SiC Semiconductor Crush Layer Design for Current Concentration

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Silicon carbide semiconductor devices face issues with dielectric breakdowns due to local current concentration, particularly in high-current density applications, and existing methods to reduce crystal defects may impair reliability during normal operations.

Innovation Solution

A silicon carbide semiconductor device design featuring a semiconductor layer, a silicon carbide substrate, and electrode layers with a crush layer on the side faces, where the thickness of the crush layer on the second side face is greater than on the first side face, effectively trapping current and reducing dielectric breakdowns while minimizing cracking risks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the second electrode layer extends outward of the interface between the semiconductor layer and first electrode layer, then current concentration occurs at the outer edges of the interface, but dielectric breakdown easily occurs at this location

Engineering Contradiction:

Improvedielectric breakdown resistanceVSAvoidcurrent concentration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention applies different quality characteristics to different regions by creating a crush layer with specific properties (amorphous or fine-grained structure) at the side face of the semiconductor layer, while maintaining the single-crystal structure in the bulk. This local modification suppresses current concentration at the critical interface edges without affecting the overall device performance

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The crush layer acts as an intermediary structure between the single-crystal semiconductor layer and the electrode layers. It provides a transition region that redistributes current flow, preventing direct current concentration at the sharp edges of the interface between the semiconductor layer and first electrode layer

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If a dicing blade is used to divide the semiconductor device, then production efficiency is improved, but cracks may be generated during dicing requiring insulation film grooves

Engineering Contradiction:

Improvedicing efficiencyVSAvoidcrack generation

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The crush layer is formed beforehand during the dicing process to absorb and distribute mechanical stresses. This pre-formed layer acts as a cushion that prevents crack propagation into the main semiconductor layer, allowing efficient blade dicing without requiring additional protective grooves in the insulation film

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS10804360B2Silicon carbide semiconductor device, electric power conversion device, method for producing silicon carbide semiconductor device, and method for producing electric power conversion device

Publication Date: 2020.10.13 MITSUBISHI ELECTRIC CORP

AI summary

A semiconductor layer has a first face, a second face, and a first side face. A silicon carbide substrate has a third face facing the second face, a fourth face, and a second side face. A first electrode layer forms an interface with part of the first face. An insulation film is provided around the first electrode layer on the first face of the semiconductor layer. A second electrode layer is provided on the fourth face and extends outward of the interface between the first face and the first electrode layer in an in-plane direction. A crush layer is provided on the first side face of the semiconductor layer and on the second side face of the silicon carbide substrate. The thickness of the crush layer on the second side face is greater than the thickness of the crush layer on the first side face.