Characterization of a capacitively coupled RF plasma for SiO2 deposition: numerical and experimental results

A fluid model including an electron beam of hot electrons is presented and used to describe the transport of charged particles in a 13.56-MHz O2 plasma. An increase in the electron density when the RF power increases is observed from Langmuir probe measurements. The calculated evolution of the electron number density shows a reasonable agreement if the secondary emission coefficient is chosen equal to 10-4 on a steel (316L) electrode. The values of the plasma potential increase with increasing RF power from 30 to 35 V at 0.5-0.6 Torr, in the range 100-300 W. Surprisingly, the electron temperature decreases with increasing applied RF power. No clear explanation for this behavior is available yet