SiC MOS Device Conformity Check via ON Voltage Rate

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Solution Overview

Problem

Conventional methods for determining the conformity of silicon-carbide semiconductor devices are prone to erroneous non-conforming product shipment due to insufficient sensitivity in evaluating the rate of change of forward voltage, leading to decreased reliability.

Innovation Solution

A method involving measuring the ON voltage of a silicon-carbide semiconductor device before and after passing a forward current, calculating the rate of change, and determining conformity if the change is less than 3%, thereby enhancing the sensitivity of the evaluation process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional methods using forward voltage rate of change are used to determine conformity, then the evaluation process is simple, but the sensitivity is insufficient leading to erroneous non-conforming product shipment

Engineering Contradiction:

Improvesensitivity of conformity evaluationVSAvoidcomplexity of measurement process

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent changes the measurement parameter from forward voltage to ON voltage. By measuring the ON voltage rate of change instead of forward voltage rate of change, the sensitivity of conformity evaluation is significantly improved. The ON voltage measurement provides a more accurate indicator of device health and conformity, reducing erroneous shipment of non-conforming products while maintaining a relatively simple evaluation process.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If forward current is passed through the built-in diode to evaluate conformity, then the evaluation can be performed, but the sensitivity is insufficient and leads to decreased reliability

Engineering Contradiction:

Improvereliability of product conformity determinationVSAvoidprecision of conformity evaluation

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent substitutes the measurement method from electrical parameter measurement (forward voltage) to a different electrical parameter measurement (ON voltage). This substitution provides a more reliable indicator of device conformity and reduces the risk of shipping non-conforming products, thereby improving overall reliability while maintaining measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11262399B2Method of determining whether a silicon-carbide semiconductor device is a conforming product

Publication Date: 2022.03.01 FUJI ELECTRIC CO LTD

AI summary

A method of determining whether a silicon-carbide semiconductor device, which has a metal oxide semiconductor (MOS) gate structure and a built-in diode, is a conforming product. The method includes measuring an ON voltage of the silicon carbide semiconductor device, passing a forward current through the built-in diode of the silicon carbide semiconductor device, measuring another ON voltage of the silicon carbide semiconductor device, which is the ON voltage of the silicon carbide semiconductor device after passing the forward current, calculating a rate of change between the ON voltage and the another ON voltage, and determining that the silicon carbide semiconductor device is a conforming product unless the calculated rate of change is less than 3%.