Unsticking mirror elements of digital micromirror device

• US 5,717,513 A
• Filed: 01/10/1995
• Issued: 02/10/1998
• Est. Priority Date: 01/10/1995
• Status: Expired due to Fees

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Weaver, Douglas J.
• Primary Examiner(s): Henry, Jon W.
• Application Number:
  US08/370,704
• Time in Patent Office: 1,127 Days
• Field of Search: 359/855, 359/221, 359/224, 359/225, 359/291, 359/295, 359/236, 359/234, 345/108, 345/214
• US Class Current: 359/221.1
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

A method of repositioning mirror elements (10) of a digital micromirror device (DMD) that have become stuck in an "on" or an "off" position. The mirror element (10) is irradiated with a short high-energy pulse of visible light. The method may be easily performed during fabrication at the wafer level, and may be followed by a passivation step to prevent further sticking.

Claims

1. A method of repositioning mirror elements of a digital micromirror device (DMD) having one or more mirror elements in a "stuck" position, comprising the steps of:

irradiating each stuck mirror element with one pulse of radiation having a wavelength in the range from ultraviolet to infrared;

wherein the pulse duration and the power of said pulse of radiation are selected so as to provide a shock wave sufficient to reposition said stuck mirror element without damage to said DMD.

2. The method of claim 1, wherein said irradiating step is performed with radiation of a single wavelength.

3. The method of claim 1, wherein said irradiating step is performed with radiation of a predetermined range of wavelengths.

4. The method of claim 1, further comprising the step of detecting the location of each mirror element that is stuck, and wherein said irradiating step is performed selectively with respect to said location.

5. The method of claim 1, wherein said irradiating step is performed by irradiating all mirror elements of said DMD at the same time.

6. The method of claim 1, wherein said irradiating step is performed by scanning said DMD.

7. The method of claim 1, wherein said pulse of radiation has a duration of approximately 500 nanoseconds or less.

8. The method of claim 1, wherein said pulse of radiation has a power of 1 microjoule or less per spot size of approximately 256 square micrometers.

9. The method of claim 1, wherein said mirror elements have a size of approximately 16 micrometers square and wherein said pulse duration is approximately 5 nanoseconds.

10. The method of claim 1, wherein said mirror elements are larger than 16 micrometers square and wherein said power is between 0.5 and 1.0 microjoule per 256 square micrometers.

20. The method of claim 1, said irradiating step comprising irradiating each stuck mirror element with a series of short pulses.

11. A method of repositioning stuck mirror elements in a wafer of digital micromirror devices, comprising the steps of:

irradiating each stuck mirror element on said wafer with one pulse of radiation having a wavelength in the range from ultraviolet to infrared, said pulse of radiation having a predetermined pulse duration and power so as to provide a shock wave sufficient to reposition said stuck mirror element without damage to said digital micromirror devices; and

performing a wafer level passivation step on said mirror elements.

12. The method of claim 11, wherein said irradiating step is performed with radiation of a single wavelength.

13. The method of claim 11, wherein said irradiating step is performed with radiation of a range of wavelengths.

14. The method of claim 11, further comprising the step of detecting the location of each mirror element that is stuck, and wherein said irradiating step is performed selectively with respect to said location.

15. The method of claim 11, wherein said irradiating step is performed by irradiating all mirror elements of said wafer at the same time.

16. The method of claim 11, wherein said irradiating step is performed by scanning said wafer.

17. The method of claim 11, wherein said pulse of radiation has a duration of approximately 500 nanoseconds or less.

18. The method of claim 11, wherein said pulse of radiation has a power of 1 microjoule or less per spot size of approximately 256 square micrometers.

19. The method of claim 11, said irradiating step comprising irradiating each stuck mirror element with a series of short pulses.