Packaging for micro electro-mechanical systems and methods of fabricating thereof

• US 8,476,096 B2
• Filed: 03/15/2005
• Issued: 07/02/2013
• Est. Priority Date: 03/15/2004
• Status: Active Grant

• Current Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Original Assignee: Georgia Tech Research Corporation (University System of Georgia)
• Inventors: Kohl, Paul A., Ayazi, Farrokh, Joseph, Paul J.
• Primary Examiner(s): Nguyen, Cuong Q
• Assistant Examiner(s): Gebreyesus, Yosef
• Application Number:
  US10/534,956
• Publication Number:
  US 20070273013A1
• Time in Patent Office: 3,031 Days
• Field of Search: 361/277, 361/760, 333/186, 333/105, 438/48, 438/468, 438/51, 438/459, 438/702, 438/32, 438/52, 438/738, 438/694, 438/519, 438/53, 257/414, 257/415, 257/416, 257/417, 257/418, 257/419, 257/420, 257/E21.511, 257/E33.056, 257/618, 257/234, 257/192, 257/486, 257/E33.56, 257/E33.58, 216/2, 735/143.2
• US Class Current: 438/50
• CPC Class Codes: B81C 1/00333 Aspects relating to packaging of MEMS devices, not covered by groups B81C1/00269 - B81C1/00325
• CPC Class Codes: B81C 2201/0108 Sacrificial polymer, ashing of organics
• CPC Class Codes: B81C 2203/0136 Growing or depositing of a covering layer
• CPC Class Codes: B81C 2203/0154 Moulding a cap over the MEMS device
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/49171 Fan-out arrangements
• 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/1461 MEMS
• CPC Class Codes: H01L 2924/181 Encapsulation

Abstract

Embodiments of the present disclosure provide systems and methods for producing micro electro-mechanical device packages. Briefly described, in architecture, one embodiment of the system, among others, includes a micro electro-mechanical device formed on a substrate layer; and a thermally decomposable sacrificial structure protecting at least a portion of the micro electro-mechanical device, where the sacrificial structure is formed on the substrate layer and surrounds a gas cavity enclosing an active surface of the micro electro-mechanical device. Other systems and methods are also provided.

Claims

1. A method for producing a micro electro-mechanical device package, comprising:

providing a substrate having a freestanding micro electro-mechanical structure thereon;

forming a thermally decomposable photodefinable sacrificial layer on said substrate, said sacrificial layer encapsulating a portion of said free-standing micro electro-mechanical structure;

image-wise exposing said thermally decomposable photodefinable sacrificial layer where said layer is patterned;

forming a contiguous overcoat layer around said patterned layer; and

thermally decomposing said patterned layer such that decomposed molecules thereof permeate through the contiguous overcoat layer by dissolving into said contiguous overcoat layer, diffusing through said contiguous overcoat layer and evaporating out of said contiguous overcoat layer thus forming a gas cavity, said contiguous overcoat layer providing an enclosure around said freestanding micro electro-mechanical structure to form a micro electro-mechanical device package.

2. The method of claim 1, where thermally decomposing said patterned layer comprises heating said patterned layer to a temperature appropriate for the thermal decomposition thereof, such temperature in the range of from 200°

C. to 300°

C.

3. The method of claim 2, where after thermally decomposing said patterned layer to form said gas cavity, said gas cavity is substantially free of residue from said patterned.

4. The method of claim 1, where said contiguous overcoat layer has a decomposition temperature greater than the decomposition temperature of said patterned layer.

5. The method of claim 1, where the substrate comprises a silicon material.

6. The method of claim 1, where the substrate comprises a non-silicon material.

7. The method of claim 1, where the thickness of said contiguous overcoat layer is within the range of from 50 nm to 500 μ

m.

8. The method of claim 1, where said contiguous overcoat layer is un-perforated.

9. The method of claim 1, further comprising:

before forming the contiguous overcoat layer, attaching the substrate having a freestanding micro electro-mechanical structure thereon to a metal packaging frame; and

where forming said contiguous overcoat layer around said patterned layer comprises forming an epoxy resin contiguous overcoat layer around said patterned layer where such epoxy resin contiguous overcoat layer further encapsulates at least a portion of said metal packaging frame assembly.

10. The method of claim 9, further comprising:

first heating the micro assembly to a first temperature appropriate for curing said epoxy resin contiguous overcoat layer; and

second heating the micro assembly to a second temperature appropriate for decomposing said patterned layer, the second temperature being higher than the first temperature.

11. The method of claim 1, further comprising:

forming a barrier layer around said continuous overcoat layer, said barrier layer comprising a metal material.

12. The method of claim 11, further comprising:

before thermally decomposing said patterned layer placing the micro electro-mechanical device into a chamber and creating a vacuum therein;

after creating the vacuum, heating the micro electro-mechanical device in the chamber to thermally decompose the patterned layer to form an evacuated gas cavity;

after forming said evacuated gas cavity, forming said barrier layer;

after forming said barrier layer, returning the chamber to atmospheric pressure; and

removing the micro electro-mechanical device package from the chamber, where such micro electro-mechanical device package has an evacuated gas cavity.

13. The method of claim 12, further comprising:

after removing the micro electro-mechanical device package from the chamber;

attaching the micro electro-mechanical device package to an integrated circuit package structure; and

encapsulating the electro-mechanical device package and integrated circuit package structure in a surrounding structure.

14. The method of claim 12, where the integrated circuit package structure comprises a metal leadframe.

15. The method of claim 12, where the integrated circuit package structure comprises a ceramic package.

16. The method of claim 1, further comprising:

after said patterned layer is decomposed, attaching the micro electro-mechanical device to an integrated circuit package structure; and

encapsulating the electro-mechanical device and integrated circuit package structure in a surrounding structure.

17. The method of claim 16, where the integrated circuit package structure comprises a metal leadframe.

18. The method of claim 16, where the integrated circuit package structure comprises a ceramic package.