Computational investigation of dual-frequency power transfer in capacitively coupled plasmas

Summary form only given. Dual frequency capacitively coupled plasmas provide the microelectronics fabrication industry flexible control, high selectivity and uniformity. The spatial variation of the phases, magnitude and wavelength of the high frequency (HF) rf bias will affect electron density, electron temperature, sheath thickness and ion transit time through the sheath. These variations ultimately affect the ion energy and angular distributions (IE-ADs) to the substrate which are of critical importance for anisotropic etching or deposition. To optimize the separate control of rates of ionization and IEADs, the HF should be significantly different than the low frequency (LF), which results in the LF being few MHz. For classical sinusoidal rf biases applied on the same electrode, the HF/LF harmonic currents can be distinguished by their Fourier transforms. Recently, non-sinusoidal bias waveforms are being applied in etching recipes to control etching speed and selectivity, which then complicates separating the HF from LF since both now have high harmonic contents.