Babak Heidari

Development and characterization of silane antisticking layers on nickel-based stamps designed for nanoimprint lithography

In this study we will report on the development of a process to establish antisticking layers on nickel-based stamps, which are used in several industrial applications of nanoimprint lithography or related methods. The fluorinated alkyl silane films have been deposited onto different Ni-based stamp surfaces in order to minimize the adhesion tendency at the stamp/polymer interface. Film thickness, chemical composition, purity, and binding mechanisms of the silane groups to different stamp surface materials have been determined by photoelectron spectroscopy (XPS). In the case of electroplated nickel stamps—where low imprint qualities are observed—multilayer thick films cover the stamp surfaces, consisting of polymerized, cross-linked alkyl silanes, which are poorly bound to the surface. In order to overcome these restrictions a 100 A thick polycrystalline titanium layer has been established in a sandwich position between the nickel substrate and the silane film. Here, silane film thicknesses in the monomolecular region together with evidences for strong covalent linkage between the silane groups and the oxidized Ti surface can be concluded from the XPS results, leading to film properties and imprint qualities, which are comparable to those formerly observed for silicon stamps.

Process development and characterization of antisticking layers on nickel-based stamps designed for nanoimprint lithography

Thin films of different derivatives of fluorinated alkyl phosphoric acids have been deposited from aqueous solutions onto surfaces of oxidized polycrystalline nickel stamps, which are commonly used in several industrial applications of nanoimprint lithography (NIL). The films have been established in order to increase the antiadhesion tendencies at the stamp polymer interface. Thicknesses, chemical compositions, and purities of the films as well as binding mechanisms to the stamp surfaces have been determined by photoelectron spectroscopy (XPS). The results demonstrate the adsorption of highly pure films having thicknesses in the monomolecular region, whose chemical compositions are characterized by large ratios of fluorinated to nonfluorinated carbon species. The high ionic nature of Ni-oxide benefits strong ionic linkages between the phosphate groups of the fluorinated antisticking film and the stamp surface, allowing a large-scale production of imprints with patterned stamps having feature sizes down t...

Breaking the limits: combination of electron beam lithography and nanoimprint lithography for production of next-generation magnetic media and optical media

The increased requirement e.g. resolution in multimedia displays creates the need for more storage capacity in both optical discs as well as hard drives. Blu-Ray-ROM and particularly future optical media formats require the employment of new lithography technologies. Todays magnetic media technology is facing difficulties to continue to higher surface densities and larger capacities due to the superparamagnetic limit. By using isolated magnetic domains to store the data, making it possible to get beyond 500 Gbits/in2 densities. The approach we describe uses a unique direct-write electron beam lithography system for lithography on a rotating substrate and creates a patterned master disc, which can be used as a mold in replication of final disks by imprint lithography. The imprint process replicates the original pattern with an exceptionally fast turn around time, making mass production of optical and magnetic media possible. However, realization of these new technologies offers challenges in implementation.

Nanoimprint - a tool for realizing nano-bio research

In this paper, we present a status report on how implementation of nanoimprint lithography has advanced our research. Contact guidance nerve growth experiments have so far primarily been done on micrometer-structured surfaces. We have made a stamp with 17 areas of different, submicron, line width and spacing covering a total 2.6 mm/spl times/0.45 mm. This has been imprinted, in PMMA, and consequently used in experiments to investigate how axonal outgrowth is affected by the nanopatterns. Protein interactions with nanostructured surfaces are also studied in a system exploring and controlling biomolecular motors, i.e., the muscle motor proteins actin and myosin.