Method for stripping sacrificial layer in MEMS assembly

• US 6,951,769 B2
• Filed: 06/04/2003
• Issued: 10/04/2005
• Est. Priority Date: 06/04/2003
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Malone, Joshua
• Primary Examiner(s): Nelms, David
• Assistant Examiner(s): Berry, Renee R.
• Application Number:
  US10/454,198
• Publication Number:
  US 20040248417A1
• Time in Patent Office: 853 Days
• Field of Search: 438/51, 438/64, 438/106, 257/682, 257/684
• US Class Current: 438/51
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81C 1/00317 Packaging optical devices
• CPC Class Codes: B81C 1/00833 Methods for preserving structures not provided for in groups B81C1/00785 - B81C1/00825
• CPC Class Codes: B81C 2201/056 Releasing structures at the end of the manufacturing process
• CPC Class Codes: B81C 2201/117 Using supercritical fluid, e.g. carbon dioxide, for removing sacrificial layers
• CPC Class Codes: B81C 2203/0145 Hermetically sealing an opening in the lid
• 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

Abstract

The present invention provides methods of manufacturing a MEMS assembly. In one embodiment, the method includes mounting a MEMS device, such as a MEMS mirror array, on an assembly substrate, where the MEMS device has a sacrificial layer over components formed therein. The method also includes coupling an assembly lid to the assembly substrate and over the MEMS device to create an interior of the MEMS assembly housing the MEMS device, whereby the coupling maintains an opening to the interior of the MEMS assembly. Furthermore, the method includes removing the sacrificial layer through the opening. A MEMS assembly constructed according to a process of the present invention is also disclosed.

Claims

1. A method of manufacturing a MEMS assembly, comprising:

mounting a MEMS device on an assembly substrate, the MEMS device having a sacrificial layer;

coupling an assembly lid to the assembly substrate and over the MEMS device to create an interior of the MEMS assembly housing the MEMS device, the coupling maintaining an opening to the interior of the MEMS assembly; and

removing the sacrificial layer through the opening.

2. A method according to claim 1, wherein the sacrificial layer is a protective photoresist.

3. A method according to claim 1, wherein the coupling comprises tack-welding.

4. A method according to claim 3, wherein the opening comprises spaces between tack-welding beads formed during the tack-welding.

5. A method according to claim 1, wherein the opening comprises a vent in the assembly substrate.

6. A method according to claim 1, wherein the removing comprises removing the sacrificial layer using a supercritical compound introduced through the opening.

7. A method according to claim 6, wherein the supercritical compound is compressed CO₂.

8. A method according to claim 1, further comprising lubricating components formed on the MEMS device by introducing a lubricant through the opening.

9. A method according to claim 1, further comprising sealing the opening after removing the protective layer.

10. A method according to claim 1, wherein the mounting includes mounting a MEMS device on an assembly substrate by removing portions of the sacrificial layer covering bond pads on the MEMS device, and wire-bonding to the exposed bond pads and to bond pads on the assembly substrate.