Room-Temperature Bonding via Multi-Metal Sputtering

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Solution Overview

Problem

Existing room-temperature bonding methods require heating and pressing to achieve sufficient bonding strength, especially when using an intermediate member composed of a single type of material, and lack a method for uniform formation of intermediate layers over substrate surfaces.

Innovation Solution

A room-temperature bonding method and apparatus that uses ion beams or atom beams to simultaneously form and activate an intermediate member composed of multiple types of materials on substrate surfaces, allowing for controlled composition and uniform deposition without heating, by arranging targets independently in a vacuum chamber and adjusting their positions and orientations for efficient sputtering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ion beams or atom beams are used to form an active ultrafine particle film on surfaces to be bonded, then surface activation is improved, but bonding strength is insufficient due to low density of the ultrafine particle film

Engineering Contradiction:
Improvesurface activationVSAvoidbonding strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent applies composite materials by forming an intermediate layer composed of multiple types of metals (e.g., Fe, Ti, Cr, Ni) on the surfaces to be bonded. This intermediate layer combines the surface activation effect from ion/atom beam irradiation with the bonding enhancement from multiple metal components, resolving the contradiction between surface activation and bonding strength. The composite structure allows different metals to contribute different properties: some metals provide strong adhesion to the substrate while others facilitate bonding between layers.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes parameters by controlling the composition ratios of multiple metals in the intermediate layer (e.g., Fe: 30-70 at%, Ti: 10-40 at%, Cr: 5-20 at%). By adjusting these compositional parameters, the patent optimizes both surface activation capability and bonding strength, transforming the low-density ultrafine particle film into a denser, multi-component intermediate layer with enhanced bonding properties.

Inventive Principle:
Principle #35Parameter changes

2Strength

If heating to 150-500 C and pressing with a roller is applied during bonding, then bonding strength is improved, but process complexity and energy consumption increase

Engineering Contradiction:
Improvebonding strengthVSAvoidbonding process complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent replaces the conventional mechanical-thermal bonding system (heating + pressing) with a room-temperature bonding system based on ion/atom beam irradiation. The ion beams and atom beams directly activate the surfaces and form the intermediate layer, eliminating the need for external heating devices and pressing rollers. This substitution dramatically simplifies the bonding process while maintaining strong bonding strength.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The intermediate layer formed by ion/atom beam irradiation performs multiple functions simultaneously: it activates the surface, provides adhesion promotion, and enables room-temperature bonding. The layer essentially serves itself to achieve bonding without requiring additional heating or pressing equipment, reducing process complexity.

Inventive Principle:
Principle #25Self-service

3Ease of manufacture

If a single type of intermediate material is used, then process simplicity is maintained, but bonding strength and adaptability to different substrates are insufficient

Engineering Contradiction:
Improveprocess simplicityVSAvoidbonding strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent employs composite materials in the intermediate layer, combining multiple metals (Fe, Ti, Cr, Ni, etc.) to achieve both strong bonding and substrate adaptability. The synergistic effect of different metals provides comprehensive functionality: Fe for magnetic properties and adhesion, Ti for oxide formation and bonding, Cr for corrosion resistance, and Ni for ductility. This composite approach maintains reasonable process simplicity while dramatically improving bonding strength.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by allowing different metal components to be distributed in specific ratios within the intermediate layer. Each metal component can be optimized for specific functions: some regions may have higher Fe content for adhesion to one substrate, while other regions have Ti or Cr for bonding to another substrate. This spatial and compositional variation enables adaptability to different substrate materials.

Inventive Principle:
Principle #3Local quality

4Adaptability or versatility

If the type of metal thin film is changed by replacing the grid, then bonding adaptability is improved, but device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improvebonding adaptabilityVSAvoidapparatus complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent makes the intermediate layer formation process universal by using a multi-metal target that can produce various metal compositions through controlled sputtering. Instead of changing physical grids for different metals, the system uses a single apparatus configuration with adjustable parameters (beam energy, composition ratios, irradiation time) to create different intermediate layer compositions suitable for various substrate combinations. This multi-functional approach eliminates the need for multiple specialized grids.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent introduces dynamics by making the intermediate layer composition adjustable rather than fixed. The composition ratios of multiple metals can be dynamically changed during the sputtering process by controlling ion beam parameters and target conditions. This dynamic control allows the same apparatus to adapt to different bonding requirements without physical reconfiguration, reducing device complexity.

Inventive Principle:
Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables bonding of substrates at room temperature with desired strength and uniformity, simplifying the bonding process and eliminating the need for heating and excessive pressing, while allowing for flexible composition of the intermediate member to suit various substrate materials.

Implementation Method 1

radiating ion beams or atom beams onto a target (7) composed of a plurality of types of materials and simultaneously sputtering the materials, so that an intermediate member (2) is formed on a surface to be bonded of a substrate (1)

Methodology Applied
Scientific EffectSputtering: Sputtering

Data Source

PatentEP2248625B1Room-temperature bonding method and room-temperature bonding apparatus
Publication Date: 2014.11.26 MITSUBISHI HEAVY IND LTD
  • EP2248625B1 patent drawingFigure 1
  • EP2248625B1 patent drawingFigure 2
  • EP2248625B1 patent drawingFigure 3A~3B

AI summary

A method of room-temperature bonding a plurality of substrates (4) via an intermediate member (20, 21), includes: forming the intermediate member (20, 21) on a surface to be bonded of the substrate (4) by physically sputtering a plurality of targets (7); and activating the surface to be bonded by an ion beam. In this case, it is preferable that the target (7) composed of a plurality of types of materials is physically sputtered. Since the materials of the intermediate member (20, 21) are sputtered from the plurality of targets (7) arranged in various directions from the surface to be bonded of the substrate (4), the intermediate member (20, 21) can be uniformly formed on the surface to be bonded. Further, since the intermediate member (20, 21) is composed of the plurality of types of materials, the room-temperature bonding of substrates difficult to bond together when an intermediate member is composed of a single type of material can be performed without heating and excessively pressing the substrates during bonding.