Ion Plating,Ion Plating,Ion Plating,Ion Plating,Ion Plating,Ion Plating
ION PLATING is a generic term applied to film deposition processes in which the substrate surface and the growing film
are subjected to a continuous or periodic flux of energetic massive bombarding particles (ions, radicals, atoms, or
molecules--reactive or inert) sufficient to cause changes in the film formation process and the properties of the deposited
film (Ref 1, 2, 3, 4). The bombarding species and the depositing species can be from a number of sources. Bombardment
can take place in a plasma or vacuum environment. When a beam of energetic particles is used in vacuum, the process is
often called ion-beam-assisted deposition (IBAD).
A vacuum can be defined as an environment where the gas density is low and the mean free path for collision is very
long. In vacuum-barrel deposition processing, this means that the pressure is lower than about 1.3 mPa (1 × 10-5 torr). A
plasma is a low-pressure gas that contains enough ions and electrons to have an appreciable electrical conductivity. This
requires a gas pressure of greater than 13 mPa (1 × 10-4 torr). Plasmas can be low-pressure (less than about 0.4 Pa, or 3
mtorr) or higher-pressure (greater than about 0.4 Pa, or 3 mtorr), depending on whether or not collisions in the gas phase
are sufficient to "thermalize" high-energy particles leaving a source (Ref 5, 6). This differentiation is important when
using sputtering as a source for deposition because reflected high-energy neutrals from the target can have an important
effect on the growing film. Figure 1 shows the distance traveled by particles of differing masses (12 and 400 atomic mass
unit, or amu) and energies (5 eV, or 0.8 aJ, and 1 keV, or 160 aJ) in argon before becoming thermalized. It should be
noted that the gas density in a plasma system can vary with position due to preferential gas motion and particle
temperature distribution There are two basic versions of the ion plating process. In plasma-based ion plating the substrate is in contact with a
plasma, and the ions are accelerated from the plasma and arrive at the surface with a spectrum of energies. In vacuumbased
ion plating the film material is deposited in a vacuum and the bombardment is from an ion or plasma "gun." The
plasma-based ion plating process was first described in the technical literature in 1963 (Ref 10, 11, 12), and the first
reference to vacuum-based ion plating was in 1973 (Ref 13). In reactive ion plating, the plasma or ion/plasma gun can form ions of a reactive species to both bombard and react with the depositing material to form a compound film material.
In some cases, such as when using low-voltage, high-current electron-beam evaporation or arc vaporization, an
appreciable portion of the vaporized source material can be ionized to allow bombardment by "film ions." Often the term
ion plating is accompanied by modifying terms such as sputter ion plating, reactive ion plating, chemical ion plating,
alternating ion plating, arc ion plating, and so on, which indicate the source of depositing material, the method used to
bombard the film, or other particular conditions of the deposition.

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