Crystalline Oxide Semiconductor Thermal Expansion Orientation
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Solution Overview
Problem
Existing methods for growing crystalline oxide semiconductors on heterogeneous substrates face challenges such as cracks, dislocations, and low deposition rates, particularly when attempting to achieve high-quality films with corundum structures for semiconductor devices requiring heat dissipation.
Innovation Solution
A crystalline oxide semiconductor is developed with a first crystal axis and a second crystal axis, where the second side is shorter than the first side, and the linear thermal expansion coefficient of the first crystal axis direction is smaller than that of the second crystal axis direction, with the sides being parallel or substantially parallel to their respective axes, enhancing crystal quality and thermal dispersibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ELO deposition or thermal expansion coefficient matching methods are used to grow crystals on heterogeneous substrates, then crystal quality is improved, but deposition rate remains low and substrate defects (cracks, dislocations, warpages) persist
Solution Approach 1:
The invention changes the deposition parameters by using a specific temperature range (500-700°C) and controlling oxygen partial pressure during deposition to achieve both high crystal quality and high deposition rate simultaneously, resolving the contradiction between manufacturing precision and productivity
Solution Approach 2:
The invention uses a composite structure with a buffer layer having a specific crystal structure that matches both the substrate and the final crystal layer, enabling high-quality crystal growth at high deposition rates without the defects associated with conventional methods
2Quantity of substance
If conventional deposition methods are used on heterogeneous substrates, then some crystal growth is achieved, but substrate defects (cracks, dislocations, warpages) and film defects occur
Solution Approach 1:
The invention introduces a buffer layer as an intermediary between the heterogeneous substrate and the crystal layer. This buffer layer has a crystal structure that bridges the lattice mismatch, preventing defects from propagating to the final film and enabling thick, reliable epitaxial growth
Solution Approach 2:
The invention selects a buffer layer material whose thermal expansion coefficient matches both the substrate and the crystal layer, preventing thermal stress-induced defects during deposition and subsequent processing, thereby maintaining film integrity at increased thickness
3Manufacturing precision
If corundum-structured gallium oxide film is deposited using ELO method, then corundum structure is obtained, but facet structure forms causing dislocations and cracks
Solution Approach 1:
The invention changes the deposition parameters by maintaining a specific temperature range (500-700°C) and controlling oxygen partial pressure to promote uniform corundum structure growth without facet formation, thereby achieving both structural quality and film integrity
Solution Approach 2:
The invention employs periodic pulse deposition cycles with specific timing and parameter variations that promote uniform layer-by-layer growth, preventing the formation of facets and associated dislocations while maintaining corundum structure
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 a high-quality crystalline oxide semiconductor suitable for semiconductor devices that require heat dissipation, reducing cracks and improving thermal distribution, thereby enhancing semiconductor characteristics.
Implementation Method 1
making a linear thermal expansion coefficient of the first crystal axis direction smaller than a linear thermal expansion coefficient of the second crystal axis direction
Data Source
AI summary
A crystalline oxide semiconductor with excellent crystalline qualities that is useful for semiconductors requiring heat dissipation is provided. A crystalline oxide semiconductor including a first crystal axis, a second crystal axis, a first side, and a second side that is shorter than the first side, a linear thermal expansion coefficient of the first crystal axis is smaller than a linear thermal expansion coefficient of the second crystal axis, a direction of the first side is parallel and/or substantially parallel to a direction of the first crystal axis, and a direction of the second side is parallel and/or substantially parallel to a direction of the second crystal axis.