On-line characterisation of copper vapour evolution from linear vapour source generated using strip electron beam

In electron beam assisted physical vapour deposition (EB-PVD) technique, the online characterization of the evaporator is essential for process optimisation and control. In applications such as decorative and corrosion resistance coating, the knowledge of time average distribution of vapour is essential, whereas in some real time applications such as isotope purification, surface hardening and alloying etc., real time knowledge of vapour distribution and vapour propagation is important. The online characterization of various parameters related to the evaporator and associated processes using least expensive techniques is necessary to know the process throughput. Measurement of atom flux using quartz crystal thickness monitor can be one such techniques. The experimental studies were carried out to characterize the evaporator using thickness monitor by measuring copper vapour propagation and distribution over the two dimensional source. The experimental data measured at two heights corresponding to aspect ratio 2 and 3 are presented and the behaviour of expanding vapour is discussed. This technique can also be used to estimate the source temperature from the deposition rate data, which is discussed in the paper with its validation using measured temperature using two-colour pyrometer.