Trench MOSFET Source Shield Structure for Faster Switching
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Solution Overview
Problem
Existing power semiconductor devices, particularly trench MOSFETs, face inefficiencies in switching between ON and OFF states due to charge accumulation between the gate and drain regions, which affects switching efficiency and performance.
Innovation Solution
The design incorporates a source conductive region with first and second connected parts, where the second part is positioned between the gate and first part of the source conductive region, reducing the charge between the gate and drain regions by optimizing the insulation regions and the configuration of the source conductive region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional source conductive region configuration is used, then the manufacturing process is simple, but the charge between the gate and drain regions is high, reducing switching efficiency
Solution Approach 1:
The source conductive region is divided into two distinct parts: a first part extending parallel to the trench sidewalls and a second part extending across the trench sidewalls. This segmentation allows the second part to act as a shield between the gate conductive region and the first part, reducing the charge between gate and drain regions. The segmented configuration improves switching efficiency by minimizing parasitic capacitance while maintaining manufacturing feasibility through sequential formation steps.
2Reliability
If the second part of the source conductive region is made taller, then the shielding effect is stronger, but the manufacturing precision requirements increase
Solution Approach 1:
The first insulation region is configured with non-uniform width: a first width in the lower portion and a second width in the upper portion, where the first width is larger than the second width. This local quality variation provides enhanced shielding in the critical upper region where the second part of the source conductive region is located, while maintaining larger clearance in the lower region for manufacturing tolerance. The differential width configuration optimizes the shielding effect without uniformly increasing manufacturing precision requirements throughout the entire structure.
Data Source
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AI summary
A semiconductor power device comprising an active region, the active region comprising a drift region of a first conductivity type, a body region of a second conductivity type provided over the drift region, wherein the second conductivity type is opposite to the first conductivity type, a trench in contact with the body region and the drift region, the trench comprising a gate conductive region, a source conductive region comprising first and second connected parts, the second part of the source conductive region being arranged between the gate conductive region and the first part of the source conductive region, a first insulation region arranged between the source conductive region and sidewalls of the trench, a second insulation region arranged between the source conductive region and the gate conductive region, and wherein the source conductive region is configured such that a first width of the first insulation region between each of the sidewalls of the trench and the first part of the source conductive region is larger than a second width of the first insulation region between each of the sidewalls of the trench and the second part of the source conductive region, and wherein a height of the second part is between 0.05 µm and 1/5 of a height of the first part of the source conductive region.