Fabrication of silicon carbide micropillar arrays from polycarbosilanes

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 6 × 10⁴ mm^-2 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 yield amorphous and nanocrystalline SiC (β-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.