MEMS capping method and apparatus

• US 6,893,574 B2
• Filed: 10/23/2001
• Issued: 05/17/2005
• Est. Priority Date: 10/23/2001
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Luo, Jing, Martin, John R., Felton, Lawrence E., Webster, William A., Collins, David J., Farrell, Peter W.
• Primary Examiner(s): Mills, Gregory
• Assistant Examiner(s): CULBERT, ROBERTS P
• Application Number:
  US10/002,953
• Publication Number:
  US 20030075794A1
• Time in Patent Office: 1,302 Days
• Field of Search: 216/2, 216/11, 216/17, 216/20, 216/24, 216/33, 216/36, 438/15, 438/33, 438/51, 438/55, 438/64, 438/66, 438/106, 438/110, 438/118, 438/126, 438/25, 438/113, 438/127, 257/433, 257/443, 257/466
• US Class Current: 216/2
• CPC Class Codes: B81B 7/0077 Other packages not provided for in groups B81B7/0035 - B81B7/0074
• CPC Class Codes: B81C 1/00896 Temporary protection during separation into individual elements
• 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 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

A MEMS capping method and apparatus uses a cap structure on which is formed a MEMS cavity, a cut capture cavity, and a cap wall. The cap wall is essentially the outer wall of the MEMS cavity and the inner wall of the cut capture cavity. The cap structure is bonded onto a MEMS structure such that the MEMS cavity covers protected MEMS components. The cap structure is trimmed by cutting through to the cut capture cavity from the top of the cap structure without cutting all the way through to the MEMS structure.

Claims

1. A method for capping a Micro-Electromechanical System (MEMS) device, the method comprising:

forming a cap structure having a bottom side with at least a MEMS cavity, a cut capture cavity surrounding the MEMS cavity, and a cap wall, the cap wall forming an outer wall of the MEMS cavity and an inner wall of the cut capture cavity;

bonding the cap wall onto a MEMS structure;

filling the cut capture cavity with a protective material; and

cutting through to the cut capture cavity from a top side of the cap structure to form a cap.

2. The method of claim 1, wherein forming the cap structure comprises:

forming the MEMS cavity and the cut capture cavity into the bottom side of the cap structure.

3. The method of claim 2, wherein forming the MEMS cavity and the cut capture cavity into the bottom side of the cap structure comprises:

etching the MEMS cavity and the cut capture cavity into the bottom side of the cap structure.

4. The method of claim 1, wherein forming the cap structure comprises:

forming the cap wall onto the bottom side of the cap structure, the cap wall forming the outside wall of the MEMS cavity and the inside wall of the cut capture cavity.

5. The method of claim 4, wherein forming the cap wall onto the bottom side of the cap structure comprises:

depositing a cap wall material onto the bottom side of the cap structure to form the cap wall.

6. The method of claim 1, wherein bonding the cap wall onto the MEMS structure comprises:

applying a bonding material to a bottom side of the cap wall; and

bonding the bottom side of the cap wall onto the MEMS structure.

7. The method of claim 6, wherein the bonding material comprises a glass material.

8. The method of claim 7, wherein applying the bonding material to the bottom side of the cap wall comprises:

screen printing a glass fit material onto the bottom side of the cap wall;

burning off organic compounds of the glass frit material; and

glazing the remaining glass fit material to form the glass material.

9. The method of claim 7, wherein bonding the bottom side of the cap wall onto the MEMS structure comprises:

bonding the bottom side of the cap wall onto the MEMS structure under pressure at a temperature sufficient to melt the glass material.

10. The method of claim 1,

wherein the cut capture cavity is filled with the protective material after the cap wall is bonded onto the MEMS structure.

11. The method of claim 1, wherein the protective material comprises a wax material.

12. The method of claim 1, further comprising:

removing residual protective material after cutting through to the cut capture cavity from a top side of the cap structure to form the cap.

13. The method of claim 1, wherein cutting through to the cut capture cavity from the top side of the cap structure to form the cap comprises cutting through to the cut capture cavity from the top side of the cap structure using at least one of:

a precision cutting technique;

a precision grinding technique;

a laser technique; and

an etching technique.

14. The method of claim 1, wherein the cap structure comprises a silicon material.