Effect Of Sputtering Pressure Research Articles

Effect of sputtering pressure of Pd underlayer on the perpendicular magnetic anisotropy in Co/Pd multilayered thin films

The magnetic properties of Co/Pd multilayers, in particular the perpendicular magnetic anisotropy, have been analyzed as a function of the sputtering pressure of Pd underlayer. With an increase of sputtering pressure of the underlayer from 6 mTorr to 25 mTorr, perpendicular coercivity of the multilayers increased with a slight decrease of saturation magnetization, and the increment of the coercivity was larger for the films with thinner cobalt layers. From the anisotropy analysis, it was found that the interface anisotropy energy decreased from 0.390 erg/cm/sup 2/ to 0.255 erg/cm/sup 2/ because of the interface roughening of the multilayers, which was mainly responsible for the decrease of perpendicular anisotropy, while the volume anisotropy energy increased from -11.37/spl times/10/sup 6/ erg/cm/sup 3/ to -7.90/spl times/10/sup 6/ erg/cm/sup 3/. The abnormally large intrinsic volume anisotropy energies of the multilayers with thin cobalt layers (<7 /spl Aring/) appears to suggest the noticeable contribution of magnetoelastic effect to the perpendicular anisotropy of the films.

Enhancement of coercivity by underlayer control in Co/Pd and Co/Pt multilayers

Co/Pd and Co/Pt multilayers were sputtered on Pd or Pt underlayers and the effects of sputtering pressure during the formation of underlayers on the magnetic properties of multilayers were investigated. It was found that the coercivity of Co/Pd multilayers was strongly dependent on the sputtering pressure of underlayer and could be increased drastically from 1.2 kOe up to around 5 kOe merely by increasing the sputtering pressure of Pd underlayer from 6 mTorr to 24 mTorr, while in case of Co/Pt films, no significant change of the coercivity could be observed with the variation of sputtering pressure of the underlayer. For both multilayers, the magnetic reversal feature was affected by the surface roughness of the underlayer and multilayers grown on the underlayer with a rough surface favored a rotation dominated process. The Kerr rotation angle was found to be hardly affected by the preparation conditions of the underlayer.

Effects of sputtering pressure and nitrogen concentration on the preferred orientation of AIN thin films

Aluminium-nitride films were prepared on glass substrates by reactive radio frequency (r.f.) magnetron sputtering in argon/nitrogen gas mixtures containing 25 ~ 75 1/2; nitrogen at substrate temperatures below 150‡C. It is important to control the crystallographic orientation and the surface morphology of the films with the deposition parameters for surface-acoustic-wave (SAW) devices. The change of crystallographic orientation with the sputtering pressure and the nitrogen concentration was calculated from the texture coefficient of the (0002) plane based on X-ray diffraction (XRD) patterns. It was found that a change of the c-axis from a parallel to a normal orientation, with respect to the substrate surface, occurred with a decrease in the sputtering pressure and an increase in the nitrogen concentration. From observations of the cross-section and the surface morphology, aluminium-nitride films exhibited a columnar structure and the grain size at the film surface increased an increase in the sputtering pressure and with a decrease in the nitrogen concentration.

Columnar microstructures of preferred oriented Aluminum Nitride films prepared by reactive sputtering

Aluminum nitride (AIN) thin films have drawn much attention as piezoelectric materials for generation and detection of surface acoustic wave (SAW) owing to high ultrasonic velocity and fairly large piezoelectric coupling factors. Since the piezoelectric properties are strongly dependent upon the c-axis orientation of AIN films, it is important to control the crystallographic orientation with deposition parameters. Though many reports have been presented, the mechanism of crystallographic orientation change with deposition parameters still remains unknown and the microstructure analysis of AIN films have been scarcely carried out. In this paper, we present the effect of sputtering pressure on thecrystallographic orientation and the microstruclure of the deposited AIN films, using X-ray diffraction (XRD) and transmission electron microscopy (TEM) study.AIN films have been deposited on Si (100) wafers by reactive RF magnetron sputtering in Ar-N2 gas mixture without substrate heating. The base pressure of vacuum chamber was below 1.5X10-6 Torr, RF power was 200 W and the ratio of gas flow rate (Ar:N2) was 3:1. Processing pressures ranged from 5 to 12 mTorr. Crystal structure of as-deposited films examined with XRD (Rigaku, D/MAX-RC, 12 kW) and microstructure analyses were carried out using crosssectional and plan-view TEM (JEOL 4000FX, 400 kV).

Effects of sputtering pressure on magnetic and magneto-optical properties in compositionally modulated Co/Pd thin films

We have investigated the effects of sputtering Ar gas pressure on magnetic and magneto-optical properties in compositionally modulated Co/Pd thin films. The samples were prepared by dc magnetron sputtering from 2-in.-diam Co and Pd targets by alternately exposing the substrates to targets. Sputtering Ar gas pressure was varied from 2 to 30 mTorr. All samples had same bilayer thicknesses composed of 2-Å-thick Co and 9-Å-thick Pd sublayers. It was observed that the intrinsic uniaxial anisotropy energy, magnetization, and polar Kerr rotation were monotonically decreased with increasing Ar gas pressures more than about 10 mTorr. Interestingly enough, the coercivity showed a thirtyfold enhancement as Ar gas pressure varied from 2 to 30 mTorr. We believe that the results are mainly ascribed to the variation of microstructure with sputtering Ar gas pressure.

The effect of sputtering pressure on microstructure and recording performance of high-density magnetic recording media

Understanding the magnetic properties of thin films applicable to high density recording requires detailed knowledge of the microstructure and microchemistry of the film. Interactions such as exchange and magnetostatic as well as anisotropies have been shown theoretically to influence the magnetic properties and recording characteristics of the media. These magnetic interactions and anisotropies are very sensitive to microstructure. This study reports the efTcct of sputtering pressure on the microstructurc and magnetic properties of thin CoPtCr films. The relation between the microstructural features and the magnetic interactions will be discussed.The film structure, C/Co77Pt6Cr17/Cr, was sequentially sputtered onto Si and NiP/AlMg substrates precleaned by an rf plasma. The thicknesses were 25/25-60/100 nm respectively. Sputtering pressures ranging from 3 to 24 mtorr were investigated. The magnetic properties of the films (coercive field, Hc, coercive squareness, S*, remanent and saturation moments, Mrand Ms) were determined by vibrating sample magnetometry. The magnetic recording measurements were made with thin film inductive write heads and experimental shielded magnetoresistive read head with a track width of about 10μm. The head-media spacing was 5 μin. Noise voltages for transition densities up to 3000 fc/mm were determined in the usual fashion. The microstructures were studied using the JEOL JEM 2000 FX and 4000 EX transmission electron microscopes.

Effect of sputtering pressure on the structure and solid-state reaction of titanium-nickel compositionally modulated film

The structure and annealing behavior of compositionally modulated nickel-titanium films is a function of the sputter deposition pressure. Films with a composition modulation wavelength of 20 close-packed atomic planes of each constituent per layer were prepared with argon sputter deposition pressures of 2, 5, and 10.2 mTorr. The structure was studied with x-ray diffraction in symmetric reflecting, and transmission geometries, and by x-ray rocking curves. Anneals of 1 h at 300 °C were performed to access the effect of the structure on solid-state formation of an amorphous alloy. Samples prepared under low deposition pressure exhibited textured, relatively high quality crystalline layers resulting from layer nucleation and growth. These films were not transformed to an amorphous phase by an anneal. Higher deposition pressures resulted in island nucleation and growth, random orientation, and a higher degree of disorder. Amorphous phase growth was observed during the anneal of the sample prepared at 10.2 mTorr of Ar. Increase in deposition pressure will result in lower impact energy of the deposited species, which will result in lower atomic mobility. Higher mobility with the negative surface tension between nickel and titanium will result in layer nucleation and growth. The disorder in the high deposition pressure samples may be acting as a nucleus for amorphous phase growth.

Deposition of zirconium boride thin films by direct current triode sputtering

Specular, crack-free thin films of the refractory conductor zirconium boride have been deposited for possible applications in combined contact/diffusion barrier metallization schemes. Films were deposited by dc triode sputtering, which allowed the independent study of the effects of sputtering pressure, target voltage, and current on the film properties. The mole ratio of boron in the films increased (composition tending to ZrB2) and the resistivity decreased with increasing deposition rates which at a fixed target voltage and sputtering pressure increased almost linearly with target current. Decrease in sputtering pressure, with only a minor change in deposition rate, dramatically decreased resistivity and caused stress in the films to change from tensile to compressive. X-ray photoelectron spectroscopy correlated reduced oxygen content to reduced resistivity. Triode sputtering permitted deposition of films at 2 mTorr with a resistivity of 162 μΩ cm which is the lowest reported value for as-deposited films.

Effect of pressure on the properties of reactively sputtered Ta2O5

Films of Ta2O5 have been prepared by reactive sputtering of tantalum in argon-oxygen dc glow discharges. Such films are of interest for capacitor dielectrics and optical waveguides, and for both applications the films must be free of pores. The effects of sputtering pressure on the density, refractive index, and dielectric constant of the films has been investigated. In the case of metal films, significant decreases in density are caused by increasing the sputtering pressure, a similar effect has been observed in the Ta2O5 case. The density decreases from 7.8 to 5.9 g/cm3 as the pressure is increased from 25 to 60 mTorr, and there are associated changes in related properties. The sputtering pressure can be controlled by adjusting the argon-oxygen mixture, but this also changed the deposition rate. Optical emission or mass spectrometry is used to ensure that the oxygen concentration is high enough for the deposition of Ta2O5 films rather than oxygen-doped tantalum; no emission from oxygen is observed until this concentration is reached.