Copper Sintered Bonding Layer for High-Temperature SiC Packaging
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Solution Overview
Problem
Current bonding techniques for semiconductor devices face challenges with high-temperature reliability due to thermal stress caused by differences in linear expansion coefficients between SiC chips and copper substrates, and existing lead-free alternatives like silver have cost and migration issues.
Innovation Solution
A sintered body of copper fine particles with a specific Vickers hardness characteristic, decreasing by 5-20% from 25°C to 150°C, is used as a bonding element, reducing thermal stress and maintaining reliability under cold-thermal shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If copper fine particles are used as a bonding material to replace lead-containing solder, then environmental compliance and cost are improved, but thermal stress resistance under high-temperature operation deteriorates due to linear expansion coefficient mismatch between SiC and copper
Solution Approach 1:
The invention changes the physical parameters of copper particles by controlling their size (0.1-10 μm) and utilizing sintering treatment to create a nanoparticle interface structure. This parameter change enables the bonding material to exhibit creep behavior at high temperatures, transforming copper from a rigid material into one with stress-relaxing capabilities that accommodates thermal expansion mismatch between SiC and copper substrates.
Solution Approach 2:
The invention creates a composite structure through sintering copper fine particles, forming a unique nanoparticle interface that combines metallic bonding with creeps-resistant characteristics. The sintered copper particle composite exhibits both strong bonding strength and stress relaxation capability through creep behavior, resolving the contradiction between environmental compliance and thermal stress resistance.
2Reliability
If silver fine particles are used as a bonding material, then thermal stress relaxation is improved through creep behavior, but cost and migration resistance deteriorate
Solution Approach 1:
The invention replaces expensive silver fine particles with copper fine particles, utilizing the same creep mechanism but with a more cost-effective and environmentally friendly material. Copper particles of 0.1-10 μm undergo sintering to create the necessary nanoparticle interface for creep-based stress relaxation, achieving the same functional effect as silver without the associated cost and migration problems.
Solution Approach 2:
The invention changes the material parameter from silver to copper while maintaining the critical particle size range (0.1-10 μm) and sintering treatment conditions. This parameter substitution preserves the creep behavior necessary for stress relaxation while eliminating the drawbacks of silver, demonstrating that copper can achieve equivalent performance through proper parameter optimization.
3Reliability
If a heat-bonding sheet combining metal fine particles with resin is used, then flexibility and reliability are improved, but bonding pressure requirement increases making existing facilities unusable
Solution Approach 1:
The invention extracts the resin component from the heat-bonding sheet, using only sintered copper fine particles as the bonding material. This extraction eliminates the need for high bonding pressure while maintaining flexibility and reliability through the inherent creep behavior of the sintered copper nanoparticle interface, making the process compatible with existing bonding facilities.
Solution Approach 2:
The sintered copper fine particles perform multiple functions simultaneously: they provide bonding strength through metallic bonding, enable stress relaxation through creep behavior, and maintain flexibility through the nanoparticle interface structure. This self-service capability eliminates the need for resin additives and high pressure requirements, allowing existing facilities to perform the bonding without modification.
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 sintered body effectively relaxes stress in semiconductor devices, preventing cracks and peeling, even under extreme temperature changes, and supports high current density operations without environmental hazards or high costs.
Implementation Method 1
a sintered body by fusing copper fine particles having a particle diameter of 1 to 300 nm by a sintering treatment at 200°C to 350°C
Implementation Method 2
when a Vickers hardness of the copper fine particle sintered body at 150°C is set as Hvb and a Vickers hardness of the same copper fine particle sintered body at 25°C is set as Hva
Data Source
AI summary
A problem to be solved by the present invention is to provide a bonding member in which copper fine particles are used as a bonding member of a semiconductor device component and which does not cause cracking, peeling, or the like in a semiconductor device when operated under a high-temperature condition of 200°C or more. To solve the problem, a copper fine particle sintered body for bonding a semiconductor device component is provided, the copper fine particle sintered body being characterized in that when the Vickers hardness of the copper fine particle sintered body at 150°C is Hvb and the Vickers hardness of the copper fine particle sintered body at 25°C is Hva, a value of (Hvb/Hva) × 100 is 5-20%.