Locally Reinforced Metallization for Power Semiconductor Heat Dissipation
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Solution Overview
Problem
Power semiconductor devices with a single metallization level face challenges in heat dissipation due to thick metal layers, which can cause structural issues such as bowing of the semiconductor substrate and limitations in structuring.
Innovation Solution
A method involving a semiconductor substrate with a first metal layer structure extending from an active area to an edge termination area, where a plating mask covers a second metal portion while leaving a first metal portion uncovered, allowing for the formation of a thick second metal layer structure in ohmic contact with the first metal portion, and subsequent etching using the upper metal layer as a mask to create a common metallization structure that enhances heat dissipation and reduces mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thick metal layer is used to dissipate heat in power semiconductor devices, then heat dissipation capability is improved, but structural issues such as bowing of the semiconductor substrate and limitations in structuring occur
Solution Approach 1:
The patent applies local quality by forming a thick metallization structure selectively only in the active area of the semiconductor device, while the edge termination area maintains a standard thin metallization structure. This is achieved through a multi-step process involving selective plating and etching operations that create different metallization thicknesses in different regions, allowing heat dissipation enhancement precisely where needed without causing substrate bowing across the entire device.
2Temperature
If a thick metal layer is used to dissipate heat, then thermal conductivity is improved, but structuring precision and device complexity increase
Solution Approach 1:
The patent segments the metallization formation process into distinct steps: forming a lower metal layer extending across both active and edge termination areas, forming an upper metal layer selectively in the active area, applying a plating mask to cover specific regions, performing selective plating to create a thick metallization structure only where needed, and using the upper metal layer as an etching mask. This segmentation allows precise control over metallization thickness and location, maintaining high structuring precision while achieving enhanced thermal conductivity.
3Temperature
If a thick metal layer is used for heat dissipation, then heat dissipation is improved, but the device structure becomes more complex
Solution Approach 1:
The patent merges multiple functions into the metallization structure: the lower metal layer provides both structural support and electrical connection across the entire device, while the upper metal layer and plated metal structure provide enhanced heat dissipation in the active area. The upper metal layer also serves dual purposes as both a conductive element and an etching mask during fabrication. This merging reduces overall process complexity compared to using separate structures for each function.
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 enables selective formation of thick metallization in active areas while maintaining fine structures in edge termination areas, improving heat dissipation and reducing substrate bowing, thus enhancing the device's thermal conductivity and mechanical stability.
Implementation Method 1
A second metal layer structure is plated at least on and in ohmic contact with the first metal portion, wherein the plating mask covers the second metal portion during plating of the second metal layer structure
Implementation Method 2
The lower metal layer of the first metal layer structure is etched using at least the upper metal layer as etching mask after plating of the second metal layer structure
Implementation Method 3
Metal layers are formed on semiconductor materials to provide a good ohmic contact to the semiconductor material and to dissipate heat generated in the semiconductor material during operation of semiconductor devices integrated in the semiconductor material
Data Source
AI summary
A semiconductor device includes a semiconductor substrate having a first side, at least a first area formed in the semiconductor substrate, at least a second area formed in the semiconductor substrate, a first metal layer structure having at least a first metal portion in the first area and at least a second metal portion in the second area, and a second metal layer structure on and in ohmic contact with the first metal portion in the first area while leaving the second metal portion of the first metal layer structure in the second area uncovered. The second metal layer structure and the first metal portion of the first metal layer structure form together a common metallization structure on the first side of the semiconductor substrate in the first area.