Polysilicon TFT technology for active matrix OLED displays

TLDR

The study seeks to integrate polysilicon TFT technology with OLED displays to achieve bright, uniform panels by resolving process integration challenges and adding transition‑metal contacts to reduce resistance and eliminate hillocks. Rapid thermal processing, silicide formation, transition‑metal ITO contacts, and spin‑on‑glass planarization were employed to produce uniform polysilicon microstructure, low‑resistance contacts, and functional active‑matrix arrays. These techniques lowered TFT drain current nonuniformity to below 5 % in 90 % of devices, and the resulting array pixel performance was demonstrated.

Abstract

The integration of active matrix polysilicon TFT technology with organic light emitting diode (OLED) displays has been investigated with the goal of producing displays of uniform brightness. This work identifies and addresses several process integration issues unique to this type of display which are important in achieving bright and uniform displays. Rapid thermal processing has been incorporated to achieve uniform polysilicon microstructure, along with silicides to reduce parasitic source and drain series resistance. Using these processes, TFT drain current nonuniformity has been reduced below 5% for 90% of the devices. This work also introduces transition metals to produce low resistance contacts to ITO and to eliminate hillock formation in the aluminum metallization. These processes, along with spin on glasses for planarization, have been used to produce functional active matrix arrays for OLED displays. The final array pixel performance is also presented.