Compound Semiconductor Polishing Reducing Oxygen Content
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Solution Overview
Problem
Existing methods for polishing compound semiconductor substrates result in the formation of oxide films, which act as impurities, trapping electrons and adversely affecting device properties and epitaxial layer morphology.
Innovation Solution
A two-step polishing method using a chloric polishing agent followed by an alkaline aqueous solution with an inorganic builder, effectively reducing oxygen content on the substrate surface, thereby minimizing oxide film formation and improving substrate quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a strongly oxidative polishing solution (e.g., aqueous hypochlorite solution) is used for polishing compound semiconductor substrates, then polishing effectiveness is improved, but oxide film formation on the substrate surface worsens
Solution Approach 1:
The polishing process is divided into two distinct steps: first using a strongly oxidative polishing solution for effective polishing, then using a reducing agent treatment to remove the oxide film. This segmentation allows each step to optimize its function without compromising the other.
Solution Approach 2:
The oxide film formed by the oxidative polishing solution is not treated as waste to be eliminated but as a useful intermediate layer that protects the substrate during polishing. The reducing agent then selectively removes this oxide film, converting the harmful oxidation effect into a beneficial protective function during the process.
2Manufacturing precision
If polishing is performed to achieve a smooth substrate surface, then surface quality is improved, but oxygen content on the surface increases due to oxide film formation
Solution Approach 1:
The reducing agent treatment is applied immediately after polishing while the oxide film is still present on the surface. This preliminary action removes oxygen from the surface before subsequent epitaxial growth or device fabrication, preventing oxygen-related defects without requiring additional surface treatment steps later.
Solution Approach 2:
The chemical environment is changed from oxidative (during polishing) to reducing (during post-polishing treatment) by introducing a reducing agent. This parameter change in oxidation-reduction potential enables selective removal of the oxide film while preserving the smooth surface morphology achieved during polishing.
3Shape
If conventional polishing methods are used, then substrate planarity is improved, but device performance deteriorates due to oxygen-related defects
Solution Approach 1:
The reducing agent acts as an intermediary substance that mediates between the polished surface and subsequent processing steps. It selectively reacts with and removes oxygen from the surface without affecting the underlying substrate structure or the smooth morphology, thereby improving device performance while maintaining planarity.
Solution Approach 2:
The polishing system uses a composite approach combining an oxidative polishing solution with a reducing agent treatment. This composite method achieves both surface planarity through mechanical-chemical polishing and low oxygen content through reducing treatment, resulting in substrates with improved device performance.
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 significantly reduces oxygen content on the substrate surface, enhancing the electrical properties and morphology of epitaxial layers, ensuring better device performance by minimizing oxide film-related defects.
Implementation Method 1
treating the compound semiconductor substrate with a reducing agent; removing oxygen from a compound semiconductor substrate by means of a reduction reaction
Implementation Method 2
superficially oxidizing a compound semiconductor substrate by means of the chloroisocyanuric acid contained in the polishing agent
Data Source
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AI summary
Compound-semiconductor-substrate polishing methods, compound semiconductor substrates, compound-semiconductor-epitaxial-substrate manufacturing methods, and compound semiconductor epitaxial substrates whereby oxygen superficially present on the substrates reduced. A compound semiconductorsubstrate polishing method includes a preparation step (S10), a first polishing step (S20), and a second polishing step (S30). In the preparation step (S10), a compound semiconductor substrate is prepared. In the first polishing step (S20), the compound semiconductor substrate is polished with a chloric polishing agent. In the second polishing step (S30), subsequent to the first polishing step (S20), a polishing operation utilizing an alkaline aqueous solution containing an inorganic builder and having pH of 8.5 to 13.0 inclusive is performed.