Photosensitive imaging devices and associated methods

• US 8,476,681 B2
• Filed: 03/17/2011
• Issued: 07/02/2013
• Est. Priority Date: 09/17/2009
• Status: Active Grant

• Current Assignee: SiOnyx, LLC (Black Silicon Holdings, Inc.)
• Original Assignee: SiOnyx, LLC (Black Silicon Holdings, Inc.)
• Inventors: Haddad, Homayoon, Jiang, Jutao, McKee, Jeffrey, Miller, Drake, Palsule, Chintamani, Forbes, Leonard
• Primary Examiner(s): Maldonado, Julio J
• Assistant Examiner(s): BACHNER, ROBERT G
• Application Number:
  US13/050,557
• Publication Number:
  US 20110220971A1
• Time in Patent Office: 838 Days
• Field of Search: 257/228, 257/432, 257/E31.13, 257/E31.127, 257/E27.151, 257/E31.073, 257/E31.001, 438/70, 438/71
• US Class Current: 257/228
• 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 27/1464 Back illuminated imager structures
• CPC Class Codes: H01L 27/14645 Colour imagers
• CPC Class Codes: H01L 27/14685 Process for coatings or optical elements

Abstract

Backside illuminated photosensitive devices and associated methods are provided. In one aspect, for example, a backside-illuminated photosensitive imager device can include a semiconductor substrate having multiple doped regions forming a least one junction, a textured region coupled to the semiconductor substrate and positioned to interact with electromagnetic radiation, and a passivation region positioned between the textured region and the at least one junction. The passivation region is positioned to isolate the at least one junction from the textured region, and the semiconductor substrate and the textured region are positioned such that incoming electromagnetic radiation passes through the semiconductor substrate before contacting the textured region. Additionally, the device includes an electrical transfer element coupled to the semiconductor substrate to transfer an electrical signal from the at least one junction.

Claims

1. A backside-illuminated photosensitive imager device, comprising:

a semiconductor substrate having multiple doped regions forming a least one junction;

a textured region coupled to the semiconductor substrate and positioned to interact with electromagnetic radiation;

a passivation region positioned between the textured region and the at least one junction, the passivation region being positioned to isolate the at least one junction from the textured region, wherein the semiconductor substrate and the textured region are positioned such that incoming electromagnetic radiation passes through the semiconductor substrate before contacting the textured region; and

an electrical transfer element coupled to the semiconductor substrate and operable to transfer an electrical signal from the at least one junction.

2. The device of claim 1, wherein the passivation region is positioned to physically isolate the textured region from the at least one junction.

3. The device of claim 1, wherein the passivation region is positioned to electrically isolate the textured region from the at least one junction.

4. The device of claim 1, wherein the passivation region is coupled directly to the at least one junction.

5. The device of claim 1, wherein the passivation region has a thickness of from about 5 nm to about 100 nm.

6. The device of claim 1, wherein the passivation region has a thickness of from about 20 nm to about 50 nm.

7. The device of claim 1, wherein the passivation region includes a material selected from the group consisting of oxides, nitrides, oxynitrides, and combinations thereof.

8. The device of claim 1, wherein the passivation region includes an oxide.

9. The device of claim 1, further comprising a reflecting region positioned to reflect electromagnetic radiation passing through the texture region back through the textured region.

10. The device of claim 9, further comprising a dielectric layer positioned between the reflecting region and the textured region.

11. The device of claim 9, wherein the reflecting region includes a member selected from the group consisting of a Bragg reflector, a metal reflector, a metal reflector over a dielectric material, and combinations thereof.

12. The device of claim 1, wherein the textured layer is a textured polysilicon layer.

13. The device of claim 1, wherein the textured layer is a textured dielectric layer.

14. The device of claim 1, wherein the textured region has a surface morphology operable to direct electromagnetic radiation into the semiconductor substrate.

15. The device of claim 14, wherein the surface morphology of the textured region relative to the semiconductor substrate is a member selected from the group consisting of sloping, pyramidal, inverted pyramidal, spherical, square, rectangular, parabolic, asymmetric, symmetric, and combinations thereof.

16. The device of claim 1, wherein the textured region includes surface features having a size selected from the group consisting of micron-sized, nano-sized, and combinations thereof.

17. The device of claim 16, wherein surface features include a member selected from the group consisting of cones, pillars, pyramids, micolenses, quantum dots, inverted features, gratings, and combinations thereof.

18. The device of claim 1, wherein the textured region has been formed by a process selected from the group consisting of plasma etching, reactive ion etching, porous silicon etching, lasing, chemical etching, nanoimprinting, material deposition, selective epitaxial growth, and combinations thereof.

19. The device of claim 1, further comprising a lens optically coupled to the semiconductor substrate and positioned to focus incident electromagnetic radiation into the semiconductor substrate.

20. The device of claim 1, wherein the textured region is doped with a dopant to generate a back surface field.

21. A back-side illuminated photosensitive imager array, comprising at least two photosensitive imager devices of claim 1.

22. The array of claim 21, further comprising at least one isolation feature positioned between the at least two photosensitive imager devices.

23. The array of claim 21, wherein the at least one isolation feature is configured to optically or electrically isolate the at least two photosensitive imager devices.

24. A method of making a backside-illuminated photosensitive imager device, comprising:

forming at least one junction at a surface of a semiconductor substrate;

forming a passivation region over the at least one junction;

forming a textured region over the passivation region, wherein the passivation region isolates the at least one junction from the textured region, and wherein the semiconductor substrate and the textured region are positioned such that incoming electromagnetic radiation passes through the semiconductor substrate before contacting the textured region; and

coupling an electrical transfer element to the semiconductor substrate such that the electrical transfer element is operable to transfer an electrical signal from the at least one junction.

25. The method of claim 24, wherein forming the textured region is by a process selected from the group consisting of plasma etching, reactive ion etching, porous silicon etching, lasing, chemical etching, nanoimprinting, material deposition, selective epitaxial growth, and combinations thereof.

26. The method of claim 24, further comprising coupling a lens to the semiconductor substrate at a surface opposite the at least one junction, wherein the lens is positioned to focus incident electromagnetic radiation into the semiconductor substrate.

27. The method of claim 24, wherein forming the textured region further includes:

depositing a semiconductor material on the passivation region; and

texturing the semiconductor material to form the textured region.

28. The method of claim 27, wherein the semiconductor material includes a member selected from the group consisting of silicon, polysilicon, amorphous silicon, and combinations thereof.

29. The method of claim 24, wherein forming the textured region further includes:

depositing a dielectric material on the passivation region; and

texturing the dielectric material to form the textured region.

30. The method of claim 24, further comprising depositing a reflective region over the textured region.

31. The method of claim 24, further comprising depositing an anti-reflective layer to the semiconductor substrate at a surface opposite the at least one junction, such that incident electromagnetic radiation passes through the anti-reflective layer prior to contacting the semiconductor substrate.

32. The method of claim 24, further comprising coupling a color filter to the semiconductor substrate at a surface opposite the at least one junction, such that incident electromagnetic radiation passes through the color filter prior to contacting the semiconductor substrate.

33. A backside-illuminated photosensitive imager device, comprising:

a semiconductor substrate having multiple doped regions forming a least one junction;

a textured region coupled to the semiconductor substrate and positioned to interact with electromagnetic radiation;

a passivation region positioned between the textured region and the at least one junction, the passivation region being positioned to isolate the at least one junction from the textured region, wherein the semiconductor substrate and the textured region are positioned such that incoming electromagnetic radiation passes through the semiconductor substrate before contacting the textured region; and

at least 4 transistors coupled to the semiconductor substrate and with at least one of the transistors electrically coupled to the at least one junction.