Imaging systems with integrated light shield structures

Patent metadata

Field	Value
Publication number	US-2016352983-A1
Application number	US-201514723147-A
Country	US
Kind code	A1
Filing date	May 27, 2015
Priority date	May 27, 2015
Publication date	Dec 1, 2016
Grant date	—

Abstract

An imaging system may include an image sensor having an array of pixels. The image sensor may include an array of microlenses formed over a substrate and an array of color filter elements interposed between the microlenses and the substrate. Dielectric wall structures may be interposed between the color filter elements. Light shield structures may be formed within or on the dielectric wall structures and may be used to reduce optical crosstalk between adjacent pixels. The light shield structures may be formed on opposing sides or corners of the color filter elements and may partially or fully extend along the height of the color filter elements. In some arrangements, the light shield structures may each have a vertical portion that contacts a side surface of an adjacent color filter element and a horizontal portion that contacts a lower surface of an adjacent color filter element.

First claim

1 . An image sensor having an array of image pixels, comprising:
a substrate; an array of microlenses formed over the substrate; an array of color filter elements interposed between the microlenses and the substrate; a plurality of dielectric walls, wherein each of the dielectric walls is interposed between a respective pair of the color filter elements, wherein each of the dielectric walls is entirely dielectric, and wherein each of the dielectric walls has first and second opposing sides; and a plurality of metal light shields, wherein each of the metal light shields is at least partially interposed between a respective one of the dielectric walls and a respective one of the color filter elements, wherein each of the dielectric walls has a first metal light shield formed on the first side of the dielectric wall and a second metal light shield formed on the second side of the dielectric wall.

2 . The image sensor defined in claim 1 , wherein the color filter elements have a first refractive index and wherein the dielectric walls have a second refractive index that is less than the first refractive index.

3 . The image sensor defined in claim 1 wherein each of the metal light shields has a height that is less than the height of the color filter elements.

4 . The image sensor defined in claim 1 wherein each of the metal light shields has a height that is equal to the height of the color filter elements.

5 . An image sensor having an array of image pixels, comprising:
a substrate; an array of microlenses formed over the substrate; an array of color filter elements interposed between the microlenses and the substrate; a plurality of color filter barrier structures, wherein each of the color filter barrier structures is interposed between a respective pair of the color filter elements; and a plurality of light barriers, wherein each of the light barriers at least partially surrounds an adjacent color filter element in the array of color filter elements, wherein each of the light barriers has a vertical portion that contacts a side surface of the adjacent color filter element and a horizontal portion that contacts a lower surface of the adjacent color filter element, wherein at least one characteristic of the light barriers varies within the array of image pixels, and wherein the characteristic is selected from the group consisting of: height, width, placement, and an amount by which the light barrier covers an adjacent color filter element.

6 . The image sensor defined in claim 5 wherein each of the color filter elements is surrounded by a respective one of the light barriers.

7 . The image sensor defined in claim 5 wherein the array of image pixels comprises first and second image pixels, wherein the first image pixel is closer to the center of the array than the second image pixel, and wherein the vertical portion of the light barrier in the second image pixel is longer than the vertical portion of the light barrier in the first image pixel.

8 . (canceled)

9 . The image sensor defined in claim 5 wherein the plurality of light barriers includes first and second light barriers formed respectively on first and second opposing corners of the adjacent color filter element.

10 . The image sensor defined in claim 9 wherein the horizontal portions of the first and second light barriers are the same length.

11 . The image sensor defined in claim 9 wherein the horizontal portion of the first light barrier has a different length than the horizontal portion of the second light barrier.

12 . The image sensor defined in claim 9 wherein the vertical portion of the first light barrier is the same length as the vertical portion of the second light barrier.

13 . The image sensor defined in claim 9 wherein the vertical portion of the first light barrier has a different length than the vertical portion of the second light barrier.

14 . The image sensor defined in claim 5 wherein the light barriers are covered by a passivation layer.

15 . A system, comprising:
a central processing unit; memory; input-output circuitry; and an image sensor, comprising:
a grid of dielectric material having an array of openings;
an array of color filter elements, wherein each color filter element is formed in a respective opening in the array of openings; and
a plurality of metal light shields, wherein each of the metal light shields at least partially surrounds a respective one of the color filter elements and wherein each metal light shield is embedded in the grid of dielectric material and does not contact the array of color filter elements.

16 . (canceled)

17 . The system defined in claim 15 wherein at least one of the metal light shields has a varying thickness along a length of the metal light shield.

18 . The system defined in claim 15 wherein the dielectric material forms a dielectric wall between a respective pair of color filter elements and wherein at least one of the metal light shields is offset with respect to a center of the dielectric wall.

19 . The system defined in claim 15 wherein at least one of the metal light shields comprises first and second vertical portions, wherein a center of the first vertical portion is offset with respect to a center of the second vertical portion.

20 . The system defined in claim 15 wherein the image sensor comprises an image pixel array having at least first and second pixels, wherein the first pixel is closer to the center of the array than the second pixel, and wherein the metal light shield surrounding the second pixel is larger than the metal light shield surrounding the first pixel.

21 . The image sensor defined in claim 1 , further comprising:
a planarization layer formed over the array of color filter elements; and a passivation layer formed under the array of color filter elements, wherein each dielectric wall directly contacts the planarization layer and the passivation layer.

22 . The image sensor defined in claim 1 , wherein at least one characteristic of the metal light shields varies within the array of image pixels, and wherein the characteristic is selected from the group consisting of: height, width, placement, and an amount by which the light barrier covers an adjacent color filter element.

Assignees

• Semiconductor Components Ind Llc

Inventors

• Boettiger Ulrich
• Perkins Andrew
• Sulfridge Marc
• Borthakur Swarnal

Classifications

• H04N25/13

  characterised by the spectral characteristics of the filter elements · CPC title

• H01L27/14623

  Electricity · mapped topic

• H04N9/045

  Electricity · mapped topic

• H01L27/14621

  Electricity · mapped topic

• H04N5/2254 Primary

  Electricity · mapped topic