Group III Nitride Stack Surface Treatment for Low-Defect Growth
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Solution Overview
Problem
Existing group III nitride-based semiconductor devices face challenges in achieving high crystal quality due to surface defects and impurities, which affect device performance and reliability.
Innovation Solution
A method involving surface treatment of a SiC substrate to form a Si-deficient region and remove it, followed by growing a group III nitride crystal, resulting in a stack structure with reduced surface defects and improved crystal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional epitaxial growth is performed on SiC substrate without special surface treatment, then manufacturing process is simple, but surface defects and impurities remain high affecting crystal quality
Solution Approach 1:
The patent applies preliminary action by performing surface treatment on the SiC substrate before epitaxial growth. Specifically, a Si-deficient region is formed in the surface layer through halogen-containing gas treatment, then removed through subsequent processing. This preliminary modification of the substrate surface eliminates surface defects and impurities before the crystal growth begins, ensuring high crystal quality without requiring complex in-situ treatments during epitaxial growth.
Solution Approach 2:
The patent applies the extraction principle by removing the Si-deficient region from the substrate surface after it has served its purpose of improving surface quality. The Si-deficient region is extracted through chemical etching or other removal processes after the epitaxial growth is completed, leaving a clean interface between the substrate and the grown crystal while eliminating potential sources of defects.
2Reliability
If surface treatment to form Si-deficient region is performed, then surface defects are reduced, but additional processing steps are required
Solution Approach 1:
The patent applies merging by combining multiple functions into the surface treatment process. The halogen-containing gas treatment simultaneously achieves several objectives: it forms the Si-deficient region to improve surface quality, prepares the surface for epitaxial growth, and can be integrated with existing cleaning or activation steps. This consolidation reduces the number of separate processing steps needed while maintaining high device reliability.
Solution Approach 2:
The patent applies parameter changes by optimizing the treatment conditions such as gas composition, temperature, and treatment duration to achieve the desired Si-deficient region formation. By carefully controlling these parameters, the process achieves high reliability outcomes while minimizing processing time and resource consumption, thereby improving manufacturing efficiency.
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 achieves a stack structure with an average defect density of 10.0 defects/cm² or less and relative yellow intensity of 1.30 or less, enhancing device characteristics and yield.
Implementation Method 1
supplying a halogen-containing gas onto the SiC substrate to desorb Si from a principal surface of the SiC substrate and form a Si-deficient region
Implementation Method 2
supplying a hydrogen-containing gas onto the SiC substrate having the Si-deficient region to remove the Si-deficient region
Implementation Method 3
growing a group III nitride crystal on the principal surface having undergone the treatment
Data Source
AI summary
This group III nitride stack includes a SiC substrate and a stack structure provided on the SiC substrate and formed by epitaxially growing a group III nitride crystal, wherein the stack structure has an average density of surface defects of 10.0 defects/cm2 or less in an internal region of a surface of the stack structure, the surface defects each having a size of 0.165 μm or more and 2.0 μm or less, the internal region being a region excluding a width of 5 mm from an outer edge of the surface of the stack structure, and when the internal region is segmented into a plurality of 10 mm-square region segments and a density of the surface defects in each region segment is measured, the maximum value of the density is 50.0 defects/cm2 or less.