Semiconductor-Grade Ethylenediamine Purification Below 50 ppm Water
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Solution Overview
Problem
Conventional methods for producing ethylenediamine (EDA) result in high residual water content and impurity species, making it unsuitable for semiconductor processing, and the use of chemical drying agents complicates the process and introduces additional contaminants.
Innovation Solution
A two-step process involving molecular sieve purification followed by distillation to achieve EDA with less than 50 ppm water and trace metals, combined with pre-treating containers to reduce metal leaching, ensures high purity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fractional distillation is used to remove water from EDA, then the dehydration process is simple, but it cannot achieve sufficient water removal due to the high-boiling azeotrope forming about 15% water by weight
Solution Approach 1:
The patent introduces molecular sieves as an intermediary substance to remove water from EDA. The molecular sieves selectively adsorb water molecules from the EDA solution, breaking the azeotropic relationship and enabling water removal beyond what conventional distillation can achieve. This intermediary approach allows achieving water content below 50 ppm without requiring complex multi-step distillation processes.
2Manufacturing precision
If chemical drying agents are used to remove water from EDA, then water content can be reduced, but the process becomes more complex and additional contaminant species are introduced
Solution Approach 1:
The patent employs molecular sieves that can be regenerated and reused multiple times, replacing the need for disposable chemical drying agents. The molecular sieves are activated by heating to remove absorbed water, then reused for subsequent drying cycles. This approach eliminates the introduction of additional contaminant species that would result from using chemical drying agents, while maintaining effective water removal capability.
3Ease of manufacture
If conventional storage containers are used for EDA, then storage is simple, but metal leaching occurs and container corrosion increases
Solution Approach 1:
The patent specifies the use of fluorinated ethylene propylene (FEV) or polytetrafluoroethylene (PTFE) lined storage containers. These composite material containers combine the mechanical strength of metal containers with the chemical inertness of fluoropolymer coatings. The fluoropolymer lining creates a barrier that prevents direct contact between EDA and metal surfaces, eliminating metal leaching and corrosion while maintaining the simplicity of container storage.
4Ease of manufacture
If EDA is synthesized in the presence of water, then the synthesis process is straightforward, but the product requires extensive purification to remove water and metallic impurities
Solution Approach 1:
The patent employs a two-stage purification process: first, molecular sieves extract water from the EDA solution to break the azeotrope and achieve low water content; second, distillation extracts remaining impurities including metallic contaminants. This extraction approach separates the purification of water and metallic impurities into distinct stages, achieving high product purity while building upon the straightforward water-based synthesis process.
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 process produces EDA with low water and metal impurities, suitable for semiconductor applications, maintaining purity and reducing container corrosion, thereby extending storage life and ensuring product quality.
Implementation Method 1
passing commercially available ethylenediamine as a liquid through a packed bed comprising a molecular sieve
Implementation Method 2
subjecting the material so treated by the molecular sieve to distillation in order to remove metallic impurities
Data Source
AI summary
Ethylenediamine (EDA) compositions and methods for making the EDA that is suitable for use in thin-film semiconductor processing applications, are disclosed. The EDA is purified to remove water and trace metals. Water levels below about 50 ppm by weight are achieved by passing liquid through 3A type molecular sieve in a packed bed. Metallic impurities are removed by distillation and the resulting product is packaged in specially dried and optionally pre-conditioned containers.