Microstructure-based analysis of fine metal mask cleaning in organic light emitting diode display manufacturing

Abstract This study proposes the unique method to analyze the cleanliness of the fine metal mask (FMM) used in OLED display manufacturing after FMM cleaning process. We developed a FMM-mimic microstructure as a substitute for the FMM, which can be used for the evaluation of cleaning efficiency. The FMM-mimic microstructure was fabricated using a combination of photolithography, reactive ion etching, anodic bonding and sand blasting processes. To demonstrate the proposed cleanliness analytical method, a 1.4 μm-thick Tris-(8-hydroxyquinoline) aluminum (Alq3) film was deposited on the FMM-mimic microstructure as a contaminant by vacuum thermal evaporation. The Alq3-deposited FMM-mimic microstructure was cleaned by N-methyl-2-pyrrolidone (NMP) with changing cleaning time. We analyzed the residual contaminants on the FMM-mimic microstructure using a fluorescence microscope. The developed FMM-mimic microstructure proves very convenient for inspecting the residual contaminant inside the gap through the transparent glass by general optical and fluorescence microscopy.