Photonic mems and structures

• US 20060284877A1
• Filed: 06/01/2006
• Published: 12/21/2006
• Est. Priority Date: 10/05/1999
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: IDC, LLC
• Inventors: Miles, Mark W.
• Granted Patent: US 7,187,489 B2
• Time in Patent Office: Days
• US Class Current: 345/540
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G01J 3/0256 Compact construction
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G01L 5/0047 measuring forces due to residual stresses
• CPC Class Codes: G02B 2006/12104 Mirror; Reflectors or the like
• CPC Class Codes: G02B 2006/12109 Filter
• CPC Class Codes: G02B 2006/12126 Light absorber
• CPC Class Codes: G02B 2006/12159 Interferometer
• CPC Class Codes: G02B 2006/12164 Multiplexing; Demultiplexing
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• CPC Class Codes: G02B 26/08 for controlling the direction of light in light guides G02B6/35
• 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 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 5/02 Diffusing elements; Afocal elements
• CPC Class Codes: G02B 6/12007 forming wavelength selective elements, e.g. multiplexer, demultiplexer
• CPC Class Codes: G02B 6/122 Basic optical elements, e.g. light-guiding paths
• CPC Class Codes: G02B 6/1225 comprising photonic band-gap structures or photonic lattices
• CPC Class Codes: G02B 6/13 Integrated optical circuits characterised by the manufacturing method
• CPC Class Codes: G02B 6/266 the optical element being an attenuator
• CPC Class Codes: G02B 6/3516 : the reflective optical element moving along the beam path, e.g. controllable diffractive effects using multiple micromirrors within the beam
• CPC Class Codes: G02B 6/3522 : the optical element enabling or impairing total internal reflection using evanescent coupling G02B6/3536
• CPC Class Codes: G02B 6/353 : the optical element being a shutter, baffle, beam dump or opaque element absorbers on light guide termination G02B6/243
• CPC Class Codes: G02B 6/3536 : involving evanescent coupling variation, e.g. by a moving element such as a membrane which changes the effective refractive index mode converters G02B6/14; adjustable lateral coupling between waveguides G02B6/283; electro- optical refractive index variations G02F1/0118
• CPC Class Codes: G02B 6/3546 : NxM switch, i.e. a regular array of switches elements of matrix type constellation
• CPC Class Codes: G02B 6/3548 : 1xN switch, i.e. one input and a selectable single output of N possible outputs
• CPC Class Codes: G02B 6/356 : in an optical cross-connect device, e.g. routing and switching aspects of interconnecting different paths propagating different wavelengths to (re)configure the various input and output links switching polarized beams G02B6/3594; power equalizers G02B6/356 and G02B6/3594; path selecting means H04Q11/0001
• CPC Class Codes: G02B 6/357 : Electrostatic force electrostatic forces controlling reflecting elements in general G02B26/0841
• CPC Class Codes: G02B 6/3578 : Piezoelectric force piezoelectric forces controlling reflecting elements in general G02B26/0858; piezo-optic devices G02F1/0131
• CPC Class Codes: G02B 6/3584 : constructional details of an associated actuator having a MEMS construction, i.e. constructed using semiconductor technology such as etching MEMS per se B81B, B81C
• CPC Class Codes: G02B 6/3594 : Characterised by additional functional means, e.g. means for variably attenuating or branching or means for switching differently polarized beams
• CPC Class Codes: G02B 6/3598 : Switching means directly located between an optoelectronic element and waveguides, including direct displacement of either the element or the waveguide, e.g. optical pulse generation based on changing the optical properties of the medium G02F1/00; optical pulse generation in optical transmitters H04B10/508; optical pulse generation by controlling laser operation H01S3/00
• CPC Class Codes: G02B 6/43 : Arrangements comprising a plurality of opto-electronic elements and associated optical interconnections
• CPC Class Codes: G09G 2310/02 : Addressing, scanning or driving the display screen or processing steps related thereto
• CPC Class Codes: G09G 2310/0254 : Control of polarity reversal in general, other than for liquid crystal displays
• CPC Class Codes: G09G 2310/06 : Details of flat display driving waveforms
• CPC Class Codes: G09G 3/3466 : based on interferometric effect

Abstract

An interference modulator (Imod) incorporates anti-reflection coatings and/or micro-fabricated supplemental lighting sources. An efficient drive scheme is provided for matrix addressed arrays of IMods or other micromechanical devices. An improved color scheme provides greater flexibility. Electronic hardware can be field reconfigured to accommodate different display formats and/or application functions. An IMod'"'"'s electromechanical behavior can be decoupled from its optical behavior. An improved actuation means is provided, some one of which may be hidden from view. An IMod or IMod array is fabricated and used in conjunction with a MEMS switch or switch array. An IMod can be used for optical switching and modulation. Some IMods incorporate 2-D and 3-D photonic structures. A variety of applications for the modulation of light are discussed. A MEMS manufacturing and packaging approach is provided based on a continuous web fed process. IMods can be used as test structures for the evaluation of residual stress in deposited materials.

Claims

1. A test structure configured to indicate residual stress, comprising:

a reflective membrane connected to a substrate; and

an interferometric cavity formed between a portion of the membrane and a portion of the substrate,

wherein the membrane behaves in a manner according to the residual stress of the test structure and modulates light indicative of a degree of residual stress.

2. The test structure of claim 1, wherein the substrate comprises glass.

3. The test structure of claim 2, wherein the substrate further comprises at least one film layer.

4. The test structure of claim 1, wherein the membrane comprises silicon, aluminum, or germanium.

5. The test structure of claim 1, wherein the membrane is configured such that light modulated by the membrane includes color information that indicates the degree of residual stress.

6. The test structure of claim 1, wherein the membrane comprises one or more edges, and wherein at least a portion of one edge of the membrane is attached to the substrate.

7. The test structure of claim 6, wherein at least a portion of only one edge of the membrane is attached to the substrate, the remaining edges of the membrane being free of attachment.

8. The test structure of claim 1, wherein the membrane comprises at least two edges, and wherein at least a portion of the two edges are attached to the substrate.

9. The test structure of claim 8, wherein the two edges of the membrane attached to the substrate are nonadjacent to each other.

10. The test structure of claim 8, wherein the two edges attached to the substrate are on opposite sides of the membrane.

11. The test structure of claim 1, wherein the membrane is configured as a parallelogram.

12. The test structure of claim 11, wherein two parallel and opposed edges of the membrane are attached to the substrate.

13. The test structure of claim 1, wherein the membrane is configured in a double cantilever form.

14. The test structure of claim 1, wherein the membrane is configured as a single cantilever form.

15. The test structure of claim 1, wherein the membrane is configured such that a first portion of the membrane is attached to the substrate and a second portion of the membrane deforms based on the residual stress in the membrane

16. The test structure of claim 1, where the membrane is freestanding.

17. The test structure of claim 1, further comprising means for placing the membrane in an actuated state or relaxed state.

18. The test structure of claim 1, the membrane having curvature relative to the amount of residual stress.

19. The test structure of claim 18, wherein no appreciable amount of residual stress in the membrane is indicated by the membrane being flat.

20. A system configured to determine residual stress, comprising:

one or more test structures, each test structure comprising a reflective membrane comprising a portion of a deposited film, wherein the test structure behaves in a manner according to the residual stress of the membrane and modulates light indicative of the degree of residual stress in the deposited film;

an imaging system positionable to receive modulated light reflecting from the one or more test structures and produce an image associated with the received light; and

a computer in communication with the imaging system, the computer configured to process the image and generate information relating to the residual stress of the deposited film.

21. The system of claim 20, wherein the computer is configured to calculate deformation data of the membrane based on the image, and further configured to determine the information relating to the residual stress of the deposited film based on the deformation data.

22. The system of claim 20, wherein each of the one or more test structures further comprises an interferometric cavity formed between a portion of the membrane and a portion of a substrate.

23. The system of claim 22, wherein a portion of the membrane of at least one of the one or more test structures is attached to the substrate.

24. The system of claim 22, wherein the substrate comprises at least one film layer.

25. The system of claim 20, wherein the membrane comprises one or more edges, and wherein at least a portion of one edge of the membrane of at least one or the one or more one test structures is attached to a substrate.

26. The system of claim 25, wherein at least a portion of only one edge of the membrane of at least one of the one or more test structures is attached to the substrate, the remaining edges of the membrane being free of attachment.

27. The system of claim 20, wherein the membrane comprises two or more edges, and wherein at least a portion of two edges of the membrane of at least of the one or more test structures are attached to a substrate.

28. The system of claim 27, wherein the two edges of the membrane connected to the substrate are nonadjacent to each other.

29. The system of claim 28, wherein the two edges connected to the substrate are on opposite sides of the membrane.

30. The system of claim 20, wherein the imaging system comprises an optical system and a high resolution imaging device.

31. The system of claim 20, wherein the membrane of at least one test structure is configured in a double cantilever form.

32. The system of claim 20, wherein the membrane of at least one test structure is configured in a single cantilever form.

33. The system of claim 20, wherein the membrane is configured as a parallelogram.

34. The system of claim 33, wherein two parallel and opposed edges of the membrane are connected to the substrate.

35. The system of claim 20, wherein at least one of the one or more test structures comprises means for placing the membrane in a relaxed state or an actuated state.

36. The test structure of claim 20, the membrane having curvature relative to the amount of residual stress.

37. The system of claim 20, wherein no appreciable amount of residual stress in the membrane is indicated by the membrane being flat.

38. A method of determining residual stress, the method comprising:

interferometrically modulating light with a reflective membrane of a test structure, wherein the membrane behaves in a manner according to the residual stress of the test structure and modulates light indicative of the degree of residual stress;

receiving the modulated light; and

determining the residual stress of the test structure based on the received modulated light.

39. The method of claim 38, wherein receiving the modulated light comprises receiving the modulated light in an imaging system.

40. The method of claim 39, further comprising providing image data associated with the modulated light for use in determining the residual stress of the test structure.

41. The method of claim 39, further comprising generating the image data based on the modulated light, and wherein determining the residual stress comprises determining deformation information of the membrane based on the image data, and generating residual stress information based on the deformation information.

42. The method of claim 40, wherein determining the residual stress comprises:

determining deformation information of the membrane based on the image data; and

generating residual stress information based on the deformation information.

43. The method of claim 42, wherein determining deformation information comprises analyzing color information in the image data, and wherein the color information is indicative of the deformation of the membrane.

44. The test structure of claim 38, wherein the membrane curves relative to the amount of residual stress.

45. The system of claim 38, wherein no appreciable amount of residual stress in the membrane is indicated by the membrane being flat.

46. A method of determining residual stress in a deposited film, the method comprising:

collecting a first set of data indicating a first residual stress state of the one or more test structures disposed on a substrate;

depositing a film over the one or more test structures;

collecting a second set of data indicating a second residual stress state of the one or more test structures, the second set of data indicating residual stress in the deposited film; and

determining the residual stress of the deposited film based on comparing the collected first data and collected second data.

47. The method of claim 46, wherein the first data comprises a first color map and the second data comprises a second color map.

48. The method of claim 46, wherein the second set of data is collected as the film is being deposited.

49. The method of claim 46, wherein the second set of data is collected in real time.

50. The method of claim 46, further comprising:

configuring a test structure for actuation;

actuating the test structure configured for actuation after the film is deposited;

collecting a third set of data indicating information of the residual stress of the deposited film from the actuated test structure; and

determining further information of the residual stress in the deposited film based on the third set of data.

51. The method of claim 50, wherein the third set of data comprises a third color map.

52. A method of manufacturing a test structure to indicate residual stress, the method comprising depositing a film on a substrate to form a deformable reflective membrane such that an interferometric cavity is formed between a portion of the membrane and a portion of the substrate, wherein the membrane is configured to behave in a manner according to the residual stress of the test structure and modulate light indicative of a degree of residual stress.

53. A system configured to determine residual stress in a deposited film, comprising:

means for interferometrically modulating light according to the degree of residual stress of the deposited film;

.

means for receiving the modulated light; and

means for determining the residual stress of the test structure based on the received modulated light.

54. The system of claim 53, wherein the light modulating means comprises a test structure, the test structure comprising

a reflective membrane attached to a substrate;

and

an interferometric cavity formed between a portion of the membrane and a portion of the substrate,

wherein the membrane behaves in a manner according to the residual stress of the device and modulates light indicative of a degree of residual stress.

55. The system of claim 53, wherein the light receiving means comprises an imaging system positionable to receive modulated light from the test structure and configured to produce image data associated with the received modulated light.

56. The system of claim 55, wherein the image data comprises color information indicating a degree of light modulation, and the determining means uses the color information to determine the residual stress.

57. The system of claim 53, wherein the determining means comprises a computer in communication with the light receiving means, the computer configured to process the image data and produce residual stress information relating to the deposited film based on the image data.

58. The test structure of claim 53, wherein the membrane curves relative to the amount of residual stress.

59. The system of claim 53, wherein no appreciable amount of residual stress in the membrane is indicated by the membrane being flat.