The invention is directed to QCM measurements in monitoring ALD processes. Previously, significant barriers remain in the ALD processes and accurate execution. To turn this exclusively dedicated in situ technique into a routine characterization method, an integral QCM fixture was developed. This new design is easily implemented on a variety of ALD tools, allows rapid sample exchange, prevents backside deposition, and minimizes both the footprint and flow disturbance. Unlike previous QCM designs, the fast thermal equilibration enables tasks such as temperature-dependent studies and ex situ sample exchange, further highlighting the feasibility of this QCM design for day-to-day use. Finally, the in situ mapping of thin film growth rates across the ALD reactor was demonstrated in a popular commercial tool operating in both continuous and quasi-static ALD modes.