Deformable electronic surfaces

In this paper a technological approach for the fabrication of deformable electronic surfaces is reviewed. The approach consists of the fabrication of thin film devices on a flat but deformable substrate such as a plastic or glass foil using conventional processing tools. After the fabrication, the foil can be deformed to other shapes by air pressure or stamping. A spherical cap shape is used as a model system. This deformation induces large stress in the substrate, which is plastically deformed. To avoid damage to the thin film devices, they are built on top of "hard" islands, which limit the strain in the devices to manageable levels. Amorphous silicon TFT's on silicon nitride islands show little qualitative change in characteristics after a plastic deformation of the substrate to strain levels over 5%. Interconnect lines between islands are subjected to a large strain if they are deposited and patterned before the substrate deformation, and require novel approaches.