Nanosized beta-SiC films were grown on negatively biased Si substrates by using a catalytic chemical vapor deposition (Cat-CVD), at the substrate temperature of 300 degreesC. The characterization data indicates that the grain size of the films is decreased with the increase of the bias, hence revealing the important role of the bias on the growing process of the films. The bias effect on the film structures is attributed to the ion bombardment, which is considered to be beneficial to the enhancement of both flux and energy of active ions induced by the negative bias. As a result, the ion bombardment leads to the increase of the nucleation sites. Combined with the low substrate temperature, it is suggested that the higher nucleation density induces effectively the growth of nanosized grains of the films. (C) 2003 Elsevier Science B.V. All rights reserved.