IGBT High-Concentration Region for Reverse Leakage

Solution Overview

Problem

Existing reverse blocking insulated gate bipolar transistors (IGBTs) face issues with high reverse leakage current due to the influence of high-concentration p-type body regions, leading to reduced forward and reverse withstand voltages, and complex manufacturing processes, which can result in oscillating voltage and current waveforms during turn-on and reverse recovery, potentially causing device breakdown.

Innovation Solution

A semiconductor device with a high-concentration region of the first conductivity type, separated from the channel forming region, and a drawing region surrounding the channel forming region, connected to the main electrode regions, along with a withstand voltage structure and isolation region, is designed to reduce reverse leakage current by controlling the depletion layer and maintaining desired withstand voltages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a high-concentration p-type body region is provided to improve device structure, then the device structure is enhanced, but reverse leakage current increases and withstand voltage decreases

Engineering Contradiction:

Improvedevice structureVSAvoidreverse leakage current

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by providing a high-concentration p-type body region only in specific areas (at least one of: near the collector region, near the channel forming region, or in a portion between them) rather than uniformly throughout the entire drift region. This localized approach allows the high-concentration region to provide structural enhancement and carrier management where needed, while avoiding the generation of excessive reverse leakage current that would occur with a uniform high-concentration structure throughout the entire device.

Inventive Principle:

Principle #3Local quality

2Reliability

If a high-concentration p-type body region is provided to improve device structure, then the device structure is enhanced, but forward and reverse withstand voltages are reduced

Engineering Contradiction:

Improvedevice structureVSAvoidwithstand voltage

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies local quality by providing a high-concentration p-type body region only in specific areas (at least one of: near the collector region, near the channel forming region, or in a portion between them) rather than uniformly throughout the entire drift region. This localized approach allows the high-concentration region to provide structural enhancement and carrier management where needed, while avoiding the generation of excessive reverse leakage current that would occur with a uniform high-concentration structure throughout the entire device.

Inventive Principle:

Principle #3Local quality

3Reliability

If a high-concentration p-type body region is provided, then device structure is improved, but manufacturing process becomes complex

Engineering Contradiction:

Improvedevice structureVSAvoidmanufacturing process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by providing a high-concentration p-type body region only in specific areas (at least one of: near the collector region, near the channel forming region, or in a portion between them) rather than uniformly throughout the entire drift region. This localized approach allows the high-concentration region to provide structural enhancement and carrier management where needed, while avoiding the generation of excessive reverse leakage current that would occur with a uniform high-concentration structure throughout the entire 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

The proposed semiconductor device effectively reduces reverse leakage current while maintaining forward withstand voltage, suppressing oscillation in voltage and current waveforms during reverse recovery, thereby enhancing the stability and reliability of the semiconductor device.

Implementation Method 1

controlling the depletion layer and maintaining desired withstand voltages

Methodology Applied

Scientific EffectDepletion layer: Electric Field

Implementation Method 2

Excess carriers are stored in the drift region of the diode by the forward current

Methodology Applied

Scientific EffectCarrier storage: Electric Field

Implementation Method 3

a pn diode is formed by a p collector region, an n drift region, an n channel region, and an n emitter region of the reverse blocking IGBT

Methodology Applied

Scientific Effectpn junction: Electric Field

Data Source

PatentUS9577088B2Semiconductor device with high concentration region

Publication Date: 2017.02.21 FUJI ELECTRIC CO LTD

AI summary

A semiconductor device includes a drift region of a first conductivity type, a channel forming region of a second conductivity type that is selectively provided in a first main surface of the drift region, a first main electrode region of the first conductivity type that is selectively provided in an upper part of the channel forming region, a second main electrode region of the second conductivity type that is provided in a second main surface of the drift region, and a high-concentration region of the first conductivity type that is provided in a portion of the drift region below the channel forming region so as to be separated from the channel forming region. The high-concentration region has a higher impurity concentration than the drift region and the total amount of first-conductivity-type impurities in the high-concentration region is equal to or less than 2.0×1012 cm−2.