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Fabrication of silicon carbide micropillar arrays from polycarbosilanes

: Jang, Y.-S.; Zollfrank, C.; Jank, M.; Greil, P.


Journal of the American Ceramic Society 93 (2010), No.11, pp.3929-3934
ISSN: 0002-7820
Journal Article
Fraunhofer IISB ()
silicon carbide; SiC; Polycarbosilane; molding; pyrolysis; micropillar

Periodic patterns of silicon carbide (SiC) micropillars of 18 µm in length and 2 µm in diameter with a hexagonal morphology and an areal number density of micropillars of 6x104 mm2 were fabricated from a mixture of two different polycarbosilane ceramic precursors. The polycarbosilanes (PCS) were molded into polydimethylsiloxane(PDMS) micromolds processed from a silicon wafer master. After cross-linking between 200° and 400°C, debonding from the elastomeric PDMS mold yielded freestanding structures of PCS micropillars. Due to the low stiffness of cross-linked PCS (E~2.5 GPa), surface adhesion forces might result in the deformation of the micropillars into ordered domains. The PCS micropillar arrays were pyrolyzed in inert atmosphere at 900° and 1500°C to yiel d amorphous and nanocrystalline SiC (b-SiC) with crystallite sizes in the range of tenths of micrometers, respectively. The formation of domains due to instability of micropillars with a high aspect ratio might be of specific interest for electrical engineering and catalytic applications.