Al2O3 atomic layer deposition to enhance the deposition of hydrophobic or hydrophilic coatings on micro-electromechcanical devices

• US 20050012975A1
• Filed: 08/02/2004
• Published: 01/20/2005
• Est. Priority Date: 12/17/2002
• Status: Active Grant

• Current Assignee: The Board of Regents of the University of Colorado (University of Colorado System)
• Original Assignee: The Board of Regents of the University of Colorado (University of Colorado System)
• Inventors: George, Steven M., Herrmann, Cari F.
• Granted Patent: US 7,553,686 B2
• Time in Patent Office: Days
• US Class Current: 438/48
• CPC Class Codes: B81B 3/0005 Anti-stiction coatings
• CPC Class Codes: B81C 1/0096 For avoiding stiction when the device is in use, i.e. after manufacture has been completed
• CPC Class Codes: B81C 2201/112 Depositing an anti-stiction or passivation coating, e.g. on the elastic or moving parts
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/0866 the reflecting means being moved or deformed by thermal means

Abstract

Micro-mechanical devices, such as MEMS, having layers thereon, and methods of forming the layers, are disclosed. In one aspect, a method may include forming a layer including an oxide of aluminum over at least a portion of a micro-mechanical device, and coating the layer by bonding material to surface hydroxyl groups of the layer. In another aspect, a method may include introducing a micro-mechanical device into an atomic layer deposition chamber, and substantially filling nanometer sized voids of the micro-mechanical device by using atomic layer deposition to introduce material into the voids. In a still further aspect, a method may include introducing an alkylaminosilane to a micro-mechanical device having a surface hydroxyl group, and bonding a silane to the micro-mechanical device by reacting the alkylaminosilane with the surface hydroxyl group.

Claims

1. A method comprising:

depositing a layer including aluminum oxide over a MicroElectroMechanical System by using atomic layer deposition; and

coating the layer by bonding alkylaminosilanes to surface hydroxyl groups of the aluminum oxide.

2. The method of claim 1, wherein said depositing the layer comprises using a sufficient number of atomic layer deposition cycles to fill nanometer-sized pores of the micro-mechanical device.

3. The method of claim 1, wherein the alkylaminosilanes are hydrophobic or hydrophilic, and wherein said bonding comprises bonding two dialkylamino groups of the alkylaminosilanes to the layer by reacting the two dialkylamino groups with two of the surface hydroxyl groups.

4. A method comprising:

forming a layer including an oxide of aluminum over at least a portion of a micro-mechanical device; and

coating the layer by bonding material to surface hydroxyl groups of the layer.

5. The method of claim 4, wherein said forming the layer comprises depositing the layer by using atomic layer deposition.

6. The method of claim 5, wherein said depositing the layer comprises depositing a layer having a thickness that is sufficient to fill nanometer-sized voids of the micro-mechanical device.

7. The method of claim 4, wherein said coating the layer comprises bonding polarity preference compounds selected from hydrophobic compounds and hydrophilic compounds to the surface hydroxyl groups of the layer.

8. The method of claim 4, wherein said coating the layer comprises bonding alkylaminosilanes to the surface hydroxyl groups of the layer.

9. An apparatus comprising:

a MicroElectroMechanical System;

a conformal layer including an oxide of aluminum over exposed surfaces of the MicroElectroMechanical System; and

a second layer including material bonded to the oxide of aluminum.

10. The apparatus of claim 9, wherein the material comprises alkylsilanes.

11. The apparatus of claim 9, wherein the second layer comprises a hydrophobic layer having a water contact angle that is greater than 95°

as measured by the sessile drop method.

12. The apparatus of claim 9, wherein the second layer comprises a hydrophilic layer having a water contact angle that is less than 85°

as measured by the sessile drop method.

13. The apparatus of claim 9, wherein the layer comprises portions filling capillaries of the MicroElectroMechanical System.

14. A method comprising:

introducing a micro-mechanical device into an atomic layer deposition chamber; and

substantially filling nanometer sized voids of the micro-mechanical device by using atomic layer deposition to introduce material into the voids.

15. The method of claim 14, wherein said substantially filling the voids comprises depositing a layer having a thickness that is based on an average cross-sectional dimension of the voids.

16. The method of claim 14, wherein said substantially filling the voids comprises substantially filling capillaries by depositing a thickness that is not less than half an average diameter of the capillaries.

17. The method of claim 14, further comprising, after said filling the capillaries, forming a hydrophobic layer over the micro-mechanical device.

18. The method of claim 14, further comprising, after said filling the capillaries, attaching an alkylaminosilane to the micro-mechanical device.

19. An apparatus comprising:

a micro-mechanical device having a surface and nanometer sized voids in the surface;

a conformal layer over the surface of the micro-mechanical device; and

portions of the layer substantially filling the nanometer sized voids.

20. The apparatus of claim 19, wherein a thickness of the layer is based on an average cross-sectional dimension of the voids.

21. The apparatus of claim 19, wherein the layer comprises an oxide of aluminum.

22. The apparatus of claim 19, further comprising a hydrophobic layer attached to the layer.

23. The apparatus of claim 22, wherein the hydrophobic layer comprises fluorinated silanes bonded to surface hydroxyl groups of the layer.

24. A method comprising:

introducing an alkylaminosilane to a micro-mechanical device having a surface hydroxyl group; and

bonding a silane to the micro-mechanical device by reacting the alkylaminosilane with the surface hydroxyl group.

25. The method of claim 24, wherein said introducing the alkylaminosilane to the micro-mechanical device comprises introducing one or more polarity preference compounds selected from hydrophobic alkylaminosilanes and hydrophilic alkylaminosilanes to the micro-mechanical device.

26. The method of claim 24, wherein said introducing the alkylaminosilane to the micro-mechanical device comprises introducing an alkylaminosilane including two dialkylamine groups to the micro-mechanical device.

27. The method of claim 24, further comprising, prior to said introducing the alkylaminosilane to the micro-mechanical device, substantially filling voids of the micro-mechanical device by depositing a layer having a thickness that is based on an average diameter of the voids by using atomic layer deposition.

28. The method of claim 24, wherein said introducing comprises introducing an alkylaminosilane having a first hydrophobic group that includes from more than one to twenty carbon atoms and a second short chain alkyl group that includes less than three carbon.