Breakthrough Achievement In Nanoimprint Lithography Using PFP Condensable Gas

Abstract

The effectiveness of condensable gas, used as ambience, in UV nanoimprint lithography has been demonstrated. Bubble defect problem, which is inherent in UV nanoimprint under non vacuum ambience, can be solved by PFP condensable gas. UV nanoimprint lithography using PFP was validated for 45 nm pattern fabrication under thin residual layer conditions, which are required for UV nanoimprint used as UV nanoimprint lithography. PFP reduces the viscosity and demolding force of UV curable resins. These properties are helpful in increasing the throughput and reliability of UV nanoimprint. PFP occasionally produces large shrinkages, and degrades pattern quality depending on UV curable resin. These drawbacks can be mitigated by selecting UV curable monomers with a low PFP absorption. In the end, we have demonstrated the satisfied LER and LWR values requested in 22 nm node NAND flash memories and 20,000 repeated imprints with a single mold by UV nanoimprint using PFP.

Secondary Patternable UV-Imprinted Reworkable Resin by Additional Photoirradiation

“…UV nanoimprint lithography (UV-NIL) has been extensively investigated due to the fabrication of not only nanopatterning for microelectronics but also functional materials for micro-electro-mechanical systems (MEMS) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. UV-NIL utilizes UV light to cure a photoresist which was pressed using a patterned master mold to obtain the patterned structures.…”

Design of Release Interface for UV-NIL Material

“…A typical condensable gas used in the approach is 1,1,1,3,3-pentafluoropropane (PFP). It was reported that PFP can reduce the viscosity and separation force of UV curable resins and 20,000 repeated imprints with a single mold by UV imprint using PFP were successfully demonstrated [22]. However, influence of mixing of PFP and resist material should be discussed in terms of etching resistance of cured resist film.…”