Thermal deformation of glass backplanes during Joule-heating induced crystallization process

Large area crystallization of amorphous silicon (a-Si) thin-films on glass backplanes is one of key technologies in manufacturing flat displays of commercial scales. Among various crystallization technologies, Joule-heating induced crystallization (JIC) has been recently introduced and considered as the highly promising one since the whole film of a-Si on glass backplane can be crystallized within tens of microseconds. Based on theoretical investigation accompanied by in-situ and ex-situ experimentations, this study clarified the critical mechanism of the glass backplane deformation during the JIC process. Simulation using a commercial FEM code with one-dimensional conduction and viscoelastic models showed that the local region of which temperature was larger than the glass softening point undergoes structural shrinkage due to stress relaxation and this shrinkage remained permanently even after the process. As a quantification factor for such plastic deformation, the radius of curvature was estimated and compared to the experimental observation. Consequently the pulse duration should be decreased for larger display applications, because the radius of curvature could be considerably increased as the pulse duration was decreased for the same peak temperature of the JIC processes.

Research highlights
► Critical mechanism of the glass backplane deformation during the JIC process.
► The JIC process for large area crystallization of a-Si thin-films on glass backplanes.
► Radius of curvature of the backplane after the process quantified the deformation.
► Radii of curvature were increased considerably with the decrease of JIC durations.