The temperature of a substrate, while the covering is drawing on it’s surface, страница 21

Fig. 6.1. Polar diagrams of angular distributions of the substance sputtered from Ni, Pt, Fe, Mo targets under action of the target bombardment on the normal to its surface by ions Hg + with energies 150 (or 100), 250, 500, 750, 1000 eV (Verner and coll. [43]).

In comparison with distribution under the cosine law the greater number of particles is sputtered in the direction of the normal to the surface of the target and smaller - in the directions parallel to the surface of the target.

On fig. 6.2 the angular distribution received by Roll. and coll. is shown. [69]. The copper target was irradiated by ions Аг + with energy 20 keV. The hade of ions on the target was 50 °. The received distribution is closer to gauss distribution, than to distribution according to the cosine low. Its form does not depend on the hade of ions that proves to be true the data of other authors (Kobich and coll. [13]. At the irradiation of targets from Ni and Мо ions Hg + with low energy (250 eV) Verner [43] has found, that the angular distribution of the sprayed particles depends on the hade of ions. Particles of the target are sputtered mainly in that direction in which the ionic beam would be. Gronlund and Moore [29] have received similar distribution at dispersion of the silver target by ions D + with energy 9 keV, falling on the target under the corner 60 °.

Fig. 6.2 Angular distribution of the substance sputtered from the copper target by ions Ar + with energy 20 keV (Roll and coll. [68])

The hade α of ion beam on the target was 50º.

Fig. 6.3 Angular distribution of the substance sputtered from the copper target by ions Ar + with energy 17 keV (Kobich and Perovich. [13]).

Temperatures of targets made: Т1=100ºС, Т2=25ºС, Т3 =-160ºС. The dotted curve corresponds to the distribution according to the cosine law.

Kobich and Perovich [13] investigated angular distribution of the sprayed atoms of copper when the irradiation was made by ions Аг + with energy 17 keV, and temperatures of targets made 100, 25 and-160ºС. While at 100 ° C experimental angular follow the cosine law very well, deviations from the cosine law grow with reduction of temperature of the target (fig. 6.3). Authors investigated also dependence of angular distribution of the sprayed atoms of copper on duration of an irradiation of the target ions Хе + with energy 17 keV. The density of the ionic current was supported by a constant, and temperatures of targets made 100 and-160ºС. It has been established, that with increasing of duration of the irradiation (0,36 m·h, 0,87 m·h, 2,78 m·h) angular distribution comes nearer to the distribution according to the cosine law and this effect practically does not depend on the temperature of the target. It is possible, that the found out law is caused by increasing of a roughness of the surface of the target owing to the long ionic bombardment.

When researching the dispersion of silver targets by ions of inert gases of low energies (Ne +, Ar +, Kr + at 100-250 eV) Koedam [44] has found (as opposed to the results of Verner received with ions of mercury of low energy), that angular distribution of the sprayed particles follows the cosine law. The same result has been received by Gronlund and Murom at the irradiation of the silver target by ions Ne + with energy 4 keV, falling on the target under the corner 60º.

As evident from the aforesaid, the results received by different researchers are rather inconsistent. But nevertheless, it is possible to draw a conclusion, that basically, in the field of low energy ions of inert gases from 100 to 4 keV the angular distribution of the sprayed particles follows the cosine law косинуса. At increasing of ion energy distributions pass to "overcosine". At energies about 20 keV received distribution is closer to gauss, than to the distribution according to the cosine law.