IGBT Collector Segmentation for Snap-back Suppression

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Solution Overview

Problem

Existing semiconductor devices experience a snap-back phenomenon during turn-on due to high resistance in the low concentration region, leading to increased current and voltage oscillations, while also facing sharp current decreases and noise at turn-off.

Innovation Solution

The semiconductor device incorporates a semiconductor substrate with a diode region and an IGBT region, featuring a collector region with vertical contact portions that facilitate carrier movement between the buffer region and low concentration regions, reducing impedance and preventing snap-back, and accumulates carriers in low concentration regions to mitigate sharp current decreases and noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a low concentration region with lower impurity concentration is provided between the buffer region and collector region, then carriers are accumulated during on-state to suppress sharp current decrease and noise at turn-off, but carriers are hindered from moving through the low concentration region at turn-on causing snap-back phenomenon

Engineering Contradiction:

Improvenoise at turn-offVSAvoidsnap-back phenomenon at turn-on

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The collector region is divided into multiple contact portions (first contact portions) that are distributed between the low concentration regions. This segmentation allows carriers to bypass the high-resistance low concentration regions through alternative paths provided by the contact portions, preventing snap-back while maintaining the noise suppression function of the low concentration regions during turn-off.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first contact portions act as intermediary regions that facilitate carrier movement between the buffer region and low concentration regions. These contact portions provide low-resistance paths that mediate the carrier flow, allowing carriers to move freely during turn-on without being hindered by the high resistance of the low concentration regions, thus preventing snap-back phenomenon.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the low concentration region has lower impurity concentration to accumulate carriers and suppress noise, then the resistance of the low concentration region increases, but this high resistance hinders carrier movement at turn-on

Engineering Contradiction:

Improvecurrent stability at turn-offVSAvoidcarrier movement at turn-on

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The collector region is segmented into multiple first contact portions that create parallel conduction paths. This segmentation reduces the overall resistance by providing multiple routes for carrier flow, compensating for the high resistance of the low concentration regions while maintaining their carrier accumulation capability for noise suppression.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The impurity concentration parameter is varied spatially across different regions. The low concentration regions have lower impurity concentration for carrier accumulation, while the first contact portions have higher impurity concentration to provide low-resistance paths. This parameter change strategy optimizes both noise suppression and carrier movement properties in different locations.

Inventive Principle:

Principle #35Parameter changes

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 effectively suppresses the snap-back phenomenon during turn-on and reduces noise and sharp current decreases during turn-off, ensuring stable operation by allowing unhindered carrier flow and efficient current management.

Implementation Method 1

carriers are accumulated in the low concentration region when the IGBT is in an on-state

Methodology Applied

Scientific EffectCarrier accumulation:

Implementation Method 2

The carriers, which have been accumulated in the low concentration region move to the collector region

Methodology Applied

Scientific EffectCarrier movement:

Implementation Method 3

the collector region comprises a first contact portion that is in contact with the buffer region between the low concentration regions adjacent to each other

Methodology Applied

Scientific EffectCarrier transport:

Data Source

PatentUS10600782B2Semiconductor device

Publication Date: 2020.03.24 DENSO CORP

AI summary

A semiconductor device may include a semiconductor substrate. A semiconductor substrate may include a diode region and an IGBT region provided adjacent to the diode region. The IGBT region may include a plurality of first conductive-type low concentration regions provided between a buffer region and a collector region, arranged with intervals therebetween in a direction parallel to the semiconductor substrate, and having a lower impurity concentration than the collector region. The collector region may include a first contact portion that is in contact with the buffer region between the low concentration regions adjacent to each other.