SiC Guard Ring with Localized Impurity at Corners

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Solution Overview

Problem

The variation in characteristics of semiconductor devices due to trapped external or injected charges in the oxide film of the termination region leads to degradation in device reliability, particularly affecting the breakdown voltage.

Innovation Solution

The semiconductor device incorporates a silicon carbide layer with strategically designed guard ring regions having dot-line or line shapes with increased p-type impurity concentration at corner portions, which suppresses the trapping of charges and maintains a stable electric field distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If charges are trapped in the oxide film of the termination region, then the electric field distribution is changed, but the breakdown voltage varies and reliability degrades

Engineering Contradiction:

Improvedevice reliabilityVSAvoidcharge trapping effect

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating guard ring regions with different impurity concentrations at different locations. Specifically, corner portions of the termination region are equipped with guard rings having higher impurity concentration compared to other regions, providing localized charge compensation where it is most needed to counteract charge trapping effects and maintain electric field distribution.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the impurity concentration parameter of the semiconductor regions to solve the problem. By adjusting the impurity concentration in the guard ring regions (making it higher than in other termination region portions), the patent modifies the electrical characteristics to compensate for charge trapping, thereby stabilizing the breakdown voltage and improving reliability.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If external charges or injected charges are trapped in the oxide film, then the electric field distribution changes, but the breakdown voltage stability deteriorates

Engineering Contradiction:

Improvebreakdown voltage stabilityVSAvoidcharge injection and trapping

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent implements preliminary anti-action by pre-configuring guard ring regions with specific impurity concentrations before the device operates. These guard rings are designed in advance to counteract the harmful effects of charge trapping that will occur during operation, thereby preventing breakdown voltage instability before it happens.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

Inventive Principle:

Principle #3Local quality

3Reliability

If the termination region has uniform structure, then manufacturing is simple, but charge trapping causes electric field distortion and reliability issues

Engineering Contradiction:

Improvebreakdown voltage consistencyVSAvoidtermination region structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent resolves this contradiction by introducing local quality variations in the termination region. Instead of a completely uniform structure, the patent creates specific guard ring regions with differentiated impurity concentrations at critical locations (corner portions), which provides the necessary charge compensation while maintaining relative structural simplicity for manufacturing.

Inventive Principle:

Principle #3Local quality

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 configuration enhances the reliability of the semiconductor device by reducing the variation in breakdown voltage and improving the margin of influence from external and injected charges, thereby maintaining consistent performance.

Implementation Method 1

the electric field distribution in the termination region is changed

Methodology Applied

Scientific EffectElectric field distribution: Electric Field

Data Source

PatentUS11728386B2Semiconductor device

Publication Date: 2023.08.15 KK TOSHIBA

AI summary

A semiconductor device of embodiments includes a silicon carbide layer including an element region and a termination region around the element region, the termination region having first straight-line portions extending in a first direction, second straight-line portions extending in a second direction, and corner portions between the first straight-line portions and the second straight-line portions, the termination region including a second-conductivity-type second silicon carbide region having a dot-line shape with first dot portions and first space portions surrounding the element region, an occupation ratio of the first dot portions is larger in the corner portions than in the first straight-line portions, and a second-conductivity-type third silicon carbide region having a dot-line shape with second dot portions and second space portions surrounding the second silicon carbide region, an occupation ratio of the second dot portions is lager in the corner portions than in the first straight-line portions.