Development of Recovery System for VOC Vapors by Ion-Induced Nucleation

在半导体制造过程中，各种挥发性有机溶剂被用于清洗晶圆表面，这些溶剂从大气中回收是人们非常关注的问题。在本工作中，我们的目标是开发浓度为ppm级的CCl_4蒸汽回收系统。CCl_4蒸汽通过电晕放电电离，通过离子诱导成核生长成颗粒，然后通过静电沉淀去除。设计了声波喷射电离器、离子诱导成核室和静电除尘器，并对其性能和回收系统进行了研究。结果表明：1)声波射流电离器能够产生高密度离子；2)CCl_4离子通过水蒸气的凝结生长为亚微米粒子；3)生长的颗粒可以被静电除尘器完全去除。此外，当四氯化碳以单一组分存在于空气中时，由这些装置组成的回收系统可以有效地去除四氯化碳。其他共存蒸汽对CCl_4脱除效率的影响有待进一步研究。

In semiconductor manufacturing process, various kinds of volatile organic solvents are used for cleaning wafer surfaces and the recovery for these solvents from the atmosphere is of great concern. In the present work, we aimed at developing recovery system of CCl_4 vapor with the concentration of ppm level. CCl_4 vapor is ionized by corona discharge and grown to particles by ion-induced nucleation and then removed by electrostatic precipitation. We designed i) sonic jet ionizer, ii) ion-induced nucleation chamber, and iii) electrostatic precipitator, and studied the individual performances as well as the recovery system assembled with these appratuses. As a result, it was shown that i) the sonic jet ionizer is capable of generating high density ions, ii) CCl_4 ions grew to submicron particles by the condensation of water vapor, and iii) the grown particles can be completely removed by the electrostatic precipitator. Further, the recovery system assembled with these apparatuses was found to be effective for the removal of CCl_4 when it exists in air as a single component. Further work is required to elucidate the influence of other coexisting vapors on the removal efficiency of CCl_4.