A study of optical propagation in polymer liquid crystal nanocomposites for photolithography applications

Technology devices today are rapidly growing in complexity while shrinking in physical size as exemplified by the ultra slim laptops and music players currently available on the market. With the downsizing of packaging and the increase in components, innovative new lithography techniques designed to push the density limit of the digital functions on a chip are becoming more available. Though many di erent forms of lithography exist, all with individual benefits, there currently exists no photolithography tool that can completely eliminate alignment error over a series of exposures; a tool that can bring the industry into the next phase of nanometer photo-patterning. The device that can achieve this goal is designed using digitally adaptable polymer light-valve films to spatially control exposure transmission creating a photomask with an arbitrary and dynamically adjustable pattern.This thesis presents the fundamental engineering behind the design of this novel photomasking application that uses a nanostructured composite. The material used is holographically-formed polymer-dispersed liquid crystal (H-PDLC) film and it is a photosensitive material formed with an interference pattern to contain layers of liquid crystal molecules held in a polymer matrix. With control over individual regions of film in a patterned electrode configuration, areas can be user defined as opaque or transmissive to resist exposing light. When used in a photomasking application, the light and dark fields can be real-time adjusted for rapid mask debugging, mask testing, and multiple exposures with no realignment. To truly understand the microscopic optical behavior of this device, aspects of propagation through the nanostructured film are investigated. Diffractive and edge interference effects are simulated and measured. In addition to this study, transmissive wavefront, scattering, coherence, intensity, and absorption are examined to assess factors limiting imaging due to transmission through the nanostructured thin film. To this point, there have been no investigations into imaging through an H-PDLC as it pertains to patterning photoresist, and limited studies regarding optical propagation within the film. Shown in this work is compelling evidence not only of the practicality of a liquid crystal adaptable photomask but also a study of the optical transmission properties within this type of thin film.Ph.D., Electrical Engineering -- Drexel University, 200