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

• US 8,394,656 B2
• Filed: 07/07/2010
• Issued: 03/12/2013
• 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: Wang, Chun-Ming, Lan, Jeffrey, Sasagawa, Teruo
• Primary Examiner(s): Richards, N Drew
• Assistant Examiner(s): SINGAL, ANKUSH K
• Application Number:
  US12/831,898
• Publication Number:
  US 20100271688A1
• Time in Patent Office: 979 Days
• Field of Search: 438/48
• 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. An unreleased microelectromechanical system (MEMS) device, comprising:

a substrate;

an optical layer over the substrate;

a heat-vaporizable polymer layer over the substrate, the heat-vaporizable polymer layer being configured to vaporize upon heating to a temperature in the range of about 200 degrees C. to about 350 degrees C.; and

an electrically conductive layer over the heat-vaporizable polymer layer;

wherein the heat-vaporizable polymer is selected such that the optical layer is at least partially reflective after heat vaporization of the heat-vaporizable polymer layer.

2. The unreleased MEMS device of claim 1, wherein the substrate comprises a partially reflective layer.

3. The unreleased MEMS device of claim 1, wherein the substrate comprises a second electrically conductive layer.

4. The unreleased MEMS device of claim 1, wherein the electrically conductive layer comprises a layer that is movable after heat vaporization of the heat-vaporizable polymer layer.

5. The unreleased MEMS device of claim 1, wherein the electrically conductive layer comprises a metal.

6. The unreleased MEMS device of claim 1, wherein the optical layer comprises a dielectric layer.

7. The unreleased MEMS device of claim 1, wherein the heat-vaporizable polymer layer comprises an organic polymer.

8. The unreleased MEMS device of claim 1, wherein the heat-vaporizable polymer layer comprises a heat-depolymerizable polycarbonate (HDP).

9. The unreleased MEMS device of claim 1, wherein the MEMS device is an interferometric modulator.

10. The unreleased MEMS device of claim 1, further comprising:

a nonconductive support structure arranged over the substrate and configured to support the electrically conductive layer after heat vaporization of the heat-vaporizable polymer layer.

11. The unreleased MEMS device of claim 3, wherein the second electrically conductive layer comprises indium tin oxide.

12. The unreleased MEMS device of claim 6, wherein the metal comprises aluminum.

13. The unreleased MEMS device of claim 8, wherein the HDP comprises an aliphatic polycarbonate.

14. The unreleased MEMS device of claim 13, wherein the aliphatic polycarbonate is poly(cyclohexene carbonate).

15. The unreleased MEMS device of claim 10, wherein at least one of the electrically conductive layer, the substrate and the support structure comprises a material that is etchable by xenon diflouride.