Validation, improvement and implementation of sorption mathematical models using a quartz crystal microbalance (QCM)

• H2O sorption onto Cu and PCBA is modeled by means of a QCM.
• Consistent H2O-PCBA diffusivity and solubility data are obtained.
• H2O-Cu sticking coefficients and multilayer sorption energies are investigated.
• QCM may potentially yield accurate equilibrium and transient state data for gas–solid systems.

This work is motivated by the issues caused by the airborne molecular contamination (AMC) in the semiconductor industry and their control needs in EUVL and the current photolithography. In order to tackle the problem, sorption mathematical models have been investigated and validated using a quartz crystal microbalance (QCM). This technique, which confers a high sensitivity (ng level), allows the study of the sorption phenomena related to any deposable material onto a quartz crystal in contact with different gases whose concentrations are accurately controlled. Consequently, it may be used for other types of experiments in any discipline requiring such precision. The conduct of our experimental plan includes two naturally different materials whose dominant matter transfer phenomena differ: a polymer (Polycarbonate bisphenol-A, PCBA) on the one hand and a metal (Copper, CuC1) on the other hand. Water vapor was selected as a studied gas because of its interest in the semiconductor industry. The resulting interaction between water vapor and the targeted substrates is continuously monitored by the QCM: this allows us not only to check the suitability of the mathematical models proposed by the literature but also to obtain the matter transfer coefficients (diffusivity, solubility and sticking coefficient) governing each system. Subsequently, these coefficients enable us to predict the transient state behavior and/or equilibrium (isotherms) of the AMC providing sorption estimations at temperatures either within or outside the experimental range.

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