Properties of the Rf-Discharge in Ar-Tetraethoxylsilane

Abstract

Thin film deposition, surface treatment, plasma etching are expanding applications of plasma technology. Silicon compounds are important precursors for thin film deposition. Tetraethoxysilane (TEOS) Si(OCH₂CH₃)₄ is used for plasma polymerization or in mixtures with O₂for SiO_x deposition¹. Anisothermal rf-discharges are widely used in plasma technology. in this paper results of mass spectrometric investigations of the ions in an Ar-rf-discharge with admixtures of TEOS are presented. Plasma parameters of the Ar-TEOS-rf-discharge are estimated by means of the measured external voltages and the dark sheath thickness in front of the powered electrode². the measured ion distribution is compared with the calculated ion production rate using the electron impact ionization cross sections³ and the estimated electron temperature. the influence of the H₂ concentration on ion molecule reactions with proton transfer for the formation of H₃ ⁺, COH+ and ArH+ ions is discussed. the calculated ion current to the grounded electrode is compared with the polymeric film deposition rate. the ion current is sufficiently high to be responsible for the thin film formation. in this way a contribution is given for the understanding of processes in such chemical active plasmas.