Super-junction Trench MOSFET with Closed Cell Layout
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Solution Overview
Problem
Conventional super-junction trench MOSFETs have longer termination areas, which occupy more space and increase costs, limiting their integration and cost-effectiveness in advanced semiconductor power devices.
Innovation Solution
A super-junction trench MOSFET design with a termination area of approximately 20 um in length, featuring a novel cell structure with P/N charge balance areas, doped column regions, and a channel stop region, along with a method for manufacturing that includes forming deep trenches, ion implantations, and depositing dielectric material with voids, reducing the need for multiple guard rings and minimizing device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple guard rings are used in the termination area, then device reliability is improved, but device area increases and cost increases
Solution Approach 1:
The patent changes the doping concentration parameter in the termination area by introducing a channel stop region with higher doping concentration than the epitaxial layer. This parameter change allows the termination area to achieve proper electrical termination without requiring multiple guard rings, thereby reducing the device area while maintaining reliability
Solution Approach 2:
The patent extracts and eliminates the multiple guard rings from the termination area design. By removing these redundant structures and replacing them with a simplified channel stop region, the device area is reduced while the essential termination function is preserved through the doped column regions and channel stop structure
2Reliability
If multiple guard rings are used in the termination area, then device reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent simplifies the manufacturing process by changing the structural parameters of the termination area. Instead of forming multiple guard rings through complex masking and doping steps, the invention uses a channel stop region with adjusted doping concentration, reducing the number of fabrication steps and lowering manufacturing cost while maintaining device reliability
Solution Approach 2:
The patent removes the multiple guard rings structure from the manufacturing process. This extraction eliminates the need for additional fabrication steps associated with creating and patterning multiple guard rings, thereby simplifying the manufacturing process and reducing production costs
3Area of stationary object
If termination area length is reduced, then device size and cost are reduced, but device reliability may deteriorate
Solution Approach 1:
The patent compensates for the reduced termination area length by changing the doping concentration parameter. The channel stop region is doped at a higher concentration than the epitaxial layer, which enhances the electrical termination effect and allows for a shorter termination area while maintaining adequate device reliability
Solution Approach 2:
The patent applies local quality enhancement by creating highly doped column regions and a channel stop region with concentrated dopant distribution in the termination area. This localized high doping concentration provides strong electrical termination in a compact space, enabling reduced device size without sacrificing reliability
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 design results in a more compact and cost-effective super-junction trench MOSFET with shorter termination length, enhancing flexibility and reducing production costs while maintaining performance.
Implementation Method 1
a method for manufacturing that includes forming deep trenches, ion implantations, and depositing dielectric material with voids
Data Source
AI summary
A super-junction trench MOSFET with closed cell layout is disclosed, wherein closed gate trenches surrounding a deep trench in each unit cell. Trenched source-body contacts are disposed between the closed gate trenches and the deep trench. The deep trench has square, rectangular, circle or hexagon shape.