TheStep and Flash Imprint Lithography (S-FIL TM ) process is a step and repeat nano-imprint lithography (NIL) technique based on UV curable low viscosity liquids. Generally nano-imprint lithography (NIL) is a negative acting process which makes an exact replica of the imprint mold and is subsequently dry developed to reveal the underlying substrate material. The authors have demonstrated a novel imprint process, which reverses the tone of the imprint and enables dry develop on nonflat wafers with good critical dimension control and resist layer thickness. This positive acting NIL process termed SFIL/R TM (reverse tone S-FIL), enables nano-imprinting over intrinsic substrate topology of the type commonly found on single side polished substrates. This paper describes the SFIL/R process and the results of pattern transfer on single side polished silicon wafers.
Imprint lithography has been shown to be an effective technique for the replication of nano-scale features 1 . When the imprint material is a UV cross linkable liquid, it is possible to perform the patterning process at room temperature and ambient pressure, which enables good pattern fidelity, short processing times, and reduced process defectivity 2 . Imprinting whole wafers using drop on demand dispense techniques offers improved throughput and nanopatterning over wafer topography which can exceed 10 µm. Template fabrication of arbitrary whole wafer patterns offers unique challenges for 1x feature fabrication. The resolution and pattern area of the imprint approach is strictly dependent on the ability to create a 1X master template. This paper provides a detailed description of whole wafer templates, imprint patterning processes, and etch processes that have been employed to create a whole wafer archetype process through hard mask patterning. Particular attention is given to high volume manufacturing focused on whole wafer template fabrication, throughput and pattern fidelity.Step and Flash Imprint Lithography (S-FIL TM ) makes use of templates that can be fabricated with the same patterning and etch transfer processes that are used for manufacturing phase-shifting photo masks. In the case of whole wafer templates the master die pattern is fabricated using conventional techniques. The replicate template carries the full wafer die pattern imprinted by step and repeat using the master. The S-FIL/R process can be used for patterning the replicate template 3 . The structure, pattern fidelity and critical dimension uniformity of the master and replicate templates and patterned wafer is shown to be within measurement errors.
The Jet and Flash Imprint Lithography (J-FIL TM ) 1-7 process uses drop dispensing of UV curable resists to assist high resolution patterning for subsequent dry etch pattern transfer. The technology is actively being used to develop solutions for memory markets including Flash memory and patterned media for hard disk drives. It is anticipated that the lifetime of a single template (for patterned media) or mask (for semiconductor) will be on the order of 10 4 -10 5 imprints. This suggests that tens of thousands of templates/masks will be required. It is not feasible to employ electronbeam patterning directly to deliver these volumes. Instead, a "master" template -created by directly patterning with an electron-beam tool -will be replicated many times with an imprint lithography tool to produce the required supply of "working" templates/masks. In this paper, we review the development of the pattern transfer process for both template and mask replicas.Pattern transfer of resolutions down to 25nm has been demonstrated for bit patterned media replication. In addition, final resolution on a semiconductor mask of 28nm has been confirmed. The early results on both etch depth and CD uniformity are promising, but more extensive work is required to characterize the pattern transfer process.
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