Analysis of electron energy probability functions in Ar/SiH₄ inductively coupled plasmas with varying gas mixing ratios

In this study, electron behavior was investigated in an Ar/SiH₄ inductively coupled plasma based on electron energy probability functions (EEPFs) and density of neutral species. Langmuir probe and quadrupole mass spectrometry measurements were employed with varying SiH₄ mixing ratios. As the SiH₄ mixing ratio increased, both electron density and electron temperature decreased, although with different trends. These differences were analyzed in terms of changes in the EEPF. A significant variation in the composition of neutral species was observed with increasing SiH₄ fraction, leading to an evolution of the EEPF from Maxwellian to Bi-Maxwellian shape. This change is attributed to the increased density of neutral species generated at higher SiH₄ mixing ratios, which contributes to electron heating and cooling mechanism. The effect was analyzed by comparing the electron-neutral collision frequency with the driving frequency.