Optical thin films

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In situ optical monitoring

Beyond the mastery of deposition technologies, a very important aspect of the work carried out within the RCMO team concerns the control of the properties of the stacks and in particular the thickness of each of the deposited layers. This activity, carried out in close collaboration with the company Bühler/Leybold Optics, is based on the development of in-situ optical control methods that allow following in real time the evolution of the optical properties during the deposition. Due to the interferometric nature of the layers, the measured signal is modulated according to the thickness of the layers, which makes it possible to define stop criteria with a high degree of precision similar to that obtained in interferometric optical sensors.

Within the framework of these activities, the RCMO team works in particular on the development of algorithms allowing the automatic determination of deposition strategies for complex multilayer stacks by monochromatic optical control. These algorithms are based on criteria that take into account the feasibility of a stop layer. These strategies are then tested using simulation software that allows to reproduce the errors associated with a deposition. Once they have been validated numerically, they are then tested experimentally by deposition on the Bühler HELIOS machine.

The RCMO team is also interested in the broadband optical monitoring technique, and in particular in the development of new signal processing methods and algorithms to make this type of monitoring more efficient and intuitive.

The "Bonne Mère" challenge or how to spectrally reproduce the profile of the famous basilica overlooking Marseille with a multilayer stack. Illustration of the combined skills in terms of synthesis, deposition strategy and fabrication of the RCMO team.

Collaborators: Bühler/Leybold Optics

Fundings: H2020/ITN, Bühler/Leybold Optics

Contacts: Fabien Lemarchand/Julien Lumeau