Modélisation/caractérisation mécanique et triboélectrique du procédé de nanoimpression en interfaces souples
Published : 8 May 2019
The flexible molds used in nanoimprint lithography allow to reduce the impact of a particle on the defectivity of a patterning step: its flexibility is used to conform the shape of the defects without impacting the surrounding structures. This flexibility is usually obtained by using single-material or composite polymer materials that have the ability to reproduce patterns having critical dimensions of a few tens of nanometers. The state of the art materials can be transformed from a viscous state (and thus able to flow in nanostructures) at room temperature to a state of elastic solid by photo-polymerization at 365 nm while having an anti-adhesive free surface. This elastic state is fundamental for the performance of replications: the material must have sufficient stiffness to prevent buckling or irreversible deformation during the process, but it must have enough flexibility to be demolded from the resin to be printed without damaging the patterns created in the latter. Nevertheless the use of these flexible molds reinforces the appearance of electrostatic charges during the separation of the mold and the substrate. These charges are usually dissipated macroscopically by means of antistatic bars or ionized air jets, but they can persist on the extreme surface of the flexible stamp and cause deformation of the structures. The objective of this thesis is to study through AFM measurements the behavior of these interfaces.