Method of fabrication of Al/Ge bonding in a wafer packaging environment and a product produced therefrom

• US 9,139,428 B2
• Filed: 01/16/2014
• Issued: 09/22/2015
• Est. Priority Date: 03/18/2005
• Status: Active Grant

• Current Assignee: Invensense Incorporated (TDK Corporation)
• Original Assignee: Invensense Incorporated (TDK Corporation)
• Inventors: Nasiri, Steven S., Flannery, Anthony F. Jr.
• Primary Examiner(s): Blum, David S
• Application Number:
  US14/157,456
• Publication Number:
  US 20140131820A1
• Time in Patent Office: 614 Days
• Field of Search: 257/415
• US Class Current: 1/1
• CPC Class Codes: B23K 20/023 Thermo-compression bonding
• CPC Class Codes: B81B 2203/0315 Cavities
• CPC Class Codes: B81B 2207/012 the micromechanical device and the control or processing electronics being separate parts in the same package
• CPC Class Codes: B81B 2207/094 Feed-through, via
• CPC Class Codes: B81B 3/0018 Structures acting upon the moving or flexible element for transforming energy into mechanical movement or vice versa, i.e. actuators, sensors, generators
• CPC Class Codes: B81B 7/007 Interconnections between the MEMS and external electrical signals
• CPC Class Codes: B81C 1/00238 Joining a substrate with an electronic processing unit and a substrate with a micromechanical structure
• 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: B81C 2203/035 Soldering
• CPC Class Codes: B81C 2203/038 Bonding techniques not provided for in B81C2203/031 - B81C2203/037
• CPC Class Codes: B81C 2203/0792 Forming interconnections between the electronic processing unit and the micromechanical structure
• CPC Class Codes: B81C 3/001 Bonding of two components
• CPC Class Codes: H01L 21/187 by direct bonding

Abstract

A method of bonding of germanium to aluminum between two substrates to create a robust electrical and mechanical contact is disclosed. An aluminum-germanium bond has the following unique combination of attributes: (1) it can form a hermetic seal; (2) it can be used to create an electrically conductive path between two substrates; (3) it can be patterned so that this conduction path is localized; (4) the bond can be made with the aluminum that is available as standard foundry CMOS process. This has the significant advantage of allowing for wafer-level bonding or packaging without the addition of any additional process layers to the CMOS wafer.

Claims

1. A MEMS device comprising:

a first substrate including a microelectromechanical systems (MEMS) feature and a patterned germanium layer; and

a second substrate, including a patterned aluminum layer, wherein the germanium of the patterned germanium layer of the first substrate is in direct contact with and matched to the aluminum of the patterned aluminum layer of the second substrate to form a contact area, wherein in the contact area the patterned aluminum layer is properly patterned to match patterned germanium layer.

2. The MEMS device of claim 1, wherein the second substrate includes electrical circuits.

3. The MEMS device of claim 1, wherein the first and second substrates are electrically connected.

4. The MEMS device of claim 1, wherein the patterned aluminum layer and the patterned germanium layer form a seal ring.

5. The MEMS device of claim 1, wherein the direct contact between germanium and the aluminum comprises a eutectic bond.