Diamond-like carbon films formed by hydrocarbon plasma immersion ion implantation with methane/toluene mixtures W. Ensinger a, * , K. Volz b , K. Baba c , R. Hatada c a Darmstadt University of Technology, Department of Materials Science, Darmstadt, Germany b Philipps-University of Marburg, Department of Physics and Materials Sciences Center, Marburg, Germany c Industrial Technology Center of Nagasaki, Applied Technology Division, Ohmura, Nagasaki, Japan Available online 17 January 2007 Abstract Plasma immersion ion implantation of silicon with methane, toluene and mixtures of both as plasma-foming gases gave films of amorphous carbon (a-C:H, or diamond-like carbon DLC) on a transition zone of silicon carbide, as shown by X-ray photoelectron spec- trometry and Rutherford backscattering spectrometry. Toluene leads to faster DLC film growth than methane. Raman spectra showed the typical D- and G-bands of DLC, in case of toluene more distinct than for toluene. IR-spectroscopy gave indications of SiC and C–H bonds. Ó 2007 Elsevier B.V. All rights reserved. PACS: 52.77.j; 52.77.Dq; 81.15.z 1. Introduction Diamond-like carbon films can be deposited by a num- ber of techniques with energetic ions involved, such as direct ion beam deposition, ion-beam-assisted deposition and ion beam sputtering. The ions are responsible for the phase and structure of the films. Several ion-induced effects may play a role such as subplantation or stress-induced phase formation. In the last two decades, another method has been used for depositing DLC films: plasma immersion ion implantation (PIII), also called plasma-based ion implantation (PBII) [1–9]. In contrast to the above men- tioned ion-based methods, PIII uses energetic ions in a pulsed mode and at higher kinetic energies. This allows one to deposit films with special properties, different from those formed by other techniques [9]. When DLC films are being deposited by PIII, the plasma-foming gas plays a crucial role. In the literature, mostly methane or acetylene has been used; in some cases, toluene served as the plasma-forming gas [10–13]. In the following, the differences in DLC films formed in either a methane plasma or in a mixed methane/toluene plasma will be discussed. 2. Experimental The samples were commercial-type Si wafers with (1 0 0) crystal orientation. The PIII apparatus consists of a cylin- drical chamber with a radiofrequency matching unit with antenna on top [14]. The plasma is formed by a 13.45 MHz RF generator with a maximum electrical power of 1.25 kW. The sample holder is an isolated steel plate which is connected to a DC power supply with a hard tube modulator as high voltage pulse generator. The samples were treated in plasmas of methane, toluene or a mixture of methane and toluene. Methane was fed into the chamber by a mass flow controller, toluene was supplied from a thermostated glass vessel by means of a needle valve. For gas mixtures, the plasma gas composition was controlled by the partial pressures of the gases. The base pressure of the apparatus was below 10 4 Pa, the working pressure 0168-583X/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2007.01.073 * Corresponding author. Tel.: +49 6151 166309; fax: +49 6151 166378. E-mail address: ensinger@ca.tu-darmstadt.de (W. Ensinger). www.elsevier.com/locate/nimb Nuclear Instruments and Methods in Physics Research B 257 (2007) 692–695 NIM B Beam Interactions with Materials & Atoms