High-Pressure Spatial CVD for Stable High-Indium Nitride Growth
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Solution Overview
Problem
Current semiconductor growth methods, such as chemical vapor deposition (CVD), face challenges in synthesizing materials like Group III-nitrides due to instability at elevated temperatures, leading to decomposition and limited access to high indium content alloys essential for advanced optoelectronic and electronic devices.
Innovation Solution
A high pressure spatial CVD (HPS-CVD) system that operates at pressures up to 1000 atm, spatially separates source gases to prevent pre-reactions, and controls the boundary layer thickness mechanically, allowing growth of high indium content alloys like InGaN, AlInN, and InN at compatible conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If elevated temperature is used for material growth, then crystal quality improves due to increased adatom mobility, but material decomposition occurs due to increased equilibrium vapor pressure
Solution Approach 1:
The patent changes the pressure parameter from atmospheric to high pressure (up to 1000 atm) to suppress material decomposition. This allows the system to operate at elevated temperatures needed for good crystal quality while preventing the vapor pressure-driven decomposition that would normally occur at such temperatures.
Solution Approach 2:
The patent creates a high pressure environment that balances the equilibrium vapor pressure of the material constituents. By raising the ambient pressure to match or exceed the decomposition vapor pressure, the system achieves a state where material stability is maintained even at high temperatures required for good crystal quality.
2Quantity of substance
If source gases are mixed before reaching the substrate, then all constituents are available for growth, but pre-reactions occur leading to loss of volatile components
Solution Approach 1:
The patent segments the gas delivery system into separate channels for different source gases (e.g., Group III precursors and nitrogen). These segmented gas flows are delivered independently to the substrate surface, preventing pre-reactions in the gas phase while ensuring all constituents are available for epitaxial growth.
Solution Approach 2:
The patent creates different local gas environments around different regions of the substrate. Each region receives specific gas compositions tailored to the local growth requirements, with gases introduced separately just before reaching the substrate surface to avoid premature mixing and reaction.
3Adaptability or versatility
If high indium content is incorporated into alloys, then access to desired band gap regimes is enabled, but decomposition into metallic indium and nitrogen occurs at growth temperatures
Solution Approach 1:
The patent uses high pressure (up to 1000 atm) to stabilize indium-containing alloys against decomposition. This pressure parameter change enables the incorporation of high indium content (up to 100% InN) at temperatures where indium nitride would normally decompose, thereby accessing desired band gap regimes for optoelectronic applications.
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
Enables the growth of high-quality, high-indium content alloys at elevated temperatures without decomposition, opening up avenues for heterostructure engineering and improved device performance in emitters, transistors, and solar cells.
Implementation Method 1
A widely used commercial platform to synthesis these materials includes chemical vapor deposition (CVD). This method delivers the constituents of the material in gas phase to a carrier wafer or substrate
Implementation Method 2
Due to the elevated temperature of the wafer or substrate, the desired material typically improves in crystal quality due to increased mobility of the adatoms on the surface
Implementation Method 3
Due to the elevated temperature of the wafer or substrate, the desired material typically improves in crystal quality due to increased mobility of the adatoms on the surface, though simultaneously can lead to degradation of the material due to increased equilibrium vapor pressures of one or more constituents of the growing solid
Data Source
AI summary
High pressure spatial chemical vapor deposition apparatuses and related process are disclosed for forming thin films on a substrate. An enclosure includes plural process chambers fluidly isolated from each other by radial separating barriers. Each chamber contains a different source gas comprising one or more volatile reactive species. The substrate is supported beneath the chambers on a rotating heated susceptor. Rotation of the susceptor carries the substrate in a path which consecutively exposes the substrate to the volatile reactive species in each process chamber. The gases first mix in the gaseous boundary layer formed adjacent the substrate. A thin film gradually grows in thickness on the substrate with each successive pass and exposure to the volatile reactive species in each of the individual process chambers. The film may be grown at high pressures exceeding 1 atmosphere in some implementations. A modular design includes an outer shell and different interchangeable process inserts.