Inertial Sensor Al-Ge Eutectic Bonding Against Hillock Formation
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Solution Overview
Problem
Existing inertial sensors face issues with decreased bonding strength and reduced long-term reliability due to non-uniform concentration of Ge in AlGe eutectic layers, leading to hillock formation and deterioration of metal interconnections.
Innovation Solution
A metal eutectic layer is formed with alternating first regions of Al as the main component with a face-centered cubic lattice structure and second regions of Ge as the main component with a diamond structure, bonded through a method involving precise temperature control and weight application to ensure uniform distribution and high bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If prolonged heat treatment is performed to achieve uniform Ge concentration distribution, then the bonding strength is improved, but hillocks form in metal interconnections reducing long-term reliability
Solution Approach 1:
The patent applies preliminary action by forming separate first and second bonding parts with different Ge concentrations before the actual bonding process. The first bonding part (with higher Ge concentration) is formed on one substrate, and the second bonding part (with lower Ge concentration) is formed on the other substrate. This pre-preparation allows the eutectic reaction to occur uniformly during bonding without requiring prolonged heat treatment, thereby preventing hillock formation in metal interconnections while achieving strong bonding.
Solution Approach 2:
The patent implements local quality by creating spatial variation in Ge concentration within the bonding parts. The first bonding part has a higher Ge concentration than the second bonding part, allowing different regions to contribute differently to the eutectic reaction. This local differentiation enables uniform eutectic layer formation across the bonding interface without the need for uniform high Ge concentration throughout, thus avoiding the harmful effects of prolonged heat treatment on metal interconnections.
2Ease of manufacture
If Ge concentration decreases with distance from the lid body, then manufacturing is simplified, but bonding strength deteriorates due to Al layer formation only
Solution Approach 1:
The patent applies local quality by designing the bonding parts with spatially differentiated Ge concentrations. The first bonding part (on the base body side) has a higher Ge concentration to ensure complete eutectic reaction and strong bonding at the base body interface. The second bonding part (on the lid body side) has a lower Ge concentration. This local differentiation ensures that both substrates achieve optimal bonding strength through the eutectic reaction, preventing the formation of weak Al-only layers.
Solution Approach 2:
The patent implements parameter changes by controlling the Ge concentration as a gradient parameter across different bonding parts. By adjusting the Ge concentration in the first bonding part to be higher than in the second bonding part, the patent optimizes the eutectic reaction conditions at each bonding interface. This parameter control ensures complete reaction and strong bonding strength while maintaining manufacturing feasibility through selective Ge deposition or implantation processes.
3Strength
If uniform Ge concentration is achieved through prolonged heat treatment, then bonding strength is improved, but manufacturing time increases
Solution Approach 1:
The patent applies preliminary action by pre-forming bonding parts with optimized Ge concentrations before the bonding process. Instead of relying on prolonged heat treatment to create uniform Ge distribution, the Ge concentration is predetermined in each bonding part during fabrication. This allows the eutectic reaction to proceed uniformly and rapidly during bonding, significantly reducing the required heat treatment time while maintaining strong bonding strength.
Solution Approach 2:
The patent implements parameter changes by optimizing the Ge concentration parameter in the bonding parts to enable rapid eutectic reaction. By setting appropriate Ge concentration levels in the first and second bonding parts, the patent accelerates the eutectic transformation during bonding, reducing the time required to achieve complete reaction and strong bonding without sacrificing bonding quality.
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 solution provides inertial sensors with enhanced bonding strength and long-term reliability by ensuring uniform Ge distribution, preventing hillock formation, and maintaining electrical stability.
Implementation Method 1
a metal eutectic layer configured to bond the base body and the lid body to each other
Implementation Method 2
the concentration of Ge becomes uniform
Data Source
AI summary
An inertial sensor or an electronic component includes a base body, a lid body, a functional element disposed between the base body and the lid body, and a metal eutectic layer configured to bond the base body and the lid body to each other on a periphery of the functional element, wherein in the metal eutectic layer, a plurality of first regions having a first metal as a main component and having a face-centered cubic lattice structure, and a second region having a second metal as a main component and having a diamond structure are present, and adjacent to each other.