Hydrogenated amorphous carbon film used as an alignment layer for liquid crystal displays

Abstract

A hydrogenated amorphous carbon (a-C:H) film has been successfully applied as an alignment layer for liquid crystal displays (LCDs) using linearly polarized UV and atomic beam (AB) alignment processes. An a-C:H film was deposited by chemical vapor deposition (CVD) or reactive DC sputtering on indium tin oxide (ITO) transparent electrodes on LCD glass. The deposition conditions for the a-C:H films, such as total pressure, power, electrode gap, and gas mixture ratio were carefully studied and optimized. Alignment of liquid crystals was also created by exposing the substrate to 257 nm polarized UV light and the directional bombardment of an Ar ion beam onto the a-C:H film. By using this non-contact alignment method, high quality large area LCD panels were successfully fabricated. The resulting LCDs showed higher quality front-of-screen characteristics than those obtained by the conventional thick polymer rubbing method particularly with respect to the lack of the rubbing tracks.