Eutectic Metal Bonding Layer Void Suppression
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Solution Overview
Problem
Existing methods of forming eutectic metal bonding layers for semiconductor light emitting devices often result in defective bonding due to voids, especially when bonding surfaces are non-flat, leading to weakened bonding strength and reliability.
Innovation Solution
A method involving the formation of first and second bonding metal layers with oxidation prevention and reaction delay layers, where the oxidation prevention layer is made of a metal with lower oxidation reactivity than the bonding metal and the reaction delay layer delays the reaction between the bonding metal layers, preventing void formation and enhancing bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a eutectic metal bonding layer is formed through a reaction between bonding metals, then bonding between objects is achieved, but voids are generated that deteriorate bonding strength
Solution Approach 1:
The patent applies preliminary action by forming an oxidation prevention layer on the bonding metal layers before the bonding reaction occurs. This pre-formed protective layer prevents oxidation during the bonding process, eliminating a key cause of void formation and ensuring reliable bonding strength from the outset rather than attempting to fix defects afterward.
Solution Approach 2:
The oxidation prevention layer acts as an intermediary between the bonding metal layers and the oxidizing environment. This intermediate layer protects the reactive bonding metals from direct oxidation while allowing the bonding reaction to proceed, thus preventing void formation without interfering with the essential bonding function.
2Ease of manufacture
If bonding is performed on a non-flat surface, then bonding between objects is achieved, but voids easily occur causing defective bonding
Solution Approach 1:
The oxidation prevention layer is formed preliminarily on the bonding surfaces before bonding, providing continuous protection even on non-flat surfaces. This pre-protection ensures that oxidation does not occur in valleys or uneven areas during bonding, maintaining high bonding quality without requiring perfectly flat surfaces.
Solution Approach 2:
The oxidation prevention layer provides localized protection specifically at the bonding interfaces where it is most needed. The layer can be applied conformally to follow the surface topology, ensuring that each local area of the non-flat surface receives appropriate protection against oxidation during the bonding process.
3Productivity
If the bonding metal layer is exposed to oxidation, then the bonding process can proceed, but the surface state of the bonding metal deteriorates causing separation
Solution Approach 1:
The oxidation prevention layer serves as an intermediary protective barrier that allows the bonding process to proceed efficiently while blocking oxygen from reaching the bonding metal layers. This mediator enables continuous production without compromising bonding stability, as the protective layer prevents surface deterioration throughout the bonding process.
Solution Approach 2:
The oxidation prevention layer creates a locally inert environment at the bonding interface by preventing oxygen access. This inert barrier allows the bonding reaction to proceed as if in a controlled atmosphere, maintaining metal surface integrity and preventing oxidation-related separation while preserving bonding process efficiency.
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
The method effectively suppresses void formation and improves bonding strength and reliability, even on non-flat surfaces, by delaying the reaction and preventing oxidation, resulting in a stable eutectic metal bonding layer.
Implementation Method 1
the oxidation prevention layer being formed of a metal having an oxidation reactivity lower than an oxidation reactivity of the corresponding bonding metal layer
Implementation Method 2
a reaction delay layer formed of a metal or an alloy thereof for delaying a reaction between the first and second bonding metal layers
Implementation Method 3
A eutectic metal bonding layer is formed through a reaction between the first and second bonding metal layers
Data Source
AI summary
A method of forming a metal bonding layer includes forming first and second bonding metal layers on one surfaces of first and second bonding objects, respectively. The second bonding object is disposed on the first bonding object such that the first bonding metal layer and the second bonding metal layer face each other. A eutectic metal bonding layer is formed through a reaction between the first and second bonding metal layers. At least one of the first bonding metal layer and the second bonding metal layer includes an oxidation prevention layer formed on an upper surface thereof. The oxidation prevention layer is formed of a metal having an oxidation reactivity lower than an oxidation reactivity of the bonding metal layer on the upper surface which the oxidation prevention layer is disposed.