Dense Trench Transistor Cell Array with Shallow Diodes
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Solution Overview
Problem
There is a need for a semiconductor device that optimizes the trade-off between area-specific on-state resistance and avalanche strength in dense trench transistors, as existing technologies face challenges in achieving both desirable breakdown characteristics and reliability.
Innovation Solution
The semiconductor device incorporates a dense trench transistor cell array with specific relationships between the width of the transistor mesa region and the trench, including semiconductor diodes with differing depths and electrode configurations, to shift avalanche breakdown from the transistor cells to the diodes, thereby optimizing electrical breakdown voltages and current capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the trench depth is increased to improve breakdown characteristics, then avalanche strength improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies different trench depths to different functional regions: deeper trenches for transistors requiring high breakdown voltage, and shallower trenches for diodes handling avalanche breakdown. This local differentiation optimizes each region's performance while simplifying manufacturing compared to uniform deep trenches across the entire device.
Solution Approach 2:
The device is segmented into distinct functional zones with different trench characteristics. Transistor regions have deeper trenches for high breakdown voltage, while diode regions have shallower trenches for controlled avalanche breakdown. This segmentation allows independent optimization of each region's trench depth according to its specific functional requirements.
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 effectively maintains the dense trench transistor concept while shifting avalanche breakdown to the semiconductor diodes, preventing unintended drifting of electrical device parameters and enhancing thermal dissipation, thus improving the trade-off between on-state resistance and avalanche strength.
Implementation Method 1
shifting avalanche breakdown from the transistor cells to the diodes, thereby optimizing electrical breakdown voltages
Data Source
AI summary
One embodiment of a semiconductor device includes a dense trench transistor cell array. The dense trench transistor cell array includes a plurality of transistor cells in a semiconductor body. A width w3 of a transistor mesa region of each of the plurality of transistor cells and a width w1 of a first trench of each of the plurality of transistor cells satisfy the following relationship: w3<1.5×w1. The semiconductor device further includes semiconductor diodes. At least one of the semiconductor diodes is arranged between first and second parts of the plurality of transistor cells and includes a diode mesa region adjoining opposing walls of second trenches. A depth d1 of the first trench and a depth d2 of the second trenches differ by at least 20%.