Peiman Mosaddegh and David C Angstadt 2008 J. Micromech. Microeng. 18 035036 doi:10.1088/0960-1317/18/3/035036
Peiman Mosaddegh and David C Angstadt
Show affiliationsThe focus of this study is on the ability of amorphous polymers to replicate micron and sub-micron features when molded at an elevated mold temperature without externally applied pressure. Molding was performed using three different types of amorphous polymers: cyclo-olefin copolymer (COC), polystyrene (PS) and poly (methyl methacrylate) (PMMA) on a silicon mold containing surface features as small as 700 nm in depth and aspect ratios ranging from 5 to 0.02. In this study, processing temperatures were selected in order to match the viscosity for all polymers used. Polymer viscosity was characterized via cone and plate rheometry and wettability was characterized via contact angle analysis to quantify interfacial effects. Feature replication was assessed using scanning electron microscopy (SEM) and atomic force microscopy (AFM) to compare the molded feature depth ratio. It was observed that for the features with an aspect ratio (depth/width) bigger than 2 the depth ratio of the molded parts decreases. PS shows the best replication because of high wettability behavior. PMMA shows the intermediate replication because of dipole–dipole interaction and its lower diffusion coefficient than PS. COC has the worse replication especially in low aspect ratio because of sticking to the silicon oxide layer. PS has the best surface roughness among all polymers.
81.20.Hy Forming; molding, extrusion etc.
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.35.B- Structure of clean surfaces (and surface reconstruction)
61.41.+e Polymers, elastomers, and plastics
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
Soft matter, liquids and polymers
Surfaces, interfaces and thin films
Issue 3 (March 2008)
Received 16 September 2007, in final form 19 December 2007
Published 13 February 2008
Peiman Mosaddegh and David C Angstadt 2008 J. Micromech. Microeng. 18 035036
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