Microelectromechanical systems (MEMS) including microchemical devices have been widely concerned, in particular, when made of an extremely stable ceramic material for their use at harsh conditions. SiCBN preceramic polymer was derived from borazine (B3N3H6) modified allylhydridopolycarbosilane (AHPCS) via hydroboration of allyl groups with B-H groups at 0oC for 24 h by following the standard Schenk technique. The extent of polymer-to-ceramic conversion with an ultimate ceramic yield of 92 wt% was investigated by simultaneous TGA, 1H, 13C-NMR, IR, and XRD measurements. The polymer-derived SiCBN ceramic remained as an amorphous solid up to 1400oC. The ceramic product obtained after pyrolysis at 1000-1400oC exhibited excellent oxidation resistance in air. In addition, ceramic microstructures were fabricated by employing soft lithographic technique.