MEMS Resonator Eutectic Bonding for Airtight Sealed Cavities
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Solution Overview
Problem
Resonance devices manufactured using MEMS techniques face issues with airtightness and bonding strength due to the formation of numerous interfaces between aluminum and germanium monolayers, leading to potential voids and separation caused by thermal stresses during eutectic bonding.
Innovation Solution
A resonance device with a bonding portion comprising a eutectic layer containing a eutectic alloy primarily composed of aluminum, germanium, and titanium or nickel, which reduces the formation of interfaces and enhances bonding strength by forming a solid alloy with reduced fluidity, thereby improving airtightness and preventing splash during the bonding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If aluminum and germanium monolayers are bonded in a eutectic-bonding manner, then bonding is achieved, but numerous interfaces are formed leading to voids and separation due to thermal stresses
Solution Approach 1:
The patent applies composite materials by creating a multi-layer eutectic alloy structure comprising an aluminum-containing layer, a germanium layer, and a titanium or nickel-containing layer. This composite structure reduces the formation of numerous Al-Ge interfaces that cause voids and separation, thereby improving both bonding strength and airtightness while mitigating thermal stress effects.
2Strength
If eutectic bonding is performed with aluminum and germanium, then bonding is achieved, but metal splash occurs from the bonding surface
Solution Approach 1:
The patent introduces titanium or nickel as an intermediary element in the eutectic alloy structure. This intermediary layer acts as a mediator between aluminum and germanium, controlling the eutectic reaction to reduce metal splash from the bonding surface while maintaining effective bonding between the substrates.
3Object-generated harmful factors
If a eutectic alloy with reduced fluidity is formed, then splash and short circuits are minimized, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the composition of the eutectic alloy to include titanium or nickel, which changes the fluidity characteristics of the alloy during bonding. This compositional parameter change reduces metal splash and short circuits while the multi-layer structure is designed to be integrated into existing manufacturing processes.
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 use of a eutectic alloy in the bonding portion significantly improves the airtightness and bonding strength of the resonance device, reducing the likelihood of voids and interfacial separation, and enhances the layout flexibility by minimizing splash and short circuits.
Implementation Method 1
The eutectic alloy is composed of a first metal containing aluminum as a main component thereof, a second metal of germanium or silicon, and a third metal of titanium or nickel
Data Source
AI summary
A resonance device that includes a MEMS substrate including a resonator, an upper lid, and a bonding portion bonding the MEMS substrate and the upper lid to seal a vibration space of the resonator. The bonding portion includes a eutectic layer containing a eutectic alloy as a main component thereof. The eutectic alloy is composed of a first metal containing aluminum as a main component thereof, a second metal of germanium or silicon, and a third metal of titanium or nickel.