MOSFET Termination Structure Curved Edge Charge Balance
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Solution Overview
Problem
Conventional MOSFET devices face challenges in achieving charge balance at high cell density, particularly at the edges or corners of the active area proximate the termination region, leading to reduced breakdown voltage due to over-shielding or under-shielding effects.
Innovation Solution
The MOSFET device incorporates a termination structure with a first edge adjacent to the gate structures and a second edge that is curved or scalloped, allowing for a balanced depletion of charge under the shield effect from both the termination and gate shield regions, thereby optimizing the breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high cell density is used to increase productivity, then the active area can be maximized, but charge balance cannot be achieved at the edges or corners proximate the termination region, leading to reduced breakdown voltage
Solution Approach 1:
The patent applies asymmetry by differentiating the treatment of termination regions at corners versus edges. Corner termination regions are configured differently from edge termination regions to account for the more severe charge imbalance and shielding effects at corner locations. This asymmetric approach allows high cell density in the active area while maintaining charge balance and breakdown voltage through specialized corner region design.
2Area of stationary object
If the termination region is positioned close to the active area to maximize device area, then space is optimized, but over-shielding or under-shielding effects occur at the edges or corners, reducing breakdown voltage
Solution Approach 1:
The patent applies local quality by providing different termination region configurations for different locations within the device. Corner termination regions have distinct properties from edge termination regions, which in turn differ from central active area regions. This localized differentiation ensures that each region's specific shielding and charge balance requirements are met, enabling maximum device area utilization while maintaining reliability through location-specific optimization.
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 enhances the breakdown voltage by ensuring balanced charge distribution, reducing the under-shielded or over-shielded issues, and achieving maximum breakdown voltage by evenly distributing charges across the gate shield regions.
Implementation Method 1
allowing for a balanced depletion of charge under the shield effect from both the termination and gate shield regions
Data Source
AI summary
A metal oxide semiconductor field effect transistor (MOSFET) device, and methods for manufacturing and using the same. In some implementations, the MOSFET device includes a plurality of gate structures which are parallel to each other and separated from each other, and a termination structure having a first edge adjacent to the plurality of gate structures and a second edge on a side of the termination structure opposite the first edge. Each of the plurality of gate structures has a curved edge adjacent to the first edge of the termination structure, and the second edge of the termination structure is curved concave to the curved edges of the plurality of gate structures.