Laser induced nanostructures formation understanding for microelectronic

In the history of semiconductors, the requirements in terms of device size have always followed a descending trend. Low thermal budget solutions are now key to manage these specifications. Within this context, nanosecond laser annealing stands as an excellent solution. Laser process conditions can be adjusted to the material structure. During heating and according to intented application, the irradiated material either remains solid (solid phase recristallisation, defects curing) or goes through the liquid state (liquid phase recristallisation, dopant activation, contact formation). In between, a transient regime is experimentally observed, where the surface is locally melted. The induced liquid islands promote nanoscale roughness during solidification. First trials already highlight the size and shape dependance of these nanostructures with various parameters.

The PhD will investigate several factors (material composition, surface state, crystalline orientation, stack heat evacuation, etc) on nanostructures features. Samples will be prepared with the LT3100 SCREEN LASSE tool, and characterized. Scanning electron microscopy observations, Haze analysis and atomic force microscope measurements will support phenomena understanding involved in these nanostructures formation.

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