SiC Terminal Member with Intermediate Thermal Expansion
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Solution Overview
Problem
The use of SiC semiconductor chips in double-sided heat dissipation structures poses a risk of cracking due to the higher Young's modulus of SiC compared to silicon, leading to potential failures in bonding members and thermal stress issues.
Innovation Solution
A semiconductor device configuration with a terminal member composed of multiple metal layers, where the coefficient of linear expansion is set between that of the SiC chip and the heat sinks, and symmetrically arranged to reduce thermal stress and warpage, using a clad member with a Cu layer and an alloy layer containing Cu and Cr to manage expansion and stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a terminal member is used to electrically interconnect the second heat sink and the semiconductor chip, then connection reliability is improved, but thermal stress and warpage occur due to coefficient of linear expansion mismatch
Solution Approach 1:
The terminal member is constructed as a composite structure with a first metal layer (e.g., Cu or Al) providing electrical conductivity and a second metal layer (e.g., alloy containing Cr, Mo, or W) providing controlled thermal expansion characteristics. This composite structure enables the terminal member to have a coefficient of linear expansion that is intermediate between the semiconductor chip and the heat sink, thereby reducing thermal stress while maintaining electrical connection reliability.
2Ease of manufacture
If the terminal member is made of a single metal layer, then manufacturing is simple, but it cannot simultaneously match the thermal expansion properties of both the semiconductor chip and heat sink
Solution Approach 1:
The terminal member employs a multi-layer composite structure where each layer serves a specific function: the first metal layer ensures electrical conductivity and bonding compatibility with the semiconductor chip, while the second metal layer adjusts the overall coefficient of linear expansion to match the heat sink. This composite approach achieves thermal expansion compatibility with both components while maintaining manufacturing feasibility through established metallurgical processes.
3Temperature
If SiC semiconductor chips are used in double-sided heat dissipation structures, then heat dissipation performance is improved, but cracking risk increases due to higher Young's modulus
Solution Approach 1:
The invention modifies the thermal expansion parameters of the terminal member by using a multi-layer metal structure with an intermediate coefficient of linear expansion. This parameter adjustment creates a gradual transition in thermal expansion properties across the bonding interfaces, reducing thermal stress concentration and preventing cracking in the SiC semiconductor chip while maintaining effective heat dissipation performance.
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
This configuration effectively reduces thermal stress on bonding members and the semiconductor chip, suppresses warpage, and enhances heat dissipation while maintaining connection reliability, suitable for SiC-based semiconductor devices.
Implementation Method 1
The terminal member as a whole has a coefficient of linear expansion at least in a direction orthogonal to the plate thickness direction in a range larger than that of the semiconductor chip and smaller than that of the second heat sink
Implementation Method 2
The first heat sink and second heat sink are disposed so as to interpose the semiconductor chip therebetween... so that the first heat sink is adjacent to the one surface of the semiconductor chip and the second heat sink is adjacent to the rear surface of the semiconductor chip
Data Source
AI summary
A semiconductor device includes a semiconductor chip made of a SiC substrate and having main electrodes on one surface and a rear surface, first and second heat sinks, respectively, disposed adjacent to the one surface and the rear surface, a terminal member interposed between the second heat sink and the semiconductor chip, and a plurality of bonding members disposed between the main electrodes, the first and second heat sinks, and the terminal member. The terminal member includes plural types of metal layers symmetrically layered in the plate thickness direction. The terminal member as a whole has a coefficient of linear expansion at least in a direction orthogonal to the plate thickness direction in a range larger than that of the semiconductor chip and smaller than that of the second heat sink.