Semiconductor Edge Termination Using Lateral Trench-Gate Transistors
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Solution Overview
Problem
Existing semiconductor devices with trenched electrode structures face premature breakdown due to high electric fields at the perimeter of the active area, requiring additional processing for effective field termination structures.
Innovation Solution
A semiconductor device with a termination structure comprising a series of lateral trench-gate transistor devices connected from the active area to the peripheral edge, where each device has a gate electrode separated by insulating material, sharing process steps with the active area features to minimize extra processing and distribute voltage evenly, thereby reducing high electric field peaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a field termination structure is added to prevent premature breakdown at the perimeter, then device reliability is improved, but device complexity and processing steps increase
Solution Approach 1:
The termination structure uses the same trench-gate fabrication process steps as the active area devices, merging the formation of both structures into a single integrated process flow. This eliminates separate processing steps while maintaining the voltage-blocking function at the perimeter.
Solution Approach 2:
The trench-gate structure serves dual functions: it acts as the active switching element in the active area and simultaneously provides field termination at the perimeter. This multi-functionality eliminates the need for dedicated termination structures with separate processing.
2Ease of manufacture
If lateral trench-gate devices are used for termination, then manufacturing complexity is reduced by sharing process steps, but device area increases
Solution Approach 1:
The trench-gate structures in the termination area are configured with specific local characteristics (extending through the first conductivity type region and partway through the second conductivity type region) that enable voltage distribution, allowing compact arrangement while maintaining manufacturing simplicity.
3Reliability
If the gate electrode extends through the first conductivity type region and partway through the second conductivity type region, then voltage distribution is improved, but manufacturing precision requirements increase
Solution Approach 1:
The trench-gate structures are formed with predetermined depth characteristics during the standard fabrication process, establishing the voltage-distributing field configuration before final device assembly. This preliminary structuring enables reliable voltage distribution without requiring post-fabrication adjustments.
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 effectively supports voltage up to the sum of the threshold voltages of the lateral devices, reducing the need for additional processing steps and minimizing the area required for the termination structure, while increasing the breakdown voltage and reducing the number of lateral devices needed.
Implementation Method 1
each lateral device comprising a trench having a gate electrode therein separated from the semiconductor body by a layer of gate insulating material
Implementation Method 2
such that a voltage difference between the active area and the peripheral edge is distributed across the lateral devices
Data Source
AI summary
A semiconductor device having a semiconductor body comprising an active area and a termination structure surrounding the active area, and a method for the manufacture thereof. The invention particularly concerns a termination structure for such devices having trenched electrodes in the active area. The termination structure comprises a plurality of lateral trench-gate transistor devices connected in series and extending from the active area towards a peripheral edge of the semiconductor body. The lateral devices are arranged such that a voltage difference between the active area and the peripheral edge is distributed across the lateral devices. The termination structure is compact and features of the structure are susceptible for formation in the same process steps as features of the active area.