MEMS devices having improved uniformity and methods for making them

• US 8,068,268 B2
• Filed: 07/03/2007
• Issued: 11/29/2011
• Est. Priority Date: 07/03/2007
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Heald, David L, Zhong, Fan, Floyd, Philip Don
• Primary Examiner(s): Mack; Ricky
• Assistant Examiner(s): Jones; James
• Application Number:
  US11/773,357
• Publication Number:
  US 20090009444A1
• Time in Patent Office: 1,610 Days
• Field of Search: 359/290, 359/291
• US Class Current: 359/290
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81B 3/0072 For controlling internal stress or strain in moving or flexible elements, e.g. stress compensating layers
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26

Abstract

Disclosed is a microelectromechanical system (MEMS) device and method of manufacturing the same. In one aspect, MEMS such as an interferometric modulator include one or more elongated interior posts and support rails supporting a deformable reflective layer, where the elongated interior posts are entirely within an interferometric cavity and aligned parallel with the support rails. In another aspect, the interferometric modulator includes one or more elongated etch release holes formed in the deformable reflective layer and aligned parallel with channels formed in the deformable reflective layer defining parallel strips of the deformable reflective layer.

Claims

1. A method of making an electromechanical device, comprising:

forming a sacrificial layer over a substrate;

forming two or more substantially parallel first channels in the sacrificial layer to thereby form at least one strip of the sacrificial layer;

forming support rails in the formed first channels;

forming a first elongated opening in the strip of the sacrificial layer;

forming an elongated post in the first elongated opening;

forming a deformable layer over the sacrificial layer, the support rails and the elongated post;

forming one or more second channels in the deformable layer to thereby form at least one strip of the deformable layer, the strip of the deformable layer being substantially perpendicular to the strip of the sacrificial layer; and

removing the sacrificial layer to form a cavity between the strip of the deformable layer and the substrate, the cavity being bordered on two sides by the support rails;

wherein the support rails support the deformable layer on the two sides of the cavity;

wherein the elongated post is within the cavity; and

wherein the elongated post is aligned so that the elongate direction is substantially parallel to the substrate and to the support rails.

2. The method of claim 1, further comprising forming at least one elongated opening in the deformable layer prior to removing the sacrificial layer, the elongated opening being aligned substantially parallel to the second channel formed in the deformable layer.

3. The method of claim 2, wherein at least one of the elongated openings is located over one of the elongated posts.

4. The method of claim 2, wherein at least one of the elongated openings is located over one of the support rails.

5. The method of claim 1, wherein forming the one or more second channels results in two parallel strips of the deformable layer, the method further comprising:

forming a second elongated opening in the strip of the sacrificial layer; and

forming a second elongated post in the second elongated opening,

wherein the elongate direction of the second elongated post is substantially parallel to the support rails and wherein the second elongated post is positioned to support the two parallel strips of the deformable layer.

6. The method of claim 5, wherein the first and second elongated posts have substantially the same dimensions.

7. An interferometric modulator made by the method of claim 1.

8. A method of making an electromechanical device, comprising:

forming a sacrificial layer over a substrate;

forming two or more substantially parallel first channels in the sacrificial layer to thereby form at least one strip of the sacrificial layer;

forming support rails in the formed first channels;

forming a deformable layer over the sacrificial layer and over the support rails;

forming one or more second channels in the deformable layer to thereby form at least one strip of the deformable layer, the strip of the deformable layer being substantially perpendicular to the strip of the sacrificial layer;

forming one or more first elongated openings in the strip of the deformable layer, wherein the elongate direction of the first elongated opening is substantially parallel to the strip of the deformable layer; and

removing the sacrificial layer to form a cavity between the strip of the deformable layer and the substrate, the cavity being bordered on two sides by the support rails.

9. The method of claim 8, further comprising:

forming one or more second elongated openings in the strip of the sacrificial layer, wherein the elongated direction of the elongated second opening is aligned substantially perpendicular to the strip of the sacrificial layer; and

forming one or more elongated posts in the second elongated openings.

10. An electromechanical device, comprising:

a substrate;

a plurality of deformable membranes;

a plurality of support structures arranged over the substrate and configured to support the deformable membranes; and

a plurality of cavities defined by the substrate, the support structures, and the deformable membranes;

wherein the plurality of support structures comprise support rails aligned in a first direction separating the plurality of cavities into one or more rows, and at least one elongated support post located between the support rails and located entirely within one of the cavities, and further wherein the elongated support post is aligned so that the elongate direction is substantially parallel to the substrate and to the support rails.

11. The device of claim 10, wherein the plurality of support structures are formed from the same material.

12. The device of claim 10, wherein the plurality of support structures support the deformable membranes on a lower surface of the deformable membranes facing the substrate.

13. The device of claim 10, wherein the plurality of deformable membranes are configured in two or more columns, each column comprising two or more of the cavities, the columns being substantially perpendicular to the one or more rows, wherein the deformable membranes comprise at least one elongated opening formed in the deformable membrane, where the axis of elongation of the elongated opening is substantially parallel to the two or more columns.

14. The device of claim 10, wherein the plurality of deformable membranes are configured in two or more columns, each column comprising two or more of the cavities, the columns being substantially perpendicular to the one or more rows, wherein the plurality of support structures further comprise at least one elongated edge post configured to support the two columns of the deformable membranes.

15. The device of claim 14, wherein the elongated support post in the interior of the cavity and the elongated edge post have substantially the same dimensions.

16. An array of interferometric modulators comprising the device of claim 10.

17. A display device comprising:

an array of interferometric modulators as claimed in claim 16;

a processor that is configured to communicate with the array, the processor being configured to process image data; and

a memory device that is configured to communicate with the processor.

18. The display device of claim 17, further comprising a driver circuit configured to send at least one signal to the array.

19. The display device of claim 18, further comprising a controller configured to send at least a portion of the image data to the driver circuit.

20. The display device of claim 18, further comprising an image source module configured to send the image data to the processor.

21. The display device of claim 20, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

22. The display device of claim 18, further comprising an input device configured to receive input data and to communicate the input data to the processor.

23. An electromechanical device, comprising:

a substrate;

two or more electrically conductive row electrodes formed on the substrate;

a plurality of support rails formed on the substrate and configured to separate the two or more row electrodes;

two or more deformable column electrodes supported by the plurality of support rails, the column electrodes being substantially perpendicular to the row electrodes;

a plurality of elongated openings formed in the deformable column electrodes, where the elongated openings are aligned such that the elongate direction is substantially parallel to the column electrodes; and

an array of cavities defined by the row electrodes, the support rails, and the deformable column electrodes;

wherein at least one elongated opening is at least partially located in each of the cavities.

24. The device of claim 23, further comprising one or more elongated posts formed on the substrate and located at least partly within one of the cavities and supporting one or more of the deformable column electrodes, the axis of elongation of the elongated post being substantially parallel to the row electrodes.

25. The device of claim 24, wherein at least one of the elongated posts is configured to support two of the column electrodes in an edge space between the two column electrodes.

26. The device of claim 24, wherein at least one of the elongated posts is positioned in the interior of one of the cavities.

27. The device of claim 26, wherein at least one of the elongated openings overlaps a portion of the elongated post positioned in the interior of the cavity.

28. The device of claim 23, wherein at least one of the elongated openings overlaps a portion of one of the support rails.

29. An interferometric modulator comprising:

means for transmitting light;

means for reflecting light, the reflecting means being movable towards or away from the transmitting means; and

means for supporting the reflecting means and for improving uniformity of a stress state of the reflecting means, wherein the supporting means comprises two rails and an elongated post, where the two rails border opposite sides of a cavity between the reflecting means and the transmitting means and the elongated post is located entirely within the cavity and is aligned parallel with the rails and parallel with the reflecting means in the elongate direction.

30. The interferometric modulator of claim 29, wherein the transmitting means comprises an optical stack.

31. The interferometric modulator of claim 29, wherein the reflecting means comprises a deformable membrane.

32. An interferometric modulator comprising:

means for transmitting light;

means for reflecting light, the reflecting means being movable towards or away from the transmitting means;

means for supporting the reflecting means; and

means for venting an etch gas from a cavity between the reflecting means and the transmitting means and for improving uniformity of a stress state of the reflecting means.

33. The interferometric modulator of claim 32, wherein the transmitting means comprises an optical stack.

34. The interferometric modulator of claim 32, wherein the reflecting means comprises a deformable membrane.

35. The interferometric modulator of claim 32, wherein the supporting means comprises two rails, where the two rails border opposite sides of the cavity.

36. The interferometric modulator of claim 32, wherein the venting means comprises an elongated opening in the reflecting means, the elongate direction of the elongated opening being aligned perpendicular to an elongate direction of the supporting means.