Effects of the Driving Voltage Amplitude and Phase on the Standing Wave Effect and Plasma Uniformity in Large‐Area Capacitively Coupled Plasmas Operated in SiH ₄ /H ₂

ABSTRACT

Standing wave effects are a major factor limiting the uniformity of large‐area capacitively coupled plasmas used for PECVD, but are usually described by the radial voltage amplitude variation alone. Using a two‐dimensional fluid model coupled with an electromagnetic transmission line model, we show that in strongly electronegative SiH ₄ /H ₂ discharges at 27.12 MHz and several Torr the standing wave effect still plays an important role, governed by both the voltage amplitude and the phase angle between the local potential at the plasma‐facing surface of the powered electrode and the potential at the power‐feed position. The radial phase variation drives vortex‐like electron transport, locally enhances ionization, and alters the SiH ₃ and H fluxes and deposition rates at both electrodes.