Spectroscopic and electrical characterization of oxygen microwave discharge used for downstream plasma oxidation of Si

Abstract

Actinometry optical emission spectroscopy (AOES), single cylindrical Langmuir, probe and electrostatic planar probe were used to characterize oxygen microwave plasma, at two distances from the plasma source (Z 1 = 15 cm and Z 2 = 25 cm), using three values of applied microwave power (800, 1000, and 1400 W) at a constant pressure of 70 Pa, involving different parameters, which are electron density (n e ), effective electron temperature (T eff ), plasma potential (V p ), floating potential (V f ), positive ion flux (Г i ), negative ion ratio (α = n À /n e , n À is the negative ion density), and atomic oxygen density (AO: [O]). The electron density and the effective electron temperature were deduced from (I-V) Langmuir probe characteristics. The atomic oxygen density was measured using actinometry method. Positive ion flux was evaluated from the positive ion saturation current (I sat ) of the planar probe. The combination of both single Langmuir probe and the planar one enabled the calculation of electronegativity of the oxygen plasma. An application of this oxygen plasma is presented, which is the silicon surface oxidation. The formed SiO 2 layer has been characterized by both scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis.