Abstract
The paper is devoted to the analysis of internal stresses generated in the silicon substrate during the ion beam sputter deposition (IBSD) which is used to produce a titanium coating and a material interface which is a mixture of Si and Ti and is denser than the original Si substrate. The stress in Si-Ti coating is difficult to measure but it can be evaluated by one of numerical methods. Much easier is to measure a variation of stress between interface layer and silicon part of coating by applying the Raman micro-spectroscopy. The numerical model of IBSD can be split in two sub-models: the first one is for elastic collisions of substrate atoms with ion impinging into the substrate, and the second is for the generation of coating structure created. Two programs: SRIM and TRIDYN, are used to this purpose. These programs are applied at the first stage of calculations based on binary collision approximation (BCA) with Monte Carlo (MC) algorithm and neglecting plastic effects. The energy loss for impinging ions appears because of their collisions with substrate atoms and appearance of a scattering angle for both particles. In each iteration of BCA the energy loss is evaluated. The density profile in respect of coating depth is calculated by using TRIDYN. On the basis of the density profile, the structure of coating can be determined from the Cerius2 program by using models of molecular dynamics (MD). Following this, stress in the coating can also be evaluated. Macroscopic properties of Si-Ti sample are computed assuming that the energy of thermodynamic system is changing but the system volume is constant. Such thermodynamic system is known also as NVT particle ensemble. The coating process is controlled by parameters such as: beam current of sputtered atoms, temperature of a substrate, and time. It is assumed that the energy of sputtering beam is equal to15keV.