3D-hot embossing of undercut structures - an approach to micro-zippers

Large area 3D masters, with dovetail like undercuts of definite geometries in the nanometer and micrometer range, are prepared in silicon substrates by laser ablation and anisotropic wet etching. These masters are replicated into thin polymer films on a Si substrate in a hot embossing process. Thermoplastic materials (PMMA and PS) as well as an elastomer (PDMS) are investigated. In contrast to the standard hot embossing procedure the elastomer is imprinted at low pressure and temperature then thermally cured. Slow curing supports the replication fidelity of undercut masters in PDMS. The replicated structures feature the smooth surfaces and sharp edges of the master. Such structures may be used to prepare polymeric zippers or joining elements. (C) 2004 Elsevier B.V. All rights reserved.