Two-Dimensional Particle-in-Cell Simulation for Phase-Resolved Ion Energy and Angle Distributions in Dual-Frequency Capacitively Coupled Ar Plasmas

Dual-frequency (DF) capacitively coupled plasmas (CCP) are commonly utilized in semiconductor etching and deposition processing because of their outstanding spatial uniformity and easy control of the ion energy and flux. With a dual-frequency, the high-frequency (HF) and the low-frequency (LF) voltage waveforms can be controlled separately, which are faster and slower than the ion transit time individually. Due to the large computational load, most simulation studies have utilized fluid models or a one-dimensional (1D) particle-in-cell (PIC) method. A two-dimensional (2D) particle-in-cell simulation parallelized with a graphics processing unit made it possible to overcome the heavy computation load in DF CCP simulation. We report the effect of DF driving on the spatial uniformity of the ion energy and angle distributions (IEAD) of Ar CCPs, including the electrode asymmetry and the sidewall effect. As the LF voltage increases, the spatial uniformity of plasma density improves. Therefore, the ion flux toward the wafer becomes uniform as well. The phase-resolved IEADs provide insight into how the ion transit time at different energy ranges affects the whole IEAD by combining the HF and the LF voltages.