Dynamic Change in Color Filter Layers during the Baking Process by Multi‐Speckle Diffusing Wave Spectroscopy

Undercut defects of color filter (CF) layers, which inevitably occur in UV curing and development processes for liquid crystal displays and white organic light‐emitting diodes, should be elucidated to ensure product quality and processability. The dynamic changes of the green CF layer are investigated during the baking process by examining the motion of pigment particles within the thin CF layer via multi‐speckle diffusing wave spectroscopy (MSDWS). Autocorrelation functions and characteristic times for the α‐relaxation, which are determined using light intensities scattered from the CF layer, directly indicate thermal melting and curing stages in the process. It is confirmed that MSDWS is a reliable non‐contact measurement tool for quantitatively analyzing the initial change of the CF layer during the baking process. The so‐called undercut defect is generated in the photolithography process for color filter layers and should be clarified to ensure product quality and processability. An innovative light scattering method, namely, multi‐speckle diffusing wave spectroscopy, for characterizing the real‐time dynamical changes of the color filter layer in the thermal baking process was developed.