Room-Temperature Solid-Phase Bonding of Low-Hardness Metal Surfaces
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Solution Overview
Problem
Conventional room-temperature bonding methods require high-vacuum conditions and low profile irregularity, making them unsuitable for semiconductor wafers or chips with thin-film or heat-treated surfaces, as they are prone to readhesion films and require extensive surface preparation.
Innovation Solution
A bonding method using a solid-phase technique at room temperature, where metal bonding portions with a hardness of 200 Hv or less are treated with an atom beam, ion beam, or plasma to activate the surface, allowing bonding in atmospheric air without the need for high-vacuum conditions or extensive surface smoothing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If bonding is performed in atmospheric air, then operation simplicity is improved, but oxidation or readhesion of organic substances prevents metal atoms from being attracted
Solution Approach 1:
The bonding surfaces are subjected to energy wave treatment (atom beam, ion beam, or plasma) before bonding to remove organic substances and oxide films in advance. This preliminary cleaning action creates active dangling bonds on the metal surface, enabling subsequent bonding in atmospheric air without immediate re-adhesion of contaminants
Solution Approach 2:
The invention changes the physical state parameters of the bonding surface by applying energy waves that modify surface chemistry. The treatment alters the surface energy and chemical composition, creating a state where metal atoms remain reactive and bondable even in atmospheric conditions, effectively changing the surface properties to resist oxidation and readhesion
2Temperature
If bonding is performed by contact under low load, then bonding temperature is reduced, but profile irregularity must be reduced to several nanometers
Solution Approach 1:
The invention changes the surface energy parameters through energy wave treatment, which compensates for profile irregularities. By activating the surface chemistry and creating dangling bonds, the bonding process becomes less sensitive to mechanical surface imperfections, allowing bonding at room temperature without requiring nanometer-level smoothness
Solution Approach 2:
The invention replaces the mechanical requirement for ultra-smooth surfaces with a chemical/physical solution using energy wave treatment. Instead of relying on mechanical contact of perfectly smooth surfaces to achieve bonding, the energy wave treatment creates chemical reactivity that enables bonding despite surface irregularities
3Temperature
If conventional room-temperature bonding is performed, then heat-sensitive devices can be bonded, but high-vacuum conditions and extensive surface preparation are required
Solution Approach 1:
Energy wave treatment is applied as a preliminary step to activate bonding surfaces, creating a state that enables atmospheric bonding. This preliminary action eliminates the need for high-vacuum environments and extensive surface preparation, simplifying the overall bonding system while maintaining room-temperature operation for heat-sensitive devices
Solution Approach 2:
The invention effectively creates a chemically active surface environment that resists contamination, replacing the need for physical vacuum isolation. The energy wave-treated surface acts as its own protective environment, allowing atmospheric bonding without requiring vacuum chambers or inert gas atmospheres
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 reliable bonding of semiconductor wafers and chips in atmospheric air with reduced surface preparation, achieving strong bonding strengths and avoiding position errors, while being applicable to devices sensitive to heat and thermal expansion.
Implementation Method 1
treating the bonding portions with an energy wave which is an atom beam, an ion beam, or a plasma
Implementation Method 2
treating the bonding portions with an energy wave which is an atom beam, an ion beam, or a plasma
Implementation Method 3
activates a bonding interface of objects to be bonded using an atom beam, an ion beam, or a plasma so as to achieve bonding at low temperature in a solid phase
Data Source
AI summary
A practical bonding technique is provided for solid-phase room-temperature bonding which does not require a profile irregularity of the order of several nanometers, in which a high-vacuum energy wave treatment and continuous high-vacuum bonding are not required.Since an adhering substance layer is thin immediately after a surface activating treatment using an energy wave, a bonding interface is spread by crushing the adhering substance layer to perform bonding, so that a new surface appears on a bonding surface, and objects to be bonded are bonded together. In order to crush the adhering substance layer more easily, a bonding metal of a bonding portion of the object to be bonded needs to have a low hardness. According to the results of various experiments conducted by the present inventors, it was found that the hardness of the bonding portion which is a Vickers hardness of 200 Hv or less is particularly effective for room-temperature bonding.