Computational and experimental investigation of an ICP with RF subrate bias in an industrial etch reactor

Hybrid discharges, which combine inductively and capacitively coupled plasmas (ICPs and CCPs), are integral to etching and deposition processes. ICPs generate plasma the via a radio frequency (RF) driven coil, while an RF-driven substrate bias manipulates the ion energy distribution function (IEDF) at the substrate, aiming for independent control of ion flux and ion energy at the substrate. This study computationally characterizes the Reactive Ion Etching (RIE) module of the ForLab cluster tool at Bochum University on an industrial scale and compares the results to experimental findings. Both simulations and experiments were conducted at a low pressure of 1 Pa in Argon for inductively as well as capacitively applied RF powers at 13.56 MHz, with variable input powers to both the RF coil and the substrate bias. The Hybrid Plasma Equipment Model (HPEM) was used for the simulations. Parameters such as ion fluxes, electron densities, and IEDFs were validated against experimental results, showing good agreement with deviations within a few percent in radial electron density profiles. The ion flux and IEDF profiles exhibited similar trends across different ICP and substrate power settings, with IEDF maxima aligning energetically with experimental observations. The study also examines capacitive and inductive power coupling, providing detailed insights into the coupling mechanisms through spatially and temporally resolved analyses of power densities, electric fields, and excitation rates.