Semiconductor Dummy Trench Segmentation for Current Balance

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Solution Overview

Problem

Current semiconductor devices with gate and dummy trenches experience current unbalance due to differing hole accumulation effects between the substrate end and center portions, leading to inconsistent on-resistance and switching losses.

Innovation Solution

A semiconductor device design featuring a third dummy trench orthogonal to the gate and other dummy trenches, positioned closer to the substrate center than the p-type well layer, separates the p-type diffusion layers between the substrate center and end portions, maintaining uniform hole accumulation and reducing current unbalance without compromising on-voltage and switching loss trade-offs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If dummy cell region is used to improve hole accumulation effect, then trade-off between on-voltage and switching loss is improved, but current unbalance occurs between substrate end portion and center portion

Engineering Contradiction:

Improveswitching lossVSAvoidcurrent unbalance

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The dummy cell region is segmented into substrate end portion and substrate center portion through the third dummy trench. This segmentation allows independent electrical connection control, where the substrate end portion is connected to the emitter electrode while the substrate center portion is isolated by the interlayer insulating film, preventing harmful current flow and achieving current balance across the substrate.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different electrical connection configurations are applied to different regions: the substrate end portion dummy cell region is connected to the emitter electrode to utilize hole accumulation effect, while the substrate center portion dummy cell region is isolated by the interlayer insulating film to prevent current unbalance. This local differentiation resolves the contradiction between energy loss reduction and reliability improvement.

Inventive Principle:

Principle #3Local quality

2Stability of the object's composition

If third dummy trench is provided closer to substrate center than p-type well layer, then separation function is maintained and hole accumulation uniformity is improved, but device structure becomes more complex

Engineering Contradiction:

Improvehole accumulation uniformityVSAvoidtrench structure

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The third dummy trench is positioned closer to the substrate center than the p-type well layer to segment the dummy cell region into distinct electrical zones. This segmentation ensures that the substrate center portion is properly isolated while maintaining the hole accumulation effect in the substrate end portion, achieving uniform hole accumulation across the device.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The third dummy trench is oriented orthogonally to the first and second dummy trenches, introducing a new spatial dimension to the trench structure. This orthogonal arrangement enables effective separation of the substrate center portion from the emitter electrode while maintaining the beneficial hole accumulation effect, resolving the contradiction between uniformity and structural complexity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 effectively reduces current unbalance across the substrate while preserving the trade-off relationship between on-voltage and switching loss, ensuring consistent performance by maintaining uniform hole accumulation across the substrate.

Implementation Method 1

the third dummy trench separates the p-type diffusion layer in the dummy cell region of the substrate center portion from the p-type diffusion layer in the dummy cell region of the substrate end portion connected to the emitter electrode

Methodology Applied

Scientific EffectPhysical separation through trench structure:

Implementation Method 2

It is possible, through a hole accumulation effect of a dummy cell region, to improve a trade-off relationship between an on-voltage and switching loss

Methodology Applied

Scientific EffectHole accumulation effect:

Implementation Method 3

an interlayer insulating film insulating the p-type diffusion layer in the dummy cell region of a substrate center portion situated between the first and second dummy trenches from the emitter electrode

Methodology Applied

Scientific EffectElectrical insulation:

Data Source

PatentUS10355082B2Semiconductor device including active and dummy cell regions

Publication Date: 2019.07.16 MITSUBISHI ELECTRIC CORP

AI summary

A third dummy trench (11) is orthogonal to the first and second dummy trenches (9,10) in the dummy cell region of a substrate end portion. An interlayer insulating film (13) insulates the p-type diffusion layer (3,4) in the dummy cell region of a substrate center portion situated between the first and second dummy trenches (9,10) from the emitter electrode (14). The third dummy trench (11) separates the p-type diffusion layer (3,4) in the dummy cell region of the substrate center portion from the p-type diffusion layer (3,4,15) in the dummy cell region of the substrate end portion connected to the emitter electrode (14). A p-type well layer (15) is provided deeper than the third dummy trench (11) in the substrate end portion. The third dummy trench (11) is provided closer to a center of the n-type substrate than the p-type well layer (15).