Buried Shield Structures for Gate Trench Electric Field Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Power semiconductor devices face challenges with high electric field degradation at gate trench corners, leading to potential device failure, especially in gate trench devices where electric fields are concentrated, and conventional doping methods in wide bandgap semiconductors like silicon carbide and gallium nitride are inefficient due to uneven dopant distribution and lattice damage.
Innovation Solution
The implementation of buried shielding structures of a second conductivity type within the drift region, laterally extending under and spaced apart from the well regions and gates, reduces electric field levels in the gate insulating layer and provides electrical contact between contact shielding structures and the bottom shield structure, allowing for improved current flow and reduced active area loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gate trench structures are used in power semiconductor devices, then device performance is improved, but electric field concentration at gate trench corners causes high electric field degradation and potential device failure
Solution Approach 1:
A buried shielding structure of second conductivity type is introduced as an intermediary element between the gate trench and the drift region. This shielding structure extends laterally under the gate trench and is spaced apart from it, creating a protective intermediate zone that redistributes and reduces electric field concentration at the gate trench corners, thereby preventing electric field degradation while maintaining device performance
Solution Approach 2:
The shielding structure is positioned in the lateral dimension under the gate trench rather than directly at the corner points, and extends in the depth dimension into the drift region. This multi-dimensional positioning allows the shielding structure to effectively intercept and redistribute electric field lines before they concentrate at the vulnerable corner points, reducing peak electric field intensity
2Ease of manufacture
If conventional doping methods are used in wide bandgap semiconductors, then device fabrication is attempted, but uneven dopant distribution and lattice damage occur due to inefficient doping
Solution Approach 1:
The shielding structure is formed with a specific lateral extent that is localized under the gate trench region, creating a locally optimized structure that addresses the electric field concentration problem precisely where it occurs without requiring extensive doping of the entire device structure. This localized approach improves manufacturing precision while maintaining ease of fabrication
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 buried shielding structures effectively reduce electric field concentrations, enhance current conduction, and increase the active area for electrical conduction, thereby improving the reliability and performance of power semiconductor devices by minimizing the impact of high electric fields and optimizing the device's active area usage.
Implementation Method 1
buried shielding structures of a second conductivity type within the drift region... reduces electric field levels in the gate insulating layer
Implementation Method 2
provides electrical contact between contact shielding structures and the bottom shield structure, allowing for improved current flow
Data Source
AI summary
A semiconductor device includes a semiconductor layer structure having a drift region of a first conductivity type and a well region of a second conductivity type above the drift region. A gate is provided on the semiconductor layer structure adjacent the well region. A buried shielding structure of the second conductivity type is provided under the well region and separated from the well region by a portion of the drift region. Related devices and fabrication methods are also discussed.