SiC Body Diode Inspection via Drain-Source Voltage Fluctuation

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Solution Overview

Problem

Conventional methods for inspecting silicon carbide semiconductor devices require multiple processes to measure ON voltage fluctuations, increasing costs and complexity, particularly when screening for stacking faults in body diodes.

Innovation Solution

A method involving a single inspection apparatus that energizes a parasitic diode with a pulse signal, measures voltage differences before and after energization, and identifies conforming products based on predetermined voltage fluctuation ranges, reducing the number of processes and enhancing screening accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple measurement processes are used to screen stacking faults, then measurement precision is improved, but device complexity and inspection cost increase

Engineering Contradiction:

Improvescreening accuracy for stacking faultsVSAvoidinspection process complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines multiple measurement functions into a single inspection apparatus that can perform both body diode energization and drain-source voltage measurement simultaneously. This merging of functions reduces the number of separate inspection devices needed while maintaining the ability to detect stacking faults through voltage fluctuation analysis during parasitic diode activation.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The inspection apparatus is designed with multi-functionality, capable of energizing the parasitic body diode while simultaneously measuring drain-source voltage. This universal device can perform both the stress test (energizing body diode) and the measurement (detecting voltage changes) in one integrated system, reducing complexity compared to separate specialized devices.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If multiple inspection processes are implemented, then measurement precision is improved, but productivity decreases

Engineering Contradiction:

Improvescreening accuracy for stacking faultsVSAvoidinspection throughput

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent enables continuous measurement of drain-source voltage while the parasitic body diode is being energized. Rather than performing discrete sequential measurements, the system continuously monitors voltage fluctuations during the entire energization process, allowing for faster screening without sacrificing detection accuracy. This continuous action approach increases inspection throughput.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The inspection method performs voltage measurements during the body diode energization process itself, rather than requiring separate pre- and post-energization measurement steps. By utilizing the energization period for simultaneous measurement, the method eliminates idle time between stress application and measurement, improving overall inspection efficiency.

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If forward voltage measurement is used, then measurement precision is improved, but object-generated harmful factors increase due to high variability

Engineering Contradiction:

Improvevoltage measurement accuracyVSAvoidvoltage variability

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent changes the measurement parameter from forward voltage (which exhibits high variability) to drain-source voltage measured during parasitic diode energization. This parameter change reduces measurement variability and improves consistency in detecting stacking faults, as the drain-source voltage fluctuation is more directly correlated with the presence of stacking faults and less affected by other factors.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach simplifies the inspection process, reduces costs, and improves accuracy by focusing on drain-source voltage measurements, which have minimal variability compared to forward voltage measurements, allowing for concurrent judgment criteria during body diode energization.

Implementation Method 1

the semiconductor chip having generated heat due to the first process

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS11693044B2Method of inspecting silicon carbide semiconductor device

Publication Date: 2023.07.04 FUJI ELECTRIC CO LTD

AI summary

A body diode is energized by inputting a BD energization pulse signal having a predetermined cycle. At the start of energization of the body diode and immediately before termination thereof, an ON signal of a Von measurement pulse signal is input to a high-temperature semiconductor chip at a timing different from that of an ON signal of the BD energization pulse signal, thereby passing a drain-source current through a MOSFET, and a drain-source voltage is measured. Thereafter, energization of the body diode is terminated. At room temperature before and after the energization of the body diode, the drain-source voltage is measured by inputting the ON signal of the Von measurement pulse signal. A semiconductor chip for which a fluctuation amount of the drain-source voltage at a high temperature and a fluctuation amount of the drain-source voltage at room temperature are within predetermined ranges is determined to be a conforming product.