Semiconductor Device Capacitance Adjusting Region
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Solution Overview
Problem
Existing insulated gate bipolar transistors (IGBTs) face challenges in improving the frequency response of input and feedback capacitances, which limits their ability to follow the switching speed, leading to increased switching losses.
Innovation Solution
A semiconductor device with a capacitance adjusting region that includes a p-type semiconductor layer, an n+-type source layer, and control trench gates, where the control trench electrodes are connected to the gate electrode, enhancing the frequency response of the input and feedback capacitances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a built-in capacitance is added to increase input capacitance, then the gate-emitter capacitance is increased, but the frequency response of the capacitance deteriorates and cannot follow the switching speed of the IGBT
Solution Approach 1:
The capacitance adjusting region is divided into multiple control trench gates, each capable of independently forming capacitance with the semiconductor layers. This segmentation allows the capacitance to be distributed across multiple small units rather than one large capacitance structure, improving frequency response while maintaining total input capacitance.
Solution Approach 2:
The control trench electrodes are electrically connected to the gate electrode, making the capacitance dynamic and controllable during switching operations. The capacitance value can change in response to gate voltage changes, allowing it to follow the switching speed of the IGBT rather than being a fixed built-in capacitance.
2Loss of energy
If the ratio between input capacitance and feedback capacitance is adjusted to reduce switching loss, then switching loss is reduced, but the frequency response of both capacitances deteriorates
Solution Approach 1:
By connecting the control trench electrodes to the gate electrode, the capacitance in the capacitance adjusting region becomes dynamic and responsive to gate voltage changes. This allows the capacitance ratio to be optimized for reduced switching loss while maintaining the ability to follow high-frequency switching operations.
Solution Approach 2:
The capacitance values and their ratio can be adjusted by modifying the structure and dimensions of the control trench gates and semiconductor layers, while the dynamic connection to the gate electrode ensures these parameters can adapt during operation to maintain both low switching loss and high frequency response.
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 semiconductor device improves the frequency response of input and feedback capacitances, allowing for optimized ratio adjustment between input and feedback capacitances, thereby reducing switching losses without altering the IGBT configuration.
Implementation Method 1
an input capacitance and a feedback capacitance are formed at a trench gate during driving of the IGBT
Implementation Method 2
The control trench insulating film is formed on an inner wall of a trench that penetrates the second semiconductor layer from the upper surface of the semiconductor substrate
Data Source
AI summary
A semiconductor device includes a capacitance adjusting region. The capacitance adjusting region includes a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, and a plurality of control trench gates. The first semiconductor layer is provided as a surface layer at an upper surface of the semiconductor substrate. The second semiconductor layer is selectively provided at an upper surface of the first semiconductor layer. The second semiconductor layer contacts a side surface of each of the control trench gates. The first semiconductor layer and the second semiconductor layer are electrically connected to an emitter electrode of a transistor. A control trench electrode of at least one control trench gate is electrically connected to a gate electrode of the transistor.