MEMS passivation with transition metals

• US 7,459,325 B2
• Filed: 01/05/2005
• Issued: 12/02/2008
• Est. Priority Date: 01/05/2004
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Miller, Seth Adrian, Jacobs, Simon Joshua
• Primary Examiner(s): Sefer; A.
• Assistant Examiner(s): Wilson; Scott R
• Application Number:
  US11/029,985
• Publication Number:
  US 20050145961A1
• Time in Patent Office: 1,427 Days
• Field of Search: 438/48, 438/38, 438/50, 438/52, 438/53, 438/763, 438/780, 427/96.2, 427/97.1, 257/642
• US Class Current: 438/38
• 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 1/105 Protective coatings
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings
• 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: 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

Abstract

Organic surfactants are employed to passivate the surfaces of MEMS devices, such as digital micromirrors. The binding of these surfactants to the surface is improved by first associating with the surface transition metal atoms or ions from Groups IVB, VB, and IVB of the periodic table.

Claims

1. A method for fabricating a MEMS device comprising:

electrochemically depositing on a surface of said device a transition metal of Group IVB VB, or VIB of the periodic chart, optionally oxidizing said metal through chemical or electrochemical means, and

contacting said surface with an organic surfactant.

2. The method of claim 1, wherein said contacting with an organic surfactant forms a self-assembled monolayer of said surfactant.

3. The method of claim 1, wherein said transition metal is zirconium or titanium, and said organic surfactant comprises a carboxylate, phosphate, phosphonate, xanthate, carbamate, thiocarbamate, thiocarboxylate, thiolate, sulfonate, sulfinate, or selenate.

4. The method of claim 3, wherein said surfactant comprises a compound of either the formula RCO₂H or the formula RPO(OH)₂, or salts of the same, or mixtures of the same, where R is a hydrocarbon straight chain of 4-18 carbon atoms;

saturated or unsaturated;

non-, partially-, or fully-fluorinated; and

may include one or more linear hetero atoms.

5. The method of claim 3, wherein said surfactant comprises perfluorodocanoic acid, n-octylphosphonic acid, octadecylphosphonic acid, salts of the same, or mixtures of the same.

6. The method of claim 1, wherein said MEMS device is a digital micromirror device.

7. The method of claim 6, wherein said transition metal is zirconium or titanium, and said organic surfactant comprises a carboxylate, phosphate, phosphonate, xanthate, carbamate, thiocarbamate, thiocarboxylate, thiolate, sulfonate, sulfinate, or selenate.