2. The quantity of the atoms emitted by one ion, is determined by the nuclear number and structure of electronic environments of an ion and atom of the target. It grows in process of electron filling external electronic environments.
3. The ions of those elements possess the maximal spraying action, which have the filled d-environments (РЬ, Тl, Нg, Аu, Сd, Рt, etc.), and also ions of the elements having filled р-environments (ions of inert gases). Similar dependence is also observed for the maximal output of emitted atoms from elements with the filled d-environments.
4. ions of that elements possess the minimal spraying action, which don’t have р-and d-environments or they only start to be filled (Н +, He +, Li +, etc.), and also elements at which these environments are filled. Similar law is shown for the elements creating the minimal output of emitted atoms.
5. The dispersion coefficient depends on the hade of ions. However in the discharge conditions in magnetron sputtering systems to operate the hade is not obviously possible, at the same time, as some researchers suppose [7, 8, 30, 32, 47] the hade practically of all ions on the cathode - target is equal to zero. Therefore influence of the hade on the dispersion coefficient of the cathode - target in magnetron sputtering systems can be neglected, and one can accept for calculations value of the dispersion coefficient at normal falling of particles.
6. There are factors, which under certain conditions, render serious influence on the emission of atoms from substance. The formation of oxides, polymeric firms, temperature and a roughness of a surface, density of a current of ions and pressure of the gas surrounding a sample, a degree of saturation of the ion target, all these factors are among them.
7. As a result of the carried out analysis it is possible to draw a conclusion, that a major factor, which influences on the process of dispersion in magnetron sputtering systems is the energy of bombarding particles. Influence of other factors is less essential.
5.7 Ways of definition of the dispersion coefficient
In the given section we shall consider various expressions for definition of the dispersion coefficient.
1) the dispersion coefficient is defined as an average of the atoms which are beaten out from the surface of a material by one falling particle. In this case the process of dispersion of materials by ionic bombardment is considered, therefore according to definition of the dispersion coefficient, a at./ion:
Yр=Na/Ni, (5.11)
where Na – the number of выбитых sputtered atoms of the material; Ni – the number of ions, bombarding the material.
2) According to the theory of physical dispersion of the amorphous and polycrystalline materials, evolved by P.Zigmund [41] at ionic bombardment on the normal to the surface in energy area Еsub<<Еi <Еi *, where Еsub – the energy of sublimation of target material atom, and
Еi*=
, (5.12)
where a - characteristic radius of a shielding electronic cloud on model Thomas - Fermi equal 0,8853а0 (Zи2/3+Zа2/3)-1/2, а0=5,29·10-11 m - Bohr radius of atom of hydrogen; Zi, Zа - nuclear numbers and weights of a bombarding ion and a material of a target accordingly. The dispersion coefficient of materials depends in direct proportion to the energy and can be estimated by the formula.
, (5.13)
where β - the dimensionless parameter dependent from ma/mи; Есуб - energy of sublimation of the target material atom.
3) Determining the dependence of the dispersion coefficient from energy Ei of bombarding particles of various type it is also convenient to use the empirical formula [72]
, (5.14)
where a *, Q,
and En
- empirical
parameters; Es
- energy of
sublimation, eV;
- Lindkhard’s function for
non-elastic collisions; 
- power of braking, eV·sm2/1015
atom;
- basic energy.
Уважаемый посетитель!
Чтобы распечатать файл, скачайте его (в формате Word).
Ссылка на скачивание - внизу страницы.