Silicon carbide and amorphous carbon film formation by plasma immersion ion implantation: a comparison of methane and toluene as plasma forming gases

In the present study a comparison of two different hydrocarbon precursor ga ses, namely methane and toluene, on the formation of silicon carbide (SiC) and amorphous carbon (a-C:H) films by plasma immersion ion implantation (PI II) of silicon is made. The samples are analyzed by using Rutherford backsc attering spectrometry (RBS) and X-ray photoelectron spectroscopy (XPS) for their element composition. XPS and Raman spectroscopy are applied to determ ine the bonding of silicon and carbon. Depending on the number of high volt age pulses the samples have been treated with, which corresponds to the ion fluence, it is possible to form stoichiometric SiC films without C layers on top of the wafers if methane is used as plasma forming species. For the same process conditions, C7H8 PIII always results in thicker SIC and thinne r a-C:H films compared with C,Hs PIII. Si-C bond formation is proven by XPS . Raman spectroscopy shows the formation of a-C:H films for high pulse numb ers for the case of a methane plasma, but already for small pulse numbers i f toluene is used for plasma forming species. (C) 2001 Elsevier Science B.V . All rights reserved.