SiC Insulating Layer Profile for Termination Field Relief

Solution Overview

Problem

Silicon carbide semiconductor devices experience electric field concentration in the termination region, leading to potential breakage due to metal residues during electrode formation.

Innovation Solution

The silicon carbide semiconductor device features an insulating layer with specific thickness variations and a curved surface design, which reduces metal residue generation and stress concentration, thereby relaxing electric field concentration in the termination region. This is achieved through a production method involving multiple layers and etching processes to form the electrode while over-etching the interlayer insulating film.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a recessed portion is formed in the termination region and a source electrode is formed, then electrode contact with the substrate is achieved, but electric field concentration occurs leading to potential breakage

Engineering Contradiction:

Improvedevice reliabilityVSAvoidelectric field concentration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The insulating layer is designed with varying thickness across different regions: a first thickness in the termination region, a second (greater) thickness in the active region, and a third thickness at the opening. This local variation in insulating layer thickness creates different electrical field distributions, concentrating the insulation where needed to prevent electric field concentration at the electrode-substrate interface while maintaining proper electrode contact.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The insulating layer acts as an intermediary between the electrode and the substrate. By positioning the opening in the insulating layer over the active region and maintaining specific thickness relationships, the insulating layer mediates the electrical field distribution, preventing direct harmful field concentration at the electrode-substrate interface in the termination region while allowing proper electrical contact through the opening.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If the insulating layer has uniform thickness, then manufacturing is simplified, but electric field concentration and stress occur in the termination region

Engineering Contradiction:

Improveinsulating layer fabricationVSAvoidelectric field concentration

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The insulating layer is designed with varying thickness across different regions: a first thickness in the termination region, a second (greater) thickness in the active region, and a third thickness at the opening. This local variation in insulating layer thickness creates different electrical field distributions, concentrating the insulation where needed to prevent electric field concentration at the electrode-substrate interface while maintaining proper electrode contact.

Inventive Principle:

Principle #3Local quality

3Reliability

If the insulating layer is made thicker to prevent electric field concentration, then reliability improves, but manufacturing complexity increases

Engineering Contradiction:

Improvedevice reliabilityVSAvoidinsulating layer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The insulating layer is designed with varying thickness across different regions: a first thickness in the termination region, a second (greater) thickness in the active region, and a third thickness at the opening. This local variation in insulating layer thickness creates different electrical field distributions, concentrating the insulation where needed to prevent electric field concentration at the electrode-substrate interface while maintaining proper electrode contact.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20240332414A1Silicon carbide semiconductor device and method for producing silicon carbide semiconductor device

Publication Date: 2024.10.03 MITSUMI ELECTRIC CO LTD

AI summary

Silicon carbide semiconductor device includes silicon-carbide-substrate including first-main-surface and second-main-surface opposite to the first-main-surface; and insulating layer in contact with the first-main-surface. In plan-view from direction perpendicular to the first-main-surface, the silicon-carbide-substrate includes active region and termination region enclosing the active region. Opening where part of the active region is exposed is formed in the insulating layer. The silicon carbide semiconductor device further includes electrode formed on the insulating layer and in contact with the first-main-surface through the opening. The insulating layer includes first-portion overlapping the termination region and having first-thickness, in the plan-view; second-portion connecting to the first-portion, overlapping the electrode, and having second-thickness, in the plan-view; and third-portion connecting to the second-portion, overlapping the electrode, and having third-thickness, in the plan-view. The opening is formed in the third-portion. The second-portion is between the first-portion and the third-portion. The second-thickness is larger than the first and third thicknesses.