# US 10,118,247 B2 · Method for bonding wafers

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- Number: US 10,118,247 B2
- Document ID: US10118247B2
- Status: Granted
- Kind: B2
- Application number: 15/599,714
- Filed: 2017-05-19
- Published: 2017-09-07
- Granted: 2018-11-06
- Earliest claimed: 2014-11-21
- Assignees: Murata Manufacturing Co., Ltd.
- Applicants: Murata Manufacturing Co., Ltd.
- Inventors: Masakazu Fukumitsu; Shuhei Yamada
- Web page: https://patentgrep.com/patent/US10118247B2

## CPC

- B23K 20/023: {Thermo-compression bonding}
- B06B 1/06: operating with piezoelectric effect or with electrostriction (piezoelectric or electrostrictive devices per se H10N30/00)
- B06B 1/0603: {using a piezoelectric bender, e.g. bimorph}
- B23K 20/16: with interposition of special material to facilitate connection of the parts, e.g. material for absorbing or producing gas
- B23K 20/22: taking account of the properties of the materials to be welded
- B81C 1/00269: {Bonding of solid lids or wafers to the substrate}
- H10N 30/073: by fusion of metals or by adhesives
- H10N 30/20: with electrical input and mechanical output, e.g. functioning as actuators or vibrators
- H10P 10/128: {by direct semiconductor to semiconductor bonding}
- B06B 1/0648: {of rectangular shape}
- B23K 2101/40: Semiconductor devices
- B81B 2201/0242: Gyroscopes
- B81C 2203/033: Thermal bonding
- B81C 2203/035: Soldering
- H03H 3/02: for the manufacture of piezoelectric or electrostrictive resonators or networks (H03H3/08 takes precedence)
- H03H 9/0595: {the holder support and resonator being formed in one body}
- H03H 9/1035: {the enclosure being defined by two sealing substrates sandwiching the piezoelectric layer of the BAW device}
- H03H 2003/026: {the resonators or networks being of the tuning fork type}
- 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
- B06B: METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, {e.g.} FOR PERFORMING MECHANICAL WORK IN GENERAL (for particular applications, see the relevant subclasses, e.g. B07B1/40, B23Q17/12, B24B31/06; measurement of mechanical vibrations G01H; in direction finding, locating, distance or velocity measuring G01S; {generating seismic energy G01V1/02}; control of mechanical vibrations in general G05D; sound-producing devices, e.g. bells, sirens, whistles G10K, {e.g. methods or devices for transmitting, conducting, or directing sound in general G10K11/00}; generation of electrical oscillations H03B; electromechanical resonators in general H03H; electromechanical transducers {for communication techniques, e.g. microphones, speakers} H04R)
- 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)
- H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- B81B: MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES (piezoelectric, electrostrictive or magnetostrictive elements per se H10N30/00, H10N35/00)
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)

## Abstract

Provided is a method for bonding wafers, which can bond the wafers to each other with high reliability while reducing the influence on the wafers. The method for bonding wafers includes the steps of: preparing a first wafer that has, on the surface thereof, a first metal layer with a first rigidity modulus, and a second wafer that has, on the surface thereof, a second metal layer with a second rigidity modulus higher than the first rigidity modulus; removing an oxide film at the surface of the second metal layer while an oxide film at the surface of the first metal layer is not removed; and bonding the surface of the first wafer to the surface of the second wafer.

## Claims

### Claim 1

A method for bonding wafers, the method comprising:
preparing a first wafer having a first metal layer with a first rigidity modulus, the first metal layer being formed from an aluminum-copper alloy, the percentage of copper in the aluminum-copper alloy by weight being 1 wt % or less, aluminum being the main constituent of the first metal layer;
preparing a second wafer having a second metal layer with a second rigidity modulus higher than the first rigidity modulus, the second metal layer being formed from a second metal containing germanium as its main constituent;
removing a first oxide film on a first surface of the second metal layer while not removing a second oxide film on a second surface of the first metal layer; and
bonding the first surface of the second metal layer to the second surface of the first metal layer in such a manner that the oxide film on the second surface of the first metal layer is broken due to mechanical shock.

### Claim 2

A method for bonding wafers, the method comprising:
preparing a first wafer having a first metal layer with a first rigidity modulus, the first metal being formed of an aluminum-copper alloy, the percentage of copper by weight in the aluminum-copper alloy by weight being 1% or less, aluminum being the main constituent of the first metal layer, the first metal being one of an alloy of aluminum and copper and an alloy of aluminum, silicon and copper;
preparing a second wafer having a second metal layer with a second rigidity modulus higher than the first rigidity modulus, the second metal layer is formed of a metal containing germanium;
removing a first oxide film on a first surface of the second metal layer while not removing a second oxide film on a second surface of the first metal layer; and
bonding the first surface of the second metal layer to the second surface of the first metal layer in such a manner that the oxide film on the second surface of the first metal layer is broken due to mechanical shock.