Semiconductor Device Thermal Strain Reduction via Composite Electrode
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Solution Overview
Problem
Existing semiconductor devices face reliability issues due to thermal expansion differences between materials, leading to defects such as poor connections and cracks, especially when using ceramics and copper, which can result in reduced operational reliability and increased risk of failure.
Innovation Solution
A semiconductor device design featuring plate-shaped substrates with integrated heat dissipation wiring patterns and a columnar electrode, where the thickness of the plate-shaped electrode is minimized to reduce thermal strain, and materials like molybdenum or tungsten are used to match the linear expansion coefficient of silicon carbide, enhancing heat dissipation and preventing peeling of heat dissipation members from the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat sink is brought into contact with the substrate to dissipate heat, then heat dissipation is improved, but distortion increases due to linear expansion coefficient difference between ceramic substrate and copper heat sink
Solution Approach 1:
An intermediate layer is introduced between the copper heat sink and the ceramic substrate. This intermediate layer has a linear expansion coefficient that matches the ceramic substrate, serving as a mediator that transfers heat while preventing distortion caused by the expansion coefficient mismatch between copper and ceramic materials.
Solution Approach 2:
The linear expansion coefficient parameter is matched by selecting appropriate materials for the intermediate layer. By changing the material parameters to match the ceramic substrate's expansion coefficient, the system achieves both effective heat dissipation and dimensional stability during temperature changes.
2Reliability
If copper is used for the first electrode to improve conductivity, then electrical conductivity is improved, but poor connection or solder crack occurs due to large linear expansion coefficient difference between copper and silicon carbide
Solution Approach 1:
A composite electrode structure is employed consisting of multiple layers: a copper layer for electrical conductivity, an intermediate layer with matched expansion coefficient for stress relief, and a solder layer for connection. This composite structure combines the advantages of different materials while mitigating their individual disadvantages.
Solution Approach 2:
An intermediate layer is inserted between the copper electrode and the silicon carbide semiconductor element. This intermediate layer acts as a mediator that accommodates the linear expansion difference, preventing direct stress transmission that would cause connection failures or solder cracks.
3Strength
If the thickness of the plate-shaped electrode is increased to improve structural strength, then strength is improved, but thermal strain and distortion increase
Solution Approach 1:
The thickness parameter of the plate-shaped electrode is optimized to a specific range that balances mechanical strength and thermal strain. By controlling the thickness within an appropriate range and selecting materials with matched expansion coefficients, the electrode maintains sufficient strength while minimizing thermal distortion.
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 design miniaturizes the semiconductor device, reduces internal thermal strain, and enhances reliability by effective heat dissipation and matching thermal expansion coefficients, thereby reducing the risk of defects and improving operational stability.
Implementation Method 1
a fourth wiring pattern that is a heat dissipation member... provided with a fourth wiring pattern that is a heat dissipation member
Implementation Method 2
due to a difference in a linear expansion coefficient between ceramics such as aluminum nitride that is a material of the substrate, and copper that is a material of the heat sink, distortion within the semiconductor device increases
Data Source
AI summary
A source terminal and a gate terminal are connected to a wiring pattern of the first substrate. A diode is provided under a second substrate such that an anode is connected to a wiring pattern of the second substrate. A plate-like portion of the first electrode is provided between the switching element and the diode, and a linking section of the first electrode connects the plate-like portion and the wiring pattern of the first substrate. A second electrode being substantially columnar and connecting the wiring pattern of the first substrate and the wiring pattern of the second substrate is provided in an opposite side to the linking section with the switching element interposed. A thickness of the plate-like portion of the first electrode is less than or equal to a thickness of each of the wiring pattern of the first substrate and the wiring pattern of the second substrate.