Soutenance de thèse : Zeinab HARAJLI

Soutenance d'une thèse de Doctorat de l’Université de Lyon en cotutelle internationale entre l’Université Libanaise (Beyrouth, Liban) et l’INSA Lyon

Doctorante : Zeinab HARAJLI

Laboratoire INSA : MATEIS
Ecole doctorale : ED34 : Matériaux de Lyon

Efficient thermal management is often considered as a key step towards a successful technological
system. The fast removal of excess heat from electronic systems exposed to temperature extremes improves the reliability and prevents the premature failure of these systems. Nowadays, the usual approaches to evacuate heat and maintain the system at a desired temperature consist in using a semiconductor heat sink or a complex fan speed control system that relies on continuous temperature measurement. However, the optimization of a highly efficient semiconductor heat sink requires the control of diverse intrinsic and extrinsic properties at different scales because the macroscopic thermal flow and heat transport depend on microscopic vibrational properties. Besides, widespread use of highly efficient semiconductor heat sinks requires the ability to metalize them and form multilayer structures. Due to its high phonon group velocities, Aluminium Nitride (AlN) appears to be one of the best candidates for the manufacturing of efficient semiconductor heat sinks. In this PhD. thesis work, we intend to develop a new substrate technology Metal/AlN/Metal structures with high thermal diffusivity for integrated power system for high temperature applications (>300°C). This PhD Aims at developing highly efficient, integrated and reliable power electronics technologies operating at high temperature for automotive, aeronautic, and energy. We adress this project by growing thin films of molybdenum to metalise aluminum nitride ceramics and synthesize our novel heat sink substrates for power modules. Then we optimize the established devices by studying their general physical properties with a focus on thermal erformance. Finally we study the high emperature performance of the samples by doing subsurface imaging of the samples while increasing the temperature in order to monitor the defect formation. The thermal characterisation and subsurface imaging of the samples were done using our novel photothermal beam deflection setup, in which we install an IR-laser for heating the samples and generating thermal bumps to be measured by probe beams deflecting at different locations on the sample.