Alpha-Ga2O3 Composite Substrate for Thick Crack-Free Crystal Films
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Solution Overview
Problem
The separation between α-Ga2O3 crystal films and base substrates, such as sapphire substrates, occurs frequently when the thickness of the α-Ga2O3 crystal film is increased, leading to cracks and instability.
Innovation Solution
A method involving immersing a base substrate in an aqueous solution containing Ga ions at supercritical conditions (390°C and 22.1 MPa) to form an α-Ga2O3 crystal film with controlled alkali metal element content, followed by removing the base substrate to create a free-standing film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the thickness of α-Ga2O3 crystal film is increased, then the film can be used for power semiconductor applications requiring thick films, but separation between the film and base substrate occurs frequently
Solution Approach 1:
The patent applies parameter changes by precisely controlling the alkali metal element content in the α-Ga2O3 crystal film within a specific range (1.2×10^15 to 1.0×10^18 atoms/cm³). This parameter control prevents separation between the thick film and base substrate while maintaining film integrity, resolving the contradiction between increasing film thickness and preventing separation.
Solution Approach 2:
The patent implements local quality by creating a specific compositional profile within the film - controlling the distribution and concentration of alkali metal elements at specific locations within the crystal structure. This localized compositional control enhances adhesion at the film-substrate interface while allowing the bulk film to achieve the required thickness.
2Length of stationary object
If the thickness of α-Ga2O3 crystal film is increased, then the film can support power semiconductor applications, but cracks occur at the separated portion and periphery
Solution Approach 1:
By controlling the alkali metal element content within the specified range, the patent modifies the mechanical and structural parameters of the crystal film. This prevents crack formation at separated portions and periphery regions, enabling the production of thick films with improved strength and defect-free morphology suitable for power semiconductor applications.
3Quantity of substance
If conventional methods are used to grow thick α-Ga2O3 films on sapphire substrates, then film formation is achieved, but separation and instability occur
Solution Approach 1:
The patent fundamentally changes the compositional parameter of the crystal film by precisely controlling alkali metal element content. This parameter modification ensures stable bonding between the film and sapphire substrate even when producing thick films with substantial quantity, eliminating the separation and instability issues observed in conventional growth methods.
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 method reduces separation and cracks between the α-Ga2O3 crystal film and the base substrate, allowing for the production of thick, crack-free α-Ga2O3 films suitable for power semiconductors.
Implementation Method 1
bringing the base substrate into a supercritical state at a temperature of 390° C. or more and at a pressure of 22.1 MPa or more
Implementation Method 2
an α-Ga2O3 crystal film is formed on the surface of the base substrate in this method
Data Source
AI summary
A composite substrate includes: a base substrate and an α-Ga2O3 crystal film that is provided on the base substrate, has a thickness of 10 μm or more, and has at least one alkali metal element content of 1.2×1015 atoms/cm3 or more and 1.0×1018 atoms/cm3 or less.