Interdigitated Gate Trench Layout for Power MOSFET
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Solution Overview
Problem
Trench power MOSFETs face challenges in optimizing both conduction and switching losses while maintaining high voltage blocking capability and low on-state resistance, which is crucial for automotive and industrial electronics applications.
Innovation Solution
The semiconductor device features a unique layout with a mesa separating two gate trenches, each comprising sections extending in a specific direction and connecting adjacent sections, forming a comb-like structure that interdigitates to enhance current flow and reduce overcompensation in the drift zone, thereby improving device characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional trench structures are used, then manufacturing is simpler, but conduction loss and switching loss cannot be optimized simultaneously
Solution Approach 1:
The gate trench is divided into multiple sections (first gate trench sections and second gate trench sections) that are arranged in an interdigitated pattern. This segmentation allows independent optimization of different trench sections, enabling reduced conduction loss through optimized current paths while maintaining voltage blocking capability, thus resolving the contradiction between energy loss reduction and structural complexity.
Solution Approach 2:
The patent transitions from a single-plane trench arrangement to a multi-dimensional interdigitated structure where first and second gate trench sections are disposed in different spatial relationships. This dimensional change creates multiple current flow paths and electric field distributions, allowing simultaneous optimization of conduction characteristics and voltage blocking without requiring excessive structural complexity.
2Area of stationary object
If gate trenches are arranged closely to reduce device area, then area is reduced, but voltage blocking capability and on-state resistance optimization become difficult
Solution Approach 1:
By segmenting the gate trench into first and second sections with different spatial arrangements, the patent creates distinct functional zones within a compact area. The first gate trench sections contribute to voltage blocking while the second sections optimize current conduction, allowing both reliability and area reduction to be achieved simultaneously.
Solution Approach 2:
Different sections of the gate trench are given different local characteristics - first gate trench sections are positioned to optimize voltage blocking in certain regions, while second gate trench sections are arranged to minimize on-state resistance in other regions. This local quality differentiation allows the device to achieve high voltage blocking capability and low on-state resistance within a reduced overall area.
3Device complexity
If conventional single trench design is used, then structure is simpler, but overcompensation in drift zone cannot be reduced
Solution Approach 1:
The segmented gate trench structure creates multiple electric field distribution patterns in the drift zone. The interdigitated first and second gate trench sections produce complementary field effects that reduce the need for overcompensation doping, thereby reducing overcompensation loss while maintaining a relatively simple overall structure.
Solution Approach 2:
The patent merges the functions of voltage blocking and current conduction into a unified interdigitated trench structure. By combining first and second gate trench sections in an alternating pattern, the structure achieves both voltage blocking and low on-state resistance simultaneously, reducing the need for separate compensation mechanisms and thereby reducing overcompensation loss.
Data Source
AI summary
A semiconductor device includes a first gate trench and a second gate trench in a first main surface of a semiconductor substrate. A mesa is arranged between the first gate trench and the second gate trench. The mesa separates the first gate trench from the second gate trench. Each of the first and second gate trenches includes first sections extending in a first direction and second sections connecting adjacent ones of the first sections. The second sections of the first gate trench are disposed opposite to the second sections of the second gate trench with respect to a plane perpendicular to the first direction.