WCl5 Crystalline Phase Control for Stable Vapor Flux
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Solution Overview
Problem
Tungsten pentachloride (WCl5) is a solid with low vapor pressure, making it difficult to provide a stable and reproducible flux for vapor deposition and etching processes, and its crystalline phases change over time, leading to performance drift and vapor pressure instability.
Innovation Solution
Conditioning WCl5 to produce compositions with specific crystalline phases, including Phase 1 and Phase 2, by heating it to controlled temperatures and times to maintain a stable Phase 1:Phase 2 ratio, using non-reactive containers to prevent contamination, and subliming the compositions to maintain consistent vapor pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If WCl5 is used as a solid precursor with low vapor pressure, then it can be used for CVD or ALD processes, but it is difficult to provide sufficient flux to the processing chamber
Solution Approach 1:
The patent changes the physical state parameter of WCl5 from solid to liquid by maintaining it above its melting point (248°C), thereby increasing its vapor pressure and flux to the processing chamber while still allowing controlled delivery through temperature management
Solution Approach 2:
The system dynamically adjusts the temperature of the WCl5 reservoir to control the vapor pressure and flux rate, allowing optimization of material delivery while maintaining stable operation throughout the process
2Reliability
If WCl5 is stored as a solid precursor, then it can be contained and transported, but the flux becomes unstable as the package is depleted
Solution Approach 1:
By maintaining WCl5 in a liquid state above its melting point, the system ensures consistent vapor pressure and flux stability throughout the operational duration, eliminating the depletion effects experienced with solid precursors
Solution Approach 2:
The system monitors and adjusts temperature to maintain stable vapor pressure and flux delivery over extended operational periods, ensuring reliability throughout the entire process duration
3Stability of the object's composition
If WCl5 crystalline phases change over time, then material transformation occurs, but vapor pressure stability deteriorates
Solution Approach 1:
The patent intentionally maintains WCl5 in a liquid phase above its melting point to prevent crystalline phase transitions, thereby ensuring stable vapor pressure and eliminating performance drift associated with solid-phase transformations
Solution Approach 2:
By controlling temperature to remain above the melting point, the system prevents crystalline phase changes and maintains consistent vapor pressure characteristics throughout operation
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
The method ensures a stable vapor pressure of WCl5 over extended periods, maintaining approximately 80-95% of the initial vapor pressure even after significant depletion, thereby stabilizing the vapor deposition and etching processes.
Implementation Method 1
Conditioning WCl5 to produce compositions with specific crystalline phases, including Phase 1 and Phase 2, by heating it to controlled temperatures and times
Implementation Method 2
subliming the compositions to maintain consistent vapor pressure
Implementation Method 3
The method ensures a stable vapor pressure of WCl5 over extended periods, maintaining approximately 80-95% of the initial vapor pressure even after significant depletion
Data Source
AI summary
A process of conditioning tungsten pentachloride to form specific crystalline phases are disclosed. The specific crystalline phases permit stable vapor pressures over extended periods of time during vapor deposition and etching processes.