Asymmetric Trench Gate Depth for Power MOS Transistor Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor devices, particularly power MOS transistors, breakdowns can occur due to excessive voltage, leading to current flow through the trench gate electrode, which fluctuates gate capacitance and affects transistor characteristics, especially when the power supply is reversely connected.
Innovation Solution
A semiconductor device design featuring two power MOS transistors with trench gate electrodes of different depths, where the first trench gate electrode is shallower than the second, to prevent characteristic fluctuations during breakdowns by directing current flow through the columnar body instead of the trench gate electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If two power MOS transistors with super junction structure are connected in series to reduce on-resistance, then the on-resistance is reduced, but the gate capacitance fluctuates during breakdown causing characteristic changes
Solution Approach 1:
The patent applies local quality by creating asymmetric trench gate electrode structures where the first power MOS transistor has a shallower trench gate electrode and the second has a deeper trench gate electrode. This local structural differentiation ensures that during breakdown, current flows through the columnar body rather than through the trench gate electrode, preventing gate capacitance fluctuation and maintaining characteristic stability while preserving the low on-resistance benefit of the super junction structure.
2Strength
If the trench gate electrode is made deeper to improve breakdown voltage, then withstand voltage is improved, but current may flow through the trench gate during breakdown causing characteristic fluctuation
Solution Approach 1:
The patent applies asymmetry by designing the first trench gate electrode to be shallower than the second trench gate electrode. This asymmetric configuration, combined with the columnar body structure, creates a preferential current path through the columnar body during breakdown rather than through the trench gate electrode. The asymmetry in trench depth ensures that the deeper trench provides better breakdown voltage while the shallower trench prevents gate capacitance fluctuation, resolving the contradiction between withstand voltage and characteristic stability.
Data Source
AI summary
A semiconductor device for suppressing a variation in characteristics caused by a current flowing at the time of breakdown is disclosed. The first power MOS transistor Q 1 and the column CLM are formed in the first element region FCM defined in the epitaxial layer NEL, and the second power MOS transistor Q 2 is formed in the second element region RCM. The first power MOS transistor Q 1 includes a first trench gate electrode TGE1, and the second power MOS transistor Q 2 includes a second trench gate electrode TGE2. The depth GDP1 of the first trench gate electrode TGE1 is shallower than the depth GDP2 of the second trench gate electrode TGE2.