High resolution templates for step and flash imprint lithography

Abstract

Step and Flash Imprint Lithography (SFIL) is an attractive method for printing sub-100 nm geometries. Relative to other imprinting processes SFIL has the advantage that the template is transparent, thereby facilitating conventional overlay techniques. In addition, the imprint process is performed at low pressures and room temperature, minimizing magnification and distortion errors. The purpose of this work was to investigate alternative methods for defining high resolution SFIL templates and study the limits of the SFIL process. Two methods for fabricating templates were considered. The first method used a very thin (< 20 nm) layer of Cr as a hard mask. The second fabrication scheme attempts to address some of the weaknesses associated with a solid glass substrate. Because there is no conductive layer on the final template, SEM and defect inspection are compromised. By incorporating a conductive and transparent layer of indium tin oxide (ITO) on the glass substrate, charging is suppressed during SEM inspection, and the transparent nature of the final template is not affected. Using ZEP-520 as the electron beam imaging resist, features as small as 20 nm were resolved on the templates. Features were also successfully imprinted using both types of templates.

Analysis of critical dimension uniformity for Step and Flash imprint lithography

“…As a result, this value of 3c 3.5 nm (or 2 1.36) was taken from previous resist studies. 2 The variance component of CD's contributed by SFIL taken across a wafer can then be estimated using a similar approach:…”

Innovative Nanoimprint Tools for Optoelectronic Applications

“…Several imprint lithography techniques are being investigated as low cost alternatives for high-resolution patterning. Investigations by S-FIL group and others in the sub-100 nm regime indicate that the resolution is limited by pattern resolution of the template [2,3,4]. That is, the resolution of S-FIL appears to be only limited by the resolution of the template fabricating process.…”

Fabrication of Step and Flash imprint lithography templates using commercial mask processes

“…The parameters in the classic photolithography resolution formula ( , k 1 , and NA) are not relevant to imprint lithography because the technology does not use depend on wavelength of light and reduction lenses. Investigations in the sub-100nm regime indicate that the resolution is only limited by the pattern resolution on the template, and replication of sub-20 nm features has been demonstrated [1,2,3]. The resolution of imprint lithography is a direct function of the resolution of the template fabricating process.…”

“…Therefore, for 1X pattern transfer with imprint lithography, there would be a need to accelerate mask feature size targets in the ITRS to coincide with the resist feature targets. The use of a high resolution Leica ebeam to write 1X templates with 20nm minimum features was discussed in [3]. However, such direct-write e-beam systems are not designed for throughput and are therefore not attractive from a cost point of view.…”