Effect of Dropping Hydrofluoroether in Thermal Nanoimprint on Polycarbonate

概要

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We introduced a hydorofluoroether (HFE) liquid with a low boiling point in thermal nanoimprint lithography (T-NIL) of polycarbonate (PC) and experimentally confirmed that molding uniformity improved at low contact pressures where conventional T-NIL had been unsuccessful. In conventional T-NIL, the conditions to imprint on PC with a glass transition temperature of 150 °C are prescribed as: heating temperature = 180 °C, cooling temperature = 140 °C, contact pressure = 20 MPa, and contact time = 10 s. With a contact pressure of 10 MPa, which is half the value normally employed in T-NIL, imprinting on PC under such low-contact pressure resulted in incomplete fillings. To investigate the cause of incomplete fillings, imprinting results of T-NIL in air and in vacuum were compared. As a result, we learned that defective molding can be avoided by simply removing the residual air trapped in the mold pattern. To solve the air bubble defect problem encountered in UV-NIL when working with low-contact pressure T-NIL, we applied a method of inserting a condensable gas into the system. In our technique, HFE gas was used, which improved the accuracy remarkably, and realized a complete filling at a contact pressure of 5 MPa. This method of employing reduced contact pressure in T-NIL is of great advantage in large-area imprinting.
2011-06-25