# US 9,751,752 B2 · Method of fabrication of Al/Ge bonding in a wafer packaging environment and a product produced therefrom > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,751,752 B2 - Document ID: US9751752B2 - Status: Granted - Kind: B2 - Application number: 15/364,478 - Filed: 2016-11-30 - Published: 2017-03-16 - Granted: 2017-09-05 - Earliest claimed: 2005-03-18 - Assignees: InvenSense, Inc. - Applicants: Invensense, Inc. - Inventors: Steven S. Nasiri; Anthony F. Flannery, Jr. - Web page: https://patentgrep.com/patent/US9751752B2 ## CPC - B81C 1/00238: {Joining a substrate with an electronic processing unit and a substrate with a micromechanical structure} - B23K 20/023: {Thermo-compression bonding} - 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} - B81B 7/007: {Interconnections between the MEMS and external electrical signals} - B81C 1/00269: {Bonding of solid lids or wafers to the substrate} - B81C 3/001: {Bonding of two components} - H10P 10/128: {by direct semiconductor to semiconductor bonding} - B81B 2203/0315: Cavities - B81B 2207/012: the micromechanical device and the control or processing electronics being separate parts in the same package - B81B 2207/094: Feed-through, via - B81C 2203/0118: Bonding a wafer on the substrate, i.e. where the cap consists of another wafer - B81C 2203/035: Soldering - B81C 2203/038: Bonding techniques not provided for in B81C2203/031 - B81C2203/037 - B81C 2203/0792: Forming interconnections between the electronic processing unit and the micromechanical structure - B81C: PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS (making microcapsules or microballoons B01J13/02; processes or apparatus specially adapted for the manufacture or treatment of piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/01) - B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM - B81B: MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES (piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/00, H10N35/00) - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 ## 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 ### Claim 1 A microelectromechanical systems (MEMS) device comprising: a first substrate comprising a MEMS feature and a patterned germanium layer in direct contact with the first substrate; and a second substrate comprising a patterned aluminum layer, wherein germanium of the patterned germanium layer of the first substrate is in direct contact with and matched to aluminum of the patterned aluminum layer of the second substrate to form a hermetic seal ring, wherein the patterned aluminum layer is properly patterned to match the patterned germanium layer in the area of the hermetic seal ring. ### Claim 2 (depends on 1) The MEMS device of claim 1, wherein the second substrate further comprises an electrical contact associated with the patterned aluminum layer, coupled with an integrated circuit within the second substrate, and located within an outer perimeter of the hermetic seal ring. ### Claim 3 (depends on 2) The MEMS device of claim 2, wherein the first substrate and the second substrate are electrically connected via an inter-substrate electrical contact comprising the electrical contact and the patterned germanium layer of the first substrate. ### Claim 4 (depends on 3) The MEMS device of claim 3, wherein the integrated circuit has a multilayer metalization electrically coupled with at least a portion of the patterned aluminum layer and configured to allow electrical under pass feedthrough via the inter-substrate electrical contact from the integrated circuit to the MEMS feature. ### Claim 5 (depends on 3) The MEMS device of claim 3, wherein the first substrate further comprises at least one via configured to provide electric feedthrough of signals to the one electrical contact of the second substrate. ### Claim 6 (depends on 1) The MEMS device of claim 1, wherein at least one of the first substrate or the second substrate comprises at least one of a silicon substrate, a multiple layer of silicon substrates, or a substrate comprising at least one of gallium arsenide (GaAs), indium phosphide (InPh), silicon germanium (SiGe), or glass. ### Claim 7 A wafer structure comprising: a first substrate comprising at least one microelectromechanical systems (MEMS) feature, wherein the first substrate further comprises at least one patterned germanium layer; and a second substrate comprising at least one patterned aluminum layer and one electrical contact, wherein the at least one patterned germanium layer is bonded to the at least one patterned aluminum layer to create an inter-substrate electrical contact and a mechanical contact between the first substrate and the second substrate. ### Claim 8 (depends on 7) The wafer structure of claim 7, wherein at least one of the first substrate or the second substrate comprises at least one of a silicon substrate, a multiple layer of silicon substrates, or a substrate comprising at least one of gallium arsenide (GaAs), indium phosphide (InPh), silicon germanium (SiGe), or glass. ### Claim 9 (depends on 7) The wafer structure of claim 7, wherein the first substrate comprises MEMS structures and a cavity. ### Claim 10 (depends on 7) The wafer structure of claim 7, wherein the second substrate comprises an integrated circuit. ### Claim 11 (depends on 10) The wafer structure of claim 10, wherein the integrated circuit has a multilayer metalization electrically coupled with at least a portion of the at least one patterned aluminum layer and configured to allow electrical under pass feedthrough via the inter-substrate electrical contact to the integrated circuit. ### Claim 12 (depends on 11) The wafer structure of claim 11, wherein a plurality of contact pads are located outside an outer perimeter of a hermetic sealing ring that provides a hermetic seal associated with the mechanical contact and wherein at least one of the plurality of contact pads is electrically coupled to the one electrical contact of the second substrate located within the outer perimeter of the hermetic sealing ring. ### Claim 13 (depends on 12) The wafer structure of claim 12, wherein the at least one patterned germanium layer and the at least one patterned aluminum layer are bonded to provide the hermetic seal. ### Claim 14 (depends on 10) The wafer structure of claim 10, wherein the first substrate further comprises at least one via configured to provide electric feedthrough of signals to the one electrical contact of the second substrate. ### Claim 15 (depends on 7) The wafer structure of claim 7, wherein the at least one patterned germanium layer is bonded to the at least one patterned aluminum layer via an eutectic composition of aluminum and germanium. ### Claim 16 A wafer structure comprising: a first substrate comprising at least one microelectromechanical systems (MEMS) feature, wherein the first substrate further comprises at least one patterned germanium layer and at least one via configured to provide electric feedthrough of signals; and a second substrate comprising at least one patterned aluminum layer and one electrical contact, wherein the at least one patterned germanium layer is bonded to the at least one patterned aluminum to mechanically couple the first substrate to the second substrate via a hermetic seal ring and to electrically couple the at least one via of the first substrate to the one electrical contact of the second substrate within the hermetic seal ring. ### Claim 17 (depends on 16) The wafer structure of claim 16, wherein at least one of the first substrate or the second substrate comprises at least one of a silicon substrate, a multiple layer of silicon substrates, or a substrate comprising at least one of gallium arsenide (GaAs), indium phosphide (InPh), silicon germanium (SiGe), or glass. ### Claim 18 (depends on 16) The wafer structure of claim 16, wherein the second substrate comprises an integrated circuit having a multilayer metalization electrically coupled with at least a portion of the at least one patterned aluminum layer and configured to provide the one electrical contact to facilitate the electric feedthrough of signals between the first substrate and the second substrate.