SF₆and C₄F₈global kinetic models coupled to sheath models

Abstract

Global kinetic models combined with Monte Carlo sheath models are developed for SF 6 and C 4 F 8 plasma discharges for silicon etching under the Bosch process. In SF 6 plasma, the dominant positive ions are SF + 5 , SF + 4 , SF + 3 and F + while in C 4 F 8 the dominant positive ions are CF + 3 and C 2 F + 3 . The simulation results show that the electrical parameters, such as the electron density and electron temperature, clearly affect the sheath dynamics and consequently the ion energy distribution function evolutions. In this context, we showed the effects of the operating conditions, such as the pressure and the radiofrequency power, on the electron density and electron temperature evolutions as well as the reactive particle fluxes (neutral and positive ions) involved in the plasma surface interactions for etching/deposition under the Bosch process. Ion energy distribution functions obtained from SF 6 and C 4 F 8 plasmas are compared with each other as regards the electrical properties of their associated plasmas. The simulation results show that the bimodal peaks of ion energy distribution functions are wider for SF 6 plasma than for C 4 F 8 plasma due to the high sheath thickness of SF 6 compared to that of C 4 F 8 . This is explained by the low electron density due to the high electronegativity of SF 6 in comparison to that of C 4 F 8 . The simulations also reveal that the bimodal peak of the ion energy distribution function is wider when the ion mass is low.

Modeling of C4F8 inductively coupled plasmas: effects of high RF power on the plasma electrical properties

“…The simulation approach developed in this study is an updated version of an approach presented in a previous work [27]. In the present version, we show strong variations of electrical parameters under some specific operating conditions for C 4 F 8 plasmas.…”

“…Details of the plasma kinetic model of C 4 F 8 have been presented in previous publications [27,32,33]. The plasma model is based on the 0D global model.…”

Surface composition and micromasking effect during the etching of amorphous Ge-Sb-Se thin films in SF6 and SF6/Ar plasmas

“…Note there is discrepancy in literature concerning the variation of the fluorine atom density which must be discussed. Yang pressure, in which the variation is thought to be related to the dissociation of SF 6 [42]. The major difference between the different simulation studies is mainly due to the electronic density which can strongly increase with the decreasing pressure, or at the opposite, exhibits a low variation.…”

Etching of iron and iron–chromium alloys using ICP-RIE chlorine plasma

“…where z is the axial coordinate (z = 0 at the sheath entrance), n is constant between 0.5 and 1. In our simulations, n is estimated to 0.75. l s is the sheath thickness that depends on T e and n e ; it is evaluated from the plasma model [75]. The potential drop acros the sheath (V CS ) depends on the DC bias [75].…”