Effects of Voltage Distribution Along an Induction Coil and Discharge Frequency in Inductively Coupled Plasmas
M Edamura, Eric C. Benck
Recent etching processes often use low to middle plasma density in order to increase etching controllability or to reduce charging damages. In inductively coupled plasmas (ICPs) in low to middle plasma density, effects of capacitively coupled discharge (E-discharge) to the total plasma characteristic cannot be neglected. It is thus more difficult to understand the ICPs in low to middle density than to understand high density ICPs which can be regarded as being generated by inductively coupled discharge (H-discharge) only. In this research, we changed the voltage distribution of the induction coil of an ICP-modified GEC reference cell by inserting a termination capacitor between the coil and the ground. We also changed discharge frequency (6.28, 13.56, and 20) MHz, and investigated their effects to AR plasmas. As a result, it was observed that the structure of the E-discharge was changed by the voltage distribution of the coil, and therefore E-to-H mode transitions were dramatically altered. It was also observed that transitions of E-to-H-mode and electron energy distribution functions were strongly effected by discharge frequency, probably due to an increase of the ratio of the E-discharge to H-discharge with increasing discharge frequency. However, no difference between the electron energy distribution functions (EEDFs) was found when the E-discharge was removed with an electrostatic shield, probably because collisionless electron heating effect is not significant for the experimental conditions studied.
Journal of Vacuum Science and Technology A
coil voltage distribution, discharge frequency, inductively coupled plasma
and Benck, E.
Effects of Voltage Distribution Along an Induction Coil and Discharge Frequency in Inductively Coupled Plasmas, Journal of Vacuum Science and Technology A
(Accessed November 28, 2023)