Int. Nano Lett., Vol. 1, No. 1, January 2011, pp. 59-61.
Simulation of Silver Thin Films' Growth and Influence of Deposition Rate on Final
Grain Size under Angle Flux and Standard Situation
Maryam Jamshidnejad a, Iraj Kazeminejad b,*, Alireza Razeghizadehc
aDepartment of Physics, Khuzestan Science and Reaserch Branch, Islamic Azad University Ahvaz, I.R. Iran bDepartment of Physics, Shahid Chamran University, Ahwaz, I.R. Iran
cDepartment of Physics, Payame Noor University, Ahvaz, I.R. Iran (Received 15 May 2010, Accepted 1 August 2010)
In this paper, a 2D stimulation model, FACET, is used for investigation of the relation between micro structure and deposition conditions such as substrate temperature, deposition rate and deposition angle of Ag thin films. It is observed that by increasing the deposition rate in standard conditions providing that the temperature of substrate is low, the average of final grain size is decreased. While, in deposition with angle flux the average of final grain size is increased.
Keywords: Stimulation, Thin film, FACET, Angle flux
Introduction
Silver*is used in reflecting infrared layers in optic pieces like low-emission glasses and sun light control systems for temperature maintenance and retrieval or for mirrors with high reflection power [1]. Silver and its compositions have recently had applications in extra-large integrated circuits [2]. By redacting the interior connections' size, maintenance and use of Al thin films for the metal coating process are not reliable due to failure in electron migration. The materials with low electric resistance and higher resistance of electron migration like silver and copper have high potentials in semiconductor industry. Primary factors related to electron migration include grain size and diffusion and the rate of film preferring orientation. One impressive approach for reduction of electron migration is construction of films with strong preferring orientation [111]. For low sputtering fcc structure films like Cu, Al and Ag,
*Corresponding author:
Email:i.kazeminezhad@scu.ac.ir
Tel.: +98 611 333 1040, Fax: +98 611 333 1040
the increase of preferred direction [111] is observed in crystal structure of films [3].
Description of thin film's structure with
FACET model
The following hypotheses are designed to show the most important physical processes by designing a model by logical simplification:
1- This model is a 2D stimulator.
2- The grain boundary surfaces are drawn via line. Each surface is described via one line.
3- Each nucleus has its specific direction which influences the rate of surface growth.
4- Nuclei's density, primary size and texture are 3 input parameters.
This model is severely reducing calculation expenses and can be performed easily on a PC. This model provides qualitative and semi-quantitative results for large systems [4].
A design of visualization tests via FACET
In the first series of tests the standard flux are postulated. In deposition flux is increased providing temperature of substrate is fixed quantity. The flux conditions are then in the second series of tests they are p angle flux. Finally, the results gained fluxes are investigated and compared. grain size in both flux conditions determined. This parameter is one important output data.
Table 1. Standard conditions
Parameter Quantity
Temperature 298 K
Type of flux Direct deposition (from PVD type) Direction of
flux
Deposition direction has no reference
Nuclie density 100 nuclie per each micron Nuclie texture Accidentally
Deposition
rate Atom/nm.s
In this stage of the computational of the deposition rate on final grain size conditions with fixed temperature of changing deposition flux are investigated. indicates the final grain size based
Fig. 2. Room temperature microstructure rates of 1 atom/nm.s (a), 30 atom/nm.s (
Jamshidnejad et al.
the conditions of
In this test, the providing that the fixed and in a low then changed and they are performed with gained from both compared. The final conditions is also is one the most
tandard conditions
Direct deposition (from PVD type) Deposition direction has no
100 nuclie per each micron
ational test, influence grain size in standard temperature of substrate and investigated. Figure 1 size based on film
thickness in standard conditio curve, by increasing depositi size is decreased.
Fig. 1.Variation of the final grain flux at T=298 K.
In this part, the influence final grain size is investigated angle flux impacts the surface angle of 10 degrees. We increase flux providing that temperature and in a low quantity.
Figure 2 shows room temperature of typical simulated thin films degree under different flux atom/nm.s.
microstructure of typical simulated thin films with angle flux of 10 degree .s (b), and 50 atom/nm.s (c).
10.5 11 11.5 12 12.5 13
0 10 20
d
f
R (atom/nm.
condition. According to this deposition rate the final grain
grain size versus deposition
influence of deposition rate on stigated under angle flux. The surface of substrate under We increase the deposition temperature of substrate is fixed
temperature microstructure films with angle flux of 10 flux rates of 1, 30, 50
10 degree under different flux
30 40 50 60
R (atom/nm.s)
b
Simulation of Silver Thin Films' Growth
61
Conclusion
In standard conditions, when deposition flux is increased providing that temperature of substrate is fixed and in a low quantity, the average of final grain size is decreased. The reason is that by increasing deposition flux, the atoms located on the surface of substrate do not find the opportunity of migration to other areas of the surface and as a result the process of surface diffusion decreases. By increase of such atoms, the surface of substrate is exposed to intense bombardment of deposition atoms. Bombardments of substrate via deposition atoms cause decrease of grain size. Therefore, in standard condition, the average of final grain size is decreased. But the case is not the same for the condition of angle flux. In angle flux, a large number of surfaces remain protected and as much
the flux's angle increases regarding perpendicular line, such surfaces increase. By increase of deposition flux, these surfaces find the opportunity to have surface diffusion with the surface. Therefore, surface diffusion is increased in this state and as a result larger grain sizes are provided.
References
[1] R. Dannenberg, E.A. Stach, J.R. Groza, B.J. Dresser, Thin Solid Films 370 (2000) 54. [2] M. Del Re, R. Gouttebaron, J.P. Dauchot,
P.Leclere, R.Lazzaroni, M. Wautelet, M. Hecq, Surf. Coat. Tech. 151-152 (2000), 86. [3] K.F. Chiu, Z.H. Barber, Thin Solid Films 358
(2000) 264.
