AbstractThe parylene is a polymer of p-xylene and it is polymerized by pyrolysis of the parylene dimer called di-p-xylene. Until now the thickness of parylene has been controlled by adjusting the amount of the parylene dimer. However, the parylene film is required of more accurate and reproducible control method. This work presents the quartz crystal microbalance (QCM) for the on-line monitoring of parylene thickness. QCM was installed at the deposition chamber and the QCM signal monitoring was carried out during the whole deposition process. The QCM sensorgrams were recorded and the resonance frequency shift by the deposition of parylene on the QCM was correlated to the thickness of parylene film from the AFM. From the linear correlation parameters between the resonance frequency shift analysis and the film thickness, the QCM monitoring was determined to be feasible for the monitoring of parylene film thickness during the parylene deposition process.