A method for undercut formation of integrated shadow mask used in passive matrix displays

This paper reports a method for making integrated shadow masks used in fabrication of passive matrix organic light emitting diode (OLED) displays. Common positive and negative photoresist were employed to produce retrograded strip pillars with large overhang and undercut by a special photolithography procedure. The pillar strips serve as an effective shadow mask for patterning the organic layers and the metal cathodes in passive OLED display devices. Such an integrated shadow mask is viable for large deposition angle up to 70°. The method is also expected to be usable for fabricating more complicated structures for other applications.