Wide Bandgap Semiconductor Trench Insulator Thickness
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Solution Overview
Problem
Wide bandgap semiconductor devices face challenges in managing the electric field within the oxide in trenches, which can lead to high electrical stress and potential breakdown, especially when operating in blocking states.
Innovation Solution
The semiconductor device design incorporates a trench with a thick insulator at the bottom and a second electrode within the trench, along with a contiguous zone that extends beyond the trench, allowing for controlled voltage application to reduce the electric field within the insulator, thereby minimizing stress and preventing breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trench with insulator is used in wide bandgap semiconductor device, then electrical isolation is achieved, but electric field stress within the insulator increases leading to potential breakdown
Solution Approach 1:
The patent applies local quality by creating a non-uniform insulator thickness distribution within the trench, where the insulator is thicker at the bottom region and thinner at the top region. This localized variation in insulator thickness optimizes the electric field distribution, reducing stress concentration at critical interfaces while maintaining effective electrical isolation throughout the trench structure.
Solution Approach 2:
The patent changes the geometric parameter of the insulator from uniform thickness to non-uniform thickness, specifically making the bottom region thickness greater than the top region thickness by a factor of at least 1.5. This parameter change fundamentally alters the electric field distribution within the insulator, reducing the maximum electric field stress while maintaining the insulating function.
2Reliability
If insulator thickness is increased to reduce electric field stress, then breakdown prevention is improved, but device area and complexity increase
Solution Approach 1:
Rather than uniformly increasing insulator thickness throughout the entire trench (which would increase device area and complexity), the patent applies the thicker insulator only at the bottom region where electric field stress is most critical. This localized approach provides breakdown prevention where needed while minimizing the overall device footprint and structural complexity.
Solution Approach 2:
The patent resolves the thickness-complexity contradiction by transitioning from a one-dimensional uniform thickness approach to a spatially varying thickness profile within the trench. By making the insulator thickness a function of position (thicker at bottom, thinner at top), the solution achieves breakdown prevention without proportionally increasing the overall device area or manufacturing complexity.
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
This design effectively reduces the electric field within the insulator, enhancing the semiconductor device's reliability and performance by preventing electrical breakdown and allowing for efficient operation across a wide range of voltages and currents.
Implementation Method 1
this specification refers to embodiments of a wide bandgap semiconductor device that may exhibit a comparatively weak electric field within an oxide included in a trench
Data Source
AI summary
A semiconductor device includes a source zone electrically connected to a first load terminal, a contiguous zone isolating the source zone from a drift zone, and a trench extending into a semiconductor body along a vertical direction and including a first electrode electrically connected to a control terminal and an insulator in contact with the contiguous zone and which isolates the first electrode from the semiconductor body. The insulator has, at a trench bottom region, a first thickness along the vertical direction, and, at a trench top region, a second thickness along a lateral direction, the first thickness being greater than the second thickness by a factor of at least 1.5. The contiguous zone is arranged in contact with the insulator and extends further along the vertical direction than the trench, and the trench bottom region and the contiguous zone overlap along the lateral direction.