Semiconductor Joint Layer with Graded Filling Rate for Thermal Stress
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Solution Overview
Problem
Conventional semiconductor devices using sinter bonding materials experience joint layer cracking and reduced reliability in high temperature environments due to thermal stress, leading to inadequate adhesion strength.
Innovation Solution
A semiconductor device with a joint layer formed by sintered metal crystal grains, featuring a concave or convex pattern on the electrode, where the filling rate of metal crystal grains differs between regions to control crack occurrence and enhance reliability, using a sinter bonding material with metal nanoparticles and an organic protection film to achieve high bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a sinter bonding material including silver nanoparticle is used to join the rear surface electrode to the circuit substrate, then the bonding strength is improved, but in high temperature environments, thermal stress causes cracks in the joint layer reducing reliability
Solution Approach 1:
The patent applies local quality by creating a joint layer with spatially varying filling rates of metal crystal grains. The first region (near the electrode) has a higher filling rate for strength, while the second region (toward the semiconductor element) has a lower filling rate to reduce thermal stress concentration and prevent crack propagation during thermal cycling in high temperature environments.
Solution Approach 2:
The patent changes the physical parameter of filling rate distribution within the joint layer. By controlling the filling rate to vary from the first region to the second region, the patent optimizes both bonding strength and thermal stress resistance, preventing crack formation while maintaining strong adhesion between the electrode and circuit substrate.
2Strength
If high hardness particles of copper or nickel are dispersed in the sinter bonding material to enhance joint layer intensity, then the strength is improved, but the complexity of the material composition increases
Solution Approach 1:
The patent employs composite materials by combining silver nanoparticles with high hardness particles of copper or nickel in the sinter bonding material. This composite structure provides both the bonding strength from silver and the enhanced mechanical intensity from the harder particles, while the filling rate gradient optimizes the overall performance without requiring overly complex material formulations.
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 enhanced joint reliability and adhesion strength in high temperature environments by controlling crack occurrence in specific regions of the joint layer, ensuring the semiconductor device's performance and longevity.
Implementation Method 1
A sinter bonding technique using a sintering phenomenon of a metal grain is applied to the semiconductor device for power conversion as a technique of joining the material replaced with the solder joint
Data Source
AI summary
A semiconductor device includes an electrode having a flat part and a non-flat part made up of a concave part, a joint layer being made of a sintered body of metal crystal grains provided on the flat part and the non-flat part of the electrode, and a semiconductor element being joined to the electrode with the joint layer therebetween, wherein the joint layer has a first region sandwiched between the non-flat part and the semiconductor element and a second region sandwiched between the flat part and the semiconductor element, and either one of the first region and the second region having a larger film thickness has a filling rate of the metal crystal grains smaller than the other one of the first region and the second region having a smaller film thickness. The present invention enhances reliability of a joint layer made of a sintered body of metal crystal grains.