Dynamics of a pulsed inductively coupled oxygen plasma

Inductively coupled plasma system (ICPs) is extensively used for a wide range of nanofabrication applications. The ICPs operated in a pulsed or power modulated mode has shown several advantages compared to the continuous discharge. In this work, the plasma dynamics in a planar coil pulsed inductively coupled plasma system (ICPs) operated in oxygen has been investigated, using phase and space resolved optical emission spectroscopy. It is well-known that the ICPs operates in two distinct operational modes as a function of power known as E and H modes, generated dominantly by capacitive and inductive couplings, respectively. The measurements show that the discharge ignites due a capacitive coupling (in the E-mode) and later transits to the H-mode as a function of time. The inductive coupling, however, starts during the E-mode along with capacitive coupling. The relative contribution of inductive coupling increases until the discharge reaches the E-H transition where the growth rate of inductive coupling becomes much faster. It is found that the time to reach E-H transition decreases with the pressure. At the E-H transition, the total emission has a spike-like feature (i. e., it first achieves a peak emission which later decreases and finally settles to a lower value). The 2D images of the discharge show that at the time of peak totalemission, the discharge structure is sharp and bright, which later decreases in brightness and becomes diffusive. Published by AIP Publishing.