Semiconductor Device With Dummy Trench Suppression Structure
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Solution Overview
Problem
Semiconductor devices with IGBTs face increased turn-on loss due to the formation of P-type inversion layers in N-type regions adjacent to dummy trenches, which is not effectively addressed by existing technologies.
Innovation Solution
The semiconductor device incorporates a suppressing structure, including a dummy trench with a thicker insulating film and a specific doping concentration distribution, to prevent the formation of P-type inversion layers, and features a gate trench and accumulation region design that penetrates deeper than the dummy trench, with a mesa portion between them where the base region is not connected to the emitter electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a dummy trench is provided in the semiconductor device, then the manufacturing process is simplified and device structure is enhanced, but a P-type inversion layer is formed in the N-type region adjacent to the dummy trench, causing increased turn-on loss
Solution Approach 1:
The patent applies local quality by creating a suppressing structure with specific doping concentration distribution (higher doping concentration in the N-type region adjacent to the dummy trench) and thicker insulating film only in the local area where the inversion layer forms. This localized modification prevents the P-type inversion layer formation without changing the entire device structure, thereby reducing turn-on loss while maintaining the benefits of the dummy trench configuration.
Solution Approach 2:
The patent changes physical parameters by increasing the doping concentration in the N-type region adjacent to the dummy trench and increasing the insulating film thickness in the suppressing structure. These parameter changes raise the potential barrier and suppress the formation of P-type inversion layers, effectively reducing turn-on loss while preserving the dummy trench's manufacturing advantages.
2Reliability
If the gate trench penetrates deeper than the dummy trench, then the gate control over the drift region is improved, but the device complexity increases
Solution Approach 1:
The patent segments the trench structure into functionally distinct parts: the gate trench that penetrates deeper into the drift region for improved gate control, and the dummy trench that terminates earlier and is้ ๅ with the suppressing structure. This segmentation allows each trench type to perform its specific function optimally without requiring complete structural redesign, balancing improved reliability with manageable device complexity.
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 reduces turn-on loss and enhances conductivity modulation, improving the switching speed and avalanche capability of the semiconductor device by suppressing the formation of P-type inversion layers and optimizing carrier extraction.
Implementation Method 1
a first conductivity-type accumulation region formed between the drift region and the base region in the semiconductor substrate and having a higher doping concentration than the drift region
Implementation Method 2
enhances conductivity modulation, improving the switching speed and avalanche capability
Implementation Method 3
The dummy trench portion may include a dummy trench insulating film formed on the inner wall of a trench and having a greater thickness than the gate insulating film
Implementation Method 4
At least one of the accumulation region and the dummy trench portion may have a suppressing structure that suppresses formation of a second conductivity-type inversion layer in a first conductivity-type region adjacent to the dummy trench portion
Implementation Method 5
The gate trench portion may include a gate conductive portion covered by the gate insulating film. The dummy trench portion may include a dummy conductive portion covered by the dummy trench insulating film
Implementation Method 6
improving the switching speed and avalanche capability of the semiconductor device
Data Source
AI summary
A semiconductor device is provided, including: a first conductivity-type drift region formed in the semiconductor substrate; a second conductivity-type base region formed between the upper surface of the semiconductor substrate and the drift region; a first conductivity-type accumulation region formed between the drift region and the base region and having a higher doping concentration than the drift region; and a dummy trench portion formed to penetrate the base region from the upper surface of the semiconductor substrate, wherein at least one of the accumulation region and the dummy trench portion has a suppressing structure that suppresses formation of a second conductivity-type inversion layer in a first conductivity-type region adjacent to the dummy trench portion.