Micromirror array assembly with in-array pillars

• US 7,787,170 B2
• Filed: 06/15/2004
• Issued: 08/31/2010
• Est. Priority Date: 06/15/2004
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Richards, Peter, Dehlinger, Dietrich, Tarn, Terry, Huibers, Andrew G., Patel, Satyadev
• Primary Examiner(s): Dinh; Jack
• Application Number:
  US10/869,539
• Publication Number:
  US 20050275930A1
• Time in Patent Office: 2,268 Days
• Field of Search: 359/290, 359/291, 359/295, 359/298
• US Class Current: 359/291
• CPC Class Codes: B81C 3/001 Bonding of two components
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: Y10S 359/90 Methods
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor

Abstract

The present invention provides a microstructure device comprising multiple substrates with the components of the device formed on the substrates. In order to maintain uniformity of the gap between the substrates, a plurality of pillars is provided and distributed in the gap so as to prevent decrease of the gap size. The increase of the gap size can be prevented by bonding the pillars to the components of the microstructure. Alternatively, the increase of the gap size can be prevented by maintaining the pressure inside the gap below the pressure under which the microstructure will be in operation. Electrical contact of the substrates on which the micromirrors and electrodes are formed can be made through many ways, such as electrical contact areas, electrical contact pads and electrical contact springs.

Claims

1. A microelectromechanical (MEMS) device, comprising:

a first substrate and a second substrate;

a plurality of MEMS elements formed on the first substrate; and

a plurality of pillars disposed between the second substrate and the MEMS elements.

2. The device of claim 1, wherein the pillars are positioned within the MEMS elements.

3. The device of claim 1, wherein the pillars are positioned within an area covered by the MEMS elements.

4. The device of claim 1, wherein the pillars electrically isolate the MEMS elements from circuitry for addressing the MEMS elements.

5. The device of claim 1, wherein each of the plurality of pillars comprises an insulating portion that insulates the MEMS elements from circuitry provided for addressing the MEMS elements.

6. The device of claim 1, further comprising:

a sealing material disposed between the substrates for bonding the substrates.

7. The device of claim 6, wherein the bonded substrate and the sealing material therebetween form a hermetically sealed space.

8. The device of claim 6, wherein a sealed space between the first and second substrates has a pressure lower than 1 atmosphere.

9. The device of claim 6, wherein the sealing material further comprises:

a first metallization material disposed on a sacrificial material that is disposed on the substrate on which the micromirrors are formed.

11. The device of claim 6, wherein the sealing material has a height that is substantially equal to a summation of the heights of the micromirror and the pillar.

12. The device of claim 6, wherein the second substrate further comprises a passivation layer.

13. The device of claim 6, further comprising:

a package substrate, wherein the second substrate is attached to the package substrate; and

a package lid on the package substrate for covering the MEMS device.

14. The device of claim 13, further comprising:

a shim that is placed between the package substrate and the substrate having the MEMS elements.

15. The device of claim 14, further comprising:

a substrate insert between the package substrate and the second substrate.

16. The device of claim 1, wherein the MEMS elements further comprise an array of micromirrors and wherein the device further comprises an array of electrodes and circuitry on the second substrate for moving the micromirrors.

17. The device of claim 16, wherein at least one micromirror of the array of micromirrors comprises:

a post on the first substrate;

a hinge held by the post on the first substrate; and

a reflective mirror plate attached to the hinge such that the mirror plate is operable to rotate on the first substrate.

20. The device of claim 17, wherein the pillar comprises a material that has a coefficient of thermal expansion (CTE) matches that of the material of the post.

21. The device of claim 17, wherein the pillar comprises a material that has a thermal conductivity equal to or less than that of the post.

30. The device of claim 1, further comprising:

an optical coating film on a surface of the substrate on which the micromirrors are disposed.

31. The device of claim 1, further comprising:

a getter material disposed on one of the two substrates for absorbing contaminants.

32. The device of claim 31, wherein the getter is disposed within a trench on the substrate having the micromirrors disposed thereon.

10. A microelectromechanical (MEMS) device, comprising:

a first substrate and a second substrate;

a plurality of MEMS elements formed on the first substrate;

a plurality of pillars disposed between the second substrate and the MEMS elements;

a sealing material disposed between the substrates for bonding the substrates, the sealing material comprising;

a first metallization material disposed on a sacrificial material that is disposed on the substrate on which the micromirrors are formed; and

a second metallization material disposed on a layer composed of the material of the pillar, wherein said layer and the second metallization material are disposed on the second substrate.

18. A microelectromechanical (MEMS) device comprising:

a first substrate and a second substrate;

an array of micromirrors formed on the first substrate, at least one micromirror of the array of micromirrors comprises;

a post on the first substrate;

a hinge held by the post on the first substrate; and

a reflective mirror plate attached to the hinge such that the mirror plate is operable to rotate on the first substrate;

an array of electrodes and circuitry on the second substrate for moving the micromirrors; and

a plurality of pillars disposed between the second substrate and the MEMS elements, wherein the pillar is connected to the post of the micromirror.

22. The device of claim 18, wherein the contact point of the pillar to the post is substantially in the middle of the substrates.

23. The device of claim 18, wherein the contact point of the pillar to the post is in the same plane as the hinge.

24. The device of claim 18, wherein the contact point of the pillar to the post is not in the same plane as the hinge.

25. The device of claim 18, wherein the mirror plate, the hinge and the contact point of the pillar to the hinge are on the same plane.

26. The device of claim 18, wherein the pillar has a first component that is connected to the post of the micromirror and a second component that is connected to the first component of the pillar and the substrate on which the electrodes are disposed.

27. The device of claim 26, wherein the first component of the pillar has a smaller dimension than the second component of the pillar.

28. The device of claim 18, wherein the pillar has a smaller area at the contact point of the pillar to the post than the area of the post at the contact point.

19. A microelectromechanical (MEMS) device comprising:

a first substrate and a second substrate;

an array of micromirrors formed on the first substrate, at least one micromirror of the array of micromirrors comprises;

a post on the first substrate;

a hinge held by the post on the first substrate; and

a reflective mirror plate attached to the hinge such that the mirror plate is operable to rotate on the first substrate;

an array of electrodes and circuitry on the second substrate for moving the micromirrors; and

a plurality of pillars disposed between the second substrate and the MEMS elements, wherein each micromirror has two adjacent posts on the first substrate, each post being connected to a pillar.

29. A microelectromechanical (MEMS) device comprising:

a first substrate and a second substrate;

a plurality of MEMS elements formed on the first substrate; and

a plurality of pillars disposed between the second substrate and the MEMS elements, wherein at least one of the substrates is deformed and the pillars are distributed within an area between the substrates according to a distribution of deformation of the at least one deformed substrate.

33. A microelectromechanical (MEMS) device, comprising:

a first substrate and a second substrate wherein the first and second substrates are bonded together through a sealing material;

a plurality of MEMS elements formed on the first substrate wherein the MEMS elements are an array of reflective and deflectable micromirrors;

a plurality of pillars disposed between the second substrate and the MEMS elements;

at least two electrical contact pads on the first substrate, each of which is electrically connected to the micromirrors such that an electrical resistance of the micromirrors of the array can be measured through the electrical contact pads;

an array of electrodes associated with the micromirrors for deflecting the micromirrors; and

a shim that electrically connects the electrical contact pads and a package substrate to which the bonded substrates are attached such that the electrical contact pads are extended to the package substrate.

34. The device of claim 33, wherein the electrodes are disposed on the second substrate.

35. The device of claim 33, wherein the second substrate further comprises:

a multiplicity of electrical contact areas at a plurality of locations corresponding to the locations of the electrical contact pads on the substrate having the micromirrors such that, when the two substrates are bonded together, the electrical contact pads are overlapped with the electrical contact areas.