3C-SiC Heteroepitaxial Wafer Growth with Low-Pressure CVD Nucleation
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Solution Overview
Problem
Existing methods for growing high-quality 3C-SiC single crystal films on large-diameter silicon substrates face challenges such as narrow process conditions, high-temperature requirements, and the need for multiple raw material gases, which complicates the process and increases costs and safety concerns.
Innovation Solution
A method using a reduced-pressure CVD apparatus involves three steps: hydrogen baking to remove natural oxide films, forming a SiC nucleus at specific pressure and temperature conditions, and growing the 3C-SiC single crystal film under optimized pressure and temperature conditions using a single type of source gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If two types of raw material gas are simultaneously flowed for forming 3C-SiC single crystal film, then the film can be formed by decomposition, but the process control becomes extremely difficult due to difference in thermal stability and diffusion coefficient, resulting in narrow range of usable process conditions
Solution Approach 1:
The patent segments the film formation process into two distinct sequential steps: first forming a SiC nucleus layer using only a carbon-containing gas, then growing the 3C-SiC single crystal film using both carbon- and silicon-containing gases. This segmentation allows each step to use optimized gas conditions without the control difficulties of simultaneous multi-gas processing.
Solution Approach 2:
The patent performs preliminary action by first forming a SiC nucleus layer on the silicon substrate before introducing silicon-containing gas for film growth. This preliminary nucleus formation step prepares the surface for subsequent epitaxial growth, enabling better control of the final single crystal film quality.
2Manufacturing precision
If high-temperature treatment (up to 1200°C) is used to decompose raw material gases for film growth, then the 3C-SiC single crystal film can be formed, but the compatibility with existing process deteriorates due to slip resistance problems on large-diameter substrates
Solution Approach 1:
The patent changes the temperature parameter by performing the nucleus formation step at a lower temperature (900-1100°C) compared to conventional high-temperature methods. This parameter change enables better adaptability to existing processes while still achieving high-quality 3C-SiC single crystal film growth in the subsequent step.
3Manufacturing precision
If multiple types of raw material gas are used for epitaxial growth, then the 3C-SiC single crystal film can be formed, but the costs of apparatus and attached equipment increase, and safety problems arise due to high reactivity of silicon source gas
Solution Approach 1:
The patent segments the gas introduction process into two phases: first using only carbon-containing gas for nucleus formation, then adding silicon-containing gas for film growth. This segmentation reduces the need for complex multi-gas handling equipment and improves safety by limiting silicon source gas exposure to only when necessary.
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 efficiently produces high-quality 3C-SiC single crystal films on large-diameter substrates with improved crystallinity and reduced lattice mismatch, allowing for the formation of heteroepitaxial wafers suitable for GaN growth and other semiconductor applications.
Implementation Method 1
a first step of removing a natural oxide film on a surface of the single crystal silicon substrate with hydrogen baking
Implementation Method 2
with using a reduced-pressure CVD apparatus, a second step of forming a SiC nucleus on the single crystal silicon substrate under a condition of a pressure of 13 Pa or higher and 13332 Pa or lower and a temperature of 600°C or higher and 1200°C or lower
Data Source
Figure 1~2
Figure 3
AI summary
The present invention is a method for producing a heteroepitaxial wafer of hetero-epitaxially growing a 3C-SiC single crystal film on a single crystal silicon substrate. The method includes: with using a reduced-pressure CVD apparatus, a first step of removing a natural oxide film on a surface of the single crystal silicon substrate with hydrogen baking; a second step of forming a SiC nucleus on the single crystal silicon substrate under a condition of a pressure of 13 Pa or higher and 13332 Pa or lower and a temperature of 600°C or higher and 1200°C or lower while a source gas containing carbon is supplied; and a third step of growing a SiC single crystal under a condition of a pressure of 13 Pa or higher and 13332 Pa or lower and a temperature of 800°C or higher and lower than 1200°C while a source gas containing carbon and silicon is supplied to form the 3C-SiC single crystal film. This provides a method for producing a heteroepitaxial wafer that can efficiently epitaxially growing the 3C-SiC single crystal film with good quality on the single crystal silicon substrate.