Magnesium-Loaded Ion Exchange for Onium Hydroxide Purification
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Solution Overview
Problem
Current methods are unable to effectively remove metal ions such as aluminum to levels below 1 part per billion (ppb) from onium hydroxide and salt solutions, making it difficult to recycle these materials for use in semiconductor processing, where high purity is required.
Innovation Solution
A process involving a weak acid ion exchange medium loaded with magnesium ions is used to remove dissolved metal ions from onium hydroxide and salt solutions, achieving significant reduction in metal content to levels acceptable for semiconductor applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional metal removal methods are used, then most metal ions can be removed to ppm levels, but metal ions such as aluminum cannot be removed to levels below 1 ppb
Solution Approach 1:
The patent changes the chemical parameters of the ion exchange system by using weak acid ion exchange resins with specific functional groups (carboxyl, phenolic, sulfonic) and controlling pH levels to optimize metal ion removal. This parameter optimization enables achievement of sub-1 ppb aluminum removal levels required for semiconductor applications
Solution Approach 2:
The patent introduces magnesium ions as an intermediary substance to load onto the ion exchange resin before treating the onium hydroxide solution. This magnesium loading creates a more effective ion exchange medium that selectively removes aluminum and other metal ions to the required ultra-low levels
2Manufacturing precision
If new onium hydroxide material is used to meet purity specifications, then metal ion content is below 10 ppb, but recycling and re-use of onium hydroxide becomes impossible
Solution Approach 1:
The patent implements a metal removal process that recovers onium hydroxide from used semiconductor processing solutions by removing accumulated metal ions. The treated onium hydroxide can then be reused in semiconductor processing, eliminating the need to discard and purchase new material while maintaining purity specifications
Solution Approach 2:
By optimizing the ion exchange conditions (resin type, magnesium loading, pH control, flow rates), the process achieves sufficient metal ion removal to restore recycled onium hydroxide to specification levels, enabling its reuse in semiconductor applications
3Productivity
If onium hydroxide is recycled for re-use in semiconductor processing, then economic and environmental benefits are achieved, but metal ion content exceeds the 10 ppb specification
Solution Approach 1:
The magnesium ion loading serves as a preparatory intermediary step that enhances the ion exchange resin's ability to remove metal ions from recycled onium hydroxide, making the recycling process effective enough to meet semiconductor purity specifications
Solution Approach 2:
The patent optimizes multiple process parameters including resin selection, magnesium concentration, pH levels, and flow rates to achieve the necessary metal ion removal efficiency that enables recycling while maintaining 10 ppb specification compliance
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 achieves metal ion contents less than 1 ppb in recycled onium hydroxide and salt solutions, enabling their reuse in demanding applications like semiconductor processing.
Implementation Method 1
providing a weak acid ion exchange medium; providing a solution comprising magnesium ions; forming a magnesium-loaded ion exchange medium by contacting the ion exchange medium with the solution comprising magnesium ions; contacting the magnesium-loaded ion exchange medium with an onium hydroxide and/or salt solution containing a first quantity of dissolved metal ions
Data Source
Figure 1
AI summary
The present invention relates to a process for removing dissolved metal ions from an onium hydroxide and/or salt solution, including providing a weak acid ion exchange medium; providing a solution comprising magnesium ions; forming a magnesium-loaded ion exchange medium by contacting the ion exchange medium with the solution comprising magnesium ions; contacting the magnesium-loaded ion exchange medium with an onium hydroxide and/or salt solution containing a first quantity of dissolved metal ions, wherein at least a portion of the dissolved metal ions are removed from the onium hydroxide and/or salt solution; and collecting the onium hydroxide and/or salt solution after the contacting, wherein the solution collected contains a second quantity of dissolved metal ions smaller than the first quantity. The onium hydroxide and/or salt may be tetramethylammonium hydroxide and/or salt, and the metal content may be reduced to about 1 part per billion or less by the process.