Semiconductor Termination Floating Region Depth Depletion
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Solution Overview
Problem
Conventional semiconductor devices require a larger termination domain to increase breakdown voltage, which is inefficient in terms of space usage.
Innovation Solution
A semiconductor device design where a conductive type floating region is only formed in the termination domain, allowing the depletion layer to spread in the depth direction of the semiconductor substrate, thereby increasing breakdown voltage without the need for lateral expansion of the termination domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the termination domain is spread laterally to increase breakdown voltage, then the breakdown voltage is improved, but the space in the termination domain where device structure is not formed must be enlarged
Solution Approach 1:
The patent changes the direction of depletion layer expansion from lateral (in-plane) to vertical (depth direction). By forming a first conductive type floating region at the bottom of the termination trench, the depletion layer is induced to extend in the depth direction of the semiconductor substrate rather than spreading laterally. This dimensional change allows breakdown voltage enhancement without increasing the lateral area of the termination domain.
Solution Approach 2:
The patent modifies the electrical parameters by introducing a floating region with specific conductivity type at the bottom of the termination trench. This floating region changes the electric field distribution and depletion layer behavior, enabling the depletion layer to penetrate deeper into the substrate. This parameter change achieves higher breakdown voltage while maintaining a compact termination domain footprint.
2Reliability
If a first conductive type floating region is provided at the bottom of the gate trench, then the device structure is modified, but the breakdown voltage cannot be effectively increased
Solution Approach 1:
The patent applies local quality by placing the floating region specifically at the bottom of the termination trench rather than at the gate trench bottom. This localized placement in the termination domain (not in the element domain with gate trench) creates the necessary electric field modulation only where needed for breakdown voltage enhancement, without complicating the gate structure in the element domain.
Solution Approach 2:
The patent segments the semiconductor device into element domain and termination domain, applying different structures to each. The floating region is exclusively placed in the termination domain at the termination trench bottom, while the gate trench in the element domain maintains its conventional structure. This segmentation allows structural modification only where it serves the breakdown voltage function.
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 increases breakdown voltage while reducing the required space in the termination domain, enhancing the semiconductor device's performance without the need for lateral expansion.
Implementation Method 1
a depletion layer extending from a P-N junction of the first drift region and the first body region when the semiconductor device is turned off spreads in a depth direction of the semiconductor substrate in the termination domain
Data Source
AI summary
A semiconductor device 10 includes an element domain 40 and a termination domain 50 that surrounds the element domain 40. The element domain 40 and the termination domain 50 respectively include a second conductive type drift region 18. A gate trench 38 may be provided in the element domain 40. The termination domain 50 may be provided with a termination trench 22 surrounding the element domain. A first conductive type floating region surrounded by the drift region 18 is not provided at a bottom of the gate trench 38, and a first conductive type floating region 20 surrounded by the drift region 18 is provided at a bottom of the termination trench 22.