Laser lift-off systems for flexible-display production

Abstract

Laser lift-off (LLO) delamination opens the path to polymer-based display backplanes for use in electrophoretic e-readers, AMOLED (Active-Matrix Organic Light Emitting Diode) smartphones, tablets, and OLED-TV. The proper choice of wavelength, optical system, and fluence enables the layer-selective LLO processing of functional thin films not achievable with other radiative or non-radiative heat sources. This becomes increasingly attractive as the feature size and film thickness in microelectronics applications are continuously being downscaled. Excimer lasers provide the 308 nm wavelength and short pulse duration required for highly localized energy coupling. The high output power of excimer lasers enables a large processing footprint and the high-throughput rates needed in mass manufacturing. Thin-film transistor structures fabricated on top of polymer layers spun on glass panels must be delaminated to create thin, lightweight, and rugged flexible-display backplanes. Low-thermal-budget lift-off processing with UV lasers protects the adjacent functional layers. When it comes to large Gen 4.5–Gen 8 substrate panels, which have to be released from polymer thin films, it is most effective to use line beam scanning for LLO within one to three consecutive scans.