Method of creating MEMS device cavities by a non-etching process

• US 7,795,061 B2
• Filed: 12/29/2005
• Issued: 09/14/2010
• Est. Priority Date: 12/29/2005
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Lan, Jeffrey, Wang, Chun-Ming, Sasagawa, Teruo
• Primary Examiner(s): Toledo; Fernando L
• Assistant Examiner(s): Singal; Ankush K
• Application Number:
  US11/321,134
• Publication Number:
  US 20070155051A1
• Time in Patent Office: 1,720 Days
• Field of Search: 438/619, 438/623, 359/260
• US Class Current: 438/48
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81C 1/00047 Cavities
• CPC Class Codes: B81C 2201/0108 Sacrificial polymer, ashing of organics
• CPC Class Codes: B81C 2201/0111 Bulk micromachining
• 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

MEMS devices (such as interferometric modulators) may be fabricated using a sacrificial layer that contains a heat vaporizable polymer to form a gap between a moveable layer and a substrate. One embodiment provides a method of making a MEMS device that includes depositing a polymer layer over a substrate, forming an electrically conductive layer over the polymer layer, and vaporizing at least a portion of the polymer layer to form a cavity between the substrate and the electrically conductive layer. Another embodiment provides a method for making an interferometric modulator that includes providing a substrate, depositing a first electrically conductive material over at least a portion of the substrate, depositing a sacrificial material over at least a portion of the first electrically conductive material, depositing an insulator over the substrate and adjacent to the sacrificial material to form a support structure, and depositing a second electrically conductive material over at least a portion of the sacrificial material, the sacrificial material being removable by heat-vaporization to thereby form a cavity between the first electrically conductive layer and the second electrically conductive layer.

Claims

1. A method of making a microelectromechanical system (MEMS) device, comprising:

depositing a polymer layer over a substrate;

forming an optical layer over the substrate, the optical layer being at least partially reflective;

forming an electrically conductive layer over the polymer layer; and

forming an optical cavity by heat vaporizing the polymer layer at a temperature no greater than about 350 degrees C., thereby exposing the optical layer to the optical cavity.

2. The method of claim 1, wherein the substrate comprises a second electrically conductive layer.

3. The method of claim 1, wherein the electrically conductive layer comprises a movable layer.

4. The method of claim 1, wherein the MEMS device is an interferometric modulator.

5. The method of claim 1, wherein the heat vaporizing comprises heating to a temperature in the range of from about 200 degrees C. to about 350 degrees C.

6. The method of claim 1, wherein the electrically conductive layer comprises a metal.

7. The method of claim 1, wherein the polymer layer comprises an organic polymer.

8. The method of claim 1, wherein the substrate comprises the optical layer.

9. The method of claim 1, further comprising patterning the polymer layer.

10. The method of claim 1, wherein depositing the polymer layer comprises at least one of spin coating, extrusion coating, spray coating, and printing.

11. The method of claim 1, comprising forming the optical layer over the polymer layer.

12. The method of claim 1, wherein the polymer layer is self planarizing.

13. The method of claim 1, wherein the polymer layer comprises a heat-depolymerizable polycarbonate (HDP).

14. The method of claim 1, wherein the polymer layer is heat vaporized at a temperature no greater than about 300 degrees C.

15. The method of claim 2, wherein the second electrically conductive layer comprises indium tin oxide.

16. The method of claim 8, wherein the optical layer comprises a dielectric layer.

17. The method of claim 8, comprising depositing the polymer layer over the optical layer.

18. The method of claim 9, wherein the patterning comprises at least one of electron beam lithography and image transfer.

19. The method of claim 9, further comprising:

forming a support structure aperture in the polymer layer; and

depositing a non-conductive material into the support structure aperture.

20. The method of claim 10, wherein printing comprises inkjet deposition.

21. The method of claim 13, wherein the HDP comprises poly(cyclohexene carbonate) or an aliphatic polycarbonate.