Solvent Purification System Using Ion Exchange and Distillation
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Solution Overview
Problem
The semiconductor industry faces challenges in producing high-purity solvents for manufacturing ultra-fine and precise integrated circuits due to contamination from metal, organic, and moisture impurities, which can lead to defects and reduced manufacturing yields.
Innovation Solution
A purification system and method that involves dehydration using a molecular sieve column, filtration with specific pore-sized filters, and subsequent distillation, followed by ion exchange filtration with negatively charged filters to remove impurities, achieving ultra-pure solvents with low organic and metal impurities and moisture content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional filtration and distillation methods are used to purify solvents, then the purification process is simple and cost-effective, but the solvent purity is insufficient with metal impurities remaining at levels that cause semiconductor defects
Solution Approach 1:
The purification system is divided into multiple independent filtration stages, each targeting specific types of impurities. The first filter unit removes particulate contaminants, while the second filter unit with ion-exchange resin specifically targets metal ions. This segmentation allows each component to be optimized for its specific function, achieving ultra-high purity without requiring a single complex purification step.
Solution Approach 2:
An ion-exchange resin is introduced as an intermediary substance between the solvent and metal impurities. The resin acts as a mediator that selectively binds metal ions through electrostatic attraction and chemical interaction, allowing metal removal without directly contacting or contaminating the solvent with filtration media particles.
2Manufacturing precision
If multiple filtration stages are added to remove metal impurities to semiconductor-grade levels, then solvent purity improves to 99.999% and below, but the purification system complexity and cost increase significantly
Solution Approach 1:
Different regions of the purification system are designed with locally optimized properties. The first filter unit uses standard filtration media for particulate removal, while the second filter unit incorporates ion-exchange resin specifically in the region where metal ion removal is needed. This local quality approach ensures each section performs its specific function efficiently without unnecessary complexity elsewhere in the system.
Solution Approach 2:
The ion-exchange resin in the second filter unit utilizes a porous structure that provides high surface area for metal ion binding. The porous material allows solvent molecules to pass through while trapping metal ions within the pores through electrostatic attraction, achieving efficient metal removal without requiring dense filtration that would impede solvent flow.
3Manufacturing precision
If aggressive filtration is used to remove all organic impurities, then organic contaminant levels decrease, but filtration media may shed particles that become new contaminants
Solution Approach 1:
The filtration media is designed as a disposable component that is replaced rather than cleaned and reused. This eliminates the problem of particle shedding from used media, as each new filter unit contains fresh, intact filtration material. The low cost of the disposable filters makes this approach economically viable for achieving ultra-high purity standards.
Solution Approach 2:
A secondary filtration stage acts as an intermediary barrier that captures any particles shed from the primary filtration media. This protective intermediary layer ensures that even if the first filter releases minimal particles, they are trapped before reaching the purified solvent, preventing contamination from filtration media degradation.
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 system effectively reduces impurities to levels of at least 99.99% purity and 200 ppt total metal impurities, improving semiconductor wafer yields by minimizing residue and particle defects.
Implementation Method 1
passing the organic solvent through at least one column containing an adsorbent to remove water in the organic solvent
Implementation Method 2
distilling the organic solvent in a distillation column to obtain a purified organic solvent
Implementation Method 3
passing the distilled organic solvent through an ion exchange filter unit to obtain a purified organic solvent
Data Source
AI summary
The present disclosure is directed to methods and systems of purifying solvents. The purified solvents can be used for cleaning a semiconductor substrate in a multistep semiconductor manufacturing process.