High Aspect Pattern Fabrication by Nano Imprint Lithography Using Fine Diamond Mold

Abstract

Fabrication of high aspect ratio patterns with an aspect ratio larger than 10 is attempted by nano imprint lithography. A fine mold using a chemical vapor deposition (CVD) diamond layer is newly developed by electron cyclotron resonance (ECR) using Cl 2 -O 2 gas. Narrow grooves less than 100 nm in width and 1.0 mm in depth are successfully obtained. Using medium molecular weight PMMA (M w ¼ 350 k) and with slow advance of the cooling sequence in the imprint process, the fatal error of the polymer fracture is eliminated at the mold release process. Based on the advanced process, we first demonstrate the fabrication of high aspect ratio patterns over 20 with 80 nm line width, however, the polymer might be stretched during the mold release process.

Polymer Viscoelasticity and Residual Stress Effects on Nanoimprint Lithography

“…Finally, there are reports showing that when imprinting very small features with a high aspect ratio, high-molecular-mass polymers are superior in terms of their cohesive strength; the low-molecular-mass analogs have a greater propensity to shear off or show cohesive failure during mold separation. [6] The knowledge developed here illustrates that the increased cohesive strength must also be balanced against increased levels of residual stress in the patterns.…”

“…It is well-known that planar polymer films can, under certain circumstances, spontaneously rupture and form droplets when their thickness is reduced to tens of nanometers; [3,4] there are already reports of similar behavior in nanoimprinted patterns. [5,6] Nanostructures fabricated by chemically amplified photoresists display an increased propensity for pattern collapse as their width decreases below 100 nm. [7] Both simulations and experiments seem to indicate that there is a strong reduction in the elastic modulus of a nanostructured material when the feature size decreases below 50 nm.…”

Low-temperature fabrication of fine structures on glass using electrical nanoimprint and chemical etching

“…4 Such fine structures are formed upon resin plates or films by ultraviolet-imprint or thermal-imprint processes. [5][6][7] However, the thermo-optical properties and chemical reliabilities of resin might sometimes be insufficient for use in high-quality optical elements. Excellent thermal and chemical properties of oxide glasses, however, are attractive from their practical aspects.…”

Multiscale patterning of a metallic glass using sacrificial imprint lithography

“…Despite being greater than what can be obtained through soft replica nanoimprinting, it is clear that the aspect ratios obtained through this method do not set any records; aspect ratios have exceeded 50 for single-use AAO mold imprinting of BMG 6 and 20 for polymer imprinting with reusable diamond molds 38 . However, the scalability of these structures is much greater because they can be easily regrown and detach instantaneously after rapid cooling without the need for a carefully optimized 30-min cooling procedure, which is required in the polymeric case.…”