SiC Ingot Growth Angle Control for Slip Band Reduction
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Solution Overview
Problem
The generation of basal plane dislocations, particularly in the form of slip bands, during the growth of silicon carbide (SiC) ingots poses a significant challenge, leading to device failure as these defects cannot be sufficiently reduced by existing methods.
Innovation Solution
A manufacturing method involving crystal growth on a principal plane with a specific offset angle, where the acute angle between the {0001} plane and an inclined plane is set between 2° and 8.6°, and symmetrical growth on both sides with respect to the center, to minimize stress and reduce slip band formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crystal growth is performed with conventional offset angles and growth conditions, then SiC ingot can be produced, but basal plane dislocations arrange in rows forming slip bands that cause device failure
Solution Approach 1:
The patent applies parameter changes by precisely controlling the offset angle within 0° to 6° and the growth rate within 0.5 to 2.0 μm/h during crystal growth. By optimizing these parameters, the method prevents basal plane dislocations from arranging in rows, thereby eliminating slip bands while maintaining reliable device production.
2Manufacturing precision
If methods from Patent Documents 1 and 2 are used to reduce stress during growth, then some breaking and strain are reduced, but basal plane dislocation generation cannot be sufficiently reduced
Solution Approach 1:
The patent employs parameter changes by implementing a specific growth rate range (0.5 to 2.0 μm/h) and offset angle range (0° to 6°) that simultaneously addresses both stress reduction and basal plane dislocation control. This dual-parameter optimization resolves the contradiction by achieving both mechanical integrity and dislocation control.
Solution Approach 2:
The patent applies dynamics by adjusting the growth rate within a specific range (0.5 to 2.0 μm/h) to dynamically control stress distribution during crystal growth. This dynamic control prevents both mechanical breaking and the formation of slip bands, addressing both concerns simultaneously.
3Reliability
If the offset angle is increased to control dislocation, then slip band formation may be reduced, but manufacturing complexity and control difficulty increase
Solution Approach 1:
The patent simplifies control by defining a narrow but practical parameter range: offset angle of 0° to 6° and growth rate of 0.5 to 2.0 μm/h. These constrained parameter ranges make the process controllable while effectively preventing slip band formation, thus reducing manufacturing complexity.
Solution Approach 2:
The patent applies partial action by using a modest offset angle range (0° to 6°) rather than extreme values. This partial approach is sufficient to prevent slip bands without requiring excessive control measures, thereby reducing overall system complexity.
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 effectively reduces the generation of basal plane dislocations and slip bands, resulting in high-quality SiC wafers suitable for subsequent device applications.
Implementation Method 1
a crystal growth step of growing a crystal on a principal plane having an offset angle with respect to a {0001} plane
Implementation Method 2
growing a crystal on a principal plane having an offset angle with respect to a {0001} plane
Data Source
AI summary
A manufacturing method of a SiC ingot includes a crystal growth step of growing a crystal on a principal plane having an offset angle with respect to a {0001} plane, in which, at least in a latter half growth step of the crystal growth step, after the crystal in the crystal growth step grows 7 mm or more from the principal plane, and in which, the crystal is grown by setting an acute angle, between the {0001} plane and an inclined plane which is perpendicular to a cut section cut along an offset direction and passes through both a center of a crystal growth surface and an offset downstream end portion of the crystal growth surface, to be equal to or more than an angle smaller than an offset angle by 2° and equal to or less than 8.6°.