SiC Bipolar Element Stacking Fault Detection

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Solution Overview

Problem

Conventional methods for testing silicon carbide semiconductor apparatuses for stacking faults are time-consuming and costly, requiring long periods of current flow to determine forward voltage degradation, which affects the reliability and efficiency of semiconductor devices.

Innovation Solution

A method involving setting the temperature of a silicon carbide bipolar semiconductor element between 150° C and 230° C and applying a forward current with a current density of 120 to 400 A/cm² to assess the saturation state of forward resistance, allowing for rapid determination of stacking faults through the percentage change in forward voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional testing methods are used to detect stacking faults by measuring forward voltage degradation after one-hour energization at 100 A/cm2, then measurement precision is improved, but loss of time increases significantly

Engineering Contradiction:

Improvedetection accuracy of stacking faultsVSAvoidtesting duration

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The invention changes the testing parameters by increasing current density from 100 A/cm2 to 200 A/cm2 or higher, and reducing testing time from one hour to significantly shorter durations. This parameter optimization allows rapid detection of stacking faults while maintaining measurement precision, resolving the contradiction between accurate detection and testing time.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If higher current density of 200 A/cm2 or more is applied to accelerate stacking fault detection, then productivity is improved, but the semiconductor device may suffer from excessive stress or damage

Engineering Contradiction:

Improvetesting speedVSAvoidstress on semiconductor device

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The invention applies preliminary protective measures by establishing optimal current density ranges (200-600 A/cm2) and time limits before conducting the accelerated testing. This preliminary parameter setting ensures that the high current density is applied within safe boundaries, enabling fast testing while preventing device damage from excessive stress.

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If photoluminescence testing is used to detect stacking faults, then measurement precision is improved, but device complexity increases due to additional equipment requirements

Engineering Contradiction:

Improvestacking fault detection accuracyVSAvoidtesting equipment complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The invention replaces the optical photoluminescence testing system with an electrical measurement system that uses current-voltage characteristics to detect stacking faults. This substitution maintains high measurement precision for stacking fault detection while significantly reducing device complexity by eliminating the need for complex optical equipment and light source systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enables the quick and accurate testing of semiconductor devices for stacking faults, reducing manufacturing time and costs by determining the presence or absence of defects in a short time frame, typically within 10 minutes or less.

Implementation Method 1

an energizing step of causing a forward current having a current density of 120 [A/cm2] or more and 400 [A/cm2] or less to continuously flow through the bipolar semiconductor element

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

The energization test apparatus includes a cooling plate 2 that is located so as to come in contact with the back surface electrode 37 of the bipolar semiconductor element and cools the bipolar semiconductor element

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS9874596B2Method for manufacturing silicon carbide semiconductor apparatus, and energization test apparatus

Publication Date: 2018.01.23 MITSUBISHI ELECTRIC CORP

AI summary

The present invention provides a method for manufacturing silicon carbide semiconductor apparatus including a testing step of testing a PN diode for the presence or absence of stacking faults in a relatively short time and an energization test apparatus. The present invention sets the temperature of a bipolar semiconductor element at 150° C. or higher and 230° C. or lower, causes a forward current having a current density of 120 [A/cm2] or more and 400 [A/cm2] or less to continuously flow through the bipolar semiconductor element, calculates, in a case where a forward resistance of the bipolar semiconductor element through which the forward current flows reaches a saturation state, the degree of change in the forward resistance, and determines whether the calculated degree of change is smaller than a threshold value.