SIMULATION OF MULTICOMPONENT FILM GROWTH IN PROCESS OF ION-PLASMA SPUTTERING TECHNOLOGY

For deposition of high quality films from single target with certain stehiometry, the energy and angular distribution of the sputtered atoms, the peculiarities of the particles transport process, and the processes going on the substrate should be known. One of the ways to describe the sputtering and the transport process is Monte Carlo simulation. The development of a near perfect simulation procedure needs to take into account as more as possible realistic features of the sputter process, such as electrodes configuration, the form of the sputtered atoms source, energy spectra of the sputtered atoms flux, the parameters determining the collisions with the particles of the background gas mixture - interaction potential, atomic masses, etc. A deviation of the film composition from the stehiometry could be caused by the different behavior of the various sort atoms moving from the target to the substrate. Heavy atoms undergo much less scattering aside than light atoms. A proper consideration of the sputtering process should give a 3D spatial distribution of accommodated atoms on the substrate, target and chambers walls.
    For thin films growth simulation, the both regression model of the cascade of the displaced atoms under sputtering of solids and model of transport of sputtered atoms was elaborated. Regression model allows to calculate the sputtering rate of multicomponent materials, both energy and angular distributions of the sputtered atoms. Model of transport of the sputtered atoms enables to calculate values and ratio of flows of the sputtered atoms in a plane of a substrate and, consequently, stehiometry uniformity and growth rate of multicomponent films. Process of the sputtered atoms transportation is determined by pressure and composition of operational gas mixture as well as by geometrical arrangement of the electrodes and substrates. Results of statistical simulation within the model developed are compared with experimental data for sputtering of amorphous and polycrystalline materials. It is shown that this model fits the experimental data up to the statistical error and adequately characterizes the ion sputtering process.

Statement of problem for ion-plasma technology process

The following simulation procedures were developed:
1. Process of ion and atom bombardment of target during sputtering.
   Results: Energy and angular distribution of bombarding particles.
2. Process of sputtering of multicomponent targets.
   Results: Sputtering rate of multicomponent targets. Energy and angular distribution of sputtered atoms.
3. Process of sputtered atom transportation.
   Results: Values of flows of sputtered atoms. Growth rate of multicomponent films. Stechiomety and uniformity of multicomponent films.

Simulation of stehiometry of thin films produced by ion-plasma technology.
Example for Ba_0.3Sr_0.7TiO₃ film

According to the theoretical simulation of the deposition process, pressure of working gas and target-substrate distance determines the stehiometry of film.

Simulation of growth rate of thin films produced by ion-plasma technology.
Example for Ba_0.3Sr_0.7TiO₃ film

Theoretical simulation of transport allows to estimate the rate of delivery of sputtering atoms on the substrate, and define the growth rate of film.

The uniformity of film can be estimated taking into account:
• Pressure of working gas
• Composition of operational gas mixture
• Geometrical arrangement of the electrodes and substrates