Finding the optimum design of the planar cutoff probe through a computational study

A new plasma diagnostic tool called the planar cutoff probe (PCP), recently developed by Kim et al. [Plasma Sources Sci. Technol. 28, 015004(2019)], can be embedded into a chamber wall or wafer chuck electrode for non-invasive electron density measurements. The application feasibility of the probe has so far been demonstrated in terms of signal-to-noise ratio; however, for the successful application of the PCP to real plasma processing, its design should first be optimized based on a comprehensive investigation of its characteristics. Therefore, in this paper, the effects of various parameters on the measurement characteristics of the PCP are investigated and analyzed via 3D full electromagnetic wave simulation. Results show that PCP measurement discrepancies vary by numerous controllable parameters, namely, wafer thickness and relative dielectric constant, antenna distance, input electron density, and chamber pressure. Based on these findings, the condition with the smallest measurement discrepancy and where PCP measurement performance is least affected by the parameters is found and discussed.