SiC Wafer Off-Angle Optimization for Epitaxial Growth

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The existing methods for manufacturing silicon carbide single crystal wafers face challenges in improving the utilization rate of bulk silicon carbide, enhancing the characteristics of the elements, and improving cleavability, particularly due to issues with off-angle orientation and surface defects during epitaxial growth.

Innovation Solution

A process involving cutting silicon carbide wafers at an off-angle of 0.4 to 2 degrees, followed by surface treatment and epitaxial growth using a specific ratio of silicon and carbon source gases within a controlled temperature range, ensures a high utilization rate and minimizes surface defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If silicon carbide is grown at a temperature range from 1700 to 1800° C. or higher, then planarity of the grown surface is improved, but exhaustion of members such as susceptors is vigorous and electrical characteristics of the epitaxially grown film are deteriorated

Engineering Contradiction:

Improveplanarity of the grown surfaceVSAvoidelectrical characteristics of the epitaxially grown film

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The invention changes the temperature parameter from the conventional 1700-1800°C range to a lower range of 1500-1600°C, while simultaneously changing the off-angle parameter from 0° to 0.4-2°. This combined parameter change achieves both improved surface planarity and maintained electrical characteristics by suppressing triangular-pit defects without causing severe susceptor exhaustion

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention applies preliminary action by pre-setting the specific off-angle range (0.4-2°) before epitaxial growth to prevent the formation of triangular-pit defects that would otherwise require high temperatures to suppress. This preliminary geometric configuration allows lower temperature growth while maintaining surface quality

Inventive Principle:

Principle #10Preliminary action

2Reliability

If a wafer having an off-angle of 3.5° is used, then epitaxial growth without dislocations is possible, but utilization rate of the bulk single crystal is remarkably decreased

Engineering Contradiction:

Improvedislocation-free epitaxial growthVSAvoidutilization rate of the bulk single crystal

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The invention optimizes the off-angle parameter to a specific range of 0.4-2°, which is smaller than the conventional 3.5° but still sufficient to prevent dislocation formation during epitaxial growth. This optimized parameter achieves the dual benefit of maintaining dislocation-free growth while significantly improving bulk crystal utilization rate

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention applies partial action by using a smaller off-angle (0.4-2°) than the conventional 3.5°, which is just sufficient to achieve dislocation-free growth. This partial application of the off-angle effect maintains the necessary dislocation suppression while minimizing the negative impact on bulk crystal utilization

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If the off-angle is large, then dislocation density on the c-plane is reduced, but separation of the manufactured element by cleavage is difficult

Engineering Contradiction:

Improvedislocation density on the c-planeVSAvoidcleavability of the element

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention optimizes the off-angle parameter to a moderate range of 0.4-2°, which balances two opposing requirements: it is large enough to suppress dislocation formation on the c-plane during epitaxial growth, but small enough to maintain good cleavability for subsequent element separation and optical device manufacturing

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 process results in a silicon carbide wafer with improved utilization rate, reduced surface dislocations, and enhanced cleavability, suitable for electronic and optical devices with a flat epitaxial growth surface, maintaining high quality and efficiency.

Implementation Method 1

silicon carbide is grown by a CVD process at a temperature range as high as from 1700 to 1800° C. or higher for allowing α-silicon carbide to epitaxially grow on (0001)c plane of α-silicon carbide single crystal

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Implementation Method 2

epitaxially growing the α (hexagonal) silicon carbide single crystal on the wafer by allowing the silicon source gas and carbon source gas to react

Methodology Applied

Scientific EffectEpitaxy: Epitaxy

Data Source

PatentUS7785414B2Process for manufacturing wafer of silicon carbide single crystal

Publication Date: 2010.08.31 RESONAC CORP

AI summary

A process for manufacturing a wafer of a silicon carbide single crystal having: cutting a wafer from an α (hexagonal)-silicon carbide single crystal so that the off-angle is totally in the range from 0.4 to 2° to a plane obtained in perpendicular to the [0001]c axis of the silicon carbide single crystal; disposing the wafer in a reaction vessel; feeding a silicon source gas and carbon source gas in the reaction vessel; and epitaxially growing the α (hexagonal) silicon carbide single crystal on the wafer by allowing the silicon source gas and carbon source gas to react.