As a consequence, the plasma is normally more positive than any object it is in contact with, as otherwise a large flux of electrons would flow from the plasma to the object. The difference in voltage between the plasma and the objects in its contacts normally occurs across a thin sheath region.
Ionized atoms or molecules that diffuse to the edge of the sheath region feel an electrostatic force and are accelerated towards the neighboring surface. Thus, all surfaces exposed to the plasma receive energetic ion bombardment. The potential across the sheath surrounding an electrically-isolated object the floating potential is typically only 10—20 V, but much higher sheath potentials are achievable by adjustments in reactor geometry and configuration.
Thus, films can be exposed to energetic ion bombardment during deposition.
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This bombardment can lead to increases in density of the film, and help remove contaminants, improving the film's electrical and mechanical properties. When a high-density plasma is used, the ion density can be high enough that significant sputtering of the deposited film occurs; this sputtering can be employed to help planarize the film and fill trenches or holes. A simple DC discharge can be readily created at a few torr between two conductive electrodes, and may be suitable for deposition of conductive materials. However, insulating films will quickly extinguish this discharge as they are deposited.
It is more common to excite a capacitive discharge by applying an AC or RF signal between an electrode and the conductive walls of a reactor chamber, or between two cylindrical conductive electrodes facing one another. The latter configuration is known as a parallel plate reactor. Frequencies of a few tens of Hz to a few thousand Hz will produce time-varying plasmas that are repeatedly initiated and extinguished; frequencies of tens of kilohertz to tens of megahertz result in reasonably time-independent discharges.
Facebook and civilians are according on this, not. Taguchi, H. A 32 , The steady state number density of surface dangling bonds is determined by the balance between the rate of generation of dangling bonds and their annihilation rate. Cassagne, V. Perrin, O.
These large voltages lead to high-energy ion bombardment of surfaces. High-frequency plasmas are often excited at the standard Thus one can adjust the chemistry and ion bombardment in the deposition by changing the frequency of excitation, or by using a mixture of low- and high-frequency signals in a dual-frequency reactor. Capacitive plasmas are usually very lightly ionized, resulting in limited dissociation of precursors and low deposition rates. Much denser plasmas can be created using inductive discharges, in which an inductive coil excited with a high-frequency signal induces an electric field within the discharge, accelerating electrons in the plasma itself rather than just at the sheath edge.
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