Acute-Angle Vertical Trench Edge Termination for Semiconductor Reliability
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Solution Overview
Problem
Conventional semiconductor devices require large peripheral areas for high blocking voltage capabilities, leading to increased costs and processing complexity, especially for vertical edge-termination structures which can cause mechanical stress and switching losses due to trapped charges.
Innovation Solution
A semiconductor device with a dielectric structure forming an acute angle with the outer edge, surrounding the active area in a vertical trench, which reduces the electric field intensity and allows for a smaller edge termination area, utilizing a dielectric material that tolerates higher electric fields and guides charge carriers effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If planar edge-termination structures are used to achieve high blocking capability, then blocking voltage is improved, but peripheral area increases significantly
Solution Approach 1:
The patent transitions from planar (2D) edge-termination structures to vertical (3D) trench structures. The insulating structure extends vertically into the semiconductor substrate, creating a three-dimensional configuration that provides effective field termination while occupying minimal horizontal space. This dimensional change allows the same blocking capability to be achieved with dramatically reduced peripheral area.
Solution Approach 2:
The patent changes the geometric parameters of the edge-termination structure by forming vertical trenches with specific depth and width dimensions. The insulating structure extends to a depth that provides adequate field termination, while the trench width is optimized to minimize horizontal space occupation. This parameter optimization enables high blocking capability with compact peripheral footprint.
2Area of stationary object
If vertical trench structures are used to reduce peripheral area, then area is reduced, but mechanical stress increases
Solution Approach 1:
The patent applies different material properties to different regions of the vertical trench structure. The trenches are filled with insulating material that provides both electrical isolation and mechanical support. The surrounding semiconductor regions maintain their original properties, creating a localized solution that reduces stress concentration while preserving overall device integrity.
Solution Approach 2:
The edge-termination structure comprises a composite of semiconductor material and insulating material arranged in vertical trenches. This composite configuration allows the insulating material to bear part of the mechanical load while providing electrical termination, thereby distributing stress more effectively than a single-material structure would.
3Reliability
If insulating material is deposited in vertical trenches, then field termination is improved, but trapped charges increase causing switching losses
Solution Approach 1:
The patent introduces a carefully controlled insulating layer as an intermediary between the semiconductor regions. This insulating structure provides the necessary field termination function while its thickness and material properties are optimized to minimize charge trapping effects. The intermediary structure mediates between the conflicting requirements of field termination and charge storage.
Solution Approach 2:
The patent optimizes parameters of the insulating structure including thickness, material composition, and deposition conditions to minimize trapped charges. By controlling these parameters, the insulating structure provides effective field termination while reducing charge trapping that would otherwise cause switching losses.
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 achieves high blocking voltage with a significantly reduced peripheral area, minimizing mechanical stress and switching losses, while maintaining robustness against external contaminations and boundary conditions.
Implementation Method 1
The edge termination structure may, for example, lower the field intensity around the termination region of the rectifying junction by spreading the electric field lines across the termination region
Data Source
AI summary
A semiconductor device having a semiconductor die and an edge termination structure is provided. The semiconductor die includes an outer edge and an active area defining a main horizontal surface and being spaced apart from the outer edge. The edge termination structure includes at least one vertical trench having an insulated side wall forming, in a horizontal cross-section, an acute angle with the outer edge. The acute angle is lower than about 20°.