Sputter‐deposited Ni/Ti double‐bilayer thin film and the effect of intermetallics during annealing

Abstract

In the present study, a double bilayer of a Ni/Ti thin film was investigated. A nanoscale NiTi thin film is deposited in a Ni-Ti-Ni-Ti manner to form a double-bilayer structure on a Si(100) substrate. Ni and Ti depositions were carried out by using d.c. and r.f. power, respectively, in a magnetron sputtering chamber. Four types of bilayers are formed by varying the deposition time of each layer (i.e. 15, 20, 25, and 30 min). The as-deposited amorphous thin films were annealed at 300, 400, 500, and 600°C for 1 h to achieve the diffusion in between the layers. Microstructures were analyzed using field-emission scanning electron microscope and high-resolution transmission electron microscope. It was found that, with the increase in annealing temperature from 300 to 600°C, the diffusion at the interface and atomic migration on the surface increase. Cross-sectional micrographs exhibited the interdiffusion between the two-layer constituents, especially at higher temperatures, which resulted in diffusion patches along the interface. Phase analyses, performed by grazing incidence X-ray diffraction, showed the formation of intermetallic compounds with some silicide phases that enhance the mechanical properties. Nanoindentation and atomic force microscopy were carried out to know the mechanical properties and surface profiles of the films. The surface finish is better at higher annealing temperatures. It was found that for annealing temperatures varying from 300 to 600°C, the increase in annealing temperature resulted in a gradual increase in atomic-cluster coarsening with improved adatom mobility.

MODELING AND SIMULATION OF MAGNETRON-SPUTTERRED NiTi THIN FILM DEPOSITION BY SRIM/TRIM

“…It may lead to nonuniformity of homogenization throughout the substrate surface. So batchwise sputtering with predefined thickness is essential which will be followed by the annealing process [18].…”

Влияние изохронных отжигов на поверхностные характеристики лент металлического стекла Ni-=SUB=-50-=/SUB=-Ti-=SUB=-50-=/SUB=-

“…появилась возможность применения различных микро-и наноустройств, таких как микронасосы, микроманипуляторы, микроприводы, импланты, зонды, датчики и пр. [1][2][3][4][5][6]. Как правило, ленты нитинола в подобных приложениях имеют толщину порядка 20−30 µm и изначально являются аморфными материалами [3,7,8].…”

“…Таким образом, с увеличением температуры отжига поверхностная шероховатость растет, достигая максимума при 500 • C (10 min), однако при 600 • C (10 min) ее значение падает. Подобные значения шероховатости при таких же режимах отжига получены и другими авторами[4,34].…”