The temperature of a substrate, while the covering is drawing on it’s surface, страница 6

As it was already spoken above, not all atoms coming on the surface of the substrate, will be precipitable and will form a coating. Some part of them will be reflected. The quantity of reflected atoms can be defined by accommodation coefficient, as it was already spoken above.

4.  Radiation of plasma (Q₄).

In magnetron sputtering systems when drawing a coating radiation of plasma is also observed and it’s also a source of heat coming on the substrate, therefore composed Q₄ in the equation of thermal balance (3.3) is positive. But according to various sources [12,34,56] the quantity of radiation in magnetron sputtering systems is usually insignificant, the degree of its influence on the substrate heating is also insignificant, hence, in comparison with other factors, the contribution of radiation to the component of the thermal stream coming on the surface of the substrate, is small, therefore its influence at definition of the thermal mode of the substrate we may not take into account.

5. As to heat removed from the substrate Q_out, some part of it can be radiated in ambient space, some part can be spent on heating of substrate holder or to be removed from the surface of the substrate in some other way. The special system of cooling can also be used for the substrate in magnetron sputtering system. But the circle of the questions considered in this work is limited by heat, brought to the substrate.

Drawing conclusions from the foregoing, it is possible to correct the basic directions of the further course of work:

1.  To consider processes in the discharge gap of MSS;

2.  To determine dispersion coefficient and to carry out the analysis of its dependence on various factors, such as a material of the target, a kind of working gas, energy of ions of working gas, working pressure, conditions of the target surface and its temperature;

3.  To determine the accommodation coefficient and to carry out the analysis of its dependence on various factors, such as a material of the substrate, energy of the sprayed atoms, energy of atoms of the surface of the substrate, angular distribution of the sprayed atoms, geometry of the cathode - target and substrate;

4.  Definition of the capacity put in the discharge of the magnetron sputtering system and dependence of the thermal stream, coming on the substrate from the put capacity;

5.  Development of the technique of the substrate thermal mode estimation when drawing coatings with help of magnetron sputtering systems;

6.       the comparison of carried out estimations with experimental data.

4. Processes in the discharge gap of magnetron sputtering systems

The basic difference of the magnetron sputtering method from others is creation above the certain sites of the cathode the plasma area of the glow discharge of low pressure by imposing an external magnetic field of the certain form on the electric field directed from the cathode to the anode. It is known [1], that plasma of the glow discharge is an area of gas concerning low temperature, which is characterized by such key parameters as density of neutral particles (atoms or molecules) N_A, electron density N_e and electronic temperature T_e (electron distribution on energy), and also ion density Ni (Ni=Ne) (tab. 4.1).

Table 4.1

Parameters of plasma of the glow discharge