Charged species dynamics in an inductively coupled Ar/SF6 plasma discharge

Abstract

The chemistry of high-density SF6 plasma discharges is not well characterized. In this article, a combination of computational modeling and experimental diagnostics has been utilized to understand charged species dynamics in an inductively coupled Ar/SF6 plasma discharge. The model is based on the two-dimensional Hybrid Plasma Equipment Model with a detailed plasma chemical mechanism for Ar/SF6. In the experiments, absolute electron density and total negative ion density have been measured using microwave interferometry and laser photodetachment, respectively. In addition, we have also utilized prior measurements of mass and energy resolved ion fluxes by Goyette et al. [J. Vac. Sci. Technol. A 19, 1294 (2001)]. Computational results show that all SFx+(x=0–5) ions are present in the plasma discharge. Important negative ions include SF6−, SF5−, and F−. Electron and positive ion densities increase with coil power due to enhanced ionization. However, negative ion densities decrease with coil power as the main negative ion precursor, SF6, is lost through neutral dissociation. An increase in SF6 concentration in the Ar/SF6 gas mixture decreases electron density due to enhanced electron loss through (dissociative) attachment, which enhances negative ion densities. RF bias power does not have an appreciable impact on the ion and electron densities for the parameter range of interest. Experiments show that electron density decreases with gas pressure while the total negative ion density increases up to 25 mTorr. This is due to a decrease in electron temperature, which enhances electron loss through (dissociative) attachment. Although the model is able to capture most of the experimentally observed trends, there are discrepancies regarding the impact of gas pressure on electron density and relative flux of large positive ions.

SiC via fabrication for wide-band-gap high electron mobility transistor/microwave monolithic integrated circuit devices

“…It has previously been reported that Ar addition to an SF 6 / O 2 ICP etch can result in an increase of 5% in the etch rate. 13 The increase of the etch rate is more prominent in the Ar/ SF 6 / O 2 plasma due to both the presence of heavy Ar ions and the lower threshold energy for electron-impact ionization of Ar ͑15.6 eV͒ with respect to that of He ͑24.8 eV͒, which produces a more important increase of the ion flux. These results are shown in Fig.…”

Decay of a low-pressure oxygen magnetized and unmagnetized plasma

“…These parameters are typical for the negative ion sources. [1][2][3][4][5][6][7][8][9][10][11][12] Two cases are studied, namely, with and without the application of a homogeneous magnetic field. In the first case, magnetic field lines are parallel to the electrodes.…”

Ion Energy and Angular Distribution in Biased Inductively Coupled Ar/O2 Discharges by Using a Hybrid Model

“…In order to improve the plasma performance, computer modeling has been employed as a powerful tool for fundamental investigations and chamber design. The computer models can be divided into two main categories: spatially resolved models and volume averaged models . The former needs to solve a series of partial differential equations.…”

“…This approach allows us to capture the space transport of plasma composition, the distribution of the induced and static electric fields, local electron heating, etc. For example, in the hybrid plasma equipment model (HPEM), a finite volume method is applied to deal with the spatial differences and the electromagnetic fields and wave propagation are solved in frequency or time domain. Zhao et al developed a 2D fluid/electron Monte‐Carlo hybrid model to investigate mode transition phenomenon.…”