SiC MOSFET Forward Conduction Inspection and Classification

Solution Overview

Problem

Conventional silicon carbide semiconductor devices with pn junctions face increased resistance due to crystal defects, leading to higher manufacturing costs and reduced yields as defective chips are removed.

Innovation Solution

A method that inspects forward conduction characteristics between epitaxial and impurity layers, classifying semiconductor devices into suitable and unsuitable groups for forward conduction, allowing effective use of unsuitable structures to prevent cost increases while maintaining forward characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If semiconductor chips with crystal defects are removed to maintain forward characteristics, then forward characteristics are maintained, but manufacturing yield decreases and cost increases

Engineering Contradiction:

Improveforward characteristicsVSAvoidmanufacturing yield

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the parameter of device classification from binary (defective/non-defective) to multi-category (first group for forward conduction, second group for reverse conduction). By inspecting forward conduction characteristics and classifying devices based on these parameters, chips that would traditionally be discarded can be reallocated to reverse conduction applications, thereby maintaining yield while ensuring forward characteristics are preserved where needed.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If semiconductor chips with crystal defects are removed to maintain forward characteristics, then forward characteristics are maintained, but manufacturing cost increases

Engineering Contradiction:

Improveforward characteristicsVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent changes the parameter of device classification from binary (defective/non-defective) to multi-category (first group for forward conduction, second group for reverse conduction). By inspecting forward conduction characteristics and classifying devices based on these parameters, chips that would traditionally be discarded can be reallocated to reverse conduction applications, thereby maintaining yield while ensuring forward characteristics are preserved where needed.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful effect of crystal defects into a beneficial classification mechanism. Instead of simply discarding chips with crystal defects, the inspection of forward conduction characteristics reveals a way to categorize and utilize these chips for reverse conduction applications. The previously harmful crystal defects become the basis for a new product category, turning waste into useful output.

Inventive Principle:

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

3Adaptability or versatility

If all chips are inspected and classified, then proper allocation to forward and reverse conduction devices is achieved, but inspection time and process complexity increase

Engineering Contradiction:

Improvedevice allocation flexibilityVSAvoidinspection time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent performs preliminary inspection of forward conduction characteristics during the manufacturing process, before final device assembly. By classifying chips into first and second groups based on this preliminary inspection, the system enables efficient downstream allocation without requiring time-consuming re-inspection or rework. The preliminary classification action saves time in subsequent manufacturing stages.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9530703B2Method for manufacturing silicon carbide semiconductor device

Publication Date: 2016.12.27 MITSUBISHI ELECTRIC CORP

AI summary

Provided is a method for manufacturing a silicon carbide semiconductor device capable of preventing an increase in a cost of manufacturing one chip while favorably maintaining forward characteristics of the semiconductor device including (a) inspecting the characteristics of the forward conduction of body diodes as element structures; (b) classifying the body diode and the body diode as either a first group suitable for forward conduction or a second group unsuitable for forward conduction on the basis of an inspection result; and (c) manufacturing a silicon carbide semiconductor MOSFET that requires forward conduction using the body diode classified into the first group or manufacturing a silicon carbide semiconductor MOSFET that does not need forward conduction using the body diode classified into the second group.