SiC Single Crystal Growth with Oriented Basal Plane Dislocations
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Solution Overview
Problem
Existing methods for growing SiC single crystals, such as the c-plane growth method, result in high densities of basal plane dislocations that are curved and intertwined with screw dislocations, leading to defects and degradation of semiconductor device characteristics due to stacking faults formed during operation.
Innovation Solution
An SiC single crystal with highly-linear and oriented basal plane dislocations is achieved by using a seed crystal with specific offset angles, where X-ray topography and Fourier transform processing are used to identify and enhance orientation regions, reducing the exposure of basal plane dislocations on the wafer surface and minimizing stacking faults during epitaxial film growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If c-plane growth method is used to obtain SiC single crystal, then SiC single crystal can be manufactured, but a large number of defects such as micro pipe defects and threading screw dislocations are generated in the direction parallel to the c-axis
Solution Approach 1:
The invention changes the growth parameters by using a seed crystal with a specific orientation (a-plane or off-c-plane) instead of the conventional c-plane seed crystal. This parameter change in crystal orientation fundamentally alters the growth mechanism to produce basal plane dislocations with high linearity and orientation, thereby reducing defect density while maintaining manufacturability
Solution Approach 2:
Instead of using the conventional c-plane seed crystal orientation, the invention inverts the approach by using a-plane or off-c-plane seed crystals. This inversion of the growth orientation leads to the formation of highly-linear basal plane dislocations that are oriented in specific crystallographic directions, thereby reducing the harmful defects associated with conventional growth methods
2Device complexity
If basal plane dislocation curves largely in c-plane by intertwinement between dislocations, then dislocation complexity increases, but one basal plane dislocation may be exposed at plural sites on the substrate surface causing device degradation
Solution Approach 1:
The invention changes the dislocation configuration parameters by controlling the seed crystal orientation to produce basal plane dislocations with high linearity and specific orientation angles (30° or 90° relative to the offset direction). This parameter control prevents the curving and intertwinement of dislocations, ensuring that each dislocation is exposed at only one site on the substrate surface, thereby preventing device degradation
Solution Approach 2:
The invention introduces asymmetry in the dislocation orientation by aligning basal plane dislocations along specific crystallographic directions (30° or 90° to the offset direction) rather than allowing random curving. This asymmetric orientation control simplifies the dislocation configuration and prevents the formation of complex intertwined patterns that would expose dislocations at multiple sites
3Adaptability or versatility
If basal plane dislocation is oriented to various directions crystallographically, then dislocation orientation varies, but stacking fault is formed during device operation causing forward degradation phenomenon
Solution Approach 1:
The invention changes the orientation parameter of basal plane dislocations by controlling the seed crystal orientation and growth conditions to produce dislocations with specific orientation angles (30° or 90° to the offset direction). This parameter control ensures that dislocations are oriented along crystallographically stable directions, preventing stacking fault formation during device operation and eliminating forward degradation phenomena
Solution Approach 2:
The invention converts the potential harm of varied dislocation orientations into a benefit by deliberately orienting basal plane dislocations along specific crystallographically stable directions. This controlled orientation, rather than random variation, prevents stacking fault formation during device operation, transforming what could be a source of degradation into a reliability-enhancing feature
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 approach significantly reduces the number of dislocations and stacking faults, improving the linearity and orientation of basal plane dislocations, thereby enhancing the characteristics and reliability of semiconductor devices.
Implementation Method 1
X-ray topography measurement by transmission arrangement is applied to the wafer and X-ray topography images corresponding to three crystallographically-equivalent {1-100} plane diffractions are photographed
Data Source
AI summary
An SiC single crystal having at least one orientation region where a basal plane dislocation has a high linearity and is oriented to three crystallographically-equivalent <11-20> directions, and an SiC wafer and a semiconductor device which are manufactured from the SiC single crystal. The SiC single crystal can be manufactured by using a seed crystal in which the offset angle on a {0001} plane uppermost part side is small and the offset angle on an offset direction downstream side is large and growing another crystal on the seed crystal.