Corundum Ga2O3 Film Structure for Thick Epitaxial Crystal Growth
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Solution Overview
Problem
Existing semiconductor devices using gallium oxide (Ga2O3) thin films face challenges in maintaining sufficient withstand voltage and are contaminated with carbon impurities, leading to unsatisfactory semiconductor properties, including conductivity. Additionally, achieving a Ga2O3 thin film with a thickness of 1 µm or more without degrading crystal quality has been difficult.
Innovation Solution
A semiconductor device with a corundum structured Ga2O3 crystalline film grown epitaxially on a sapphire substrate with an off-angle between 0.2° and 12.0°, and a thickness of 1 µm or more, which includes an n-type dopant to enhance semiconductor properties such as mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a Ga2O3 thin film is grown thicker to achieve sufficient withstand voltage, then the film thickness increases, but the crystal quality degrades
Solution Approach 1:
The patent changes the substrate orientation parameter from conventional c-plane to a-plane or m-plane sapphire substrates. This parameter change enables the growth of thick Ga2O3 films (1 µm or more) while maintaining high crystal quality, resolving the contradiction between film thickness and crystal quality degradation
Solution Approach 2:
The patent employs a composite structure consisting of a corundum-structured Ga2O3 film grown on a sapphire substrate with specific off-angles (0.2° to 12.0°). This composite material approach allows the film to achieve both sufficient thickness for withstand voltage and maintained crystallinity
2Reliability
If a dopant is added to improve conductivity, then semiconductor properties improve, but carbon impurities are introduced
Solution Approach 1:
The patent changes the dopant type parameter from conventional dopants to group 14 element dopants (Si, Ge, Sn). These dopants provide the necessary carrier concentration for semiconductor properties without introducing carbon impurities, thus improving reliability while avoiding harmful contamination
Solution Approach 2:
The patent converts the potential harm of dopant addition (which could introduce impurities) into a benefit by carefully selecting group 14 elements that provide necessary doping effects while avoiding carbon contamination, thus improving conductivity without the harmful side effects
3Manufacturing precision
If the substrate off-angle is increased to improve crystal growth, then crystallinity improves, but the range of suitable off-angles becomes restricted
Solution Approach 1:
The patent identifies and specifies an optimal parameter range for substrate off-angles (0.2° to 12.0°) that balances crystallinity improvement with manufacturing flexibility. This parameter optimization allows sufficient substrate selection flexibility while achieving the desired crystallinity level
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 semiconductor device exhibits excellent crystallinity and mobility, achieving improved semiconductor properties while maintaining high crystalline film quality even at thicker film dimensions.
Implementation Method 1
a corundum structured Ga2O3 crystalline film grown epitaxially on a sapphire substrate
Data Source
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AI summary
A multilayer structure with excellent crystallinity and a semiconductor device of the multilayer structure with good mobility are provided. A multilayer structure includes: a corundum structured crystal substrate; and a crystalline film containing a corundum structured crystalline oxide as a major component, the film formed directly on the substrate or with another layer therebetween, wherein the crystal substrate has an off angle from 0.2° to 12.0°, and the crystalline oxide contains one or more metals selected from indium, aluminum, and gallium.