Copper Electrode Thickness Optimization for Semiconductor Chip Cooling
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Solution Overview
Problem
The challenge is to enhance the cooling effect of semiconductor chips while minimizing the stress and warp caused by thick copper electrodes, which can lead to cracks and voids in the solder, thereby improving the reliability of power semiconductor devices.
Innovation Solution
The use of copper electrodes with specific thickness ranges (5 μm to 50 μm) on both planes of the semiconductor chip, along with additional elements like iron, cobalt, or nickel, to balance stress and maintain effective cooling, is proposed. The electrodes are formed using an electroplating method with controlled thickness variations and additional element segregation to reduce tensile stress and prevent solder protrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thickness of copper electrodes is increased to enhance cooling effect, then temperature suppression is improved, but stress in electrodes increases and warp of semiconductor chips becomes large
Solution Approach 1:
The patent optimizes the thickness parameter of copper electrodes to a specific range (5 μm to 50 μm) to achieve the desired cooling effect while maintaining acceptable stress levels. This parameter optimization resolves the contradiction by finding the optimal thickness value that balances thermal performance with mechanical stability.
Solution Approach 2:
The patent employs composite electrode structures combining copper with other materials (such as tungsten or molybdenum) to achieve both high thermal conductivity for cooling and appropriate mechanical properties for stress management. The composite structure allows simultaneous achievement of temperature suppression and stress control.
2Temperature
If the thickness of copper electrodes is increased to enhance cooling effect, then temperature suppression is improved, but cracks and voids in solders are produced
Solution Approach 1:
The patent controls electrode thickness within the range of 5 μm to 50 μm to prevent excessive warp that would cause solder cracks and voids. This parameter control ensures both effective cooling and maintenance of solder joint integrity, resolving the reliability issue.
Solution Approach 2:
The patent employs stress management techniques during the electrode formation process to prevent excessive warp before soldering occurs. By controlling the electrode structure and stress distribution in advance, the patent prevents solder cracks and voids from forming during subsequent packaging processes.
3Temperature
If the thickness of copper electrodes is increased to enhance cooling effect, then thermal conductivity is improved, but device complexity increases
Solution Approach 1:
The patent simplifies the electrode structure by optimizing copper thickness to a specific range (5 μm to 50 μm) rather than using excessively thick electrodes. This parameter optimization achieves effective cooling while maintaining manufacturing simplicity and avoiding unnecessary device complexity.
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 approach effectively suppresses temperature rise due to heat generation, balances electrode stress, prevents cracks and voids, and enhances the reliability of semiconductor chips by maintaining optimal thickness and material distribution.
Implementation Method 1
copper having high thermal conductivity is used for electrodes provided on top planes of semiconductor chips. The copper electrodes cool semiconductor chip, and suppress a rise in a temperature caused by heat generation
Implementation Method 2
The electrodes are formed using an electroplating method with controlled thickness variations
Data Source
AI summary
A semiconductor device according to an embodiment includes a first electrode pad containing copper as a main component and having a thickness equal to or more than 5 μm and less than 50 μm; an electrode layer containing copper as a main component and having a thickness equal to or more than 5 μm and less than 50 μm; and a semiconductor layer provided between the first electrode pad and the electrode layer.