Semiconductor Anode Transition Region for Low Ohmic Contact

Solution Overview

Problem

Creating a low ohmic contact between a low-doped anode and metal metallization in semiconductor devices, such as diodes and IGBTs, is challenging due to the low doping level, which affects switching behavior and requires materials like platinum silicide that can be impractical or cause contamination.

Innovation Solution

A semiconductor device structure with a transition region, a contact region having a higher concentration of charge carriers, and a damage region that reduces carrier lifetime and mobility, allowing for a low ohmic contact without increasing emitter efficiency, using a diffusion barrier layer and a metallization layer to manage contact resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a low doping level is used in the anode to achieve soft recovery switching behavior, then the dynamic switching behavior is improved, but the ohmic contact resistance between the anode and metallization increases

Engineering Contradiction:

Improveswitching behaviorVSAvoidcontact resistance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating a contact region with higher doping concentration specifically at the metallization interface, while the bulk anode region maintains low doping concentration for soft recovery. This spatial differentiation allows the contact region to provide low contact resistance while the bulk region maintains advantageous switching characteristics.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The anode is segmented into at least two regions: a contact region with higher doping concentration for low contact resistance and a bulk region with lower doping concentration for soft recovery. This segmentation allows each region to independently optimize its function without compromising the other.

Inventive Principle:

Principle #1Segmentation

2Object-affected harmful factors

If a high doping level is used in the anode to achieve low ohmic contact, then the contact resistance is reduced, but the emitter efficiency increases causing hard switching behavior

Engineering Contradiction:

Improvecontact resistanceVSAvoidswitching behavior

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies local quality by creating a contact region with higher doping concentration specifically at the metallization interface, while the bulk anode region maintains low doping concentration for soft recovery. This spatial differentiation allows the contact region to provide low contact resistance while the bulk region maintains advantageous switching characteristics.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The anode is segmented into at least two regions: a contact region with higher doping concentration for low contact resistance and a bulk region with lower doping concentration for soft recovery. This segmentation allows each region to independently optimize its function without compromising the other.

Inventive Principle:

Principle #1Segmentation

3Object-affected harmful factors

If platinum silicide is used to achieve low ohmic contact with low-doped anode, then the contact resistance is reduced, but material cost and contamination risk increase

Engineering Contradiction:

Improvecontact resistanceVSAvoidmanufacturing complexity

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent changes the doping concentration parameter in the contact region to achieve low contact resistance without requiring exotic materials like platinum silicide. This parameter change allows the use of conventional, cost-effective metallization systems while maintaining low contact resistance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces expensive platinum silicide with a simpler doping-based solution that uses conventional materials. The high doping concentration in the contact region inherently provides low contact resistance without requiring additional expensive material layers.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 structure enables a low ohmic contact with reduced switching losses and snappy behavior, avoiding the drawbacks of high p-dopant levels and platinum contamination, while maintaining efficient charge carrier management.

Implementation Method 1

a damage region between the contact region and the transition region, the damage region being configured for reducing lifetime and/or mobility of the first charge carriers of the damage region

Methodology Applied

Scientific EffectCarrier scattering:

Data Source

PatentUS9685504B2Semiconductor to metal transition for semiconductor devices

Publication Date: 2017.06.20 INFINEON TECHNOLOGIES AG

AI summary

A semiconductor device includes a first semiconductor region having first charge carriers of a first conductivity type and a second semiconductor region having second charge carriers. The first semiconductor region includes a transition region in contact with the second semiconductor region, the transition region having a first concentration of the first charge carriers, a contact region having a second concentration of the first charge carriers, wherein the second concentration is higher than the first concentration, and a damage region between the contact region and the transition region. The damage region is configured for reducing lifetime and/or mobility of the first charge carriers of the damage region as compared to the lifetime and/or the mobility of the first charge carriers of the contact region and the transition region.