SiC Super Junction Termination for Peripheral Field Reliability

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Solution Overview

Problem

Silicon carbide semiconductor devices face challenges in improving reliability due to the concentration of electric fields in peripheral regions, which can lead to insulating layer breakdown and reduced reliability compared to silicon-based devices.

Innovation Solution

A silicon carbide semiconductor device structure is designed with a substrate having a first conductivity type, featuring an active region with a first super junction layer and an element layer, and a peripheral region with a second super junction layer, termination layer, and insulating layer, where the impurity concentration of specific regions is optimized to distribute electric fields effectively, reducing concentration at the semiconductor-insulating layer interface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional MOSFET structure is used in silicon carbide semiconductor devices, then the device can be manufactured with standard processes, but electric field concentration in peripheral regions leads to insulating layer breakdown and reduced reliability

Engineering Contradiction:

Improvedevice reliabilityVSAvoidelectric field concentration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The device structure is segmented into distinct regions: active region with first super junction layer, peripheral region with second super junction layer, termination layer, and insulating layer. Each segment serves a specific function in managing electric fields, with the peripheral region specifically designed to handle and distribute electric fields away from the insulating layer interface.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the semiconductor device are given different impurity concentrations and structural properties tailored to their specific functions. The peripheral region has optimized impurity concentration (68 times or less than the fifth region) to locally manage electric fields, while the active region maintains properties suitable for high-current conduction.

Inventive Principle:

Principle #3Local quality

2Strength

If the impurity concentration in the peripheral region is increased to improve electric field distribution, then breakdown voltage may increase, but electric field concentration at the semiconductor-insulating layer interface worsens

Engineering Contradiction:

Improvebreakdown voltageVSAvoidinsulating layer reliability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The impurity concentration parameter is precisely controlled in the sixth region to be larger than the fifth region but 68 times or less, creating an optimized gradient that balances breakdown voltage enhancement with electric field distribution at the interface. This parameter optimization prevents both insufficient breakdown voltage and excessive interface field concentration.

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If the device structure is simplified to reduce manufacturing complexity, then manufacturing cost decreases, but the ability to suppress electric field concentration in peripheral regions is reduced

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidperipheral electric field concentration

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

Multiple functions are merged into integrated structures: the second super junction layer and termination layer work together to manage peripheral electric fields, while the insulating layer simultaneously provides electrical isolation and mechanical support. This merging achieves effective electric field suppression without requiring excessively complex multi-layer structures.

Inventive Principle:

Principle #5Merging (Combining)

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 structure enhances the reliability of silicon carbide semiconductor devices by suppressing electric field concentration in the peripheral region and promoting avalanche breakdown in the active region, achieving higher breakdown voltages and improved reliability.

Implementation Method 1

the impurity concentration of the sixth region is larger than an impurity concentration of the fifth region and is 68 times or less as large as the impurity concentration of the fifth region

Methodology Applied

Scientific EffectElectric field distribution: Electric Field

Implementation Method 2

promoting avalanche breakdown in the active region, achieving higher breakdown voltages

Methodology Applied

Scientific EffectAvalanche breakdown: Avalanche Breakdown

Data Source

PatentUS20230282695A1Silicon carbide semiconductor device

Publication Date: 2023.09.07 SUMITOMO ELECTRIC INDUSTRIES LTD

AI summary

An active region includes a first super junction layer and an element layer. The first super junction layer alternately has a first region and a second region. A peripheral region includes a second super junction layer, a termination layer, and an insulating layer. The second super junction layer alternately has a third region and a fourth region. The termination layer is provided on and in contact with the second super junction layer, and alternately has a fifth region and a sixth region. The fifth region is provided to correspond to the third region, and the sixth region is provided to correspond to the fourth region. An impurity concentration of the sixth region is larger than an impurity concentration of the fifth region and is 68 times or less as large as the impurity concentration of the fifth region.