Semiconductor Bonding Layer Using Ag3Sn Alloy
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Solution Overview
Problem
The existing semiconductor devices face defects such as cracks and peeling in the bonding between the lead and semiconductor element due to processes exceeding the melting point of Sn-based solder, which is around 240 degrees C or lower.
Innovation Solution
A semiconductor device is designed with a bonding layer containing an alloy of Sn and Ag, where the Ag3Sn alloy has a higher melting point, and this bonding layer is formed by heating and contacting a Sn-containing third layer with an Ag-containing surface layer on the support member, thereby increasing the bonding strength and suppressing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Sn-based solder is used for bonding the lead and semiconductor element, then the bonding process is simple and cost-effective, but the bonding layer has low melting point (around 240°C or lower) which causes defects such as cracks and peeling during mounting processes exceeding this temperature
Solution Approach 1:
The bonding layer is formed as a composite material containing both Sn and Ag metals in specific proportions (Sn: 70-90 mass%, Ag: 10-30 mass%). This composite structure combines the low melting point and good bondability of Sn with the high melting point and strength of Ag, creating a bonding layer that maintains integrity at high temperatures while remaining manufacturable through conventional processes
Solution Approach 2:
The invention changes the compositional parameters of the bonding layer by controlling the ratio of Sn to Ag metals. By adjusting these parameters within specific ranges, the bonding layer achieves an optimal balance between melting point, bondability, and high-temperature strength, resolving the contradiction between ease of manufacture and reliability
2Ease of manufacture
If Sn-based solder is used for bonding, then the bonding layer has good bondability and low cost, but it exhibits low strength and susceptibility to thermal stress
Solution Approach 1:
The bonding layer utilizes a composite material system combining Sn and Ag metals. The Sn component provides excellent bondability and ease of formation, while the Ag component contributes high strength and thermal stability. This composite approach allows the bonding layer to maintain both manufacturability and mechanical strength
3Reliability
If a higher melting point bonding material is used to prevent defects at high temperature, then bonding reliability improves, but the bonding process becomes more complex and costly
Solution Approach 1:
Rather than completely changing the bonding material system, the invention modifies the compositional parameters of existing Sn-based solder by adding Ag metal within specific proportion ranges. This parameter adjustment achieves high-temperature reliability while maintaining compatibility with conventional bonding processes and cost structures
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 use of the Ag3Sn alloy in the bonding layer raises the melting point, preventing cracks and peeling during mounting processes, improving manufacturing efficiency, and reducing thermal stress, while also enhancing thermal conductivity and bonding strength.
Implementation Method 1
the bonding layer contains an alloy of first metal and second metal
Implementation Method 2
forming a bonding layer that is interposed between the semiconductor element and the support member and contains an alloy of the first metal and the second metal, by contacting and heating the third layer and the surface layer
Implementation Method 3
forming a bonding layer that is interposed between the semiconductor element and the support member and contains an alloy of the first metal and the second metal, by contacting and heating the third layer and the surface layer
Data Source
AI summary
A semiconductor device includes a semiconductor element, a support member, and a bonding layer interposed between the semiconductor element and the support member, wherein the bonding layer contains an alloy of first metal and second metal.