer of dummy metal lines over the plurality of first metal lines and non-overlapping with the photodiode in the light receiving direction; and

a micro lens over the first layer of dummy metal lines and overlapping with the photodiode in the light receiving direction.

2. The image sensor of claim 1, wherein the first layer of dummy metal lines includes one or more dummy metal lines having at least one of a rhombus shape, a cross shape or a square shape.

3. The image sensor of claim 1, wherein the first layer of dummy metal lines includes one or more dummy metal lines having an irregular, non-symmetric shape.

4. The image sensor of claim 1, wherein the light receiving direction is a direction corresponding to a location of a pixel adjacent to the image sensor.

5. The image sensor of claim 1, wherein the first layer of dummy metal lines includes a plurality of dummy metal lines, wherein a central point of the plurality of dummy metal lines corresponds to a location at which corner portions of unit pixels adjacent to the image sensor commonly meet.

6. The image sensor of claim 1, wherein the first layer of dummy metal lines includes at least one dummy metal line positioned adjacent to and above the plurality of second metal lines in the peripheral region.

7. The image sensor of claim 1, further comprising a second layer of dummy metal lines, wherein the second layer is positioned adjacent to and above the first layer of dummy metal lines.

8. A method for receiving light to reduce optical interference of an image sensor, the method comprising:

receiving first light through a micro lens of the image sensor positioned over a first layer of dummy metal lines that does not overlap with a photodiode positioned under the first layer of dummy metal lines in a light receiving direction substantially orthogonal to the first layer of dummy metal lines;

focusing the first light on the photodiode overlapping with the micro lens in the light receiving direction; and

reflecting second light otherwise incident on the photodiode with the first layer of dummy metal lines.

9. The method of claim 8, wherein the first layer of dummy metal lines includes one or more dummy metal lines having at least one of a rhombus shape, a cross shape or a square shape.

10. The method of claim 8, wherein the first layer of dummy metal lines includes one or more dummy metal lines having an irregular, non-symmetric shape.

11. The method of claim 8, further comprising positioning the first layer of dummy metal lines in a pixel region of the image sensor.

12. A method of manufacturing an image sensor, the method comprising:

forming a photodiode in a pixel region of a substrate;

forming a plurality of first metal lines in the pixel region;

forming a plurality of second metal lines in a peripheral region of the substrate, the peripheral region non-overlapping with the pixel region in a light receiving direction;

forming a first layer of dummy metal lines over the plurality of first metal lines and non-overlapping with the photodiode in the light receiving direction; and

forming a micro lens over the first layer of dummy metal lines and overlapping with the photodiode in the light receiving direction.

13. The method of claim 12, wherein forming the first layer of dummy metal lines includes forming one or more dummy metal lines, wherein each of the one or more dummy metal lines is formed of titanium nitride.

14. The method of claim 12, wherein forming the first layer of dummy metal lines includes forming one or more dummy metal lines, wherein each of the one or more dummy metal lines is formed to a thickness of approximately 1,500 Å

.

15. The method of claim 12, wherein forming the first layer of dummy metal lines includes forming one or more dummy metal lines simultaneously with forming one or more of the plurality of second metal lines in the peripheral region.

16. The method of claim 12, wherein forming the first layer of dummy metal lines includes forming a plurality of dummy metal lines having at least one of a rhombus shape, a cross shape or a square shape.

17. The method of claim 12, wherein forming the first layer of dummy metal lines includes forming a plurality of dummy metal lines having an irregular, non-symmetric shape.

18. The method of claim 12, wherein forming the first layer of dummy metal lines includes forming a plurality of dummy metal lines, wherein a central point of the plurality of dummy metal lines is formed to correspond to a location at which corner portions of unit pixels adjacent to the image sensor commonly meet.

19. The method of claim 12, wherein forming the first layer of dummy metal lines includes forming the first layer of dummy metal lines adjacent to and above the plurality of second metal lines in the peripheral region.

20. The method of claim 12, further comprising forming a second layer of dummy metal lines, wherein the second layer of dummy metal lines is formed adjacent to and above the first layer of dummy metal lines.