Paper SE-ThP2
Influence of Oblique Incidence on the Properties of Ion Beam Sputtered Chromium and SmCo Films

Thursday, October 23, 2008, 6:00 pm, Room Hall D

Ion Beam Sputter Deposition (IBSD) technique with its unique characteristics like lower operating pressure, well collimated mono energetic beam, independent control over the energy and flux is considered superior over the conventional sputtering techniques in processing thin films with tailored properties. In addition to the above features, the energy of the sputtered species is also relatively higher in IBSD. The spatial and angular distribution of the sputtered species here, also could be controlled by controlling the incident angle of ions over the target. This ability to fine control the energy of the sputtered species has been well utlized in depositing high density optical films. This energy imparting kinetics also forms the basis for the commonly used ion assisted deposition. Though the energy advantages have been well utilized, the angular distribution has not been explored much. In this work, we explore the advantages of angular distribution of the sputtered species, in modifying the properties of Cr and SmCo films. In the IBSD system used in the present study , ions were incident over the targets at an angle of 45^o degrees and substrates were placed at angles 10^o, 20^o and 30^o measured from the target normal. The substrates were heated to 600^o C. Chromium and SmCo films were deposited sequentially without breaking the vaccum. The deposited films were studied for their composition, structure and their magnetic properties. The structural studies indicate different structural orientations with different substrate position. Self shadowing of the condensed atoms, higher mobility on the plane of the substrate during oblique incidence have been found to be responsible for the structural variations which otherwise would not have been possible with other process parameter combinations. The change in the structure has also been found to alter the magnetic properties of the films. The films deposited at normal incidence show a coercivity of 4kOe whereas the films deposited at an angle of 30^o show a coercivity of 6kOe. The increase in the coercivity has been attributed to the preferential orientation of SmCo films caused due to the oblique incidence. The results obtained will be discussed in detail from the context of oblique deposition.