Replication of HARMST and large area nanostructured parts using UV cationic polymerization

Abstract

This paper reports on the development of a reaction casting process for the fabrication of high aspect ratio microstructures (HARMST) and large area nanostructured parts, using UV cationic polymerization. Besides the process itself, materials had to be characterized to achieve thick layers. An epoxide resin, a bis-cycloaliphatic epoxide (BCE) and a divinylether of triethylene glycol (DVE-TEG) were used as monomers and triaryl sulfonium salt (TAS) was used as the photoinitiator. The materials were characterized relative to their rheological properties, the degree of polymerization and their hardness. The test structure consists of columns with an aspect ratio of 10. The results reveal that the materials used show excellent behavior for the replication of high aspect ratio structures. The replication of a nanostructured area of 10 × 10 cm 2 could also be realized with the presented process. The used structure is a 2D optical grating with a period of 2.5 μm and a diameter of the tip of 300 nm.

Replica molding for multilevel micro-/nanostructure replication

“…The replication of the structures was done with a mixture of diglycidyl ether of bis-phenol A (DGE-BPA) and 3 wt% of triaryl sulfonium salt (TAS) as a photoinitiator (Aldrich) [19][20][21]. To achieve a lower viscosity, the mixture was heated up to 70 • C [15]. This mixture was cast onto the PDMS stamp.…”

“…0960-1317/10/115012+08$30.00 Alternatively, casting processes offer the possibility of replicating complex nano-and microstructures as well as through-hole features [10,11] in a single step. Among these, the UV casting process is interesting because it is capable of replicating small structure features as well as complex geometrics combining micro-and nanostructures over large areas [11][12][13][14][15]. The UV curing materials that can be used include all kinds of photochemical materials, for example, polyurethane (PU) [3] or epoxy-based materials [15].…”

“…Among these, the UV casting process is interesting because it is capable of replicating small structure features as well as complex geometrics combining micro-and nanostructures over large areas [11][12][13][14][15]. The UV curing materials that can be used include all kinds of photochemical materials, for example, polyurethane (PU) [3] or epoxy-based materials [15].…”

Integration of moth-eye structures into a poly(dimethylsiloxane) stamp for the replication of functionalized microlenses using UV-nanoimprint lithography

“…20 The UV/VIS spectroscopy was performed using the Lambda 950 equip-ment from Perkin Elmar. Flat samples (without microlenses) with a thickness of 1 mm, containing structured and unstructured areas, were fabricated by replica molding.…”

Nanoimprint lithography for solar cell texturisation

“…Acrylate systems potentially need lower exposure doses and the polymerisation reaction proceeds very fast as a result of the presence of highly reactive radicals and monomers [153]. Cationic polymerising systems do not suffer from oxygen inhibition, show potentially less shrinkage and exhibit dark polymerisation after an exposure is stopped [154]. One cationic system investigated during this work belongs to the SU8 product family developed by IBM [155], which is commercially available from MicroChem.…”