SUPPRESSING NONLINEARLY-DRIVEN INHOMOGENEITIES IN HIGH FREQUENCY CCP’s Large area, high frequency capacitively coupled plasmas (CCP’s), widely used in the semiconductor and thin film industries, require extreme processing uniformity. Nonlinear sheath motion excites harmonics of the driving frequency that can be radially near-resonant, enhancing the on-axis power deposition and degrading uniformity (Fig 1). Adding a dielectric layer over the substrate electrode improves process uniformity by increasing the radial wavelengths (Fig. 2). Fig. 1 – Harmonic power deposition versus normalized radius (10 mTorr Cl2, 60 MHz). Note large central 4th harmonic. Fig. 2 – 2D fluid-analytical results of rf sheath voltage at the wafer electrode without and with a dielectric layer. DOE Plasma Science Center Control of Plasma Kinetics HIGHLIGHT February 2018 1

DOE Plasma Science Center Control of Plasma Kinetics EFFECT OF WEAK STATIC MAGNETIC FIELD ON LOW PRESSURE CAPACITIVE DISCHARGES Independent control of ion flux and energies onto surfaces is important in plasma processing for microelectronics. We computationally demonstrate with particle-in-cell simulations that simultaneous control of the flux and energy of ions impacting on a wafer is possible using a weak magnetic field parallel to the electrodes a single frequency capacitively coupled plasma. Simulations show an 80% reduction in sheath width (improved control of ion energy) and a seven fold increase in the ion flux at the electrode due to the applied magnetic field. Plasma density as a function of height for magnetic fields (0 – 50 G) parallel to electrodes. (10 mTorr, He, 27 MHz, 1000V). Asymmetry is maximum at 30G. DOE Plasma Science Center Control of Plasma Kinetics HIGHLIGHT February 2018 2