System and method for micro-electromechanical operation of an interferometric modulator

• US 20060024880A1
• Filed: 07/26/2005
• Published: 02/02/2006
• Est. Priority Date: 07/29/2004
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Gally, Brian J., Chui, Clarence, Cummings, William J., Tung, Ming-Hau
• Granted Patent: US 7,567,373 B2
• Time in Patent Office: Days
• US Class Current: 438/222
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 3/001 Structures having a reduced contact area, e.g. with bumps or with a textured surface
• 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

Abstract

An interferometric modulator is formed by a stationary layer and a mirror facing the stationary layer. The mirror is movable between the undriven and driven positions. Landing pads, bumps or spring clips are formed on at least one of the stationary layer and the mirror. The landing pads, bumps or spring clips can prevent the stationary layer and the mirror from contacting each other when the mirror is in the driven position. The spring clips exert force on the mirror toward the undriven position when the mirror is in the driven position and in contact with the spring clips.

Claims

1. An interferometric modulator, comprising:

a first layer comprising a first reflective planar portion;

a second layer comprising a second reflective planar portion located substantially parallel to the first reflective planar portion, the second layer movable between a first position and a second position, the first position being a first distance from the first layer, the second position being a second distance from the first layer, the second distance being greater than the first distance; and

a member having a surface located between the first layer and the second layer, the member defining one or more gap regions between the first layer and the second layer when the second layer is in the first position, wherein the second layer in the one or more gap regions does not contact either the first layer or the member.

3. The interferometric modulator of claim 1, wherein the first reflective planar portion is partially reflective and partially transmissive to light in a predetermined wavelength range.

4. The interferometric modulator of claim 1, wherein the second planar portion is substantially reflective to light in a predetermined wavelength range.

5. The interferometric modulator of claim 1, further comprising a third layer between the first layer and the second layer, the third layer substantially transparent to light in a predetermined wavelength range, wherein the third layer comprises a dielectric layer.

6. The interferometric modulator of claim 5, wherein the second layer in the one or more gap regions does not contact at least a portion of the third layer when the second layer is in the first position.

7. The interferometric modulator of claim 1, wherein the member is spaced from the second layer when the second layer is in the second position, and is contacted by the second layer when the second layer is in the first position.

71. A display system comprising:

the interferometric modulator of claim 1;

a display;

a processor that is in electrical communication with the display, the processor being configured to process image data; and

a memory device in electrical communication with the processor.

72. The display system of claim 71, further comprising:

a first controller configured to send at least one signal to the display; and

a second controller configured to send at least a portion of the image data to the first controller.

73. The display system of claim 71, further comprising:

an image source module configured to send the image data to the processor.

74. The display system of claim 73, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

75. The display system of claim 71, further comprising:

an input device configured to receive input data and to communicate the input data to the processor.

2. (canceled)

8. (canceled)

9. (canceled)

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11. (canceled)

12. A microelectromechanical device, comprising:

a first surface having a first surface area;

a second surface having a second surface area, the second surface being located substantially parallel to the first surface, the second surface movable between a first position and a second position, the first position being a first distance from the first surface, the second position being a second distance from the first surface, the second distance being greater than the first distance; and

a third surface located between the first surface and the second surface, the third surface defining one or more gap regions between the first surface and the second surface when the second surface is in the first position, wherein the second surface in the one or more gap regions does not contact either the first surface or the third surface.

13. The microelectromechanical device of claim 12, wherein the third surface provides a contact area which contacts at least one of the first surface and the second surface when the second surface is in the first position.

14. The microelectromechanical device of claim 12, wherein the third surface comprises a surface of a member that is positioned on a peripheral portion of at least one of the first surface and the second surface.

15. The microelectromechanical device of claim 14, wherein the third surface contacts the second surface when the second surface is in the first position.

16. The microelectromechanical device of claim 15, wherein the third surface comprises a material different from a material which comprises either the first or second surfaces.

17. The microelectromechanical device of claim 15, wherein the third surface comprises a material which also comprises either the first or second surfaces.

18. The microelectromechanical device of claim 14, wherein the third surface comprises a substantially non-transparent material.

19. The microelectromechanical device of claim 14, wherein the third surface comprises a substantially transparent material.

20. The microelectromechanical device of claim 14, wherein the third surface contacts the first surface when the second surface is in the first position.

21. The microelectromechanical device of claim 12, wherein the third surface comprises a surface of a member that is located on a central portion of at least one of the first layer and the second layer.

22. (canceled)

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27. (canceled)

28. A microelectromechanical device, comprising:

a first surface;

a second surface located substantially parallel to the first surface, the second surface movable relative to the first surface between a driven position and an undriven position, wherein the driven position is closer to the first surface than is the undriven position; and

at least one structure on at least one of the first surface and the second surface, wherein the at least one structure is compressed by the first surface and the second surface when the second surface is in the driven position, and wherein the at least one structure provides a force to the second surface when the second surface is in the driven position, the force assisting movement of the second surface from the driven position toward the undriven position.

29. A microelectromechanical device of claim 28, wherein the at least one structure is a spring.

30. A microelectromechanical device of claim 28, wherein the at least one structure comprises a body and a tip extended from the body, the body connected to at least one of the first surface and the second surface, the tip bent away from the surface to which the body is connected when the second surface is in the undriven position.

31. A microelectromechanical device of claim 30, wherein the tip is compressed and substantially flattened when the second surface is in the driven position.

32. A method of making an interferometric modulator, the method comprising:

providing a first layer comprising a first reflective planar portion;

forming a second layer comprising a second reflective planar portion, the second reflective planar portion located substantially parallel to the first reflective planar portion, the second layer movable between a first position and a second position, the first position being a first distance from the first layer, the second position being a second distance from the first layer, the second distance being greater than the first distance; and

forming a member comprising a surface located between the first layer and the second layer, the member defining one or more gap regions between the first layer and the second layer when the second layer is in the first position, wherein the second layer in the one or more gap regions does not contact either the first layer or the member.

33. The method of claim 32, wherein the member separates the first layer from the second layer when the second layer is in the first position.

34. The method of claim 32, wherein the member is on at least one of the first layer and second layer.

35. The method of claim 32, wherein the member comprises a bump.

36. The method of claim 32, wherein the member comprises a landing pad.

37. The method of claim 32, wherein the member comprises a spring.

38. The method of claim 32, further comprising forming one or more additional members, wherein each additional member comprises a surface located between the first layer and the second layer.

39. (canceled)

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46. A microelectromechanical device, comprising:

first means for partially reflecting and partially transmitting incident light;

second means for substantially reflecting incident light;

means for moving the first means relative to the second means between a driven position and an undriven position, the driven position being closer to the first means than is the undriven position; and

means for providing a separation between the first means and the second means when the second means is in the driven position.

47. The microelectromechanical device of claim 46, wherein the means for providing separation comprises at least one of a bump, a landing pad or a spring clip.

48. The microelectromechanical device of claim 46, wherein the means for providing separation is located between the first means and second means.

49. The microelectromechanical device of claim 46, wherein the first means comprises a partial mirror surface.

50. The microelectromechanical device of claim 46, wherein the second means comprises a full mirror surface.

51. The microelectromechanical device of claim 46, wherein the means for moving comprises a deformable layer.

52. A microelectromechanical device, comprising:

first means for partially reflecting and partially transmitting incident light;

second means for substantially reflecting incident light;

means for moving the first means relative to the second means between a driven position and an undriven position, the driven position being closer to the first means than is the undriven position; and

means for applying a force on the second means in a direction toward the undriven position when the second means is in the driven position.

53. The microelectromechanical device of claim 52, wherein the means for applying force comprises a spring clip.

54. The microelectromechanical device of claim 52, wherein the means for applying force comprises a bump or a landing pad, which comprises an elastomeric material.

55. The microelectromechanical device of claim 52, wherein the means for applying a force is in contact with both the first layer and the second layer when the second means is in the driven position.

56. The microelectromechanical device of claim 52, wherein the first means comprises a partial mirror surface.

57. The microelectromechanical device of claim 52, wherein the second means comprises a full mirror surface.

58. The microelectromechanical device of claim 52, wherein the means for moving comprises a deformable layer.

59. (canceled)

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76. A method of making a microelectromechanical system (MEMS) device, comprising:

forming a first electrode;

depositing a dielectric material over at least a portion of the first electrode;

removing a portion of the dielectric material from over the first electrode, thereby forming a variable thickness dielectric layer; and

forming a second electrode over at least a portion of the variable thickness dielectric layer.

77. The method of claim 76 further comprising depositing a sacrificial layer over at least a portion of the dielectric material.

78. The method of claim 77 in which the MEMS device comprises an interferometric modulator.

79. The method of claim 77 in which the second electrode comprises a surface facing the variable thickness dielectric layer, the surface of the second electrode facing the variable thickness dielectric layer having an average peak-to-valley surface profile variation that is less than an average peak-to-valley surface profile variation of the variable thickness dielectric layer.

80. The method of claim 76 in which the dielectric material comprises at least a first layer and a second layer.

81. The method of claim 80 in which the first layer has a first thickness that is greater than a second thickness of the second layer.

82. The method of claim 81 in which the first thickness is in the range of about 200 Å

to about 3000 Å

.

83. The method of claim 81 in which the second thickness is in the range of about 50 Å

to about 500 Å

.

84. The method of claim 80 further comprising patterning the dielectric material to define stops.

85. The method of claim 84 in which removing a portion of the dielectric material comprises removing a portion of the second layer of the dielectric material such that the stops remain.

86. The method of claim 85 further comprising depositing a sacrificial layer over at least a portion of the dielectric material.

87. The method of claim 86 further comprising removing the sacrificial layer and at least a portion of the first layer of the dielectric material.

88. The method of claim 87 in which removing the sacrificial layer and the at least a portion of the first layer of the dielectric material further comprises etching with an etchant.

89. The method of claim 88 in which etching further comprises removing the first layer of the dielectric material at a first etch rate that is higher than a second etch rate for removing the second layer.

90. The method of claim 76 in which the dielectric material is compositionally graded.

91. The method of claim 90 in which the dielectric material is a graded dielectric material selected from the group consisting of graded silicon oxide and graded silicon nitride.

92. The method of claim 91 in which the graded dielectric material at an interface with the first electrode is enriched in Si relative to the overall composition of the graded dielectric material.

93. The method of claim 76 further comprising depositing an intermediate layer over the at least a portion of the first electrode.

94. The method of claim 93 in which the intermediate layer comprises at least one of an optical layer, a barrier layer or a non-conductive layer.

95. The method of claim 93 comprising depositing the dielectric material over the intermediate layer.

96. An interferometric modulator made by the method of claim 76.

97. (canceled)

98. (canceled)

99. (canceled)

100. A method of making an interferometric modulator, comprising:

forming a first electrode;

depositing a dielectric layer over at least a portion of the first electrode;

removing a portion of the dielectric layer to form a variable thickness dielectric layer;

depositing a sacrificial layer over the variable thickness dielectric layer;

planarizing the sacrificial layer; and

forming a second electrode over the sacrificial layer.

101. The method of claim 100 further comprising forming a planarization layer over the sacrificial layer.

102. The method of claim 100 further comprising removing the sacrificial layer.

105. An interferometric modulator made by the method of claim 100.

103. (canceled)

104. (canceled)

106. A method of making an interferometric modulator, comprising:

forming a first electrode;

depositing a dielectric layer over at least a portion of the first electrode;

removing a portion of the dielectric layer to form a variable thickness dielectric layer;

depositing a sacrificial layer over the a variable thickness dielectric layer;

depositing a planarization layer over the sacrificial layer; and

forming a second electrode over the planarization layer.

107. The method of claim 106 further comprising removing the sacrificial layer.

108. The method of claim 106 further comprising planarizing the sacrificial layer.

111. An interferometric modulator made by the method of claim 106.

109. (canceled)

110. (canceled)