Preliminary parameters for Roll-to-Roll (R2R) overlay photolithography directly onto flexible substrates

Flexible electronics is a field that is driving semiconductor technology to explore new materials that are flexible and pushing the envelope in patterning technologies. In this work, flexible electronics refers to substrates that are bendable, conformally shaped and lightweight and that can be Roll-to-Roll (R2R) manufacturable. Unlike the current generation of flexible electronics that are developed on flat pieces of substrates such as glass and silicon wafers, this dissertation deals with circuit fabrication directly on unsupported flexible substrates using high resolution photolithography.;This research provides parameters for the photolithographic process to develop two layer stacked (overlay) flexible substrates that are unsupported and R2R manufactured. Such flexible substrates are polyethylene terephthalate (PET) and polyimide (PI). Overlay data are utilized to characterize the photolithography process by using overlay glass substrates data as a comparison to the overlay flexible substrates data. Overlay data are acquired by the photolithography equipment after finding optical alignment fiducials using the reflective alignment system (RAS) prior to exposing the second layer on the substrates. Optical verniers are also utilized to measure the overlay offset of the patterned flexible substrates in order to corroborate that large area flexible electronics R2R manufacturing is achievable. Consequently, overlay offsets are graphed in control charts, thus characterizing the behavior of such charts to identify runs rules for the photolithography process parameters.;Other objectives of this research endeavor is the analysis and attempt to breach the gap for within virtual plate (VP) (area of substrate exposure: 200x250mm) and virtual plate to virtual plate (VP-to-VP) stitching. At the same time, parameters for develop, etch and stripping (wet chemical) processes, along with work instruction procedures, are established.;Behavioral trends of the various substrates are identified through the work that involved the development of artwork overlay of unsupported flexible substrates while applying comparison techniques such as descriptive statistics, run-charts, control charts among other SPC techniques. Thus, an understanding of the process conditions and their effects on the photolithographic and wet chemical processes are detailed in this research.