Vacuum ultraviolet emission in low-pressure capacitively coupled argon discharges*

Low-pressure plasma discharges are a key technology in industrial applications such as semiconductor processing. Capacitively coupled plasmas are often driven by single, dual, or multi-frequency radio-frequency sources that sustain the bulk plasma and control the flux of ions and their corresponding energies to surfaces. In the plasma, high-lying excited states emit radiation that could influence plasma processing parameters by not only interacting with impurities in the gas but also by liberating electrons from the plasma containing surfaces. In this work, a one-dimensional capacitively coupled (CCP) plasma is simulated using particle-in-cell (PIC) with Direct Simulation Monte Carlo (DSMC) to quantify the effects of vacuum ultraviolet radiation and subsequent photoemission from surfaces on plasma properties, ion energies, and ion fluxes. Radiation is emitted stochastically from excited states and transported through the volume using a discrete approach. The plasma is driven by a single 13.56 MHz source operating in pure argon gas. Results from the simulation show the influence of photons in different operating regimes from 1 Pa to 100 Pa with different input voltages.