AgCuSn Bonding Layer for High-Temperature Power Semiconductor Modules
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Solution Overview
Problem
Existing semiconductor devices bonded to copper members using intermetallic compounds face issues with bonding strength and reliability due to the formation of large Kirkendall voids and cracks at high temperatures, particularly when using CuSn-based intermetallic compounds without the addition of silver.
Innovation Solution
The integration of a conductive layer containing a CuSn intermetallic compound with added silver (AgCuSn) improves bonding by reducing Kirkendall void formation and enhancing stress resistance, ensuring a continuous interface without cracks, thereby improving thermal conductivity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If CuSn-based intermetallic compounds are used for bonding semiconductor chips to copper members, then bonding strength is improved, but large Kirkendall voids and cracks form at high temperatures reducing reliability
Solution Approach 1:
The invention changes the compositional parameters of the intermetallic compound layer by adding silver (Ag) to the CuSn system, creating AgCuSn-based intermetallic compounds. This compositional modification alters the diffusion characteristics and void formation behavior, suppressing Kirkendall void growth while maintaining bonding strength at high temperatures.
Solution Approach 2:
The invention uses a composite intermetallic compound system (AgCuSn) instead of a simple CuSn system. The multi-element composition creates a more complex but stable intermetallic structure that resists void formation and cracking under thermal stress, thereby improving high-temperature reliability while preserving bonding strength.
2Loss of energy
If intermetallic compound layers are formed for bonding, then thermal conductivity is improved, but Kirkendall void formation increases thermal resistance
Solution Approach 1:
By modifying the intermetallic compound composition to include silver (AgCuSn), the invention changes the physical and chemical parameters of the bonding layer. This compositional change suppresses Kirkendall void formation, maintaining interface continuity and ensuring low thermal resistance through the bonding layer even at elevated temperatures.
3Ease of manufacture
If CuSn intermetallic compounds are used without silver, then manufacturing cost is reduced, but bonding strength deteriorates at elevated temperatures
Solution Approach 1:
The invention optimizes the compositional parameters by adding a controlled amount of silver to the CuSn system. This moderate compositional adjustment significantly improves high-temperature bonding strength while keeping the overall material cost reasonable, achieving a balance between manufacturing cost and thermal performance.
Solution Approach 2:
By creating an AgCuSn composite intermetallic system, the invention achieves superior high-temperature bonding strength that outweighs the additional material cost. The composite structure provides enhanced thermal stability and bonding performance compared to simple CuSn compounds.
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 AgCuSn layer enhances bonding strength and reduces thermal resistance, ensuring high heat resistance and reliability of the semiconductor device, even at elevated temperatures, while maintaining cost-effectiveness without the use of lead.
Implementation Method 1
the formation of large Kirkendall voids and cracks at high temperatures, particularly when using CuSn-based intermetallic compounds without the addition of silver
Implementation Method 2
enhancing stress resistance, ensuring a continuous interface without cracks, thereby improving thermal conductivity and reliability
Data Source
AI summary
According to one embodiment, a semiconductor device includes: a semiconductor chip; and a first conductive layer provided on a side of a first surface of the semiconductor chip, wherein the first conductive layer includes an intermetallic compound layer containing copper (Cu), tin (Sn), and silver (Ag), and a concentration of the silver relative to the tin in the first conductive layer is equal to or greater than 1.0 at % and equal to or less than 7.9 at %.