Double-Trench MOSFET Layout for Gate Corner Field Shielding
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Solution Overview
Problem
Vertical-channel MOSFETs face challenges in maintaining low on-resistance while ensuring the reliability of the gate trench structure due to high electric fields at the corner regions, which can degrade the gate dielectric layer.
Innovation Solution
A double-trench semiconductor device design with a source trench structure that protects the corner of the gate trench structure by controlling the top view area of the source trench structure to less than 20% of the device unit, ensuring the depletion region effectively shields the gate trench from high electric fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the gate trench structure is made deeper to reduce on-resistance, then the current capability is improved, but the reliability of the gate dielectric layer deteriorates due to high electric fields at corner regions
Solution Approach 1:
A source trench structure is introduced as an intermediary element between the source region and the gate trench structure. This source trench acts as a mediator that modifies the electric field distribution, preventing direct exposure of the gate dielectric layer to high electric fields at corner regions while maintaining the deep gate trench structure for current capability.
Solution Approach 2:
The source trench structure is positioned beforehand to cushion or shield the gate trench structure from high electric fields. By placing the source trench at a predetermined location and size (projection area between 10-30% of device unit), it creates a protective buffer zone that reduces electric field intensity at critical corner regions before the fields can affect the gate dielectric layer.
2Reliability
If the source trench structure is enlarged to protect the gate trench structure, then the reliability is improved, but the device area increases
Solution Approach 1:
The invention optimizes the parameters of the source trench structure, specifically controlling its projection area to be between 10-30% of the device unit area. This parameter optimization ensures sufficient protection for the gate trench structure while minimizing the additional area consumed, achieving a balance between reliability improvement and area efficiency.
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
The solution maintains low on-resistance while enhancing the reliability of the gate trench structure by properly sizing the source trench structure to protect the corner regions, thus improving the overall performance of the semiconductor device.
Implementation Method 1
ensuring the depletion region effectively shields the gate trench from high electric fields
Data Source
AI summary
A semiconductor device includes a substrate, a source trench structure, a gate trench structure and a drain electrode. The source trench structure is in the substrate. The gate trench structure is in the substrate, and a bottom of the gate trench structure is higher than a bottom of the source trench structure. The gate trench structure surrounds the source trench structure and defines a device unit, and a first projection area of the source trench structure along a fixed direction is less than 20% of a second projection area of the device unit along the fixed direction. The drain electrode is below the substrate.