Gallium Oxide Laminated Structure for Smooth Large-Area Thin Films
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Solution Overview
Problem
Existing methods for forming α-gallium oxide thin films result in surfaces that are not smooth enough for semiconductor devices, leading to unsatisfactory semiconductor characteristics, and surface treatments like etching can degrade the films.
Innovation Solution
A laminated structure with a crystalline oxide film containing gallium oxide, where the root-mean-square roughness is 0.2 μm or less, and a ground substrate with a diameter of 50 mm or more and total thickness variation of 30 μm or less, is used, along with a method involving mist formation and heat treatment to achieve a smooth surface and excellent semiconductor characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mist CVD method is used to form gallium oxide thin film, then electrical conductivity is improved, but surface smoothness deteriorates
Solution Approach 1:
The invention performs preliminary surface preparation by selecting substrates with specific flatness characteristics (ITV ≤ 30 μm) before film formation. This preliminary action ensures that the substrate surface is sufficiently smooth to produce a smooth final film surface without requiring additional surface treatment steps that might damage the film.
Solution Approach 2:
The invention changes the parameter of substrate flatness (ITV) to resolve the contradiction. By specifying that the substrate must have ITV of 30 μm or less, the invention ensures that the underlying surface quality directly translates to film surface smoothness, achieving RMS ≤ 0.2 μm while maintaining the electrical conductivity benefits of mist CVD.
2Manufacturing precision
If surface treatment such as etching is applied to smooth the film surface, then surface smoothness is improved, but film integrity deteriorates
Solution Approach 1:
The invention extracts the surface treatment step (etching) from the process entirely. Instead of applying etching to improve smoothness, the invention achieves smooth surfaces through proper substrate selection and control of film formation parameters, thereby avoiding the harmful effects of etching on film integrity.
Solution Approach 2:
The invention takes preliminary anti-action by preventing surface degradation before it occurs. By controlling substrate flatness and film formation conditions from the outset, the invention avoids the need for subsequent surface treatment that would compromise film integrity.
3Area of stationary object
If substrate diameter is increased for larger semiconductor devices, then device scalability is improved, but surface flatness control becomes more difficult
Solution Approach 1:
The invention changes the parameter specification for substrate flatness from a qualitative requirement to a quantitative one (ITV ≤ 30 μm). This clear parameter specification enables consistent control of surface flatness across different substrate sizes, allowing scalability to 50 mm diameter and beyond while maintaining the required surface quality.
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 approach results in a smooth crystalline oxide film with improved semiconductor characteristics, reducing damage to transfer systems and substrates, and allowing for stable high-quality film manufacturing at a lower cost.
Implementation Method 1
a mist CVD and other film-forming methods using water particles are known
Implementation Method 2
The raw material solution is microparticulated to produce raw material particles, and the raw material particle is supplied to a film-formation surface of the specimen to be filmed by a carrier gas. Then the gallium oxide-based thin film having high crystallinity is formed on the specimen to be filmed by a formation of a thin film on the film-formation surface through the reaction of raw material particles.
Data Source
AI summary
A laminated structure including, a ground substrate with a crystalline oxide film containing gallium oxide as a main component and a root-mean-square of a roughness on a surface of the crystalline oxide film is 0.2 μm or less. A diameter of the ground substrate is 50 mm or more and TTV of the ground substrate is 30 μm or less.