Sense IGBT Floating Region Depth for Current Detection Accuracy
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Solution Overview
Problem
In IGBTs with a trench configuration, the absence of an emitter electrode in certain regions leads to inadequate electron spread and a loss of balance between electrons and holes, resulting in inaccurate electric current detection, which affects the precision of electric-current sensing devices.
Innovation Solution
The electric-current sensing device incorporates a sense IGBT with a drift region, buffer layer, collector layer, trench gates, emitter region, channel region, and floating region, where the depth of the floating region is shallower than in the main IGBT, ensuring accurate current detection by maintaining electron balance even under emitter electrode non-arranging regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an emitter electrode non-arranging region is provided in the IGBT, then the adjusting margin for electrode arrangement is improved, but the electron spread becomes insufficient and the balance between electrons and holes is lost
Solution Approach 1:
The invention introduces a floating region specifically in the emitter electrode non-arranging region to locally compensate for the lack of electrons. This floating region has different properties (conductive type and depth) than the drift region, creating local electron supply exactly where needed without affecting other regions. This resolves the contradiction by maintaining electron-hole balance in the specific problem area while preserving the adjusting margin benefit.
Solution Approach 2:
The floating region acts as an intermediary between the emitter electrode and the drift region. It mediates the electron supply issue by providing electrons to the drift region from its stored supply, enabling the emitter electrode non-arranging region to function properly without direct emitter electrode coverage. This intermediary structure resolves the electron spread problem while maintaining the design flexibility.
2Reliability
If the floating region depth is increased to improve electron supply, then the electron spread improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The invention optimizes the floating region depth parameter to be within a specific range (0.5-5.0 μm) that balances electron supply capability with manufacturing feasibility. By carefully controlling this parameter, the invention achieves adequate electron supply without creating excessive structural complexity or manufacturing difficulty. The depth parameter is tuned to provide just enough electron supply while maintaining simplicity.
3Measurement precision
If a floating region is added to maintain electron balance, then the current detection accuracy is improved, but the device structure becomes more complex
Solution Approach 1:
The floating region is introduced only in the emitter electrode non-arranging region where it is specifically needed for current detection accuracy, rather than throughout the entire device. This localized approach maintains measurement precision in the critical area while minimizing overall structural complexity. The floating region's conductive type and depth are specifically tailored to the detection requirements.
Data Source
AI summary
There are provided an electric-current sensing device capable of detecting an electric current with high accuracy, a load driving system, and a method for manufacturing the electric-current sensing device. According to one embodiment, the electric-current sensing device includes a sense IGBT through which an electric current proportional to an electric current flowing through a main IGBT flows. Further, a depth of a P type floating region from a lower end of each of a plurality of trench gates provided in the sense IGBT is shallower than a depth of another P type floating region from a lower end of each of a plurality of trench gates provided in the main IGBT.