A simple route to synthesize carbon nanotube (CNT) has been reported in this article. Vacuum annealing of diamond-like carbon (DLC) films, grown by microwave (MW - 2.45 GHz) excited electron cyclotron resonance (ECR) technique with a radio frequency (RF) bias applied to the substrate, mixed with catalyst in argon atmosphere leads to the formation of carbon nanotube. High-resolution transmission electron microscopy studies reveal highly graphitized multi-walled nanotubes (MWNT) or amorphous fibre like structures, depending on the catalyst amount. This synthesis process may give a new approach to understand the phase transition of different carbon allotropes into nanotube or nanostructure. @FootnoteText@ D. Sarangi's Present Address: Institut de Physique Experimentale, EPFL - Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, Switzerland. C. Godon and O. Chauvet - Laboratoire de Physique Cristalline.