Micro-mechanical device with non-evaporable getter

• US 5,610,438 A
• Filed: 03/08/1995
• Issued: 03/11/1997
• Est. Priority Date: 03/08/1995
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Wallace, Robert M., Webb, Douglas A.
• Primary Examiner(s): BROWN, PETER T
• Application Number:
  US08/401,048
• Time in Patent Office: 734 Days
• Field of Search: 257/678, 257/680, 257/913, 257/729, 257/417-419, 257/682, 359/846, 359/896, 359/894
• US Class Current: 257/682
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

The present invention relates to micro-mechanical devices including actuators, motors and sensors with improved operating characteristics. A micro-mechanical device (10) comprising a DMD-type spatial light modulator with a getter (100) located within the package (52). The getter (100) is preferably specific to water, larger organic molecules, various gases, or other high surface energy substances. The getter is a non-evaporable getter (NEG) to permit the use of active metal getter systems without their evaporation on package surfaces.

Claims

1. A micro-mechanical device including a first element selectively movable relative to a second element, portions of the elements contacting in one position of the first element, the device comprising:

(a) a deposit of a surface energy-decreasing material on at least that portion of the second element which is engageable by the portion of the first element;

(b) a package enclosing the device; and

(c) a non-evaporating getter within the package, wherein said non-evaporating getter is an active metal based alloy.

2. A device as in claim 1, wherein:

the getter is specific to water, to larger organic molecules, or to carbon monoxide, carbon dioxide, oxygen or nitrogen.

3. A device as in claim 2, wherein:

the getter is specific to larger organic molecules.

4. A device as in claim 2, wherein:

the getter is specific to water.

5. A device as in claim 1 wherein:

the getter has a high surface area to volume ratio.

6. The device as in claim 1, wherein:

the non-evaporating getter includes one or more of Zr-Al, Zr-Fe, Zr-V-Fe or Zr-Ni.

7. A device as in claim 1, wherein:

the getter is deposited as a film.

8. A device as in claim 7, wherein:

the film resides on a portion of the device other than the portions of the first element and the second element which are engageable.

9. A device as in claim 1, wherein:

the package is hermetic.

10. A device as in claim 1, wherein:

the second element is a landing electrode maintainable at the same electric potential as the first element.

11. A device as in claim 1, wherein:

the material is a long-chain aliphatic halogenated polar compound.

12. A device as in claim 11, wherein:

the compound is a perfluoroalkanoic acid of the general formula F₃ C(CF₂)_X COOH.

13. A device as in claim 12, wherein:

X is 10 or more.

14. A device as in claim 13, wherein:

X is 16.

15. A device as in claim 12, wherein:

the compound is vapor deposited as a film containing defects which serve as sites for the adhesion of water vapor and other high surface energy substances;

the package encloses the device via a package-device interface which contains a sealant, the sealant outgassing and permitting the passage therethrough of water and the other high surface energy substances; and

the getter is specific to water and to the other high surface energy substances.

16. A DMD of the type which includes a movable mirror element having a normal position set by a deformable beam in its undeformed state and a deflected position in which the beam is deformed and a portion of the mirror element engages a portion of a stationary member, deformation of the beam storing energy therein which tends to return the mirror element to the normal position, the mirror element being selectively electrostatically attractable into its deflected position;

the DMD comprising;

a package enclosing the DMD; and

a non-evaporating getter within the package, wherein said non-evaporating getter is an active metal based alloy.