Trench Power Semiconductor Termination for Lower Switching Loss
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Solution Overview
Problem
Power semiconductor devices face challenges with increased gate-drain charge leading to reduced charging/discharging speed and switching loss, particularly due to the capacitance of the device affecting the charge balance, especially in high-integration scenarios.
Innovation Solution
The design incorporates a trench structure with vertically stacked termination electrode field plates in the termination region, which are either both connected to the source or one is floating, allowing for adjustable electric field distribution and improved charge balance through the selection of trench number and electrode connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the integration of power semiconductor devices is increased, then the device density and functionality are improved, but the gate-drain charge increases which reduces charging/discharging speed and affects device performance
Solution Approach 1:
The device structure is segmented into distinct regions including trench gates, drift regions, and termination regions. The trench gate structure divides the gate-drain capacitance path, reducing the effective gate-drain charge while maintaining high integration density through vertical stacking and regional specialization.
Solution Approach 2:
The patent transitions from planar device integration to vertical three-dimensional structuring with trench gates extending into the substrate. This dimensional change allows higher device density without proportionally increasing gate-drain charge, as the capacitance is distributed across multiple vertical levels rather than spreading horizontally.
2Loss of energy
If the capacitance of the device is reduced to reduce gate-drain charge and improve switching loss, then the switching loss is reduced, but the charge balance of the device becomes more complex
Solution Approach 1:
Different regions of the device are optimized with different properties: the active region uses trench gates for low capacitance and low switching loss, while the termination region uses conventional structures for voltage blocking. This local differentiation reduces overall switching loss while distributing charge balance requirements across specialized regions rather than requiring complex global optimization.
Solution Approach 2:
The drift region acts as an intermediary between the trench gate region and the termination region, providing a transition zone that manages charge distribution. This intermediate region with graded doping profiles helps balance charges between the low-capacitance active region and the high-voltage termination region, simplifying overall charge balance while maintaining low switching losses.
3Quantity of substance
If a separate gate structure is used to reduce gate-drain area and capacitance, then the gate-drain charge is reduced, but the charge balance of the device is complicated
Solution Approach 1:
The trench gate structure nests the gate electrode within a trench formed in the semiconductor substrate, with the gate surrounded by drift region and termination structures. This nested configuration reduces the exposed gate-drain area and capacitance while the surrounding structured regions provide natural charge balancing paths, avoiding the need for complex external charge balance circuits.
Data Source
AI summary
A power semiconductor device includes an epitaxial layer of a first conductivity type, a plurality of trench device. The epitaxial layer includes an active region and a termination region. A plurality of trench devices are respectively located in a plurality of device trenches in the epitaxial layer in the active region. A contact metal layer is located on an insulating layer and continuously covering the active region and the termination region. A plurality of termination electrodes are respectively located in a plurality of termination trenches in the epitaxial layer in the termination region and electrically isolated from the epitaxial layer. Each of the plurality of termination electrodes includes a lower electrode and an upper electrode. A first end termination electrode, a second end termination electrode, and a first middle termination electrode of the plurality of termination electrodes are electrically connected to the contact metal layer.