Optimum Frequency for Inductively Coupled Plasma Generation with a Single-Loop Antenna

Abstract

The frequency dependence of the inductively coupled plasma is experimentally studied using a single-loop antenna. In particular the transition from the capacitive to the inductive coupling mode is examined for the frequencies from 13 to 60 MHz. The results show that the frequency at which the transition from the capacitive to the inductive mode appears at the lowest power is 27 MHz. At the frequency of 60 MHz, the inductive coupling mode does not appear within the power considered. A simple model that includes the two power absorption mechanisms through capacitive coupling and inductive coupling is proposed. It is demonstrated that the electron density at which the absorption energy through inductive coupling exceeds that through capacitive coupling is a key parameter.

New Emissive Probe Measurements of Electron Temperature in Two Modes of Radio-Frequency Plasmas

“…4, that the values of ÁV F obtained at the pressures of 50 and 30 mTorr almost lie on one curve, demonstrating that the plasma electron is in Maxwellian in these conditions. As has been previously reported, 10) in these conditions of the power and gas pressure the plasma is in the inductive coupling and in a high density of more than 10 11 cm À3 . In these high density plasmas, the electron energy is likely to be Maxwellian, 11) because of dominant electron-electron collisions, indicating that the measurements by the present method are reasonable.…”

“…One should note, here with a particular interest, that in the condition of 300 W and 10 mTorr, the plasma electrons are in Maxwellian energy distribution, and the plasma is in the inductively coupled mode with the electron density more than 10 11 cm À3 . 10) The electron energy distribution function will be discussed later again.…”

Mode Transition Enhancement by Permittivity of Window Materials in Low Frequency Plasmas

“…Particularly, in the power dependence, the electron density shows a stepwise increase at a certain value of RF power at each gas pressure and the power at which the stepwise increase is occurred, is monotonically lowered as the gas pressure is increased. This stepwise behavior is also observed in the antenna voltage as will be later shown, and its responsible mechanism has already been found 6) to be the mode transition from the capacitvely coupled plasma to the inductively coupled one.…”

“…We have previously reported several preliminarily data which were obtained in the frequency range of 13 to 60 MHz. 6) In this work, the experimental verifications are more generalized in the following two points: the frequency range is extended down to 2 MHz and the pemittivity effect of the window material is examined.…”

A New Floating-Probe for Measurement of Insulated Plasma Produced by Radio-Frequency Power

“…In this work, the two types of plasma sources are employed and the first one is a conventional planar type of inductively coupled plasma (ICP) which is produced in a stainless-steel chamber of 350 mm in diameter with a single-loop antenna, the details of which has been already shown in our previous paper. 17) Hereafter, we call this plasma source as the metal ICP.…”