Cu Bonding Layer Structure to Limit SiC Thermal Diffusion
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Solution Overview
Problem
Semiconductor power devices generate significant heat during operation, leading to potential failures due to low heat-resistant bonding materials, especially when copper-based fillet layers come into contact with SiC-based semiconductor elements, causing thermal diffusion and cracking.
Innovation Solution
A bonded body with a Cu-containing bonding layer that includes an extending portion spaced apart from the semiconductor element, manufactured by applying a composition containing Cu and a solid reducing agent, forming a coating film, drying it, and sintering it under pressure to minimize Cu diffusion and enhance heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Cu-based bonding layer is used to replace Ag-based bonding layer, then manufacturing cost is reduced, but Cu diffusion into semiconductor element occurs causing element failure
Solution Approach 1:
The bonding layer is segmented into two distinct parts: a first bonding layer in direct contact with the semiconductor element that prevents Cu diffusion, and a second bonding layer containing Cu that provides cost-effective thermal conductivity. This segmentation allows each layer to perform its specific function without the harmful effects of Cu diffusion into the semiconductor element.
Solution Approach 2:
The first bonding layer acts as an intermediary barrier between the Cu-containing second bonding layer and the semiconductor element. This intermediate layer prevents direct contact and thermal diffusion of Cu into the semiconductor element while still allowing the Cu-based bonding structure to provide the desired cost and thermal performance benefits.
2Volume of moving object
If bonding layer is placed close to semiconductor element for compactness, then device size is reduced, but thermal diffusion of Cu into semiconductor element increases
Solution Approach 1:
The bonding structure is divided into two functional layers with the first bonding layer serving as a protective interface layer that is directly contact with the semiconductor element, while the second bonding layer provides Cu-based thermal management. This segmentation enables compact design while preventing harmful thermal diffusion.
Solution Approach 2:
The first bonding layer functions as an intermediary protective barrier that physically separates the Cu-containing second bonding layer from the semiconductor element, preventing thermal diffusion while maintaining compact device geometry. This intermediate layer is essential for preventing harmful effects in compact designs.
3Ease of manufacture
If soldering material with low heat-resistance is used, then bonding process is simpler, but module failure occurs under high temperature
Solution Approach 1:
The bonding structure uses a composite configuration combining two different bonding materials: a first bonding layer material that provides high heat resistance and compatibility with semiconductor elements, and a Cu-based second bonding layer material that provides thermal conductivity and cost benefits. This composite structure achieves both manufacturing simplicity and high-temperature reliability.
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 a bonded body with high heat resistance and reduced Cu diffusion into the semiconductor element, preventing cracking and maintaining the element's characteristics, while offering sufficient strength and electrical conductivity at a lower manufacturing cost compared to Ag-based bonding layers.
Implementation Method 1
heating the stack while applying a pressure thereto to sinter the metal powder to thereby bond the conductor and the semiconductor element together
Implementation Method 2
thermal diffusion of Cu into the semiconductor element occurs in a high-temperature environment that is created during driving
Data Source
AI summary
A bonded body is provided including: a bonding layer containing Cu; and a semiconductor element bonded to the bonding layer. The bonding layer includes an extending portion laterally extending from a peripheral edge of the semiconductor element. In a cross-sectional view in a thickness direction, the extending portion rises from a peripheral edge of a bottom of the semiconductor element or from the vicinity of the peripheral edge of the bottom of the semiconductor element, and includes a side wall substantially spaced apart from a side of the semiconductor element. Preferably, the extending portion does not include any portion where the side wall and the side of the semiconductor element are in contact with each other. A method for manufacturing a bonded body is also provided.