MEMS device with controlled gas space chemistry

• US 6,746,886 B2
• Filed: 03/18/2002
• Issued: 06/08/2004
• Est. Priority Date: 03/19/2001
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Duncan, Walter M., Jacobs, Simon Joshua, Gale, Richard O., Douglass, Michael R.
• Primary Examiner(s): THAI, LUAN C
• Application Number:
  US10/101,669
• Publication Number:
  US 20030016337A1
• Time in Patent Office: 813 Days
• Field of Search: 438/25-27, 438/49, 438/116
• US Class Current: 438/27
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 7/0012 Protection against reverse engineering, unauthorised use, use in unintended manner, wrong insertion or pin assignment
• 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: G03B 27/42 for automatic sequential copying of the same original G03B27/34, G03B27/53 take precedence
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• CPC Class Codes: G03F 7/70983 Optical system protection, e.g. pellicles or removable covers for protection of mask

Abstract

A process for protecting a MEMS device used in a UV illuminated application from damage due to a photochemical activation between the UV flux and package gas constituents, formed from the out-gassing of various lubricants and passivants put in the device package to prevent sticking of the MEMS device'"'"'s moving parts. This process coats the exposed surfaces of the MEMS device and package'"'"'s optical window surfaces with a metal-halide film to eliminate this photochemical activation and therefore significantly extend the reliability and lifetime of the MEMS device.

Claims

1. A process for preventing damage to a MEMS device from the reaction caused by the exposure of photo-sensitive package materials to UV illumination, the process comprises:

forming a MEMS device;

forming a package having a window; and

coating the exposed surfaces of said MEMS device

and the inside surface of said package window,

with a thin or thick metal-halide film.

2. The process of claim 1, comprising sealing said MEMS device in said package along with modalities of the form U_vC_wCl_xF_yH_z where U represents any element and the subscripts represent the relative amount of said elements.

3. The process of claim 1, wherein said coating step prevents, under exposure to optical UV flux, h_v, compounds of the type U_vC_wCl_xF_yH_z from fragmenting to form Cl*, F*, CCl*, CF*, CFCl*, HCCl*, and HCF* reactive intermediate compound radicals, as follows:

4. The process of claim 1, said coating step comprising coating said MEMS device with a M_gF₂ metal-halide film.

5. The process of claim 1, said step of forming a MEMS device comprising forming a digital micro-mirror device.