Spatial Distribution Of Plasma Parameters Research Articles

Gas Species Dependent Charge Build-Up in Reactive Ion Etching

The effects of gas species on the charge build-up in reactive ion etching (RIE) have been investigated. The charge build-up was evaluated using metal/nitride/oxide/silicon (MNOS) capacitors and metal/oxide/silicon (MOS) capacitors. It was found that etching with electronegative gases such as O2 and CF4 results in considerable charge build-up. The spatial distribution of plasma parameters was diagnosed using a Langmuir probe. It was found that the spatial distribution of plasma parameters is non-uniform in plasmas of negative gases,while it is uniform in H2, He, Ar, and Xe gas plasmas. The results suggest that we must take the effect of the gas species into consideration for the nonuniformity in a plasma, which causes the significant charge build-up. Models that can be used to explain the effect of gas species are discussed. It was also found that the charge build-up can be drastically reduced by adding H2 gas to negative gases.

Modeling the uniformity in a magnetron etching system

Magnetically enhanced reactive ion etch (MERIE) systems are increasingly popular for etching applications which demand high anisotropy and high etch rates without sacrificing etch selectivity. Conventional planar magnetron etch systems in which the magnetic fields are radial, exhibit a nonuniform race track etch. We report on an adjustable, rotating field, planar MERIE system. An etch uniformity of ±5% (6 in. wafer diameter) for resist etching in an O2 plasma has been obtained over a wide range of conditions. The impact of magnetic field adjustment and contoured electrodes on resist etch uniformity is characterized. An equivalent circuit model coupled with a diffusion model, and a Monte Carlo simulation of secondary electron transport have been used to predict the spatial distribution of plasma parameters in an Ar plasma sustained between planar electrodes. The measured magnetic field distribution, radio-frequency power, current, and voltage are used as inputs to the model. The spatial distribution of the magnetic field has a profound influence on the plasma parameters. The calculated spatial distribution of the ion flux in an Ar plasma is in qualitative agreement with the resist etch rate distribution across the wafer in an O2 plasma.

Contribution to hydrodynamic equations from interaction of oblique magnetosonic waves with plasmaspheric thermal electrons

The contribution to hydrodynamic equations from thermal electron interactions on Cerenkov resonance with magnetosonic (MS) waves propagating at “large” angles to the Earth's magnetic field. The Grad 13-moment approximation is used to calculate the moments of quasilinear collision integrals. The moments describe the variations of the macroscopic parameters of electron components in the respective hydrodynamic equations due to resonance interaction. The dependence of the collision moments on plasma concentration and electron temperature for a set of MS-wave spectra measured in the outer plasmasphere is studied. The MS-waves are shown to give rise to the particle and energy transport from the interaction region, thereby markedly affecting the spatial distribution of plasma parameters. In turn, this leads to self-adjustment of the process of resonance interactions of MS-waves with thermal electrons. One of the consequences of the feature discussed is that the inhomogeneities of the electron number density and temperature may be formed in the Earth's outer plasmasphere.