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Carbon rich Nano-crystalline grain size tantalum carbide (Ta-C) thin films were prepared by non- reactive simultaneously dual magnetron sputtering. The main purpose of the current work was to investigate the influence of deposition method, deposition power, film thickness and annealing temperature on structural, surface morphology and electrical resistivity of TaC thin films. The experimental result shows that the growth rate of film was about 6.7 nm min−1 and films are growth like spherical structure. The atomic percentage of elements in the films were very sensitive to the deposition power, which even if the small amount of increases in the deposition power of Ta lead the increase of Ta content. However, a small change in Ta percentage did not result in a change in film structure and surface morphology. Annealing temperature did not cause structural changes in the films, but lead small changes in the grain size (range from 7.0 to 9.1 nm) and surface roughness. Resistivity variation of deposited TaC films on the annealing temperature shows random behavior which may cause by the deposition method. Nevertheless, the resistivity of the film decreases first and then increases when the thickness increases from 79.2 nm to 134 nm. Minimum resistivity of film appears at the thickness of 79.2 nm, about 235.2 μΩ.cm. In the end, deposited TaC thin films shows good thermal stability and low enough resistivity for gate electrode application.

Direction detection of a magnetic field by spin-valve-type magnetic tunnel junction (MTJ) has been investigated at temperatures ranging from room to 150/spl deg/C, concentrating on the magnetic property of the pinned layer. Angular dependencies of resistance curves show that detection errors from cosine curve increase with rising temperatures in MTJ with the IrMn/CoFe pinned layer. Measurements of the magnetization curves of the pinned layer found that detection errors are caused by rotation of the pinned layer magnetization. Direction detection of a magnetic field by MTJ with a IrMn/CoFe/Ru/CoFe of synthetic antiferromagnetic (SyAF) pinned layer, in which magnetizations of two CoFe layers nearly cancel each other, was also investigated. We confirmed that the pinned layer of SyAF structure in MTJ effectively reduces the dependence of detection errors on temperature.

The read-cycle endurance of a magnetic tunneling junction (MTJ) has been investigated, focusing on the spin-dependent tunneling current at high temperatures. The MTJ structure used in this study consisted of Ta-NiFe-CoFe-AlOx-CoFe-IrMn-NiFe-Ta prepared on a thermally oxidized Si wafer. Both the tunneling current and tunneling magnetoresistance ratio showed no significant degradation during the 1E9 read-cycle test using unipolar voltage pulses of 0.5 V at room temperature. Temperature dependence of the MTJs resistance calculated from the measured tunneling current has also been examined in a temperature range from room temperature to 175/spl deg/C. Furthermore, in the case of read-cycle tests for thermally stressed MTJs, the variation of the tunneling current was less than 2% after 1E9 cycles at a stress temperature of 175/spl deg/C. This indicates that MTJs have sufficient read-cycle endurance under high-temperature operation.