IGBT Third Trench Gate Isolates P+ Bars
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Solution Overview
Problem
Existing power semiconductor devices face challenges with high on-state and switching losses, limited blocking capability, and increased conduction losses due to the presence of highly doped p+ bars, which also lead to drainage of holes accumulated during the conduction state.
Innovation Solution
The design incorporates a third trench gate electrode that disconnects the highly doped p+ bar from the base layer on the side of the second gate unit, preventing hole drainage and maintaining low conduction losses while enhancing blocking capability, and this trench gate electrode is manufactured simultaneously with the first gate unit without additional masks, improving charge accumulation and reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If highly doped p+ bars are used to provide alternative path for holes during dynamic avalanche, then reliability is improved, but conduction losses increase due to low impedance path enabling hole drainage
Solution Approach 1:
The device is segmented into active cell regions with controlled p+ bars and dummy trench regions with deep p-type bars. The third trench gate electrodes divide the base layer, preventing hole drainage from active cells to dummy trenches while maintaining avalanche protection in active regions.
Solution Approach 2:
Different regions have different p-type bar configurations: active cells have controlled p+ bars for avalanche protection, while dummy trenches have deep p-type bars that are electrically isolated from the base layer to prevent unwanted hole drainage paths.
2Loss of energy
If deep p-type bars are arranged below planar gate electrodes to prevent hole drainage, then conduction losses are reduced, but blocking capability is limited
Solution Approach 1:
The solution extends into the vertical dimension by creating deep trenches that penetrate through the base layer to isolate deep p-type bars. This vertical segmentation prevents lateral hole drainage while maintaining the beneficial low conduction losses in active cell regions.
3Manufacturing precision
If additional masks are used to manufacture third trench gate electrodes for disconnecting p+ bars, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The manufacturing process merges the formation of third trench gate electrodes with the existing first gate unit fabrication. Both are created simultaneously using the same mask and etching processes, eliminating additional manufacturing steps while achieving precise alignment.
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 configuration reduces on-state and switching losses, improves blocking capability, and maintains low conduction losses while being easier to manufacture, ensuring robustness against dynamic avalanche and efficient charge handling.
Implementation Method 1
The third trench gate electrodes are arranged between one of the at least two planar gate electrodes and the second gate unit such that at least one first and third trench gate electrodes are electrically connected and form a second shape closed in itself so that the second shape encloses the second gate unit
Implementation Method 2
Each first trench gate electrode has a first electrically conductive layer and a first insulating layer, wherein each first electrically conductive layer is separated from any layer of the first or second conductivity type, which adjoins said first trench gate electrode, by one of the at least two first insulating layers
Data Source
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AI summary
An IGBT is provided having a first gate unit having first trench gates with first conductive layers and planar gates with second conductive layers. A second gate unit having a second trench gates may be connected to the emitter electrode, with the first and second conductive layers forming a first shape closed in itself and enclosing the second gate unit. Third trench gates are arranged between a planar gate and the second gate unit such that first and third trench gates are connected and form a second shape closed in itself by which the second gate unit is enclosed. P+ doped bars below the planar gale contact the emitter electrode with each third trench gate separating a bar and a planar gate electrode from the second gate unit, with a p doped base layer separating the second gate unit from the enclosing second shape.