Effect of C：F deposition on SiCOH etching in a CHF3 dual-frequency capacitively couple plasma, driven by a high-frequency source of 60 MHz （HF） and a low-frequency source of 2 MHz （LF） simultaneously, is investigated. With the increase in LF power, the change of C：F layer from dense C：F layer to porous C：F layer and further to C：F filling gaps was observed, which led to the transition from films deposition to films etching. The change of C：F layer is related to the bombardment by energetic ions and CF2 concentration in the plasma. As the LF power increased to 35 - 40 W, the energetic ions and the low CF2 concentration led to a suppression of C：F deposition. Therefore, the SiCOH films can be etched at higher LF power.
The characteristics of SiCOH low dielectric constant film treated by a trifluromethane （CHF3） electron cyclotron resonance （ECR） plasma was investigated. The flat-band voltage VFB and leakage current of the Cu/SiCOH/Si structure, and the hydrophobic property of the SiCOH film were obtained by the measurements of capacitance-voltage, current-voltage and water contact angle. The structures of the SiCOH film were also analyzed by Fourier transform infrared spectroscopy and atomic force microscopy. The CHF3 plasma treatment of the SiCOH film led to a reduction in both the fiat-band voltage VFB shift and leakage current of the Cu/SiCOH/Si structure, a decrease in surface roughness, and a deterioration of the hydrophobic property. The changes in the film＇s characteristics were related to the formation of Si-F bond, the increase in Si-OH bond, and the C：F deposition at the surface of the SiCOH film.
This paper investigated the radical behaviour of the plasma of a mixture of methane （CH4） and decamethylcyclopentasiloxane （DMCPS） by optical emission spectroscopy. The plasma was generated by electron cyclotron resonance （ECR） discharge and was used for depositing porous SiCOH low dielectric-constant film. In the ECR discharge plasma, CH, H, H2, C2, Si, O and SiO radicals were obtained. The CH, H and C2 radicals were from the dissociation of CH4, while the SiO. Si and O radicals from the dissociation of the Si-O chain. CHx radicals absorbed in the film were thermally unstable and could be removed by annealing. The dissociation of the Si-O chain led to an increase in a ratio of the Si-Ocage to Si-Onetwork. The removed of CHx radicals and the increased Si-Ocage to Si-Onetwork ratio were beneficial for reducing the film density and dielectric constant.
