Imager method and apparatus employing photonic crystals

• US 20060274189A1
• Filed: 06/07/2005
• Published: 12/07/2006
• Est. Priority Date: 06/07/2005
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Mouli, Chandra
• Granted Patent: US 7,688,378 B2
• Time in Patent Office: Days
• US Class Current: 348/340
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 1/005 made of photonic crystals or photonic band gap materials photonic band-gap structures or photonic lattices in integrated optics G02B6/1225; photonic band-gap structures or photonic lattices in optical fibres G02B6/02295
• CPC Class Codes: H01L 27/14621 Colour filter arrangements
• CPC Class Codes: H01L 27/14623 Optical shielding
• CPC Class Codes: H01L 27/14645 Colour imagers
• CPC Class Codes: H01L 27/14649 Infrared imagers
• CPC Class Codes: H01L 27/14685 Process for coatings or optical elements
• CPC Class Codes: H01L 27/148 Charge coupled imagers individual charge coupled devices H01L29/765
• CPC Class Codes: H01L 31/02162 for filtering or shielding light, e.g. multicolour filters for photodetectors
• CPC Class Codes: H01L 31/02165 using interference filters, e.g. multilayer dielectric filters interference filters G02B5/28
• CPC Class Codes: Y10S 977/954 Of radiant energy

Abstract

An image sensor and a method of forming an image sensor. The image sensor includes an array of pixel cells at a surface of a substrate. Each pixel cell has a photo-conversion device. At least one a micro-electro-mechanical system (MEMS) element including a photonic crystal structure is provided over at least one of the pixel cells. The MEMS-based photonic crystal element is supported by a support structure and configured to selectively permit electromagnetic wavelengths to reach the photo-conversion device upon application of a voltage. As such, the MEMS-based photonic crystal element of the invention can replace or compliment conventional filters, e.g., color filter arrays.

Claims

1. An image sensor comprising:

an array of pixel cells at a surface of a substrate, each pixel cell comprising a photo-conversion device; and

at least one micro-electro-mechanical system element comprising a photonic crystal structure over at least one of the pixel cells for selectively permitting electromagnetic radiation having a predetermined wavelength to reach the photo-conversion device of the at least one cell in response to at least one applied voltage.

2. The image sensor of claim 1, further comprising a plurality of elements stacked over the at least one pixel cell.

3. The image sensor of claim 2, wherein the elements are configured to be controllable by applied voltages to selectively permit green wavelengths of light, red wavelengths of light, and blue wavelengths of light to reach the photo-conversion device at different times.

4. The image sensor of claim 2, wherein the elements are configured to be controllable by applied voltages to selectively permit visible wavelengths of light and infrared wavelengths of light to reach the photo-conversion device at different times.

5. The image sensor of claim 1, further comprising at least two elements stacked over at least one of the pixel cells.

6. The image sensor of claim 1, wherein the element is supported by a support structure for causing the element to be displaced with respect to a surface of the substrate in response to the applied voltage.

7. The image sensor of claim 1, wherein the element comprises a plurality of pillars being spaced apart from each other.

8. The image sensor of claim 7, wherein the element further comprises a material within the spacing between the pillars, the material having a dielectric constant that is lower than a dielectric constant of the pillars.

9. The image sensor of claim 8, further comprising a metal layer in contact with at least a portion of the pillars.

10. The image sensor of claim 8, wherein the element further comprises a conductive material in contact with the pillars.

11. The image sensor of claim 8, wherein the pillars comprise aluminum oxide.

12. A processor system comprising:

a processor; and

an optoelectronic device coupled to the processor, the device comprising;

an array of pixel cells at a surface of a substrate, each pixel cell comprising a photo-conversion device, and

at least one micro-electro-mechanical system element comprising a photonic crystal structure over at least one of the pixel cells for selectively permitting electromagnetic radiation having a predetermined wavelength to reach the photo-conversion device of the at least one cell in response to at least one applied voltage.

13. The processor system of claim 12, wherein the image sensor is a CMOS image sensor.

14. The processor system of claim 12, wherein the device is a charge coupled device image sensor.

15. The processor system of claim 12, wherein the at least one element is configured to be controllable by applied voltages to selectively permit predetermined electromagnetic wavelengths to reach the photo-conversion device in response to an applied a voltage.

16. A micro-electro-mechanical system element for an optoelectronic device, the element comprising:

a substrate;

a support structure over the substrate;

an insulating layer supported by the support structure;

a plurality of pillars forming a photonic crystal structure on the insulating layer, the pillars being spaced apart from each other; and

a metal layer in contact with at least a portion of the pillars, the support structure configured to be controllable by applied voltages to displace the photonic crystal structure with respect to a surface of the substrate to selectively permit electromagnetic wavelengths to reach the photo-conversion device based upon voltage applied to the metal layer.

17. The element of claim 16, further comprising a material within the spacing between the pillars, wherein a dielectric constant of the material within the spacing is lower than a dielectric constant of the pillars.

18. The element of claim 16, further comprising a conductive film on the pillars.

19. The element of claim 18, wherein the conductive film comprises copper.

20. The element of claim 16, wherein the pillars have a height within the range of approximately 100 Å

to approximately 5000 Å

.

21. The element of claim 16, wherein a ratio of the spacing between the pillars to a height of the pillars is within the range of approximately 1 to approximately 10.

22. The element of claim 16, wherein the pillars each have a circular horizontal cross-sectional shape.

23. The element of claim 16, wherein the pillars each have a substantially pentagonal horizontal cross-sectional shape.

24. The element of claim 16, wherein the pillars each have a substantially rectangular horizontal cross-sectional shape.

25. The element of claim 16, wherein the pillars comprise aluminum oxide.

26. The element of claim 16, wherein the pillars comprise tantalum oxide.

27. The element of claim 16, wherein the pillars comprise zirconium oxide.

28. The element of claim 16, wherein the pillars comprise hafnium oxide.

29. The element of claim 16, wherein the pillars comprise a hafnium-based silicate.

30. The element of claim 16, wherein the pillars comprise a conductive oxide.

31. A method of forming an image sensor, the method comprising the acts of:

forming an array of pixel cells at a surface of a substrate, each pixel cell formed comprising a photo-conversion device; and

forming at least one micro-electro-mechanical system element comprising a photonic crystal structure over at least one of the pixel cells, each element for selectively permitting electromagnetic radiation having a predetermined wavelength to reach the photo-conversion device of the at least one cell in response to at least one applied voltage.

32. The method of claim 31, further comprising the act of forming a plurality of elements over the at least one pixel cell.

33. The method of claim 32, wherein the act of forming the plurality of elements comprises configuring the photonic crystal elements to be controllable by applied voltages to selectively permit green wavelengths of light, red wavelengths of light, and blue wavelengths of light to reach the photo-conversion device at different times.

34. The method of claim 32, wherein the act of forming the plurality of elements comprises configuring the photonic crystal elements to be controllable to selectively permit visible wavelengths of light and infrared wavelengths of light to reach the photo-conversion device at different times.

35. The method of claim 31, further comprising the act of forming least two elements over at least one of the pixel cells.

36. The image sensor of claim 35, wherein a first element is formed over a second photonic crystal element.

37. The method of claim 31, further comprising the act of providing a support structure for supporting the element and for causing the element to be displaced with respect to a surface of the substrate in response to the at least one applied voltage.

38. The method of claim 31, wherein the act of forming the element comprises forming a plurality of pillars spaced apart from each other.

39. The method of claim 38, wherein the act of forming the element further comprises forming a material within the spacing between the pillars, the material having a dielectric constant that is lower than a dielectric constant of the pillars.

40. The method of claim 38, wherein the act of forming the element further comprises forming a metal layer in contact with at least a portion of the pillars.

41. The method of claim 38, wherein the act of forming the element further comprises forming a conductive material in contact with the pillars.

42. A method of forming a micro-electro-mechanical system element for an optoelectronic device, the method comprising the acts of:

providing a substrate;

providing a support structure over the substrate;

forming an insulating layer supported by the support structure;

forming a layer of a photonic crystal material over the insulating layer;

patterning the photonic crystal material layer to form a plurality of pillars forming a photonic crystal structure, the pillars formed spaced apart from each other and each having a height and a horizontal cross-sectional shape; and

a metal layer in contact with at least a portion of the pillars, the support structure configured to be controllable to displace the photonic crystal structure with respect to a surface of the substrate to selectively permit electromagnetic wavelengths to reach the photo-conversion device based upon a voltage applied to the metal layer.

43. The method of claim 42, further comprising the act of forming a material within the spacing between the pillars, wherein the dielectric constant of the material within the spacing is lower than the dielectric constant of the pillars.

44. The method of claim 42, further comprising the act of forming a conductive film on the pillars.

45. The method of claim 44, wherein the conductive film is formed comprising copper.

46. The method of claim 42, wherein the pillars are formed having a height within the range of approximately 100 Å

to approximately 5000 Å

.

47. The method of claim 42, wherein the pillars are formed such that a ratio of the spacing between the pillars to a height of the pillars is within the range of approximately 1 to approximately 10.

48. The method of claim 42, wherein the pillars are formed having a circular horizontal cross-sectional shape.

49. The method of claim 42, wherein the pillars are formed having a substantially pentagonal horizontal cross-sectional shape.

50. The method of claim 42, wherein the pillars are formed having a substantially rectangular horizontal cross-sectional shape.

51. The method of claim 42, wherein the pillars are formed comprising aluminum oxide.

52. The method of claim 42, wherein the pillars are formed comprising tantalum oxide.

53. The method of claim 42, wherein the pillars are formed comprising zirconium oxide.

54. The method of claim 42, wherein the pillars are formed comprising hafnium oxide.

55. The method of claim 42, wherein the pillars are formed comprising a hafnium-based silicate.

56. The method of claim 42, wherein the pillars are formed comprising a conductive oxide.