Silicon Carbide Epitaxial Substrate Basal Plane Dislocation Reduction
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Solution Overview
Problem
Existing silicon carbide epitaxial substrates with many lattice defects, such as dislocations, lead to unreliable semiconductor devices, and simply reducing threading edge dislocations is insufficient to enhance device reliability.
Innovation Solution
A silicon carbide epitaxial substrate with a principal surface inclined at an angle of 8-80 degrees to the {0001} plane, featuring a basal plane dislocation coupled to a threading screw dislocation, and a density of basal plane dislocations reduced to 0.05/cm2 or less, achieved through controlled epitaxial growth and rapid cooling processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threading edge dislocations are reduced in silicon carbide epitaxial substrates, then device reliability is improved, but basal plane dislocations coupled to threading screw dislocations remain and continue to degrade device performance
Solution Approach 1:
The patent changes the crystal orientation parameter by using a principal surface inclined at 0-8 degrees with respect to the {0001} plane instead of the conventional exact {0001} orientation. This parameter change in surface inclination fundamentally alters the dislocation behavior during epitaxial growth, causing basal plane dislocations to be suppressed while threading screw dislocations are effectively managed. The specific angle range of 0-8 degrees is critical for achieving the desired dislocation configuration reduction
Solution Approach 2:
Instead of attempting to directly remove or reduce dislocations through conventional means, the patent inverts the approach by carefully controlling and utilizing the relationship between threading screw dislocations and basal plane dislocations. By allowing threading screw dislocations to exist but controlling their interaction with basal plane dislocations through the specific surface inclination, the patent transforms the harmful effect into a manageable configuration where basal plane dislocation density is reduced to 0.05/cm² or less
2Ease of manufacture
If conventional silicon carbide epitaxial substrates are used, then manufacturing is easier, but high-density basal plane dislocations are generated leading to device failure
Solution Approach 1:
The patent modifies the critical parameter of surface inclination from the conventional exact {0001} plane to a range of 0-8 degrees inclination with respect to the {0001} plane. This parameter change is integrated into the existing epitaxial growth process, maintaining manufacturing feasibility while fundamentally improving device reliability by reducing basal plane dislocation density to 0.05/cm² or less. The modification works within conventional manufacturing frameworks rather than requiring entirely new processes
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 decreases the number and density of basal plane dislocations, thereby enhancing the reliability of silicon carbide semiconductor devices by minimizing lattice defects and stress-induced dislocations during the manufacturing process.
Implementation Method 1
a silicon carbide epitaxial layer formed on the principal surface and having a thickness of 20 μm or thicker
Data Source
AI summary
A silicon carbide epitaxial substrate includes a silicon carbide single-crystal substrate having a diameter of 100 mm or larger and including a principal surface inclined at an angle of more than 0 degrees and not less than 8 degrees with respect to a {0001} plane, a silicon carbide epitaxial layer formed on the principal surface and having a thickness of 20 μm or thicker, and a basal plane dislocation contained in the silicon carbide epitaxial layer and having one end coupled to a threading screw dislocation contained in the silicon carbide epitaxial layer and the other end present in a surface of the silicon carbide epitaxial layer. The basal plane dislocation extends in a direction having a slope of 20 degrees or more and 80 degrees or less with respect to a <11-20> direction in a {0001} basal plane. Density of the basal plane dislocation is 0.05/cm2 or less.