Semiconductor Superjunction Device Charge Balance

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Solution Overview

Problem

In semiconductor devices, the formation of a super-junction structure in the main body and current detecting regions can lead to a decrease in reverse breakdown voltage due to charge imbalance between p-type and n-type impurities, especially when an edge termination structure is present.

Innovation Solution

A semiconductor device design that includes a main body region, a current detecting region, and an intermediate region with alternating conductivity-type columns, where the intermediate region features a field plate and diode portions adjacent to both regions, helping to maintain charge balance and reverse breakdown voltage through a superjunction structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a super-junction structure is formed in the main body region and current detecting region, then ON-state resistance is reduced, but reverse breakdown voltage decreases due to charge imbalance between p-type and n-type impurities

Engineering Contradiction:

ImproveON-state resistanceVSAvoidreverse breakdown voltage

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The semiconductor substrate is divided into three distinct regions: main body region, intermediate region, and current detecting region. Each region has specific structural characteristics - the main body and current detecting regions contain super-junction structures with alternating p-type and n-type columns, while the intermediate region contains only n-type columns without high concentration regions, creating a gradual transition that maintains charge balance while enabling low resistance and high breakdown voltage

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The intermediate region acts as a transition zone between the main body region and current detecting region. It contains n-type columns that extend from the drift region but lacks the high concentration regions found in other areas, serving as a buffer that maintains electric field distribution and charge balance, thereby preventing breakdown voltage degradation while allowing the super-junction structures in adjacent regions to achieve low ON-state resistance

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If an edge termination structure is added to surround the current detecting region, then device reliability is improved, but charge balance is lost in the super-junction structure

Engineering Contradiction:

Improvedevice reliabilityVSAvoidcharge balance

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

Different regions are assigned different structural qualities: the main body and current detecting regions have super-junction structures with both p-type and n-type columns for low resistance, while the intermediate region has only n-type columns to maintain charge balance near the edge termination structure. This local differentiation allows the edge termination structure to improve reliability without causing charge balance loss in the overall device

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 design effectively maintains high reverse breakdown voltage and reduces ON-state resistance by ensuring charge balance between p-type and n-type impurities, while also allowing for precise current detection and mitigating electric field concentration.

Implementation Method 1

the reverse breakdown voltage decreases in some cases due to the charge balance being lost between p-type and n-type impurities in the super-junction structure

Methodology Applied

Scientific EffectCharge balance between p-type and n-type impurities:

Implementation Method 2

an intermediate region that is provided between the main body region and the current detecting region and inside the semiconductor substrate and that includes an edge termination structure unit

Methodology Applied

Scientific EffectElectric field distribution: Electric Field

Implementation Method 3

In the intermediate region, a diode portion may be formed in a region adjacent to the main body region and in a region adjacent to the current detecting region

Methodology Applied

Scientific EffectDiode detection: Diode

Data Source

PatentUS10157911B2Semiconductor device

Publication Date: 2018.12.18 FUJI ELECTRIC CO LTD

AI summary

In a semiconductor device having an SJ structure, the reverse breakdown voltage decrease is suppressed while a main body region and a current detecting region are separated. Provided is a semiconductor device that has a semiconductor substrate, a main body region including one or more operation cells formed inside the semiconductor substrate, a current detecting region including one or more current detecting cells formed inside the semiconductor substrate, and an intermediate region that is provided between the main body region and the current detecting region and inside the semiconductor substrate and that includes an edge termination structure unit. A first conductivity-type column and a second conductivity-type column are alternately arranged at equal intervals in the main body region, the current detecting region, and the intermediate region.