A one-dimensional fluid model is proposed to simulate the dual-frequency capac-itively coupled plasma for Ar discharges.The influences of the low frequency on the plasmadensity,electron temperature,sheath voltage drop,and ion energy distribution at the poweredelectrode are investigated.The decoupling effect of the two radio-frequency sources on the plasmaparameters,especially in the sheath region,is discussed in detail.
Electron cyclotron resonance radio frequency (ECR-rf) hybrid krypton-diluted oxygenplasmas were used to pattern the surfaces of diamond films with the assistance of a physicalmask, while optical emission spectroscopy was employed to characterize the plasma. It was foundthat with krypton dilution the etching rate decreased, and also the aspect ratios of nanotips formedin micro-holes were significantly modified. The oxygen atomic densities were estimated by oxygenatom optical emission and argon actinometry. Under a microwave power of 300 W and rf biasof-300 V, the absolute density of ground-state oxygen atoms decreased from 1.3×10^(12) cm^(-3) to1.4×10^(11) cm^(-3) as the krypton dilution ratio increased to 80%, accompanied by the decrease inthe plasma excitation temperature. It is concluded that oxygen atoms play a dominant role indiamond etching. The relative variations in the horizontal and vertical etching rates induced bythe addition of krypton are attributed to the observations of thicker nanotips at a high kryptondilution ratio.
Effect of C:F deposition on SiCOH etching in a CHF_3 dual-frequency capacitivelycouple plasma, driven by a high-frequency source of 60 MHz (HF) and a low-frequency source of2 MHz (LF) simultaneously, is investigated. With the increase in LF power, the change of C:Flayer from dense C:F layer to porous C:F layer and further to C:F filling gaps was observed, whichled to the transition from films deposition to films etching. The change of C:F layer is relatedto the bombardment by energetic ions and CF_2 concentration in the plasma. As the LF powerincreased to 35～40 W, the energetic ions and the low CF_2 concentration led to a suppression ofC: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 (CHF_3) electron cyclotron resonance(ECR) plasma was investigated.The flat-band voltage V_(FB) 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 CHF_3 plasma treatment of the SiCOH film led to a reduction in both the flat-band voltage V_(FB) 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.
