WCl6 Purification via Fluidized Bed Condensation
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Solution Overview
Problem
Current methods for purifying tungsten hexachloride (WCl6) often result in a mixture of alpha and beta crystal forms, with sublimation producing mostly alpha form and mechanical harvesting leading to wide particle sizes and impurity contamination, making it unsuitable for semiconductor applications.
Innovation Solution
A system and method involving a boiler, condenser, and fluidizing gas to vaporize WCl6, followed by condensation in a fluidizing bed, which selectively produces at least 95% beta-form crystals with controlled particle size and low impurity levels, using a process that maintains temperatures between 100°C to 180°C and employs a carrier gas to separate impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sublimation is used for purification, then productivity is enhanced and operation temperature is reduced, but the product attaches to cold wall requiring additional labor and mechanical apparatus for harvesting, and produces wide particle size distribution
Solution Approach 1:
The patent replaces mechanical scraping apparatus with a fluidization-based harvesting system. The fluidizing gas fluidizes the condensed product particles, allowing them to be easily removed through gas flow without requiring mechanical scraping tools or additional labor-intensive processes.
Solution Approach 2:
The patent uses fluidizing gas flow to transport and remove the purified product particles from the condensation zone. The pneumatic fluidization system enables easy product recovery and control of particle size distribution through adjustment of gas flow parameters.
2Productivity
If mechanical harvesting is used, then product can be collected, but particle size becomes wide and impurity contamination increases
Solution Approach 1:
The patent replaces mechanical harvesting with a fluidization-based collection system. The fluidizing gas gently suspends and transports particles, avoiding the mechanical contact and scraping that cause particle size variation and impurity contamination associated with traditional mechanical harvesting methods.
3Productivity
If alpha-form WCl6 is produced, then sublimation is effective, but vaporization rate is inconsistent and shelf life is reduced
Solution Approach 1:
The patent changes the crystal form parameter from alpha-form to beta-form WCl6 through controlled condensation conditions. The beta-form crystals exhibit consistent vaporization rates and improved shelf life, resolving the reliability issues associated with alpha-form material while maintaining purification effectiveness.
4Reliability
If high temperature processing is used, then decomposition is prevented, but corrosion hazards increase and special equipment is required
Solution Approach 1:
The patent changes the processing temperature parameter to a lower range that is sufficient to prevent decomposition of WCl6 without requiring the high temperatures that cause corrosion. This reduces equipment complexity and eliminates the need for special corrosion-resistant materials while maintaining product integrity.
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 achieves high purity WCl6 with greater than 95% beta-form crystals, suitable for semiconductor manufacturing, ensuring consistent vaporization rates and improved shelf life, while avoiding mechanical scraping and impurity contamination.
Implementation Method 1
the boiler is heated to one or more temperatures at or above the boiling point of WCl6 to cause at least a portion of the crude material to vaporize
Implementation Method 2
the condenser stream is maintained at one or more temperatures ranging from 100 to 180°C wherein at least a portion of the condenser stream condenses
Implementation Method 3
the condenser comprises a fluidizing bed which selectively produces at least 95% beta-form crystals
Data Source
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AI summary
Condensable metal halide materials, such as but not limited to tungsten chloride (WCl6), can be used deposit films metal or metal containing films in a chemical vapor deposition (CVD) or atomic layer deposition process. Described herein are high purity compositions comprising condensable materials and methods to purify condensable materials. In one aspect, there is provided a composition comprising: tungsten hexachloride which is substantially free of at least one impurity and wherein the tungsten hexachloride comprises at least 90%, preferably 95 % and more preferably 99 % by weight or greater of a β- WCl6 and 5% by weight or less of the α- WCl6 as measured by X-ray diffraction.