Method for fabricating a structure for a microelectromechanical systems (MEMS) device

• US 7,642,110 B2
• Filed: 07/30/2007
• Issued: 01/05/2010
• Est. Priority Date: 02/12/2002
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Miles, Mark W.
• Primary Examiner(s): Mulpuri; Savitri
• Application Number:
  US11/830,750
• Publication Number:
  US 20080026328A1
• Time in Patent Office: 890 Days
• Field of Search: 438/29, 438 48- 53
• US Class Current: 438/29
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 2203/0315 Cavities
• CPC Class Codes: B81C 1/00396 Mask characterised by its composition, e.g. multilayer masks
• CPC Class Codes: B81C 2201/0109 Sacrificial layers not provided for in B81C2201/0107 - B81C2201/0108
• CPC Class Codes: B81C 2203/0136 Growing or depositing of a covering layer
• 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

The invention provides a microfabrication process which may be used to manufacture a MEMS device. The process comprises depositing one or a stack of layers on a base layer, said one layer or an uppermost layer in said stack of layers being a sacrificial layer; patterning said one or a stack of layers to provide at least one aperture therethrough through which said base layer is exposed; depositing a photosensitive layer over said one or a stack of layers; and passing light through said at least one aperture to expose said photosensitive layer.

Claims

1. A method of fabricating a microelectromechanical systems (MEMS) device, the method comprising:

forming at least one layer over a substrate, said layer comprising a sacrificial material;

patterning said sacrificial layer;

depositing an additional layer over said sacrificial layer;

patterning said additional layer using said sacrificial layer as a photomask;

forming an upper layer over the sacrificial layer; and

removing said sacrificial layer to form a MEMS cavity through which the upper layer is movable.

2. The method of claim 1, additionally comprising forming a conductive layer over the substrate, wherein the sacrificial layer is formed over the conductive layer.

3. The method of claim 1, wherein the conductive layer is at least partially transmissive to light.

4. The method of claim 1, wherein the conductive layer is substantially transparent.

5. The method of claim 1, wherein the upper layer is conductive.

6. The method of claim 1, wherein the upper layer is at least partially reflective to incident light.

7. The method of claim 1, wherein the upper layer is formed after the patterning of said additional layer, the upper layer being supported by portions of the patterned additional layer.

8. The method of claim 1, wherein the additional layer comprises a negative-acting photoresist.

9. The method of claim 1, wherein the substrate is at least partially transmissive to light.

10. A method of forming a microelectromechanical systems (MEMS) device, the method comprising:

providing a light-transmissive substrate;

providing a sacrificial layer over the substrate;

patterning the sacrificial layer to remove at least a portion of the sacrificial layer;

providing an additional layer over the sacrificial layer;

patterning the additional layer by exposing the additional layer to light through the removed portion of the sacrificial layer, wherein patterning the additional layer additionally comprises blocking the light with the remaining portions of the sacrificial layer;

providing an upper layer over the sacrificial layer; and

removing the remainder of the sacrificial layer to form a cavity within which the upper layer is movable.

11. The method of claim 10, additionally comprising providing a lower layer, wherein the lower layer is located between the substrate and the sacrificial layer.

12. The method of claim 10, wherein at least a portion of the lower layer is at least partially reflective.

13. The method of claim 10, wherein at least a portion of the lower layer is conductive.

14. The method of claim 13, wherein the conductive portion of the lower layer is substantially transparent to visible light.

15. The method of claim 10, wherein at least a portion of the upper layer is at least partially reflective to visible light.

16. The method of claim 10, wherein at least a portion of the upper layer is conductive.

17. The method of claim 10, wherein the upper layer is provided over and supported by the patterned additional layer.

18. The method of claim 10, wherein the upper layer comprises aluminum or nickel.

19. The method of claim 10, wherein the sacrificial layer is etchable by XeF₂.

20. The method of claim 10, wherein the sacrificial layer is not transmissive to light.

21. A method of fabricating a microelectromechanical systems (MEMS) array, the method comprising:

forming a transparent electrode over a substrate, the substrate permitting light to pass therethrough;

forming a sacrificial layer over said transparent electrode, wherein the sacrificial layer is not transmissive to light;

depositing an additional layer over said sacrificial layer;

patterning said additional layer by exposing the additional layer to light through the substrate; and

using the patterned additional layer to produce a MEMS structure within the array.

22. The method of claim 21, wherein exposing the additional layer to light through the substrate comprises exposing the additional layer to ultraviolet light through the substrate.