Trench Power Transistor Shield Electrode Field Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional trench power transistors face challenges in supporting high forward blocking voltage while maintaining low on-state resistance and high-frequency operation due to unsatisfactory gate-to-drain capacitance and doping concentration in the drift region.
Innovation Solution
The trench power transistor design includes a semiconductor body with a trench electrode structure featuring multiple insulating layers and a shield electrode, where the gate electrode is surrounded by a specific insulating layer to reduce interaction with nitride material, enhancing voltage withstand capability and reducing on-state resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the doping concentration in the drift region is reduced to support higher forward blocking voltage, then the voltage withstand capability is improved, but the on-state resistance increases
Solution Approach 1:
The patent introduces a shield electrode with specific insulating layers at the bottom of the trench, creating localized electric field control. This allows the drift region to have optimized doping concentration distribution - higher doping near the trench bottom where the shield electrode is located, and lower doping in upper regions. This local quality variation enables simultaneous achievement of high voltage withstand capability and low on-state resistance.
Solution Approach 2:
The shield electrode acts as an intermediary element between the gate electrode and the drift region. By introducing this intermediate structure with controlled insulating layers (first insulating layer and second insulating layer made of nitride material), the patent mediates the electric field distribution, allowing the drift region to maintain lower overall doping concentration for high voltage blocking while having localized high doping regions for low on-state resistance.
2Ease of operation
If the gate electrode volume is increased, then the gate control capability is improved, but the gate-to-drain capacitance increases
Solution Approach 1:
The patent introduces a vertical dimension to gate control by adding the shield electrode at the trench bottom, extending the gate structure's influence deeper into the drift region. This dimensional extension allows effective gate control with a more compact gate electrode volume, thereby reducing gate-to-drain capacitance while maintaining or improving control capability.
Solution Approach 2:
The gate control function is segmented into two parts: the main gate electrode for primary control and the shield electrode for extended field control. This segmentation allows the main gate electrode to be smaller in volume (reducing Cgd) while the shield electrode provides additional control depth, collectively achieving effective gate control with reduced capacitance.
3Ease of manufacture
If a simple trench electrode structure is used, then the manufacturing complexity is reduced, but the high-frequency switching characteristics are insufficient
Solution Approach 1:
The patent optimizes specific parameters of the insulating layers - the second insulating layer is made of nitride material with controlled thickness, and the shield electrode has specific dimensional parameters. These parameter changes enhance the electric field control and reduce parasitic effects, improving high-frequency switching characteristics while maintaining manufacturing feasibility through standard semiconductor processing techniques.
Data Source
AI summary
A trench power transistor includes a semiconductor body having opposite first and second surfaces, and including at least one active region. Such region includes a trench electrode structure, a well, and a source. The trench electrode structure has an electrode trench recessed from the first surface, and includes first, second, and third insulating layers sequentially disposed over bottom and surrounding walls of the electrode trench, a shield electrode enclosed by the third insulating layer, a fourth insulating layer disposed on the first, second, and third insulating layers, and a gate electrode surrounded by the fourth insulating layer. The second insulating layer made of a nitride material and the fourth insulating layer are different in material. A production method of the transistor is also disclosed.