Bubble-free high-speed UV nanoimprint lithography using condensable gas with very low global warming potential

Abstract

Bubble-free filling needs to be achieved to realize high-throughput mass production in ultraviolet nanoimprint lithography (UV-NIL). Although bubble-free filling can be accomplished by performing UV-NIL under vacuum, nonvacuum processes can lower equipment and operation costs. UV-NIL in 1,1,1,3,3-pentafluoropropane (PFP) has been recognized as a promising method of realizing ultrahigh-speed UV-NIL; however, the global warming potential (GWP) of PFP of 1030 might restrict its industrial use. In this work, UV-NIL of a spin-coated UV-curable resin in trans-1-chloro-3,3,3-trifluoropropene (CTFP), which has a low GWP of <5, was studied with the aim of identifying an alternative to PFP. The cavity filling speed of resin and mold release force in CTFP were comparable to those in PFP, and superior to those in helium atmosphere. Sub-100 nm patterns were successfully fabricated by UV-NIL in CTFP, although the line width shrinkage ratio of patterns fabricated in CTFP was slightly larger than that of patterns fabricated in PFP.

Solubility Property of Condensable Gases of Trans-1-Chloro-3,3,3-Trifluoropropene and Trans-1,3,3,3-Tetrafluoropropene in UV Nanoimprint

“…As the cause of this, we considered that the patterns were stretched and collapsed owing to the problem in mold release. As reported in previously [18,20], the average release force following UV-NIL in CTFP was approximately 14% smaller than that after UV-NIL in PFP and TFP. From these results of the patterning of PAK-02 with nominal 22 nm 1:3 L/S pattern, it was considered that a condensable gas atmosphere should be introduced with mixed gases of TFP/CTFP rather than only an atmosphere of TFP.…”

“…The amount of gas dissolution in the solvent was corrected by subtracting the volatilization amount for 10 minutes in air. The number of solvents with a gas dissolution of over 2% were 16,18, and 13 for PFP, CTFP, and TFP, respectively. In particular, it was found that large quantities of gas dissolution were observed in acetone, dimethyl formamide, and tetrahydrofuran.…”

“…One is trans-1-chloro-3,3,3trifluoropropene (CTFP) [17,18] which has similar properties to PFP, such as a vapor pressure of 0.13 MPa, as shown in Table 1. The other is trans-1,3,3,3tetrafluoro-propene (TFP) [19,20], which has a higher saturated vapor pressure of 0.5 MPa in comparison with that of PFP.…”

Continuous roller nanoimprinting: next generation lithography

“…However, this small mold requires a high-precision calibration system to complete the imprinting process, which increases the processing cost. 107 Compared with plate imprinting, the roller imprinting method can significantly expedite the imprinting process. Besides, the linear contact between the roller mold and the resist film during the imprinting and demolding process substantially reduces the problems seen in plate imprinting, including uneven force exerted on the mold and the unevenness of the substrate, thereby avoiding the generation of bubbles.…”

Fabrication process for micropatterned ceramics via UV-nanoimprint lithography using UV-curable binder

“…Therefore, to fabricate ceramic micro-pillar patterns, our study focused on UV nanoimprint lithography (UV-NIL), which can produce nano-and microstructures on a resist polymer using a UV-curable polymer. [25][26][27][28][29] The UV-NIL technique has attracted attention in micro-electronic fields such as large-scale integrated circuit (LSI) and MEMS fabrication owing to its advantages in high-aspect-ratio fabrication [30][31][32] by directly molding the liquid resin on a substrate, unlike the hot embossing process that molds a solid material. To the best of our knowledge, no reports on a UV-NIL process to fabricate high-aspect-ratio GDC micro-pillar patterns have been made.…”