Group III Nitride Substrate Surface Treatment for Carbon Impurity Control
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Solution Overview
Problem
Light-emitting diodes using epitaxial layers on semiconductor substrates face limitations in improving emission intensity and yield due to the formation of high-resistivity layers caused by impurities like carbon accumulating at the epitaxial layer/semiconductor substrate boundary.
Innovation Solution
A group III nitride semiconductor substrate with specific surface compositions, including sulfides, oxides, chlorides, silicon compounds, and controlled carbon and copper content, is used to prevent the formation of high-resistivity layers, thereby reducing electrical resistance and enhancing crystal quality and emission performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional preprocessing (cutting, lapping, etching, mechanical polishing, CMP) is performed on semiconductor substrates, then a mirror surface is obtained, but carbon impurities accumulate at the epitaxial layer/substrate boundary forming high-resistivity layers
Solution Approach 1:
The invention applies preliminary chemical treatment to the substrate surface before epitaxial growth to modify surface chemistry and prevent carbon impurity accumulation. By treating the surface with specific chemicals beforehand, the substrate is prepared to resist impurity formation during subsequent processing and growth stages.
Solution Approach 2:
The invention introduces an intermediary chemical treatment step that acts as a mediator between mechanical polishing and epitaxial growth. This chemical intermediary layer or treatment modifies the surface properties to prevent direct carbon accumulation at the boundary, serving as a protective interface during the epitaxial process.
2Productivity
If the epitaxial layer is formed on a conventional substrate surface, then the device can be manufactured, but electrical resistance at the boundary increases due to high-resistivity layer formation
Solution Approach 1:
The invention changes the chemical and physical parameters of the substrate surface through chemical treatment, modifying surface composition, roughness, or contamination levels. These parameter changes create optimal surface conditions that prevent high-resistivity layer formation during epitaxial growth, thereby maintaining low electrical resistance.
Solution Approach 2:
The invention replaces or supplements mechanical surface preparation methods with chemical treatment approaches. Instead of relying solely on mechanical polishing and CMP, chemical processes are used to achieve the desired surface properties, thereby preventing carbon impurity accumulation that mechanical methods alone cannot avoid.
3Ease of manufacture
If impurities are present on the substrate surface, then the substrate can be used, but emission intensity and yield of light-emitting diodes decrease
Solution Approach 1:
The invention extracts or removes carbon impurities from the substrate surface through chemical treatment before epitaxial growth. By taking out the harmful carbon contaminants that would otherwise accumulate at the boundary, the surface is cleaned to enable proper epitaxial layer formation and maintain high emission intensity.
Solution Approach 2:
The invention converts the potentially harmful presence of carbon impurities into a beneficial outcome by using chemical treatment to selectively remove or transform carbon contamination. The chemical process that might seem to add complexity actually eliminates the harmful effect, turning the problematic carbon presence into an opportunity for improved surface quality and device performance.
Data Source
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AI summary
In a semiconductor device 100, it is possible to prevent C from piling up at a boundary face between an epitaxial layer 22 and a group III nitride semiconductor substrate 10 by the presence of 30×1010 pieces/cm2 to 2000×1010 pieces/cm2 of sulfide in terms of S and 2 at% to 20 at% of oxide in terms of O in a surface layer 12. By thus preventing C from piling up, a high-resistivity layer is prevented from being formed on the boundary face between the epitaxial layer 22 and the group III nitride semiconductor substrate 10. Accordingly, it is possible to reduce electrical resistance at the boundary face between the epitaxial layer 22 and the group III nitride semiconductor substrate 10, and improve the crystal quality of the epitaxial layer 22. Consequently, it is possible to improve the emission intensity and yield of the semiconductor device 100.