Antireflective coating for semiconductor devices and method for the same

• US 7,502,155 B2
• Filed: 03/15/2005
• Issued: 03/10/2009
• Est. Priority Date: 03/15/2005
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Neidrich, Jason M., Carter, William D., Adams, Robert L., Frederic, Judith C., Sudak, Paul G., Wills, Linda M., Jacobs, Simon Joshua, Wesneski, Lisa Ann
• Primary Examiner(s): Sugarman; Scott J
• Assistant Examiner(s): Thomas; Brandi N
• Application Number:
  US11/080,727
• Publication Number:
  US 20060209386A1
• Time in Patent Office: 1,456 Days
• Field of Search: 359/291, 359/290, 359/292, 359/295, 359/298, 359/248, 359/245, 359/263, 359/584, 290/291, 290/292, 290/295, 290/298, 290/248, 290/245, 290/263, 290/584
• US Class Current: 359/248
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 3/0083 Optical properties
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 27/0018 with means for preventing ghost images anti-reflection coatings G02B1/11
• CPC Class Codes: G02B 5/003 Light absorbing elements
• CPC Class Codes: G02B 5/22 Absorbing filters G02B5/201 - G02B5/208 take precedence

Abstract

According to one embodiment of the present invention, a semiconductor device includes a first layer of dielectric material disposed upon an upper surface of a substrate of a semiconductor device and a first non-conductive layer of metal disposed upon an upper surface of the dielectric material. The first layer of dielectric material and the first non-conductive layer of metal act as an optical trap for electromagnetic radiation received by the first non-conductive layer of metal. In particular embodiments, the semiconductor device may further comprise a second layer of dielectric material disposed upon an upper surface of the first non-conductive layer of metal and a second non-conductive layer of metal disposed upon an upper surface of the second layer of dielectric material.

Claims

1. A digital micro-mirror device having a low-reflectivity substrate, comprising:

first and second micro-mirrors forming an aperture above a substrate;

a layer of oxide having a thickness from about 150 angstroms to about 1000 angstroms disposed upon an upper surface of the substrate;

a non-conductive layer of aluminum having a thickness from about 5 angstroms to about 120 angstroms disposed upon an upper surface of the layer of oxide; and

wherein the layer of oxide and the non-conductive layer of aluminum act as an optical trap for electromagnetic radiation received through the aperture by the non-conductive layer of aluminum.

2. A semiconductor device, comprising:

a first layer of dielectric material disposed upon an upper surface of a substrate of a semiconductor device;

a first non-conductive layer of metal disposed upon an upper surface of the first layer of dielectric material; and

wherein the first layer of dielectric material and the first non-conductive layer of metal act as an optical trap for electromagnetic radiation incident upon the first non-conductive layer of metal.

3. The device of claim 2, wherein the semiconductor device comprises a device selected from the group consisting of a variable diffraction grating, a digital micro-mirror device, and a liquid crystal light valve.

4. The device of claim 2, further comprising first and second mirrors forming an aperture above the substrate of the semiconductor device,

wherein the electromagnetic radiation is received by the first non-conductive layer of metal through the aperture.

5. The device of claim 2, wherein the metal comprises aluminum or aluminum oxide.

6. The device of claim 2, wherein the dielectric material comprises an oxide.

7. The device of claim 2, wherein the first layer of dielectric material has a thickness from about 150 angstroms to about 1000 angstroms.

8. The device of claim 2, wherein the first non-conductive layer of metal has a thickness from about 5 angstroms to about 120 angstroms.

9. The device of claim 2, wherein the first non-conductive layer of metal has a thickness less than the percolation threshold for a thin film of the metal.

10. The device of claim 2, further comprising:

a second layer of dielectric material disposed upon an upper surface of the first non-conductive layer of metal; and

a second non-conductive layer of metal disposed upon an upper surface of the second layer of dielectric material.

11. The device of claim 10, wherein the second layer of dielectric material has a thickness from about 150 angstroms to about 1000 angstroms;

and

the second non-conductive layer of metal has a thickness from about 5 angstroms to about 120 angstroms.

12. A method for reducing stray radiation in a semiconductor device, comprising:

allowing electromagnetic radiation to pass through a first low reflectivity, non-conducting layer of metal disposed upon an upper surface of a first layer of dielectric material, the first layer of dielectric material disposed upon an upper surface of a substrate of the semiconductor device;

allowing the electromagnetic radiation to pass through the first layer of dielectric material;

allowing the electromagnetic radiation to reflect off of the upper surface of the substrate; and

at least partially reducing an amount of the electromagnetic radiation that is allowed to pass back out of the first non-conducting layer of metal.

13. The method of claim 12, wherein the semiconductor device comprises a device selected from the group consisting of a variable diffraction grating, a digital micro-mirror device, and a liquid crystal light valve.

14. The method of claim 12, wherein the semiconductor device comprises a digital micro-mirror device;

and further comprising;

allowing the electromagnetic radiation to pass through an aperture formed by a first micro-mirror and a second micro-mirror positioned above the substrate of the semiconductor device.

15. The method of claim 12, wherein the dielectric material comprises an oxide.

16. The method of claim 12, wherein the metal comprises aluminum or aluminum oxide.

17. The method of claim 12, wherein the first layer of dielectric material has a thickness from about 150 angstroms to about 1000 angstroms.

18. The method of claim 12, wherein the first non-conducting layer of metal has a thickness from about 5 angstroms to about 120 angstroms.

19. The method of claim 12, wherein the semiconductor device further comprises a second layer of dielectric material on an upper surface of the first non-conducting layer of metal and a second non-conducting layer of metal on an upper surface of the second layer of dielectric material;

and further comprising;

allowing the electromagnetic radiation to pass through the second non-conducting layer of metal;

allowing the electromagnetic radiation to pass through the second layer of dielectric material; and

at least partially reducing an amount of the electromagnetic radiation that is allowed to pass back out of the second non-conducting layer of metal.

20. The method of claim 19, wherein the second layer of dielectric material has a thickness from about 150 angstroms to about 1000 angstroms;

and

the second non-conducting layer of metal has a thickness from about 5 angstroms to about 120 angstroms.