Reduced edge effect from recesses in imagers

• US 7,952,155 B2
• Filed: 02/20/2007
• Issued: 05/31/2011
• Est. Priority Date: 02/20/2007
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Liu, Saijin
• Primary Examiner(s): Pham; Thanh V
• Assistant Examiner(s): NGUYEN, DUY T V
• Application Number:
  US11/708,790
• Publication Number:
  US 20080198248A1
• Time in Patent Office: 1,561 Days
• Field of Search: 438 57- 70, 257/432, 257/98, 257/586, 257/635, 257/40, 257/E31.121, 257/E31.127
• US Class Current: 257/432
• CPC Class Codes: G02B 3/0056 arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085
• CPC Class Codes: G02B 5/201 in the form of arrays

Abstract

Methods for making a recessed color filter array for a semiconductor imager employing a sidewall spacer for reducing an edge effect from the array are disclosed. In one embodiment, a substrate is provided having an upper surface. Then, a recess is formed into the upper surface of the substrate. The recess has a bottom and a sidewall. Subsequently, a sidewall spacer is formed on the sidewall of the recess. A color resist is deposited into the recess after forming the sidewall spacer. In the embodiment, the sidewall spacer is formed of a material having a surface energy lower than that of a material defining the bottom of the recess. The color resist adheres less to the sidewall than to the bottom of the recess. Thus, the color resist does not conform to a shape of an edge portion of the recess, thereby reducing the edge effect.

Claims

1. A semiconductor imaging device comprising:

a die including a substrate having an upper surface, the substrate including a recess formed into the upper surface, the recess including a bottom and a sidewall;

a sidewall spacer formed on the sidewall of the recess, wherein the sidewall spacer comprises a layer that does not extend across the recess, wherein the spacer is formed of an organic material; and

an array of color filters formed on the bottom of the recess.

2. The device of claim 1, wherein the bottom of the recess includes a first material having a first surface energy, and wherein the spacer is formed of a second material having a second surface energy lower than the first surface energy.

3. The device of claim 2, wherein the first surface energy is from about 55 dynes/cm² to about 65 dynes/cm².

4. The device of claim 2, wherein the second surface energy is not greater than about 40 dynes/cm².

5. The device of claim 2, wherein the color filters are formed of a color resist having a third surface energy greater than the second surface energy.

6. The device of claim 5, wherein the color resist comprises at least one of propylene glycol monomethyl ether acetate (PGMEA), ethyl 3-ethoxypropionate (EEP), cyclohexanone and acrylic resin.

7. The device of claim 1, wherein the bottom of the recess is defined by a dielectric material.

8. The device of claim 7, wherein the dielectric material comprises silicon nitride (Si₃N₄).

9. The device of claim 1, wherein the organic material comprises a self-assembled monolayer material.

10. The device of claim 9, wherein the self-assembled monolayer material comprises a fluorinated self-assembled monolayer material.

11. The device of claim 10, wherein the fluorinated self-assembled monolayer material comprises 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane (FDTS).

12. The device of claim 1, further comprising a passivation layer on the bottom of the recess.

13. The device of claim 12, wherein the passivation layer is formed of silicon nitride (Si₃N₄).

14. The device of claim 12, wherein the passivation layer further comprises a portion interposed between the spacer and the sidewall of the recess.

15. The device of claim 1, further comprising a protrusion extending from an edge of the recess where the sidewall of the recess meets an upper surface of the substrate.

16. The device of claim 15, wherein the protrusion extends substantially horizontally over the recess.

17. The device of claim 15, wherein the protrusion extends substantially vertically.

18. The device of claim 15, wherein the sidewall spacer further comprises a portion at least partially covering the protrusion.

19. The device of claim 18, further comprising a passivation layer interposed between the protrusion and the portion of the spacer.

20. The device of claim 1, further comprising a plurality of photodiodes embedded in the substrate under the bottom of the recess.

21. The device of claim 1, further comprising one or more conductive lines embedded in the substrate, the conductive lines being positioned lateral to the recess.

22. The device of claim 1, wherein the recess has a depth from about 1 μ

m to about 3 μ

m.

23. The device of claim 1, wherein the substrate has no more than one recess.

24. The device of claim 1, wherein the array of color filters is formed inside the recess, and has substantially the same thickness in an edge region extending along and adjacent to the sidewall of the recess as a thickness of a central region of the array.

25. The device of claim 24, wherein the edge region has a width of about 50 μ

m to about 100 μ

m from the sidewall.