UV-Nanoimprint Lithography with Film Mold for LED-PSS Fabrication Process

摘要

The recent progress in the sophisticated fabrication using nanoimprint lithography technologies has stimulated the research on the development of many kinds of industrial products such as display, semiconductor chip, media storage and so on [1-2]. A patterned sapphire substrate (PSS), which is widely used for GaN-based light emitting diodes (LEDs) is known to a one of the techniques of increasing brightness of LEDs. The effect of PSS attributes to enhancement of photon extraction efficiency of LEDs due to reducing total internal reflection of light at the interface in LEDs. Currently, almost of all industrial PSS was formed through the process of conventional photolithography techniques such as stepper or mask-aligner. However, in the case of using the conventional method, there are the issues that are high cost and low throughput. On the other hand, nanoimprint lithography technique has the possibility of easier to fabricate micro- or nano-structures on various surfaces and higher throughput than conventional method [3-5]. When using nanoimprint lithography, it is important that avoiding user from the damaging expensive quartz or silicon-wafer master mold and the transcript accuracy in repeated imprint process. In order to solve these problems, we applied UV-nanoimprint lithography (UV-NIL) to PSS fabrication process with using our developing FleFimo~R; it is flexible, reasonable and highly UV transparent film mold. Actually, we demonstrated that the replicating FleFimo from master mold and the fabricating high accuracy PSS by UV-NIL with FleFimo~R in this report.