Semiconductor Drift Zone for Soft Diode Behavior

Solution Overview

Problem

Semiconductor components face a challenge in achieving soft diode behavior with low switching power loss, as increasing diode softness either increases collector-emitter saturation voltage or switching losses, making it difficult to simultaneously optimize on-state properties and diode softness.

Innovation Solution

The semiconductor component is structured with a drift zone that includes regions where charge carriers do not flow in diode mode but do in IGBT mode, using increased n-type emitter zone doping and varying p- and n-type zone dimensions to achieve diode softness without increasing storage charge, and incorporating regions with reduced charge carrier lifetime to minimize switching losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If the charge carrier lifetime is reduced near the front-side anode to improve diode softness, then the diode softness increases, but the collector-emitter saturation voltage increases and on-state losses increase

Engineering Contradiction:

Improvediode softnessVSAvoidon-state losses

Core Design Contradiction:

Object-generated harmful factorsVSLoss of energy

Solution Approach 1:

The patent applies local quality by creating a non-uniform charge carrier lifetime distribution within the drift zone. Specifically, the lifetime is reduced in a first region adjacent to the anode while maintaining a longer lifetime in a second region farther from the anode. This spatial differentiation allows the anodal carrier flooding to be reduced (improving diode softness) while preserving sufficient charge carriers in the second region to maintain low saturation voltage and minimize on-state losses.

Inventive Principle:

Principle #3Local quality

2Object-generated harmful factors

If the doping concentration of the rear-side n-type emitter zone is increased to improve diode softness, then the diode softness increases, but the storage charge increases and switching losses increase

Engineering Contradiction:

Improvediode softnessVSAvoidswitching losses

Core Design Contradiction:

Object-generated harmful factorsVSLoss of energy

Solution Approach 1:

The patent applies local quality by creating a non-uniform charge carrier lifetime distribution within the drift zone. Specifically, the lifetime is reduced in a first region adjacent to the anode while maintaining a longer lifetime in a second region farther from the anode. This spatial differentiation allows the anodal carrier flooding to be reduced (improving diode softness) while preserving sufficient charge carriers in the second region to maintain low saturation voltage and minimize on-state losses.

Inventive Principle:

Principle #3Local quality

3Loss of energy

If the p-conducting emitter zones are made wider to improve on-state properties, then the on-state properties improve, but the n-conducting zones become more widely distributed reducing diode current flow

Engineering Contradiction:

Improveon-state voltageVSAvoiddiode current flow

Core Design Contradiction:

Loss of energyVSProductivity

Solution Approach 1:

The patent applies local quality by creating a non-uniform charge carrier lifetime distribution within the drift zone. Specifically, the lifetime is reduced in a first region adjacent to the anode while maintaining a longer lifetime in a second region farther from the anode. This spatial differentiation allows the anodal carrier flooding to be reduced (improving diode softness) while preserving sufficient charge carriers in the second region to maintain low saturation voltage and minimize on-state losses.

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 approach allows for a smaller effective diode area, reducing switching losses and maintaining low saturation voltage, thereby resolving the conflict between diode softness and switching power loss.

Implementation Method 1

incorporating regions with reduced charge carrier lifetime to minimize switching losses

Methodology Applied

Scientific EffectCharge carrier lifetime variation:

Implementation Method 2

the drift zone contains at least one region 2a through which no charge carriers flow in the diode operating mode, but through which charge carriers can flow in the IGBT operating mode

Methodology Applied

Scientific EffectCharge carrier flow:

Implementation Method 3

using increased n-type emitter zone doping and varying p- and n-type zone dimensions to achieve diode softness without increasing storage charge

Methodology Applied

Scientific EffectDoping: Dopants

Data Source

PatentUS8860133B2Semiconductor component

Publication Date: 2014.10.14 INFINEON TECH AUSTRIA AG

AI summary

A semiconductor component is disclosed. One embodiment provides a semiconductor body having a cell region with at least one zone of a first conduction type and at least one zone of a second conduction type in a rear side. A drift zone of the first conduction type in the cell region is provided. The drift zone contains at least one region through which charge carriers flow in an operating mode of the semiconductor component in one polarity and charge carriers do not flow in an operating mode of the semiconductor component in an opposite polarity.