Ultra high-purity gases are vital to many processes in the microelectronics industry. For example, in plasma etching to fabricate integrated circuits, even minor impurities can cause significant defects that interfere with the process.
Despite decades of engineering and research, performing the bulk separations necessary to produce ultra high-purity gases is extremely difficult or energy intensive with traditional methods, such as swing adsorption, cryogenic distillation or membrane separation. Achieving optimal purity levels requires ultra-fine tuning at a molecular level to remove persistent impurities at a part per billion (ppb), part per trillion (ppt), or even part per quadrillion (ppq) level.
MOFs provide unprecedented molecular-level customization to selectively tune specific physical and chemical parameters critical for effective separations. As described in two case studies below, NuMat has used Next NineTM to successfully solve seemingly impossible separations for industrial partners, dramatically improving the purity of electronic gases critical for the advancement of next-node technologies.
Case Study 1: A path toward displacing cryogenic distillation for ultra high-purity gases
Ultra high-purity gases are exceptionally energy intensive to produce, often requiring multiple separation and purification steps and multiple cryogenic distillation columns. Even then, residuals impurities remain that cannot be removed in a cost effective manner. This is the case for an in-demand etchant gas that is often produced using expensive electrolysis. While cryogenic distillation is also used to produce this gas, it leaves a persistent impurity that is exceptionally difficult to remove given the near identical boiling point as the product gas.
Using the Next Nine platform, NuMat tailor designed a MOF to this application and then built an engineered pressure swing adsorption (PSA) system, which showed an unprecedented selectivity factor of 10,000:1 for the product gas over the impurity. The PSA system was able to achieve ppb level purities where previously only ppm levels were possible with cryogenic distillation and electrolysis.
Beyond achieving next-node purity specifications, the Next Nine has enabled novel supply-chains and adjacent product categories. For example, given system performance, low-grade gas (<60%) can now be upgraded to electronic grade in a single pass, increasing its market value by a factor of more than 200 times. This Next Nine™ separation technology is also being leveraged across a broader portfolio of product innovation, enabling the development of advanced point of use purification and abatement systems in the fab.
Case Study 2: Separating “inseparable” gases
NuMat was approached by a global tier-1 electronic materials company with an “impossible” separation, which involved removing an impurity for a critical etchant gas. Traditional separation techniques had been ineffective as the two gases had nearly identical molecular sizes and boiling points. An exhaustive computational screening revealed a MOF adsorbent capable of discriminating on an unprecedented 1 Angstrom difference in molecular diameter between the two species.
The Numat team synthesized the MOF material at a small scale and used single-component adsorption experiments to confirm the predicted selectivity. As part of Next Nine™, the material was scaled to pilot scale quantities, formed into an optimized shape for PSA use, and then evaluated at the partner facility for integration into a large commercial separation system. Next Nine™ will allow them to achieve the highest purity specification in the world today at a cost-advantaged position. This technology is also enabling the development of advanced point-of-use purification and abatement systems in the fab.
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