Substrate bonding with bonding material having rare earth metal

• US 7,981,765 B2
• Filed: 05/04/2009
• Issued: 07/19/2011
• Est. Priority Date: 09/10/2008
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Tsau, Christine H., Frey, Timothy J., Martin, John R.
• Primary Examiner(s): Dang; Phuc T
• Application Number:
  US12/434,886
• Publication Number:
  US 20100062565A1
• Time in Patent Office: 806 Days
• Field of Search: 438/107, 438/113, 438/455, 257/E21.499, 257/E21.599
• US Class Current: 438/455
• CPC Class Codes: B81C 1/00269 Bonding of solid lids or wafers to the substrate
• CPC Class Codes: B81C 2203/0118 Bonding a wafer on the substrate, i.e. where the cap consists of another wafer
• 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
• CPC Class Codes: H01L 2924/01079 Gold [Au]

Abstract

A microchip has a bonding material that bonds a first substrate to a second substrate. The bonding material has, among other things, a rare earth metal and other material.

Claims

1. A method of bonding a MEMS wafer to a second wafer, the method comprising:

providing the MEMS wafer with a two-dimensional array of MEMS devices;

providing the second wafer;

depositing a metal alloy onto one or both the MEMS wafer and the second wafer, the metal alloy comprising a rare earth metal;

aligning the MEMS wafer and the second wafer;

forming an intermediate apparatus having the metal alloy between the MEMS wafer and the second wafer;

heating the intermediate apparatus at least to within 75 degrees C. of the melting point of the metal alloy between the MEMS wafer and the second wafer; and

cooling the wafers to form a plurality of conductive hermetic sealing rings about the plurality of the MEMS devices on the MEMS wafer, the sealing rings bonding the MEMS wafer to the second wafer.

2. The method as defined by claim 1 wherein the metal alloy further comprises aluminum/germanium.

3. The method as defined by claim 1 further comprising dicing the wafers to form a plurality of individual, hermetically sealed MEMS devices.

4. The method as defined by claim 1 further comprising:

forming at least one pedestal ring on the MEMS wafer.

5. The method as defined by claim 1 wherein at least one of the MEMS wafer and second wafer includes electronic circuitry.

6. The method as defined by claim 1 further comprising adding a cover material to the metal alloy to mitigate oxidation of the alloy, adding being performed before forming the intermediate apparatus.

7. The method as defined by claim 1 wherein the metal alloy electrically connects the MEMS wafer with the second wafer.

8. The method as defined by claim 1 wherein the metal alloy has a width that is generally parallel to the surface of the second wafer, the width being no greater than about 100 microns.