Imager method and apparatus employing photonic crystals

• US 8,115,854 B2
• Filed: 02/22/2010
• Issued: 02/14/2012
• Est. Priority Date: 06/07/2005
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Mouli, Chandra
• Primary Examiner(s): Ye, Lin
• Assistant Examiner(s): HOGUE, DENNIS A
• Application Number:
  US12/709,798
• Publication Number:
  US 20100164045A1
• Time in Patent Office: 722 Days
• Field of Search: None
• US Class Current: 348/342
• 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. A micro-electro-mechanical system (MEMS) 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 a photo-conversion device based upon voltage applied to the metal layer.

2. The MEMS element of claim 1, 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.

3. The MEMS element of claim 1, further comprising a conductive film on the pillars.

4. The MEMS element of claim 3, wherein the conductive film comprises copper.

5. The MEMS element of claim 1, 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.

6. The MEMS element of claim 1, wherein the pillars each have a circular horizontal cross-sectional shape.

7. The MEMS element of claim 1, wherein the pillars each have a substantially pentagonal horizontal cross-sectional shape.

8. The MEMS element of claim 1, wherein the pillars each have a substantially rectangular horizontal cross-sectional shape.

9. The MEMS element of claim 1, wherein the pillars comprise aluminum oxide, tantalum oxide, zirconium oxide, hafnium oxide, or a halfnium-based silicate.

10. The MEMS element of claim 1, further comprising:

a second support structure over the substrate;

a second insulating layer supported by the second support structure;

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

a second metal layer in contact with at least a portion of the pillars, the second support structure configured to be controllable by applied voltages to displace the second 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, wherein the photonic crystal structures are displaced over one another at different heights from the surface of the substrate.

11. 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

forming 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 a photo-conversion device based upon a voltage applied to the metal layer.

12. The method of claim 11, 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.

13. The method of claim 11, further comprising the act of forming a conductive film on the pillars.

14. The method of claim 13, wherein the conductive film is formed comprising copper.

15. The method of claim 11, 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.

16. The method of claim 11, wherein the pillars are formed having a circular horizontal cross-sectional shape.

17. The method of claim 11, wherein the pillars are formed having a substantially pentagonal horizontal cross-sectional shape.

18. The method of claim 11, wherein the pillars are formed having a substantially rectangular horizontal cross-sectional shape.

19. The method of claim 11, wherein the pillars comprise aluminum oxide, tantalum oxide, zirconium oxide, hafnium oxide, or a hafnium-based silicate.

20. The method of claim 11 further comprising:

providing a second support structure over the substrate;

forming a second insulating layer supported by the second support structure;

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

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

forming a second metal layer in contact with at least a portion of the pillars, the second support structure configured to be controllable to displace the second 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, wherein the photonic crystal structures are displaced over one another at different heights from the surface of the substrate.