3C-SiC Heteroepitaxial Wafer Growth Under Reduced-Pressure CVD
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Solution Overview
Problem
Current methods for growing high-quality 3C-SiC single crystal films on silicon substrates face challenges such as controlling thermal stability and diffusion coefficients of gases, leading to narrow process conditions, contamination, high-temperature requirements, and increased costs, especially when scaling to larger diameters, and often result in low formation speed and crystal defects.
Innovation Solution
A method using a reduced-pressure CVD apparatus with hydrogen baking to remove native oxide films, followed by nucleation and growth steps at specific pressure and temperature conditions (13332 Pa or lower and 800° C. to 1200° C.) with monomethylsilane or trimethylsilane as source gas, allowing for efficient and reliable formation of 3C-SiC single crystal films without the need for additional carbonization steps, thus preventing polycrystallization and reducing lattice mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If two types of raw material gases (carbon source and silicon source) are introduced simultaneously for 3C-SiC film growth, then film formation can proceed, but it becomes extremely difficult to control thermal stability and diffusion coefficients differences, narrowing the applicable process conditions and risking gas phase reactions that contaminate the reactor
Solution Approach 1:
The film formation process is segmented into two distinct steps: first introducing only carbon source gas to form a carbonized layer, then introducing silicon source gas to form the 3C-SiC film. This segmentation avoids simultaneous introduction of multiple reactive gases, eliminating gas phase reactions and simplifying process control while maintaining film formation capability
Solution Approach 2:
A carbonized layer is formed as a preliminary step before introducing silicon source gas. This preliminary carbonization creates a stable foundation that facilitates subsequent 3C-SiC film growth and reduces lattice mismatch, while avoiding the need to control simultaneous reactions of multiple gases
2Manufacturing precision
If high-temperature treatment (up to 1200°C) is used to decompose raw material gases for film growth, then 3C-SiC single crystal film can be formed, but affinity with existing processes decreases and problems with anti-slip property arise when diameter is enlarged to 300 mm
Solution Approach 1:
The process utilizes reduced pressure conditions to enable film formation at lower temperatures compared to conventional atmospheric pressure methods. This parameter change maintains crystal quality while improving compatibility with existing processes and eliminating anti-slip problems associated with high-temperature processing of large diameter substrates
3Productivity
If multiple types of raw material gases are used for 3C-SiC film growth, then film formation can proceed, but equipment cost and ancillary facilities increase along with safety issues due to high reactivity of silicon source gases
Solution Approach 1:
The process segments gas introduction into separate steps, using carbon source gas first followed by silicon source gas. This eliminates the need for complex gas mixing systems and safety infrastructure required for simultaneous introduction of multiple highly reactive gases, while maintaining film growth capability
Solution Approach 2:
The silicon source gas introduction step is extracted and separated from the carbon source gas step. This extraction eliminates the need for complex gas handling infrastructure for simultaneous multi-gas introduction, reducing equipment complexity and safety requirements while preserving the ability to form high-quality 3C-SiC films
4Manufacturing precision
If extremely low-pressure condition (2×10−4 to 3×10−4 Torr) is used for 3C-SiC single crystal layer formation, then layer can be grown on single crystal silicon substrate, but formation speed becomes very low
Solution Approach 1:
The process uses reduced pressure conditions that are significantly higher than the extremely low pressures used in conventional methods. This parameter change accelerates film formation speed by several orders of magnitude while maintaining single crystal quality through the controlled two-step gas introduction process and precise temperature management
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 enables the efficient production of high-quality 3C-SiC single crystal films on large-diameter substrates with controlled growth, preventing crystal defects and allowing for further heteroepitaxial growth of GaN or Si layers, improving the reliability and speed of film formation.
Implementation Method 1
a first step of removing a native oxide film on a surface of the single crystal silicon substrate by hydrogen baking
Implementation Method 2
a third step of forming the 3C-SiC single crystal film by growing a SiC single crystal on condition of pressure of 13332 Pa or lower and a temperature of 800° C. or higher and lower than 1200° C., while supplying a source gas containing carbon and silicon into the reduced-pressure CVD apparatus
Implementation Method 3
a second step of nucleation of SiC on the single crystal silicon substrate on condition of pressure of 13332 Pa or lower and a temperature of 300° C. or higher and 950° C. or lower
Data Source
AI summary
The present invention provides a method for producing a heteroepitaxial wafer heteroepitaxially growing a 3C-SiC single crystal film on a single crystal silicon substrate, the method including: with using a reduced-pressure CVD apparatus, a first step of removing a native oxide film on a surface of the single crystal silicon substrate by hydrogen baking; a second step of nucleation of SiC on the single crystal silicon substrate on a condition of pressure of 13332 Pa or lower and a temperature of 300° C. or higher and 950° C. or lower and a third step of forming the 3C-SiC single crystal film by growing a SiC single crystal on condition of pressure of 13332 Pa or lower and a temperature of 800° C. or higher and lower than 1200° C., while supplying a source gas containing carbon and silicon into the reduced-pressure CVD apparatus. This provides the method for producing the heteroepitaxial wafer that can efficiently grow high-quality 3C-SiC single crystal film heteroepitaxially on the single crystal silicon substrate.