Wire-bondable image sensor having integral contaminant shadowing reduction structure

• US 20060138304A1
• Filed: 12/23/2004
• Published: 06/29/2006
• Est. Priority Date: 12/23/2004
• Status: Active Grant

• Current Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Original Assignee: Micron Technology, Inc.
• Inventors: Afshari, Bahram, Hartlove, Jason, Ma, Guolin
• Granted Patent: US 7,129,459 B2
• Time in Patent Office: Days
• US Class Current: 250/208.100
• CPC Class Codes: H01L 27/1462 Coatings
• CPC Class Codes: H01L 27/14685 Process for coatings or optical elements

Abstract

A wire-bondable image sensor having an integral contaminant shadowing reduction structure is described. In one aspect, an image sensor includes a substrate that has a side supporting at least one imaging area and at least one wirebonding area. Light detectors are constructed and arranged to receive light through the imaging area. Bond pads are exposed in the wirebonding area for connecting to respective bond wires. A contaminant shadowing reduction structure on the imaging area has an exposed contaminant displacement surface over the imaging area and separated from the imaging area by a distance of at least 300 μm. The contaminant shadowing reduction structure is substantially transparent to radiation within an operative wavelength range specified for the image sensor. Methods of making the above-mentioned image sensor also are described.

Claims

1. An image sensor, comprising:

a substrate having a side supporting at least one imaging area and at least one wirebonding area;

light detectors constructed and arranged to receive light through the imaging area;

bond pads exposed in the wirebonding area for connecting to respective bond wires; and

a contaminant shadowing reduction structure on the imaging area having an exposed contaminant displacement surface over the imaging area and separated from the imaging area by a distance of at least 300 μ

m, wherein the contaminant shadowing reduction structure is substantially transparent to radiation within an operative wavelength range specified for the image sensor.

2. The image sensor of claim 1, wherein the contaminant shadowing reduction structure comprises an integral infrared light absorption filter.

3. The image sensor of claim 2, wherein the infrared light absorption filter comprises a layer of organic material comprising at least one infrared light absorbing dye.

4. The image sensor of claim 3, wherein the organic material layer comprises a cured epoxy resin.

5. The image sensor of claim 3, wherein the organic material layer comprises a cross-linked photoresist layer.

6. The image sensor of claim 3, wherein the organic material layer has a thickness of at least 200 μ

m.

7. The image sensor of claim 1, wherein the contaminant shadowing reduction structure comprises a patterned, cross-linked photoresist layer having a thickness of at least 300 μ

m.

8. The image sensor of claim 1, wherein the contaminant shadowing reduction structure comprises a patterned, cured epoxy resin layer having a thickness of at least 300 μ

m.

9. The image sensor of claim 1, wherein the contaminant shadowing reduction structure comprises a glass layer attached to the imaging area by a cured epoxy resin layer.

10. The image sensor of claim 9, wherein the epoxy resin layer comprises at least one infrared light absorbing dye and has a thickness of at least 200 μ

m.

11. The image sensor of claim 10, wherein the glass layer has a thickness of at least 500 μ

m.

12. A method fabricating an image sensor, comprising:

forming image sensor dice on a wafer, wherein each of the dice comprises light detectors constructed and arranged to receive light through a respective imaging area and bond pads in a wirebonding area;

forming on the dice a contaminant shadowing reduction structure having an exposed contaminant displacement surface over the imaging areas and separated from the imaging areas by a distance of at least 300 μ

m, wherein the contaminant shadowing reduction structure is substantially transparent to radiation within an operative wavelength range specified for the image sensor;

removing regions of the contaminant shadowing reduction structure over the wirebonding areas of the dice to expose the bond pads; and

separating the dice into respective image sensor chips.

13. The method of claim 12, wherein the formed contaminant shadowing reduction structure comprises an integral infrared light absorption filter.

14. The method of claim 13, wherein the forming of the contaminant shadowing reduction structure comprises forming an infrared light absorption filter comprises a layer of organic material comprising at least one infrared light absorbing dye.

15. The method of claim 14, wherein the organic material layer comprises a cured epoxy resin having a thickness of at least 200 μ

m.

16. The method of claim 14, wherein the organic material layer comprises a cross-linked photoresist layer having a thickness of at least 200 μ

m.

17. The method of claim 12, wherein the forming of the contaminant shadowing reduction structure comprises forming a patterned, cross-linked photoresist layer having a thickness of at least 300 μ

m.

18. The method of claim 12, wherein the forming of the contaminant shadowing reduction structure comprises forming a patterned, cured epoxy resin layer having a thickness of at least 300 μ

m.

19. The method of claim 12, wherein the forming of the contaminant shadowing reduction structure comprises attaching to the dice a glass substrate having a thickness of at least 500 μ

m.

20. The method of claim 19, wherein the attaching comprises applying an uncured epoxy resin layer comprising at least one infrared light absorbing dye and having a thickness of at least 200 μ

m over the dice, placing the glass substrate on the uncured epoxy resin layer, and curing the epoxy resin layer.