| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 89 === Abstract
The purpose of this study was to investigate the interface reaction between Nb and Si substrates after Nb was deposited on Si substrate by sputtering. Si substrates cleaned with (or without) dipping in a diluted HF solution (HF:H2O=1:50) were conducted to study the effect of native oxide layer formed on the surface of Si substrate. Samples which were deposited with Nb in a thickness of 1000Å were conducted with heat treatments in the temperature range between 400 and 1000℃ in a vacuum system with a pressure of 1×10-5 Torr. The interfacial compositions were evaluated by a compositional depth profile method in Auger electron spectroscopy (AES). X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to identify the phases formed at the interface. High resolution transmission electron microscopy (HRTEM), a JEOL 4000EX, operating at 400 kV with a point-to-point resolution of 0.18 nm, was used to distinguish the oxide layer at the interface. The surface resistivity of the phases in the interface was measured by a DC four-point probe method.
For the AES depth profile in samples without HF dipping, low level of oxygen content could be found at the interface. But the native oxide could be clearly observed in the as-deposited samples by the HRTEM method. The native oxide buffer layer between Nb and Si substrate hinders the formation of NbSi2.
In the DC four-point probe measurement, the resistivity increased as the annealing temperature increased. After annealing at 700℃, the resistivity decreased rapidly, and the lowest resistivity was found at 1000℃. The formation of NbSi2 phase could be attributed to the decreasing of the resistivity.
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