To verify that the measured mass evolution with time is truly associated with film deposition, selected QCM crystals were analyzed post-deposition. Cross-section SEM analysis with compositional mapping by EDS for a QCM crystal that was used to study film deposition with continuous CVD at 10 W plasma power and +40 V bias, is shown in Fig. . The EDS map shows that iron has been deposited on the quartz crystal. The platinum layer was deposited to prevent ion beam associated sample damage during preparation of the cross-section. The cross-section micrograph shows that close to 1.8 µm film was deposited on the gold coated QCM crystal. The cross-section view reveals significant porosity and an approximately 160 nm thick void close to the substrate (Fig. ), indicating that continuous CVD with +40 V bias and 10 W plasma power is an unoptimized condition for film deposition. In Fig. it is shown that the modified QCM can be used to monitor mass evolution in time, using the quartz crystal as a substrate, ferrocene as the metal precursor and plasma electrons as reducing agents in continuous CVD. This opens for studying the surface chemistry more closely by monitoring growth during sequential precursor adsorption followed by plasma exposure. To this purpose we employed a time-resolved CVD process where the Fe precursor and the plasma discharge were individually pulsed into the system with 5 s of FeCp2 exposure followed by 5 s of plasma exposure. Note that no purge with inert gas, as done in atomic layer deposition (ALD), was used in between the FeCp2 and the plasma pulses. The plasma discharge power was 10 W, and the bias was set to +40 V. Figure shows the mass evolution during film deposition with this time-resolved CVD process. We note that the mass gain is high during the early stage of the precursor pulse, indicating surface adsorption. It is followed by a slower mass gain after about 3 s, which may indicate an onset of saturation. During the entire plasma pulse, the QCM signal suggests a significant mass loss, albeit with a total mass gain after the full cycle. The grey areas correspond to igniting and maintaining the plasma, while not allowing the precursor into the deposition system.