Spatial light modulators with light blocking and absorbing areas

US 6,952,301 B2
Filed: 11/26/2002
Issued: 10/04/2005
Est. Priority Date: 06/19/1995
Status: Expired due to Term

First Claim

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1. A method for making a spatial light modulator, comprising:

providing a first substrate and a second substrate;

forming an array of circuitry and electrodes on the second substrate;

depositing a light blocking thin film on the first substrate to selectively block the passage of light through the first substrate;

forming an array of deflectable reflective elements on the first or second substrate; and

bonding the first and second substrates to form a substrate assembly.

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Abstract

A projection system, a spatial light modulator, and a method for forming a MEMS device are disclosed. The spatial light modulator can have two substrates bonded together with one of the substrates comprising a micro-mirror array. The two substrates can be bonded at the wafer level after depositing a getter material and/or solid or liquid lubricant on one or both of the wafers if desired. In one embodiment of the invention, one of the substrates is a light transmissive substrate and a light blocking layer that is preferably a light absorbing layer is provided on the light transmissive substrate to selectively block light from passing through the substrate. The light blocking layer can be formed as a pattern, such as a grid or strips for blocking light from entering gaps between adjacent micro-mirrors.

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141 Claims

1. A method for making a spatial light modulator, comprising:
- providing a first substrate and a second substrate;
  
  forming an array of circuitry and electrodes on the second substrate;
  
  depositing a light blocking thin film on the first substrate to selectively block the passage of light through the first substrate;
  
  forming an array of deflectable reflective elements on the first or second substrate; and
  
  bonding the first and second substrates to form a substrate assembly.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58)
- - 2. The method of claim 1, wherein the bonding of the first and second substrates comprises bonding the first and second substrates together to form the substrate assembly followed by singulating the substrate assembly into a set of assembly dies, each of which comprises a plurality of deflectable reflective elements.
  - 3. The method of claim 2, wherein the deflectable reflective elements correspond to pixels in a direct-view or projection display.
  - 4. The method of claim 2, further comprising the singulated die into a projection system that comprises a light source, a color sequencer and projection optics.
  - 5. The method of claim 1, wherein the light blocking thin film is a light absorbing layer that is formed as a grid for decreasing the amount of light that enters gaps between the deflectable elements.
  - 6. The method of claim 5, wherein an additional light absorbing area is formed as a rectangular frame on the first substrate surrounding the array of deflectable reflective elements.
  - 7. The method of claim 6, wherein the light absorbing thin film is deposited after forming the array of deflectable reflective elements.
  - 8. The method of claim 5, wherein the light absorbing thin film is deposited prior to forming the array of deflectable reflective elements.
  - 9. The method of claim 1, wherein the light blocking thin film is black.
  - 10. The method of claim 1, wherein the light blocking thin film absorbs at least 50% of the visible light incident thereon.
  - 11. The method of claim 10, wherein the light blocking thin film absorbs at least 75% of the light incident thereon.
  - 12. The method of claim 11, wherein the light blocking thin film absorbs at least 85% of the light incident thereon.
  - 13. The method of claim 1, wherein the light blocking thin film is a light absorbing matrix.
  - 14. The method of claim 13, wherein the number of reflective elements in each die is from 6,000 to about 6 million.
  - 15. The method of claim 1, wherein the first substrate is an optically transmissive substrate or a substrate having one or more layers that when removed result in an optically transmissive substrate in an area other than in the area of the light blocking layer.
  - 16. The method of claim 15, wherein the first substrate is glass, borosilicate, tempered glass, quartz or sapphire.
  - 17. The method of claim 1, wherein the second substrate is a dielectric or semiconductor substrate.
  - 18. The method of claim 17, wherein the second substrate comprises GaAs or silicon.
  - 19. The method of claim 1, wherein the first and second substrates are bonded together with an adhesive.
  - 20. The method of claim 1, wherein the light blocking thin film is formed as a grid on the first substrate surrounding each deflectable element, and as a block of rectangular frames on the first substrate, each frame surrounding one or more of the arrays of deflectable reflective elements.
  - 21. The method of claim 1, wherein the bonding comprises applying an adhesive and spacers, the spacers having a size of from 1 to 100 microns.
  - 22. The method of claim 21, wherein the spacers have a size of from 1 to 20 microns.
  - 23. The method of claim 1, wherein the plurality of deflectable elements are reflective mirror elements and are formed on the second substrate which is a light transmissive substrate when in use except in areas of the light absorbing layer.
  - 24. The method of claim 1, wherein the circuitry and plurality of electrodes are formed prior to forming the plurality of deflectable elements, wherein the plurality of deflectable elements are formed above the plurality of electrodes on the second substrate.
  - 25. The method of claim 24, wherein a plurality of light absorbing masks are formed on the first substrate.
  - 26. The method of claim 25, wherein when the substrate assembly is singulated into substrate assembly dies, a light absorbing mask is disposed on a first substrate portion within each substrate assembly die.
  - 27. The method of claim 1, wherein the plurality of deflectable elements are formed on the first substrate.
  - 28. The method of claim 27, wherein when the first and second substrates are aligned and bonded together, the deflectable elements on the first substrate are each disposed proximate to a corresponding electrode on the second substrate.
  - 29. The method of claim 1, wherein the deflectable elements are micromirrors having jagged or zig-zag edges.
  - 30. The method of claim 1, further comprising applying a stiction reducing agent to one or both substrates before or alter bonding the two substrates together, but before singulating the substrate assembly into dies.
  - 31. The method of claim 30, wherein the stiction reducing agent is a silane applied to the deflectable elements.
  - 32. The method of claim 30, wherein the stiction reducing agent is a chlorosilane.
  - 33. The method of claim 1, wherein the light blocking thin film is provided as a grid or matrix on the light transmissive substrate.
  - 34. The method of claim 1, wherein the light blocking thin film is provided as strips or bands on the light transmissive substrate.
  - 35. The method of claim 1, wherein the light blocking thin film is black nickel or black chrome.
  - 36. The method of claim 1, wherein the light blocking thin film is a black or dark colored metal or metal alloy.
  - 37. The method of claim 1, wherein the light blocking thin film is a carbon containing polymer.
  - 38. The method of claim 1, wherein the light blocking thin film is deposited by sputtering.
  - 39. The method of claim 1, wherein the light blocking thin film is a carbon containing film.
  - 40. The method of claim 1, wherein the light blocking thin film comprises a carbon compound.
  - 41. The method of claim 1, wherein the light blocking thin film is a multilayer laminate.
  - 42. The method of claim 1, wherein the light transmissive substrate comprises an AR coating on a surface opposite to the surface having the light blocking thin film.
  - 43. The method of claim 1, wherein the light blocking thin film is a light absorbing frame around each die area.
  - 44. The method of claim 43, wherein the light blocking thin film is a set of light absorbing frames, each of which surrounding a micromirror.
  - 45. The method of claim 44, wherein the light absorbing frame surrounding each micromirror is on the same side of the first substrate as the micromirrors.
  - 46. The method of claim 45, wherein the light absorbing frame is on a side of the first substrate opposite to the side on which the micromirrors are formed.
  - 47. The method of claim 1, wherein the light blocking thin film is a light absorbing frame surrounding each micromirror.
  - 48. The method of claim 1, wherein the light blocking thin film comprises a plurality of light blocking strips, each of which are proximate to a gap between adjacent micromirrors.
  - 49. The method of claim 1, wherein the first substrate is bonded to the second substrate at a distance of less than 100 microns from the second substrate.
  - 50. The method of claim 49, wherein the first substrate is bonded to the second substrate at a distance of less than 10 microns from the second substrate.
  - 51. The method of claim 1, wherein the light blocking thin film is a ceramic thin film.
  - 52. The method of claim 1, further comprising:
    - patterning the deposited light blocking thin film.
  - 53. The method of claim 1, wherein the light blocking thin film absorbs 97 percent or more of the light incident thereon.
  - 54. The method of claim 1, wherein the light blocking thin film is opaque or dark in color.
  - 55. The method of claim 1, wherein the light blocking thin film comprises Ni.
  - 56. The method of claim 1, wherein the light blocking thin film comprises Cr.
  - 57. The method of claim 1, wherein the light blocking thin film comprises Niobium.
  - 58. The method of claim 1, further comprising:
    - directly bonding the first and second substrate together.

59. A spatial light modulator, comprising:
- a first substrate and a second substrate;
  
  an array of circuitry and electrodes on the second substrate;
  
  a light blocking thin film on the first substrate disposed to selectively block the passage of light through the first substrate; and
  
  an array of deflectable reflective elements on the first or second substrate;
  
  wherein the first and second substrates are positioned proximate to each other as a substrate assembly.
- View Dependent Claims (60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113)
- - 60. The spatial light modulator of claim 59, wherein the reflective elements correspond to pixels in a direct-view or projection display.
  - 61. The spatial light modulator of claim 59, wherein the light blocking thin film is formed as a grid for blocking light between each deflectable element.
  - 62. The spatial light modulator of claim 61, wherein the light blocking thin film is further formed as a rectangular frame on the first substrate surrounding the array of deflectable reflective elements.
  - 63. The spatial light modulator of claim 59, wherein the first and second substrates arc bonded together.
  - 64. The spatial light modulator of claim 59, wherein the light blocking thin film is a light absorbing layer that is black.
  - 65. The spatial light modulator of claim 59, wherein the light blocking thin film is a layer that absorbs at least 50% of the light incident thereon.
  - 66. The spatial light modulator of claim 65, wherein the light blocking thin film is a layer that absorbs at east 75% of the light incident thereon.
  - 67. The spatial light modulator of claim 66, wherein the light blocking thin film is a light absorbing layer that blocks at least 85% of the light incident thereon.
  - 68. The spatial light modulator of claim 59, wherein the light blocking thin film is a light absorbing layer that is a light absorbing matrix.
  - 69. The spatial light modulator of claim 68, wherein the number of reflective elements in a die area is from 6,000 to about 6 million.
  - 70. The spatial light modulator of claim 59, wherein the first substrate is an optically transmissive substrate in areas other than in the area of the light blocking thin film.
  - 71. The spatial light modulator of claim 70, wherein the first substrate is glass, borosilicate, tempered glass, quartz or sapphire.
  - 72. The spatial light modulator of claim 59, wherein the second substrate is a glass or quartz substrate.
  - 73. The spatial light modulator of claim 59, wherein the second substrate is a dielectric or semiconductor substrate.
  - 74. The spatial light modulator of claim 73, wherein the second substrate comprises GaAs or silicon.
  - 75. The spatial light modulator of claim 59, wherein the first and second substrates are bonded together with an adhesive.
  - 76. The spatial light modulator of claim 59, wherein the second substrate is a glass substrate.
  - 77. The spatial light modulator of claim 59, wherein the plurality of deflectable elements are reflective mirror elements and are held on the second substrate which is a light transmissive substrate.
  - 78. The spatial light modulator of claim 59, wherein the plurality of deflectable elements are formed on the second substrate.
  - 79. The spatial light modulator of claim 78, wherein the circuitry and plurality of electrodes are disposed on the second substrate, wherein the plurality of deflectable elements are formed spatted above the plurality of electrodes on the second substrate.
  - 80. The spatial light modulator of claim 79, wherein a plurality of light absorbing masks are formed on the first substrate.
  - 81. The spatial light modulator of claim 80, wherein the substrate assembly is a substrate assembly die having a light absorbing mask disposed on a first substrate portion within the substrate assembly die.
  - 82. The spatial light modulator of claim 59, wherein the plurality of deflectable elements are formed on the first substrate.
  - 83. The spatial light modulator of claim 59, wherein the deflectable elements are micromirrors having jagged or zig-zag edges.
  - 84. The spatial light modulator of claim 59, further comprising a stiction reducing agent on one or both substrates.
  - 85. The spatial light modulator of claim 59, further comprising a getter on one or both substrates.
  - 86. The spatial light modulator of claim 85, wherein the getter is a molecular, hydrogen and/or particle getter.
  - 87. The spatial light modulator of claim 85, wherein the getter is a particulate and moisture getter.
  - 88. The spatial light modulator of claim 85, wherein the getter is capable of absorbing moisture.
  - 89. The spatial light modulator of claim 59, wherein the light blocking thin film is provided as strips or bands on the light transmissive substrate.
  - 90. The spatial light modulator of claim 59, wherein the light blocking thin film is a light absorbing layer that is black nickel or black chrome.
  - 91. The spatial light modulator of claim 59, wherein the light blocking thin film is a light absorbing layer that is a black or dark colored metal or metal alloy.
  - 92. The spatial light modulator of claim 59, wherein the light blocking thin film is a light absorbing layer that is a carbon containing polymer.
  - 93. The spatial light modulator of claim 59, wherein the light blocking thin film is a light absorbing layer that is deposited by sputtering.
  - 94. The spatial light modulator of claim 59, wherein the light blocking thin film is a light absorbing layer that is a carbon containing film.
  - 95. The spatial light modulator of claim 59, wherein the light blocking thin film is a light absorbing layer that comprises a carbon compound.
  - 96. The spatial light modulator of claim 59, wherein the light blocking thin film is a light absorbing layer that is a multilayer laminate.
  - 97. The spatial light modulator of claim 59, wherein the light transmissive substrate comprises an AR coating on a surface opposite to the surface having the light absorbing layer.
  - 98. The spatial light modulator of claim 59, wherein the light blocking thin film is a light absorbing layer that is a light absorbing frame around each die area.
  - 99. The spatial light modulator of claim 98, wherein the light blocking thin film is a light absorbing layer that is a light absorbing frame surrounding each micromirror.
  - 100. The spatial light modulator of claim 99, wherein the light absorbing frame surrounding each micromirror is on the same side of the first substrate as the micromirrors.
  - 101. The spatial light modulator of claim 100, wherein the light absorbing frame surrounding each die is on a side of the first substrate opposite to the side on which the micromirrors are formed.
  - 102. The spatial light modulator of claim 59, wherein the light blocking thin film is a light absorbing layer that is a light absorbing frame surrounding each micromirror.
  - 103. The spatial light modulator of claim 59, wherein the light blocking thin film is a light absorbing layer that comprises light absorbing strips proximate to gaps between adjacent micromirrors.
  - 104. The spatial light modulator of claim 59, wherein the first substrate is bonded to the second substrate at a distance of less than 100 microns from the second substrate.
  - 105. The spatial light modulator of claim 104, wherein the first substrate is bonded to the second substrate at a distance of less than 10 microns from the second substrate.
  - 106. The spatial light modulator of claim 105, wherein the first substrate is bonded to the second substrate at a distance of from 1 to 10 microns from the second substrate.
  - 107. The spatial light modulator of claim 59, wherein light blocking thin film comprises Ni.
  - 108. The spatial light modulator of claim 59, wherein light blocking thin film comprises Cr.
  - 109. The spatial light modulator of claim 59, wherein tight blocking thin film comprises Niobium.
  - 110. The spatial light modulator of claim 59, wherein tight blocking thin film is a ceramic thin film.
  - 111. The spatial light modulator of claim 59, wherein light blocking thin film is opaque or dark in color.
  - 112. The spatial light modulator of claim 59, wherein light blocking thin film is operable to absorb 97% or more of the light incident thereon.
  - 113. The spatial light modulator of claim 59, wherein the first and second substrate is directly bonded together.

114. A projection system, comprising:
- a light source;
  
  a spatial light modulator for reflecting a beam of light from the light source; and
  
  projection optics for projecting light reflected off of the spatial light modulator;
  
  wherein the spatial light modulator comprises;
  
  a first substrate and a second substrate;
  
  an array of circuitry and electrodes on the second substrate;
  
  a light blocking thin film on the first substrate disposed to selectively block the passage of light through the first substrate; and
  
  an array of deflectable reflective elements on the first or second substrate; and
  
  wherein the first and second substrates are bonded together other as a substrate assembly.
- View Dependent Claims (115, 116, 117, 118, 119, 120, 121)
- - 115. The projection system of claim 114, wherein light blocking thin film comprises Ni.
  - 116. The projection system of claim 114, wherein light blocking thin film comprises Cr.
  - 117. The projection system of claim 114, wherein light blocking thin film comprises Niobium.
  - 118. The projection system of claim 114, wherein light blocking thin film is a ceramic thin film.
  - 119. The projection system of claim 114, wherein light blocking thin film is opaque or dark in color.
  - 120. The projection system of claim 114, wherein the light blocking thin film is operable to absorb 97% or more of the light incident thereon.
  - 121. The projection system of claim 114, wherein the first and second substrate is directly bonded together.

122. A method for making a spatial light modulator, comprising:
- providing a first substrate and a second substrate;
  
  forming an array of circuitry and electrodes on the second substrate;
  
  forming a plurality of strips or frame areas on the first substrate to block at least 50% of the light from pausing through the first substrate in the areas of the strips or frame areas;
  
  forming an array of deflectable reflective elements on the first or second substrate; and
  
  bonding the first and second substrates together to form a substrate assembly.

123. A spatial light modulator, comprising:
- a first substrate and a second substrate;
  
  an array of circuitry and electrodes on the second substrate;
  
  an opaque layer that forms a pattern on the first substrate in order to selectively block at least 50% of the light from passing through the first substrate in the areas where the opaque layer is disposed; and
  
  an array of deflectable reflective elements on the first or second substrate;
  
  wherein the first and second substrates are bonded together other as a substrate assembly.

124. A spatial light modulator comprising:
- a first substrate and a second substrate within or forming a MEMS package; and
  
  an array of circuitry, electrodes and micromirrors on the second substrate;
  
  wherein the first substrate is a substrate transmissive to visible light and is disposed at a distance from the second substrate of 100 microns or less; and
  
  wherein a light blocking thin film is present on the first or the second substrate for selectively blocking light.
- View Dependent Claims (125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138)
- - 125. The spatial light modulator of claim 124, wherein the first substrate is disposed at a distance of 50 microns or less from the second substrate.
  - 126. The spatial light modulator of claim 125, wherein the first substrate is disposed at a distance of 10 microns or less from the second substrate.
  - 127. The spatial light modulator of claim 124, wherein the first and second substrates are bonded together.
  - 128. The spatial light modulator of claim 127, wherein the light blocking thin film is present on the light transmissive substrate and is disposed to selectively block a passage of light through the light transmissive substrates.
  - 129. The spatial light modulator of claim 128, wherein the light blocking thin film is a light absorbing layer that is formed as a grid for blocking light between each deflectable element.
  - 130. The spatial modulator of claim 128, wherein the light blocking thin film is a light absorbing layer that is formed as a rectangular frame on the first substrate surrounding the array of deflectable reflective elements.
  - 131. The spatial light modulator of claim 128, wherein the light blocking thin film is a light absorbing layer that is formed as a grid on the first substrate surrounding each deflectable element, and as a rectangular frame on the first substrate surrounding the array of deflectable reflective elements.
  - 132. The spatial light modulator of claim 128, wherein the light blocking thin film is black.
  - 133. The spatial light modulator of claim 128, wherein the light blocking thin film is a light absorbing layer that absorbs at least 50% of the light in areas where the light absorbing layer is disposed.
  - 134. The spatial light modulator of claim 133, wherein the light blocking thin film is a light absorbing layer that absorbs at least 75% of the light in areas where the light absorbing layer is disposed.
  - 135. The spatial light modulator of claim 134, wherein the light blocking thin film is a light absorbing layer that absorbs at least 85% of the light in areas whore the light absorbing layer is disposed.
  - 136. The spatial light modulator of claim 128, wherein the light blocking thin film is a light absorbing matrix.
  - 137. The spatial light modulator of claim 136, wherein the number of reflective elements in a die area is from 6000 to about 6 million.
  - 138. The spatial light modulator of claim 124, wherein the micromirrors correspond to pixels in a direct-view or projection display.

139. A projection system, comprising:
- a light source;
  
  a spatial light modulator for reflecting abeam of light from the light source; and
  
  a series of projection optics for projecting light reflected off of the spatial light modulator;
  
  wherein the spatial light modulator comprises;
  
  a first substrate and a second substrate within or forming a MEMS package; and
  
  an array of circuitry, electrodes and micromirrors on the second substrate; and
  
  wherein the first substrate is a substrate transmissive to visible light and is disposed at a distance from the second substrate of 100 microns or less.

140. A method for making a spatial light modulator, comprising:
- providing a first substrate and a second substrate;
  
  forming an array of circuitry and electrodes on the second substrate;
  
  forming a light blocking thin film on the first substrate to selectively block the passage of light through the first substrate;
  
  forming an array of deflectable reflective elements; and
  
  bonding the first and second substrates to form a substrate assembly such that the array of deflectable reflective elements are located between the first and the second substrates.

141. A projection system, comprising:
- a light source;
  
  a set of optical elements;
  
  a spatial light modulator, comprising;
  
  a first substrate and a second substrate;
  
  an array of circuitry and electrodes on the second substrate;
  
  a light blocking thin film on the first substrate to selectively block the passage of light through the first substrate; and
  
  an array of deflectable reflective elements positioned between the first and the second substrates; and
  
  a display target.

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Current Assignee
Texas Instruments, Inc.
Original Assignee
Reflectivity, Inc. (Texas Instruments, Inc.)
Inventors
Huibers, Andrew G.
Primary Examiner(s)
Lester, Evelyn A.

Application Number

US10/305,631
Publication Number

US 20040012838A1
Time in Patent Office

1,043 Days
Field of Search

359/223, 359/224, 359290-292, 359/295, 359/298
US Class Current

359/291
CPC Class Codes

B82Y 30/00 Nanotechnology for material...

Spatial light modulators with light blocking and absorbing areas

First Claim

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141 Claims

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Spatial light modulators with light blocking and absorbing areas

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Abstract

63 Citations

141 Claims

Specification

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