Color deformable mirror device having optical thin film interference color coatings

• US 5,619,059 A
• Filed: 09/28/1994
• Issued: 04/08/1997
• Est. Priority Date: 09/28/1994
• Status: Expired due to Fees

• Current Assignee: National Research Council Canada
• Original Assignee: National Research Council Canada
• Inventors: Li, Li, Grant, Peter D., Sullivan, Brian T., Dobrowolski, Jerzy A.
• Primary Examiner(s): Saadat, Mahshid D.
• Assistant Examiner(s): CLARK, SHEILA V
• Application Number:
  US08/314,003
• Time in Patent Office: 923 Days
• Field of Search: 257/431, 257/432, 257/433, 257/436
• US Class Current: 257/431
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

A semiconductor device comprises a plurality of colored deformable mirrors controllable by electrical circuitry. Groups of mirrors, responsive to the electronic signals, are selectably operable to reflect incident light. The deformable mirrors are coated with an optical thin film interference color coating having at least a layer that is substantially transparent to the visible light. As well the optical thin film interference color coating includes at least one further layer that is partially absorbing with respect to the visible light. The spectral reflectance and absorptance of the deformable mirror is modified in order to obtain a desired reflected color by the process of optical interference enhanced absorption in the optical thin film interference color coating. The optical thin film interference color coating has predetermined layer thicknesses and materials; the substantially transparent layer substantially determines the desired reflected color.

Claims

1. A semiconductor device comprising:

circuitry for accepting electronic signals;

a plurality of deformable mirrors selectably operable to reflect incident light, responsive to the electronic signals; and

a first group of said plurality of deformable mirrors being coated with an optical thin film interference colour coating having at least a layer that is substantially transparent with respect to the incident light, the optical thin film interference colour coating including at least one further layer that is partially absorbing with respect to the incident light, so that the spectral reflectance and absorptance of the deformable mirror is modified to produce a desired reflected colour by the process of optical interference enhanced absorption in the optical interference colour coating, the layers being of predetermined thicknesses and materials, wherein the thickness of the substantially transparent layer substantially determines the desired reflected colour.

2. A semiconductor device as defined in claim 1, wherein the deformable mirrors have a coating with a high reflectance.

3. A semiconductor device as defined in claim 1, wherein the substantially transparent layer in the optical thin film interference colour coating is between the partially absorbing layer and a reflecting surface of the deformable mirrors.

4. A semiconductor device as defined in claim 2, wherein the substantially transparent layer is between the partially absorbing layer and the coating having a high reflectance.

5. A semiconductor device as defined in claim 4, wherein the substantially transparent layer is comprised of SiO₂ or Al₂ O₃.

6. A semiconductor device as defined in claim 4, wherein the partially absorbing layer is comprised of an alloy of nickel.

7. A semiconductor device as defined in claim 4 wherein the coating having a high reflectance is comprised of aluminum.

8. A semiconductor device as defined in claim 1 wherein the optical thin film interference colour coating includes a plurality of substantially transparent and partially absorbing alternating layers.

9. A semiconductor device as defined in claim 1, further comprising a second group of said plurality of deformable mirrors being coated with a second optical thin film interference colour coating having at least a layer that is substantially transparent with respect to the incident light, the optical thin film interference colour coating including at least one further layer that is partially absorbing with respect to the incident light, so that the spectral reflectance and absorptance of the deformable mirror is modified to produce a second desired reflected colour by the process of optical interference enhanced absorption in the optical interference colour coating, the layers being of predetermined thicknesses and materials, wherein the thickness of the substantially transparent layer substantially determines the second desired reflected colour.

10. A semiconductor device as defined in claim 9, further comprising a third group of said plurality of deformable mirrors being coated with a third optical thin film interference colour coating having at least a layer that is substantially transparent with respect to the incident light, the optical thin film interference colour coating including at least one further layer that is partially absorbing with respect to the incident light, so that the spectral reflectance and absorptance of the deformable mirror is modified to produce a third desired reflected colour by the process of optical interference enhanced absorption in the optical interference colour coating, the layers being of predetermined thicknesses and materials, wherein the thickness of the substantially transparent layer substantially determines the third desired reflected colour.

11. The semiconductor device as defined in claim 10, wherein the first, second and third groups of mirrors form three-colour pixels.

12. A semiconductor device as defined in claim 1 wherein the plurality of deformable mirrors are made of a conducting metal, metal alloy, or semiconductor selected from the group consisting of Al, Cr, Co, Cu, Au, Hf, Mo, Ni, Nb, Pt, Ag, Ta, Ti, W, Yr, Zr, Si, Ge, and their alloys.

13. A semiconductor device as defined in claim 2, wherein the plurality of deformable mirrors have a coating with a high reflectance, the coating being a layer of a metal, metal alloy or semiconductor selected from the group consisting of Al, Cr, Co, Cu, Au, Hf, Mo, Ni, Nb, Pt, Ag, Ta, Ti, W, Yr, Zr, Si, Ge, and their alloys.

14. A semiconductor device as defined in claim 1 wherein the substantially transparent layer is comprised of a dielectric material selected from the group consisting of oxides, nitrides, fluorides, selenides and sulfides.

15. The semiconductor device as defined in claim 14, wherein the dielectric material is selected from the group consisting of SiO₂, Al₂ O₃, HfO₂, Nb₂ O₅, Ta₂ O₅, TiO₂, Y₂ O₃, ZrO₂, SiN, AlN, MgF₂, CaF₂, ZnSe, and ZnS.

16. The semiconductor device as defined in claim 1, wherein the at least partially absorbing layer is made of a material selected from the group consisting of metals, metal alloys, and semiconductors.

17. The semiconductor device as defined in claim 16, wherein the at least partially absorbing layer is made of a material selected from the group consisting of Al, Fe, Cr, Co, Cu, Au, Hf, Mo, Ni, Nb, Pt, Ag, Ta, Te, Ti, W, Yr, Zr,, Si, Ge and their alloys.

18. The semiconductor device as defined in claim 1, wherein the all the deformable mirrors have only one optical thin film interference colour coating.