Silicon Carbide Epitaxial Growth With Substrate Reforming

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Solution Overview

Problem

Existing silicon carbide epitaxial substrates suffer from high defect densities of trapezoidal defects, which are trapezoidal depressions with specific dimensions, affecting the reliability of semiconductor devices.

Innovation Solution

A method involving a silicon carbide single crystal substrate with an off-angle of 1° to 8°, where the substrate is treated with hydrogen and hydrocarbon gases under controlled temperature and pressure conditions before epitaxial growth, reducing trapezoidal defect density to ≤1/cm² by reforming the substrate surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional epitaxial growth is performed without substrate reforming, then the manufacturing process is simple, but trapezoidal defect density is high

Engineering Contradiction:

Improvetrapezoidal defect densityVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The substrate reforming step is performed before epitaxial growth to modify the substrate surface in advance. This preliminary action reduces trapezoidal defect density by reconstructing the substrate surface, preventing defect formation during subsequent epitaxial growth, thereby resolving the contradiction between reliability improvement and process complexity

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The substrate reforming process changes physical parameters including temperature (heating to high temperature), pressure (controlling chamber pressure), and gas composition (introducing hydrogen and hydrocarbon gases). These parameter changes modify the substrate surface properties to reduce trapezoidal defects while maintaining manageable process complexity

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If substrate reforming with hydrogen and hydrocarbon gases is performed, then trapezoidal defect density is reduced, but the manufacturing process becomes more complex

Engineering Contradiction:

Improvetrapezoidal defect densityVSAvoidease of manufacture

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The substrate reforming step introduces controlled changes in temperature, pressure, and gas composition parameters. By optimizing these parameters within specific ranges, the process achieves high manufacturing precision (trapezoidal defect density ≤1/cm²) while keeping the process complexity manageable through systematic parameter control

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The substrate reforming process continuously exposes the substrate to hydrogen and hydrocarbon gases at controlled temperatures and pressures for a predetermined period. This continuous action ensures uniform surface modification across the substrate, achieving consistent defect reduction while maintaining ease of manufacture through automated continuous processing

Inventive Principle:

Principle #20Continuity of useful action

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

The method significantly reduces trapezoidal defect density, enhancing the reliability of oxide films in semiconductor devices and improving the manufacturing process by controlling defect formation during epitaxial growth.

Implementation Method 1

a substrate reforming step of increasing the temperature within the chamber to a second temperature and holding the temperature at the second temperature for a predetermined time, with the adjusted pressure within the chamber and a flow rate of the hydrogen gas being maintained and the hydrocarbon gas being introduced

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Implementation Method 2

a step of growing an epitaxial layer on the silicon carbide single crystal substrate by introducing silane gas into the chamber with the second temperature being maintained

Methodology Applied

Scientific EffectEpitaxy: Epitaxy

Implementation Method 3

growing an epitaxial layer on the silicon carbide single crystal substrate by introducing silane gas into the chamber

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Data Source

PatentUS9777404B2Method for manufacturing silicon carbide epitaxial substrate, and silicon carbide epitaxial substrate

Publication Date: 2017.10.03 SUMITOMO ELECTRIC INDUSTRIES LTD

AI summary

A method for manufacturing a silicon carbide epitaxial substrate includes: a step of placing a silicon carbide single crystal substrate within a chamber and reducing a pressure within the chamber; a step of increasing a temperature within the chamber to a first temperature; a step of introducing hydrogen gas into the chamber and adjusting the pressure within the chamber; a step of introducing hydrocarbon gas into the chamber; a substrate reforming step of increasing the temperature within the chamber to a second temperature and holding the temperature at the second temperature for a predetermined time, with the adjusted pressure within the chamber and a flow rate of the hydrogen gas being maintained and the hydrocarbon gas being introduced; and a step of growing an epitaxial layer on the silicon carbide single crystal substrate by introducing silane gas into the chamber with the second temperature being maintained.