Lineshape and morphology study of structures formed using a reconfigurable photomasking element

Abstract

The proposed application of holographically formed polymer dispersed liquid-crystal (H-PDLC) thin films is a real-time dynamically reconfigurable mask for the resist exposure step in the photolithographic process. An adaptable photomask has advantages over traditional binary masks that include multiple fabrication patterns using a single mask, reduction in realignment error between different masks, real-time correction and adjustment of fabricated structures, and the ability to alter the mask pattern during exposure. H-PDLC films, or thin periodic nanostructures of alternating layers of polymer and liquid crystal, have unique electro-optic properties, including the ability to modulate a particular wavelength as a function of bias applied to the film. Structures formed using the H-PDLC photomask device have been compared to similar structures formed with a static photomask using an optical profilometer. Features studied were decreasing lines with a maximum width of 121 µm to a minimum width of 84 µm. Edge width between structures formed using the H-PDLC mask and static photomask differ by <5%. Additionally, morphology studies have been performed on developed regions of glass and resist formed using a static and an H-PDLC mask to demonstrate that no structural defects exist due to formation under an H-PDLC grating.