Study on interaction between molecules adsorbed on silicon surface using quartz crystal microbalance and the multi-component organic species adsorption-induced contamination model

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A method and a process are studied for evaluating an interaction between organic molecules which are physisorbed on silicon surface. For this purpose, the quartz crystal microbalance (QCM) is used; the data obtained by the QCM is analyzed linked with the rate theory (The Multi-component Organic Species Adsorption-Induced Contamination (MOSAIC) model).In this study, the following processes are employed.(a) Water, isopropanol (IPA) and diethyl phthalate (DEP) are supplied to silicon surface of the QCM in the form of vapor diluted with gas nitrogen.(b) In each single-component system of IPA and DEP, the rate constants of physisorption and desorption are obtained in nitrogen ambient having humidity, from the behavior of increase and decrease in its concentration on silicon surface.(c) Next, the mixture of IPA vapor and DEP vapor is supplied to the silicon surface in nitrogen ambient having humidity.(d) In this multi-component system, the increase and decrease behavior is calculated on the … More basis of the MOSAIC model using the rate constants obtained from each single-component system.Because the calculation agreed with the measurement, the following conclusions are stated.(1) The adsorption and desorption behavior in a two-component system can be described using the rate constants obtained in each single-component system.(2) The larger limit of the surface concentration of physisorbed organic compounds is functions of rate constants and concentration of the organic compounds existing in the gas phase.(3) The area occupied by organic molecule is obtained by the measurement. The area for DEP is 2 times larger than that for IPA. This relationship is acceptable on the basis of the estimation accounting for bond length between C, H and 0 atoms.(4) The area occupied in the two component system (IPA and DEP) is explained using the area for IPA and DEP in a single-component system. This indicates that there is not a significant interaction between IPA and DEP molecules.From these, the measurement using the QCM method can provide with the information of a relative value of an area occupied by an organic molecule and an interaction between organic molecules. Less