Reduced stiction and mechanical memory in MEMS devices

• US 8,120,155 B2
• Filed: 07/31/2008
• Issued: 02/21/2012
• Est. Priority Date: 07/31/2008
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Atnip, Earl V., Jacobs, Simon Joshua
• Primary Examiner(s): Vu, David
• Assistant Examiner(s): Taylor, Earl
• Application Number:
  US12/183,601
• Publication Number:
  US 20100025832A1
• Time in Patent Office: 1,300 Days
• Field of Search: 257/682, 257/687, 257/E23.002, 257/E23.137, 257/E21.501, 438/115, 438/127, 438/471, 438/476, 438/477
• US Class Current: 257/682
• CPC Class Codes: B81C 1/00285 using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
• CPC Class Codes: H01L 21/54 Providing fillings in containers, e.g. gas fillings
• CPC Class Codes: H01L 23/10 characterised by the material or arrangement of seals between parts, e.g. between cap and base of the container or between leads and walls of the container
• CPC Class Codes: H01L 23/26 including materials for absorbing or reacting with moisture or other undesired substances , e.g. getters
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/16195 Flat cap [not enclosing an internal cavity]

Abstract

A MEMS device is packaged in a process which hydrogen (H) deuterium (D) for reduced stiction. H is exchanged with D by exposing the MEMS device with a deuterium source, such as deuterium gas or heavy water vapor, optionally with the assistance of a direct or downstream plasma.

Claims

1. A process for packaging a MEMS device, comprising the steps of:

placing the MEMS device in a package;

introducing a material including deuterium at levels beyond a naturally occurring level into the package; and

sealing the package;

wherein the introducing step comprises the step of introducing water into the package wherein the water includes deuterium at levels beyond a naturally occurring level for water.

2. The process of claim 1, wherein the percentage of deuterium in the water is more than 1% of the hydrogen in the water.

3. The process of claim 2, wherein the percentage of deuterium in the water is more than 30% of the hydrogen in the water.

4. The process of claim 1, wherein the introducing step comprises the step of introducing heavy water into a getter.

5. The process of claim 4, wherein the step of introducing heavy water into the getter comprises the step of displacing solvent in the getter with heavy water.

6. The process of claim 4, wherein the step of introducing heavy water into the getter comprises the step of displacing non-heavy water in the getter with heavy water.

16. The method of claim 4, wherein the getter is a dessicant compound including a polymer and a drying agent.

17. The method of claim 16, wherein the drying agent comprises a zeolite material.

18. The method of claim 17, wherein the polymer comprises at least one of a polysaccharide, a polyamine, a polyamide or a polysulfone.

19. The method of claim 18, wherein the drying agent comprises powdered hydrated aluminosilicate material.

20. The method of claim 17, wherein the dessicant compound is a polymer-zeolite mixture with a polymer to zeolite weight ratio of 1 part polymer to 2.1 to 100 parts zeolite.

21. The method of claim 20, wherein the polymer to zeolite weight ratio is 1 part polymer to 4 to 10 parts zeolite.

22. The method of claim 21, wherein the polymer-zeolite mixture is mixed with a carrier solvent prior to being introduced into the package.

23. The method of claim 22, wherein the polymer-zeolite mixture comprises a solid mixed with the carrier solvent at a solid to solvent weight ratio of 1 part solid to 0.5 to 100 parts solvent.

24. The method of claim 23, wherein the solid to solvent ratio is 1 part solid to 1 to 10 parts solvent.

25. The method of claim 16, wherein the introducing step includes:

introducing a polymer-zeolite mixture into the package;

curing the introduced polymer-zeolite mixture; and

introducing heavy water to the cured polymer-zeolite mixture.

26. The method of claim 25, wherein the introducing step includes heating the polymer-zeolite mixture in a vacuum to remove heavy water vapor for setting an initial moisture content of the polymer-zeolite mixture.

27. The method of claim 26, further comprising exposing the polymer-zeolite mixture to perfluorodecanoic acid (PFDA).

7. A process for packaging a MEMS device, comprising the steps of:

placing the MEMS device in a package;

introducing a material including deuterium at levels beyond a naturally occurring level into the package; and

sealing the package;

wherein the introducing step comprises the step of introducing a passivating source material with deuterium into the package in an ambient of heavy water vapor.

8. A process for packaging a MEMS device, comprising the steps of:

placing the MEMS device in a package;

introducing a material including deuterium at levels beyond a naturally occurring level into the package; and

sealing the package;

wherein the introducing step comprises the step of introducing a passivating source material including deuterium into the package; and

wherein the passivating material includes CH₃(CH₂)nCOOD.

9. A process for packaging a MEMS device, comprising the steps of:

placing the MEMS device in a package;

introducing a material including deuterium at levels beyond a naturally occurring level into the package; and

sealing the package;

wherein the introducing step comprises the step of introducing a passivating source material including deuterium into the package; and

wherein the passivating material includes CD₃(CD₂)nCOOH.

10. A packaged MEMS device, comprising:

a MEMS device;

a sealed package surrounding the MEMS device; and

a material including deuterium at levels beyond a naturally occurring level disposed in the package;

wherein the material includes water with deuterium at levels beyond a naturally occurring level for water.

11. The packaged MEMS device of claim 10, wherein the percentage of deuterium in the water is more than 1% of the hydrogen in the water.

12. The packaged MEMS device of claim 11, wherein the percentage of deuterium in the water is more than 30% of the hydrogen in the water.

13. The packaged MEMS device of claim 10, wherein the material comprises a getter including heavy water.

28. The method of claim 10, wherein the material is a dessicant compound including a polymer and a drying agent.

29. The method of claim 28, wherein the drying agent comprises a zeolite material.

30. The method of claim 29, wherein the polymer comprises at least one of a polysaccharide, a polyamine, a polyamide or a polysulfone.

31. The method of claim 30, wherein the drying agent comprises powdered hydrated aluminosilicate material.

32. The method of claim 30, wherein the MEMS device is a micromirror device.

14. A packaged a MEMS device, comprising:

a MEMS device;

a sealed package surrounding the MEMS device;

a material including deuterium at levels beyond a naturally occurring level disposed in the package;

wherein the material is a passivating source material including deuterium; and

wherein the passivating material includes CH₃(CH₂)nCOOD.

15. A packaged a MEMS device, comprising:

a MEMS device;

a sealed package surrounding the MEMS device;

a material including deuterium at levels beyond a naturally occurring level disposed in the package;

wherein the material is a passivating source material including deuterium; and

wherein the passivating material includes CD₃(CD₂)nCOOH.