Photo-Nanoimprinting Using Sample-on-Flexible-Thruster Stage

We designed a novel sample stage named sample-on-flexible-thruster (SOFT) stage, which has a unique compliant contact mechanism working on the sample side, and installed it in a full-function photo-nanoimprinter. The pressing uniformity of an imprint area using the SOFT stage was preserved with a tolerance of 1 mrad in parallelism between a mold and a wafer. Such parallelism requires no adjustment once the mold is preset to an appropriate orientation. Pressing uniformity is improved using a soft pad, which supports a wafer backside, of the SOFT stage. The built-in flexible thruster of the SOFT stage controls wafer warping precisely with a force resolution of 0.01 N and a full contact between the mold and sample accompanied by air evacuation in a warping contact sequence. The thickness uniformity of cured resin using the SOFT stage was 9.8 nm for an initial resin thickness of 160 nm. The SOFT stage enables step-and-repeat photo-nanoimprinting for an initial resin thickness of as small as 60 nm. The SOFT stage separates the compliant contact mechanism from the mold side and realizes flexible arrangements of mark detection and UV illumination on the mold side of the full-function photo-nanoimprinter.