SiC Semiconductor Dislocation Conversion Layer

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Solution Overview

Problem

Semiconductor devices using silicon carbide substrates face challenges in maintaining stable operating characteristics due to the expansion of stacking faults caused by basal plane dislocations, which affect the device's performance and reliability.

Innovation Solution

A semiconductor device structure is developed with a base body of silicon carbide, featuring a first semiconductor region with a dislocation conversion layer and a second semiconductor region acting as a recombination enhancement layer, where the first semiconductor region includes a first intermediate region with a lower concentration of impurities and the second intermediate region has a higher concentration, effectively converting basal plane dislocations into threading edge dislocations and suppressing stacking fault expansion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional silicon carbide substrate is used, then the device structure is simple, but stacking faults expand due to basal plane dislocations causing unstable operating characteristics

Engineering Contradiction:

Improveoperating characteristics stabilityVSAvoidsemiconductor region structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The first semiconductor region is divided into a first intermediate region and a second intermediate region with different impurity concentrations. This segmentation allows the dislocation conversion layer to have a gradient structure that effectively converts basal plane dislocations into threading edge dislocations while suppressing stacking fault expansion, thereby stabilizing operating characteristics without requiring complete structural redesign

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The dislocation conversion layer (first intermediate region) is positioned specifically at the interface between the base body and the drift layer where dislocation conversion is most critical. This localized approach with specific impurity concentration gradients addresses the dislocation problem at its source while maintaining simpler structures in other regions, balancing reliability improvement with device complexity

Inventive Principle:

Principle #3Local quality

2Reliability

If the impurity concentration is uniformly distributed, then the manufacturing process is simple, but the dislocation conversion efficiency is insufficient leading to stacking fault expansion

Engineering Contradiction:

Improvestacking fault suppressionVSAvoidimpurity concentration distribution

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The impurity concentration parameter is changed from uniform distribution to a gradient distribution in the dislocation conversion layer. The first intermediate region has a lower impurity concentration than the second intermediate region, creating a concentration gradient that enhances dislocation conversion efficiency. This parameter change effectively suppresses stacking fault expansion while the gradient profile can be controlled during epitaxial growth to manage manufacturing precision requirements

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If basal plane dislocations are present, then the substrate is easier to manufacture, but the dislocations expand into stacking faults degrading device performance

Engineering Contradiction:

Improvesubstrate productionVSAvoiddevice performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The dislocation conversion layer is designed to convert harmful basal plane dislocations into less harmful threading edge dislocations through a controlled impurity concentration gradient. This transformation process, occurring in the first intermediate region adjacent to the base body, turns the originally harmful dislocation structure into a beneficial configuration that suppresses stacking fault expansion while maintaining ease of substrate manufacture

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The first intermediate region acts as an intermediary layer between the base body and the drift layer. It mediates the dislocation conversion process by providing a transition zone with specific impurity concentration that facilitates the transformation from basal plane to threading edge dislocations, thereby protecting the device performance while maintaining substrate manufacturability

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10998401B2Semiconductor device having a base body of silicon carbide

Publication Date: 2021.05.04 KK TOSHIBA

AI summary

According to one embodiment, a semiconductor device includes a base body including silicon carbide, a first semiconductor region including silicon carbide and a first element, and a second semiconductor region including silicon carbide and the first element. The first semiconductor region includes first and second intermediate regions. A first concentration of the first element in the first intermediate region satisfies a first or a second condition. In the first condition, the first concentration is lower than a second concentration of the first element in the second intermediate region. In the second condition, the first concentration is higher than a third concentration of a second element included in the first intermediate region, the second concentration is higher than a fourth concentration of the second element in the second intermediate region, and a difference between the first and third concentrations is smaller than a difference between the second and fourth concentrations.