Ga2O3 Crystalline Film via HVPE on Patterned Sapphire
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Solution Overview
Problem
The challenge lies in producing high-quality crystalline films with low Si content and improved deposition rates for semiconductor devices, particularly for gallium oxide with a corundum structure, which is a metastable phase, and requires specific deposition methods to overcome issues like high dislocation densities and impurity incorporation.
Innovation Solution
A method involving HVPE (Hydride Vapor Phase Epitaxy) using GaCl3 under high partial pressure and an oxygen-containing atmosphere to grow crystalline films on sapphire substrates with formed unevenness portions, achieving a deposition rate of 90 μm/hour and reducing Si content to 2×10^15 cm^-3 or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If sapphire substrate is used for growing α-Ga2O3 crystal film, then the crystal structure compatibility is improved, but the dislocation density increases due to large lattice mismatch
Solution Approach 1:
The substrate surface is divided into multiple regions with different properties (Patterned Sapphire Substrate with recesses and protrusions). The recess portions have different lattice orientation relationships with the crystal film compared to the protrusion portions, allowing selective growth regions with reduced dislocation propagation.
Solution Approach 2:
Different regions of the substrate surface are given different local properties (recess vs protrusion). The recess portions create specific local stress fields and lattice orientations that are more favorable for reducing dislocation density in the grown crystal film, while protrusion portions serve other functional purposes.
2Manufacturing precision
If conventional deposition methods are used for α-Ga2O3, then the crystal structure can be formed, but the deposition rate is insufficient for industrial application
Solution Approach 1:
The deposition parameters are optimized by controlling the partial pressure of GaCl3 at 1 kPa or more and maintaining specific temperature gradients between the substrate and source. These parameter changes enable high-rate deposition while preserving crystal quality through enhanced precursor supply and controlled reaction kinetics.
3Productivity
If high deposition rate is achieved, then productivity is improved, but impurity content (Si) increases
Solution Approach 1:
The deposition is performed in a highly controlled inert atmosphere with minimized contamination sources. The use of high-purity GaCl3 precursor and controlled gas flow systems prevents Si and other impurity incorporation even at high deposition rates, achieving both productivity and purity requirements.
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 results in high-quality crystalline films with reduced impurities and improved deposition rates, suitable for semiconductor devices, particularly power devices, by effectively managing the metastable phase and lattice mismatch issues.
Implementation Method 1
a method involving HVPE (Hydride Vapor Phase Epitaxy) using GaCl3 under high partial pressure
Implementation Method 2
an oxygen-containing atmosphere to grow crystalline films
Implementation Method 3
HVPE (Hydride Vapor Phase Epitaxy) using GaCl3 under high partial pressure and an oxygen-containing atmosphere to grow crystalline films on sapphire substrates
Data Source
AI summary
A high-quality crystalline film having less impurity of Si and the like and useful in semiconductor devices is provided. A crystalline film containing a crystalline metallic oxide including gallium as a main component, wherein the crystalline film includes a Si in a content of 2×1015 cm−3 or less.