Characteristics of films deposited by the irradiation of GeCHx+ ions produced from hexamethyldigermane and their dependence on the injected ion energy

Abstract

The characteristics of films deposited by the irradiation of GeCHx+ ions and their dependence on the injected ion energy were investigated. GeCHx+ ion beams were produced by the decomposition of hexamethyldigermane in a Freeman-type ion source. GeCHx+ ions were then mass-selected and irradiated for film deposition on Si substrates at room temperature. The GeCHx+ ion energy was set at about 100, 30, 20, and 10 eV. The Fourier transform infrared spectroscopy (FTIR) analyses of the deposited films suggested that Ge-C bonds of GeCHx+ ions were broken due to the collision between GeCHx+ ions and the substrate surface in the cases of 100 and 30 eV. In contrast, Ge-C bonds remained in the film at the ion energy of 20 or 10 eV. Subsequently, the GeCHx+ ion energy was set at 20 eV, whereas the Si substrate temperature was set at 300 °C. FTIR and X-ray diffraction analyses of the films obtained suggested that the Ge-C bonds were broken at 300 °C and the resulting Ge atoms recombined with each other to form a metallic Ge film.