The manufacturing of multilayer Laue (MLL) components for X-ray optics by physical vapor deposition (PVD) requires
high precision and accuracy that presents a significant process control challenge. Currently, no process control system
provides the accuracy, long-term stability and broad capability for adoption in the manufacturing of X-ray optics. In situ
atomic absorption spectroscopy is a promising process control solution, capable of monitoring the deposition rate and
chemical composition of extremely thin metal silicide films during deposition and overcoming many limitations of the
traditional methods. A novel in situ PVD process control system for the manufacturing of high-precision thin films, based on combined
atomic absorption/emission spectrometry in the vicinity of the deposited substrate, is described. By monitoring the
atomic concentration in the plasma region independently from the film growth on the deposited substrate, the method
allows deposition control of extremely thin films, compound thin films and complex multilayer structures. It provides
deposition rate and film composition measurements that can be further utilized for dynamic feedback process control.
The system comprises a reconfigurable hardware module located outside the deposition chamber with hollow cathode
light sources and a fiber-optic-based frame installed inside the deposition chamber. Recent experimental results from in
situ monitoring of Al and Si thin films deposited by DC and RF magnetron sputtering at a variety of plasma conditions
and monitoring configurations are presented. The results validate the operation of the system in the deposition of
compound thin films and provide a path forward for use in manufacturing of X-Ray optics.
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