Semiconductor Switching Element Dual Trench Gate Design
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Solution Overview
Problem
In semiconductor switching elements, the reduction in breakdown voltage occurs when the charge storage layer fails to be depleted upon interruption, especially when trench-type gate electrodes are partially omitted to suppress current during short-circuiting.
Innovation Solution
A semiconductor switching element design that includes a charge storage layer, base region, emitter region, conductive region, first gate electrode, and second gate electrode, where the second trench is smaller in depth and width than the first trench, allowing for effective depletion of the charge storage layer during OFF state and maintaining breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If trench-type gate electrodes are partially omitted to suppress current during short-circuiting, then current suppression is improved, but breakdown voltage reduces
Solution Approach 1:
The gate electrode structure is segmented into two types: first gate electrodes in first trenches that extend through the charge storage layer for current suppression, and second gate electrodes in second trenches that extend deeper to maintain breakdown voltage. This segmentation allows each gate electrode type to perform its specific function independently, resolving the contradiction between current suppression and breakdown voltage maintenance.
Solution Approach 2:
Different regions of the semiconductor device have different gate electrode configurations: regions with first gate electrodes focus on current suppression during short-circuiting, while regions with second gate electrodes focus on maintaining breakdown voltage. This local differentiation allows the device to optimize performance in different operational conditions simultaneously.
2Quantity of substance
If charge storage layer is provided to reduce ON resistance, then ON resistance is reduced, but breakdown voltage reduces when charge storage layer fails to be depleted
Solution Approach 1:
The second gate electrodes are positioned to extend deeper than the charge storage layer, creating a preliminary structural arrangement that ensures the charge storage layer can be effectively depleted when voltage is applied. This preliminary positioning prevents the charge storage layer from failing to deplete, thereby maintaining breakdown voltage while still benefiting from reduced ON resistance.
Solution Approach 2:
The second gate electrodes act as intermediaries that extend into the charge storage layer region, facilitating its depletion during voltage application. These gate electrodes mediate between the charge storage layer and the applied voltage, ensuring proper depletion occurs and preventing breakdown voltage reduction.
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 effectively suppresses the reduction in breakdown voltage and reduces parasitic capacitance, preventing increased current flow and maintaining switching speed.
Implementation Method 1
The first gate electrode is disposed, via a first gate insulating film, inside a first trench that extends from an upper surface of the emitter region to reach the semiconductor layer, and intersects with the emitter region, the base region, and the charge storage layer. The second gate electrode is disposed, via a second gate insulating film, inside a second trench that extends from the upper surface of the emitter region and an upper surface of the conductive region to reach the semiconductor layer
Data Source
AI summary
A semiconductor switching element includes a first gate electrode and a second gate electrode. The first gate electrode is disposed, via a first gate insulating film, inside a first trench that extends from an upper surface of an emitter region to reach a semiconductor layer, and intersects with the emitter region, a base region, and a charge storage layer. The second gate electrode is disposed, via a second gate insulating film, inside a second trench that extends from the upper surface of the emitter region and an upper surface of a conductive region to reach the semiconductor layer, and is adjacent to the emitter region, the base region, the charge storage layer, and the conductive region. The second trench is smaller in depth than the first trench, and the second trench is smaller in width than the first trench.