Light modulator with a light-absorbing layer

• US 20060023287A1
• Filed: 07/30/2004
• Published: 02/02/2006
• Est. Priority Date: 07/30/2004
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Monroe, Michael G., Piehl, Arthur R., Przybyla, James R.
• Granted Patent: US 7,187,487 B2
• Time in Patent Office: Days
• US Class Current: 359/237
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 5/22 Absorbing filters G02B5/201 - G02B5/208 take precedence

Abstract

A spatial light modulator includes a first region and a second region. A light-absorbing layer contacts at least a portion of the second region. The light absorbing layer includes a first layer and a second layer, the second layer having a reflectivity less than about 75%.

Claims

1. A spatial light modulator, comprising:

a first region;

a second region; and

a light-absorbing layer contacting at least a portion of the second region, the light-absorbing layer including;

a reflective first layer; and

a second layer connected to the reflective first layer, the second layer having a reflectivity less than about 75%.

2. The spatial light modulator as defined in claim 1 wherein the second layer comprises at least one of tantalum aluminum alloys, tungsten silicon nitride alloys, tantalum nitride alloys, nickel, nickel alloys, titanium nitride alloys, and mixtures thereof.

3. The spatial light modulator as defined in claim 1 wherein the second layer comprises tantalum aluminum.

4. The spatial light modulator as defined in claim 1 wherein the second layer is capable of absorbing at least a portion of directed light having a wavelength between 400 and 700 nanometers.

5. The spatial light modulator as defined in claim 1 wherein the light-absorbing layer further comprises a third layer interposed between the first layer and the second layer.

6. The spatial light modulator as defined in claim 5 wherein the third layer is a standoff layer that has an optical transparency and a thickness so as to absorb at least a portion of the light.

7. The spatial light modulator as defined in claim 5 wherein the third layer comprises at least one of silicon dioxide, silicon nitride, silicon carbide, and air.

8. The spatial light modulator as defined in claim 5 wherein the third layer has a thickness between about 300 angstroms and about 8000 angstroms.

9. The spatial light modulator as defined in claim 1 wherein the light-absorbing layer further comprises a fourth layer disposed on the second layer.

10. The spatial light modulator as defined in claim 9 wherein the fourth layer comprises a transparent dielectric.

11. The spatial light modulator as defined in claim 10 wherein the transparent dielectric has a graded refractive index adapted to reduce surface reflections from the transparent dielectric.

12. The spatial light modulator as defined in claim 9, wherein the fourth layer comprises a series of layers.

13. The spatial light modulator as defined in claim 12 wherein the series of layers comprises at least one of magnesium difluoride, titanium dioxide, silicon dioxide, magnesium oxide, alumina, zirconium dioxide, yttrium oxide, barium difluoride, calcium difluoride, lead fluoride, thorium dioxide, chromium oxide, hafnium dioxide, tin dioxide, zinc oxide, tantalum pentoxide, cadmium sulfide, zinc sulfide, and mixtures thereof.

14. The spatial light modulator as defined in claim 1 wherein the first layer comprises at least one of aluminum, aluminum alloys, silver, silver alloys, gold, gold alloys, tantalum aluminum, titanium nitride, tungsten silicon nitride, tungsten, silicon, chromium, copper, and mixtures thereof.

15. The spatial light modulator as defined in claim 1 wherein the first layer has a thickness between about 300 angstroms and about 5000 angstroms.

16. The spatial light modulator as defined in claim 1 wherein the second layer has a thickness between about 50 angstroms and about 300 angstroms.

17. The spatial light modulator as defined in claim 1 wherein the light-absorbing layer absorbs at least a portion of light in a wavelength between about 400 nm and about 700 nm.

18. The spatial light modulator as defined in claim 1 wherein the second region comprises a support post.

19. The spatial light modulator as defined in claim 1 wherein a passivation layer is disposed between the second region and the light-absorbing layer.

20. A method of making a spatial light modulator, comprising:

providing a first region capable of color generation by modulation and a second region coupled to the first region; and

establishing a light-absorbing layer in contact with the second region, the light-absorbing layer including;

a reflective first layer; and

a second layer connected to the first layer, the second layer having a reflectivity less than about 75%.

21. The method as defined in claim 20 wherein the second layer comprises at least one of tantalum aluminum alloys, tungsten silicon alloys, tantalum nitride alloys, nickel, nickel alloys, titanium nitride allows, and mixtures thereof.

22. The method as defined in claim 20, further comprising depositing a passivation layer in contact with the first and second regions prior to establishing the light-absorbing layer.

23. The method as defined in claim 20 wherein the light-absorbing layer further comprises a third layer established between the first and second layers.

24. A method of making a spatial light modulator, comprising:

providing a first region capable of light generation by modulation and a second region coupled thereto;

establishing a sacrificial layer overlying at least a portion of the first region and the second region;

removing a portion of the sacrificial layer from an area over the second region, thereby forming an exposed second region;

establishing a light-absorbing layer on the exposed second region and on a remaining portion of the sacrificial layer overlying the second region, whereby a portion of the light-absorbing layer is in contact with the exposed second region and a second portion of the light-absorbing layer is in contact with the remaining portion of the sacrificial layer and is suspended relative to the second region; and

removing the remaining portion of the sacrificial layer.

25. The method as defined in claim 24 wherein establishing the light-absorbing layer further comprises:

establishing a first layer having a reflectivity characteristic; and

establishing a second layer connected to the first layer, the second layer having a reflectivity less than about 75%.

26. The method as defined in claim 25 wherein establishing the light-absorbing layer further comprises:

establishing a standoff layer between the first and second layers; and

establishing a transparent dielectric layer connected to the second layer.

27. The method as defined in claim 26, wherein the transparent dielectric layer is adapted to function as an anti-reflective coating.

28. A method of making a spatial light modulator, comprising the steps of:

providing a substrate, the substrate having a first region and a second region disposed thereon, wherein the first region comprises a pixel and wherein the second region comprises at least one post and at least one flexure;

depositing a sacrificial layer over the pixel, the at least one flexure, and the at least one post;

removing a portion of the sacrificial layer disposed on the at least one post, thereby forming a supportive connector region for a light-absorbing layer;

depositing a light-absorbing layer on the supportive connector region and on the sacrificial layer disposed on the at least one flexure; and

etching a portion of the sacrificial layer disposed on the at least one flexure, whereby a portion of the light-absorbing layer is connected to the at least one post and a second portion of the light-absorbing layer is suspended relative to the at least one flexure.

29. A device, comprising:

means for modulating light;

means for supporting the means for light modulating; and

means for absorbing light, contacting at least a portion of the supporting means, the absorbing means including;

a reflective first layer; and

a second layer connected to the first layer, the second layer having a reflectivity less than about 75%.

30. The device as defined in claim 29 wherein the second layer comprises at least one of tantalum aluminum alloys, tungsten silicon nitride alloys, tantalum nitride alloys, nickel, nickel alloys, titanium nitride alloys, and mixtures thereof.

31. The device as defined in claim 29 wherein at least a portion of the light absorbed has a wavelength between about 400 nm and about 700 nm.

32. An integrated circuit, comprising:

a semiconductor substrate;

a first region disposed on a first portion of the semiconductor substrate;

a second region disposed on a second portion of the semiconductor substrate;

a passivation layer disposed on the first region and the second region; and

a light-absorbing layer disposed on the passivation layer and contacting at least a portion of the second region, the light-absorbing layer including;

a first layer; and

a second layer connected to the first layer, the second layer having a reflectivity less than about 75%.

33. An integrated circuit, comprising:

a semiconductor substrate;

a first region disposed on the semiconductor substrate;

a second region disposed on the semiconductor substrate; and

a light-absorbing layer suspended relative to the second region.

34. The integrated circuit as defined in claim 33 wherein the second region comprises at least one post and at least one flexure.

35. The integrated circuit as defined in claim 33 wherein the light-absorbing layer is in contact with the at least one post and is suspended in indirect contact with the at least one flexure.

36. A display device, comprising:

a light source for providing a beam of light along a first light path;

a light modulation device on the first light path for selectively reflecting a portion of the beam of light along a second light path in response to image data signals;

a controller for providing image data signals to the light modulation device; and

at least one element on the second light path for resolving the selectively reflected light into an image;

wherein the light modulation device includes;

a first region;

a second region; and

a light-absorbing layer contacting at least a portion of the second region, the light-absorbing layer including;

a first layer; and

a second layer connected to the first layer, the second layer having a reflectivity less than about 75%.

37. The display device as defined in claim 36 wherein the display device is a dual gap device and wherein the light modulation device has a passivation layer disposed on the first region and interposed between the second region and the light-absorbing layer.

38. The display device as defined in claim 36 wherein the display device is a single gap device and wherein the second region comprises at least one post and at least one flexure.

39. The display device as defined in claim 38 wherein the light modulation device further comprises a removable sacrificial layer interposed between the at least one flexure and the light-absorbing layer.

40. The display device as defined in claim 36 wherein the light-absorbing layer is configured to substantially prevent light from being reflected off of the second region and wherein the second layer comprises at least one of tantalum aluminum, alloys thereof, and mixtures thereof.

41. A projector, comprising:

a light source for providing a beam of light along a first light path;

a light modulation device on the first light path for selectively reflecting a portion of the beam of light along a second light path in response to image data signals;

a controller for providing image data signals to the light modulation device; and

at least one element on the second light path for resolving the selectively reflected light into an image;

wherein the light modulation device includes;

a first region;

a second region; and

a light-absorbing layer contacting at least a portion of the second region, the light-absorbing layer including;

a first layer; and

a second layer connected to the first layer, the second layer having a reflectivity less than about 75%.

42. A spatial light modulator, comprising:

a first region;

a second region; and

a light-absorbing layer contacting at least a portion of the second region, the light-absorbing layer including;

a first layer having a reflectivity less than about 75%; and

a tantalum aluminum layer connected to the first layer.

43. The spatial light modulator as defined in claim 42 wherein the light-absorbing layer further comprises a third layer interposed between the first layer and the tantalum aluminum layer.

44. The spatial light modulator as defined in claim 42 wherein the third layer is a standoff layer that has an optical transparency and a thickness so as to absorb at least a portion of the light.

45. The spatial light modulator as defined in claim 44 wherein the standoff layer comprises at least one of silicon dioxide, silicon nitride, silicon carbide, and air.

46. The spatial light modulator as defined in claim 44 wherein the standoff layer has a thickness between about 250 angstroms and about 1000 angstroms.

47. The spatial light modulator as defined in claim 42 wherein the light-absorbing layer further comprises a transparent dielectric layer disposed on the second layer.

48. The spatial light modulator as defined in claim 42 wherein the first layer comprises at least one of aluminum, aluminum alloys, silver, silver alloys, gold, gold alloys, tantalum aluminum, titanium nitride, tungsten silicon nitride, tungsten, silicon, chromium, copper, and mixtures thereof.

49. The spatial light modulator as defined in claim 42 wherein the first layer comprises tantalum aluminum having a reflectivity of about 46%, and wherein the tantalum aluminum layer has a reflectivity of about 18%.