Seminars

Pulsed capacitively coupled plasmas (CCPs) are widely employed in various applications, including the optimization of plasma reactor performance and as testbeds for the study of non-equilibrium plasma phenomena. They are widely used in semiconductor processing because they offer added control over species parameters compared to continuous-wave operation. However, computational study regarding the first few microseconds immediately after the power is switched back on (“re-ignition phase”) remain relatively scarce, even though this phase can strongly affect plasma development. This dissertation combines two modeling studies to understand the physics of re-ignition heating mechanisms and to record its effects on process surface parameters.
A 1D pulsed CCP study is used to explain how electron power absorption changes during re-ignition as a function of pulse frequency. When the pulse-off time is short, the plasma retains sufficient conductivity and re-ignites primarily through sheath-driven (α-mode) heating. When the pulse-off time is long, the reduced conductivity and strong electron number density gradients during early re-ignition produce drift–ambipolar electric fields, which modifies the heating mechanism involved in argon plasma. Furthermore, this study is extended to a 2D geometry where the effects of both geometric and operating parameters like radio frequency, power supply, inter- electrode gap etc. are used as tunable knobs to understand their impact on species fluxes and impact energies.
Overall, the findings from this study provide insights into the working of pulsed re-ignition of both argon and CF4 plasmas and address its scarcity of literature particularly in 2D CCPs by providing new insights.