The temperature of a substrate, while the covering is drawing on it’s surface, страница 5

1. Energy of condensation of the sprayed atoms (Q₁).

As it was specified in the previous section, the dislodging particles from the cathode surface owing to bombardment by ions of working gas in magnetron sputtering systems takes place. Further these particles move to the surface of the substrate. The energy exchange between the came atoms and the surface of the substrate takes place on reaching by the sprayed atoms of the cathode - target this surface. Some particles remain on it, forming a covering, and the some particles are reflected from its surface. Processes of a covering formation and reflection of particles directly depend on quantity of energy of the sprayed atom. Energy, which the sprayed atoms transfer to the substrate at sedimentation on its surface is considered energy of condensation. When formatting the coating it results in heating the substrate, therefore in the equation of thermal balance (3.3) item Q₁ is positive.

The quantity of particles, settled on the substrate surface is the important factor in definition of its heat mode. This quantity can be characterized by such parameter as accommodation coefficient. Hence, in work it is necessary to determine 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 substrate surface, angular distribution of the sprayed atoms, geometry of the cathode - target and the substrate.

It is natural also, that the quantity of atoms, came on the substrate surface directly depends on quantity of the atoms, sprayed from the cathode surface. The parameter describing quantity of sprayed atoms from the cathode surface unit is the dispersion coefficient. Hence, in work it is necessary to determine this parameter 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.

During the process of moving of the sprayed atoms from the cathode surface to the surface of the substrate various factors will influence on them, such as pressure of residual gases, etc. Therefore, in work it is necessary to understand the processes occuring in the inetrelectrode interval and to analyse, in what way these processes will influence on the energy of the sprayed atoms and the quantity of atoms, coming on the substrate surface.

The quantity of the sprayed atoms will depend very strongly on the energy of the ions bombarding the cathode surface, and this energy will depend directly on the capacity, put in process of dispersion. Thus, in work it is necessary to consider these questions, because from all capacity, brought to magnetron sputtering system, not all will be directly used on the process of dispersion, the part of it will go on other processes, such as heating of walls of the chamber, radiation, etc.

As is obvious from the foregoing the quantity of heat coming on the substrate directly depends on the capacity put in process of dispersion. Hence, for estimation of the heat mode of the substrate in work it is necessary to establish this dependence.

2. Kinetic energy of precipitable atoms (Q₂).

The sprayed atoms of the cathode - target, except for energy of the condensation allocated at their sedimentation on the surface of the substrate, possess also kinetic energy which depends on speed of their moving in interelectrode area, a material of the cathode - target and consequently from energy and corner of ions of working gas falling on the cathode surface. And this will depend again on the capacity put in the process of dispersion. Kinetic energy of atoms precipitable on the surface of the substrate will result also in its heating, therefore in the equation of thermal balance (3.3) item  Q₂ is positive.

3. Energy of the neutral atoms, reflected from the target (Q₃).