IGBT Bent Trench Gate Reduces On-Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing insulated-gate bipolar transistors (IGBTs) face challenges in reducing on-resistance without increasing manufacturing costs, as reducing mesa width requires fine processing, which is costly.
Innovation Solution
The IGBT design features a semiconductor substrate with a trench extending in a bent shape, an insulating film covering the trench's inside surface, and specific regions for the emitter, body, drift, and collector, allowing high hole concentration near the inside corner portions of the trench, reducing electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the mesa width is reduced to lower on-resistance, then the on-resistance decreases, but the manufacturing cost increases due to the need for fine processing
Solution Approach 1:
The patent applies curvature by forming the trench gate electrode with rounded corners instead of sharp corners. This curved geometry at the inside corner portions modifies the electric field distribution, enabling hole concentration in the drift region without requiring reduced mesa width, thus lowering on-resistance without increasing manufacturing cost
Solution Approach 2:
The patent applies local quality by creating a specific structural feature at the inside corner portions of the trench where the insulating film is formed. This localized curved geometry at specific positions (inside corners) generates the desired electric field effect to concentrate holes in the drift region, achieving low on-resistance without affecting the overall mesa width
2Loss of energy
If the mesa width is reduced to lower on-resistance, then the on-resistance decreases, but the manufacturing precision requirements increase
Solution Approach 1:
The rounded corner geometry of the trench gate electrode provides a more tolerant manufacturing structure compared to sharp corners. The curvature radius can be controlled within a reasonable range without requiring extreme precision, while still achieving the desired hole concentration effect in the drift region
Solution Approach 2:
The patent changes the geometric parameter of the trench from sharp corners to rounded corners with a specific curvature radius. This parameter change modifies the electric field distribution to achieve hole concentration without requiring reduction of the mesa width, thereby avoiding the need for high-precision fine processing
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 lowers the on-resistance of the IGBT without the need for fine processing, reducing manufacturing costs and inhibiting latch-up and saturation current, while maintaining low electrical resistance.
Implementation Method 1
allowing high hole concentration near the inside corner portions of the trench, reducing electrical resistance
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
In an IGBT (10), a trench (70a, 70b) extending in a bent shape to have a corner is formed in an upper surface of a semiconductor substrate. The inside of the trench (70a, 70b) is covered with an insulating film. A gate is placed inside the trench (70a, 70b). An emitter and a collector are formed on an upper surface and a lower surface of the semiconductor substrate, respectively. An emitter region, a body region, a drift region, and a collector region are formed in the semiconductor substrate. The emitter region is formed of an n-type semiconductor, is in contact with the insulating film, and is in ohmic contact with the emitter electrode. The body region is formed of a p-type semiconductor, is in contact with the insulating film below the emitter region, is in contact with the insulating film of an inner corner portion (72-1, 72-2) of the trench (70a, 70b), and is in ohmic contact with the emitter electrode.