Effects of the Substrate Temperature on the Crystallization and Development of Texture of Mn-Zn Ferrite thin Films Depos
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INTRODUCTION Mn-Zn ferrite with spinel structure is widely used in magnetic recording head due to good soft magnetic properties such as high permeability and low coercivity. Mn-Zn ferrite thin films have been prepared by conventional sputtering' and Facing Target Sputtering.2 It was Co ferrite thin film that was first deposited by Ion Beam Sputtering among various ferrite systems.3 Co ferrite films could be crystallized at substrate temperature as low as 40r, since crystallization of Co ferrite films was enhanced by bombardment of Ar ions from the secondary ion source during ion beam sputtering. Ion bombardment during deposition is believed to transfer kinetic energy and momentum to adatoms on substrate, and thus enhance 45 the crystallization of deposited films. , In this paper, we investigated the effects of the substrate temperature(T,) on the crystallization and development of texture of Mn-Zn ferrite thin film under ion bombardment during ion beam sputtering with single ion source. The effects of several process parameters in ion beam sputtering on the properties of Mn-Zn ferrite thin films were also discussed.
EXPERIMENT Mn-Zn ferrite films were deposited by ion beam sputtering system with single ion source shown in Fig. 1. The disk-shaped (110)Mn0 543Zn0. 36oFe 2.097 0 4.y single crystal of 60mm in diameter was used as a target, and thermally oxidized silicon wafer(Si0 2(1000A)/Si(100)) that is compatible to MMIC technology was used as a substrate and placed at a distance of 541 Mat. Res. Soc. Symp. Proc. Vol. 317. ©1994 Materials Research Society
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Fig. 1 Schematic diagram of lBS with single ion source. The ion beam reflected from the target bombards the deposited film during deposition.
Fig. 2 Typical XRD patterns of the film deposited without oxygen flow(a), and post-annealed at 700'C for 30min under vacuum(b) and under the flow of oxygen(O.7sccm) and nitrogen( 14 sccm)(c).
120mm from the target. After the chamber was evacuated to less than 9 x 106 Torr, Ar and 02 gases were introduced into the ion source, and the operating pressure of the chamber was 5 x 10- Torr'. The ion beam (2.1 keV, 2. lnmA/cm 2 ) generated in a DuoPIGatron-type source sputtered the target, and the reflected ion beam from the target bombarded the deposited ferrite film. The maximum enhancement of crystallization due to ion bombardment was made at the incident beam angle of 55*. The incident beam angle was changed by tilting the target, which also changed the shape of the ion beam on the target from circle to ellipsoid, and a little part of target holder made of Fe or Cu(99.9%) metal was also sputtered. Crystallographic structures of as-deposited films were investigated by X-ray diffractometer(XRD) with Cu K. radiation, and morphologies of surface and cross-section of the films by SEM and TEM, respectively. The thickness was measured by the stylus method using the a-step 200. Magnetic properties were measured by the vibrating sample magnetometer(VSM) for in-plane applied field direction. Ferrite thin films of about 1000A
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