Trench-Gate Semiconductor Device With Outside Trench Corner Protection
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Solution Overview
Problem
In trench-gate semiconductor devices, the concentration of electric fields at the corners of outside trenches leads to a decrease in the reliability of the insulating film due to high voltage applications, causing potential disconnection of the gate line and breakdown of the insulating film at the open ends of these trenches.
Innovation Solution
A semiconductor device design that includes a p-type second impurity region at the corner of the outside trench, which increases the resistance and reduces the electric field applied to the insulating film, thereby enhancing the reliability by forming a gate line leading portion to cover the corner of the open end of the outside trench and electrically connecting the gate electrode to the gate line through an insulating film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gate line leading portion is formed to cover the corner of the outside trench to prevent disconnection, then the mechanical strength and connection reliability are improved, but the electric field concentration at the corner increases causing insulating film breakdown
Solution Approach 1:
An insulating film is introduced as an intermediary layer between the gate line leading portion and the drift layer at the corner of the outside trench. This insulating film mediates the interaction by providing electrical isolation, thereby preventing electric field concentration and insulating film breakdown while maintaining the mechanical protection and electrical connection functions of the gate line leading portion.
Solution Approach 2:
The corner region of the outside trench is given a different structure from the rest of the gate line leading portion. Specifically, the insulating film is formed only at the corner portion where electric field concentration occurs, while other regions maintain direct electrical contact. This local differentiation resolves the contradiction by addressing the specific problem area without compromising the overall connection reliability.
2Reliability
If the outside trench is formed to grade the electric field at the outermost cell region, then the withstand performance is improved, but the corner of the outside trench becomes a point of electric field concentration reducing insulating film reliability
Solution Approach 1:
The corner region of the outside trench is given a different structure from the rest of the trench. The insulating film is formed specifically at the corner portion where electric field concentration occurs, while other regions of the outside trench maintain their original structure for electric field grading. This local differentiation allows the corner to be protected from breakdown while the rest of the trench continues to provide withstand performance enhancement.
Solution Approach 2:
The insulating film acts as an intermediary element at the corner of the outside trench, separating the high electric field region from the metal gate line leading portion. This intermediary layer prevents direct interaction between the concentrated electric field and the conductive material, thereby preventing breakdown while allowing the outside trench to maintain its electric field grading 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
The increased resistance of the p-type second impurity region reduces the electric field applied to the insulating film, improving the reliability and preventing disconnection and breakdown, thus enhancing the overall performance and longevity of the semiconductor device.
Implementation Method 1
the surface layer of the drift layer that is in contact with the corner has a second impurity region of p-type, and the second impurity region is a part of the well region
Data Source
AI summary
A trench-gate semiconductor device including an outside trench, increases reliability of an insulating film at a corner of an open end of the outside trench. The semiconductor device includes: a gate trench reaching an inner part of an n-type drift layer in a cell region; an outside trench outside the cell region; a gate electrode formed inside the gate trench through a gate insulating film; a gate line formed inside the outside trench through an insulating film; and a gate line leading portion formed through the insulating film to cover a corner of an open end of the outside trench closer to the cell region, and electrically connecting the gate electrode to the gate line, and the surface layer of the drift layer in contact with the corner has a second impurity region of p-type that is a part of the well region.