MEMS Resonator Bonding Structure With Anti-Diffusion Layer
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Solution Overview
Problem
Resonance devices using micro electromechanical systems (MEMS) technologies face bonding defects due to metal diffusion from the bonding part into the aluminum wiring line, affecting the eutectic ratio and bonding strength.
Innovation Solution
Incorporating an anti-diffusion layer that electrically connects the wiring line layer and the bonding part, preventing metal diffusion and maintaining the eutectic ratio, while using a eutectic layer with a eutectic alloy of aluminum and germanium for bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bonding part is connected to the lower electrode by an aluminum wiring line, then good electrical connectivity is achieved, but metal diffusion occurs from the bonding part into the wiring line causing bonding defects
Solution Approach 1:
An anti-diffusion layer is introduced as an intermediary component between the aluminum wiring line and the bonding part. This layer prevents metal diffusion from the bonding part into the wiring line while maintaining electrical connectivity, thus resolving the contradiction between good electrical connectivity and bonding quality.
2Ease of manufacture
If metal diffusion is allowed during bonding, then the bonding process is simple, but the eutectic ratio changes and bonding strength is reduced
Solution Approach 1:
The anti-diffusion layer serves as a mediator that prevents metal diffusion during the bonding process. This allows the bonding to proceed without complex diffusion control measures while maintaining the eutectic ratio and ensuring strong bonding, thus resolving the contradiction between manufacturing simplicity and bonding strength.
3Ease of manufacture
If the bonding part metal composition is allowed to change during bonding, then the bonding process is easier, but the eutectic reaction becomes insufficient
Solution Approach 1:
The anti-diffusion layer acts as a protective intermediary that prevents metal composition changes in the bonding part during the bonding process. This ensures complete eutectic reaction and reliable bonding while maintaining ease of manufacturing, resolving the contradiction between manufacturing ease and reaction completeness.
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
This approach effectively suppresses bonding defects by maintaining the integrity of the eutectic alloy composition and enhancing the bonding strength of the resonance device.
Implementation Method 1
a bonding part that includes a eutectic layer, the eutectic layer having a eutectic alloy of a first metal of the first metal layer and a second metal of the second metal layer as a main component
Implementation Method 2
an anti-diffusion layer that electrically connects the wiring line layer and the bonding part to each other
Data Source
AI summary
A resonance device that includes a MEMS substrate, a top cover, and a bonding part. The MEMS substrate includes a resonator. The bonding part is electrically conductive and bonds the MEMS substrate and the top cover to each other. The MEMS substrate further includes a wiring line layer and an anti-diffusion layer. The wiring line layer is electrically connected to a Si substrate serving as a lower electrode of the resonator. The anti-diffusion layer electrically connects the wiring line layer and the bonding part to each other.