The crystalline structure, thermal stability, and electrical properties of TaN and TaSiN thin films formed by reactive RF-sputtering with a broad range of N and Si composition ratios were investigated. TaSiN with a Si/(Si+Ta) ratio less than 25% were crystalline, whereas that with a ratio more than 25% was amorphous, regardless of the N2 partial pressure. The amorphous films exhibited excellent thermal stability with no crystallization up to 900°C. Crystalline films consisted of columnar grains with sizes ranging from 20–30 nm. Electrical resistivity showed a strong dependence on the Si and N composition ratios. However, amorphous films deposited at low N2 partial pressure exhibited constant resistivity, regardless of the Si/Ta ratio. These results clarify that the crystalline structure and electrical resistivity of TaSiN films can be controlled by varying the Si and N composition ratios.

The conductivity of TaSiN thin film was investigated in a wide temperature range from room temperature to 900°C, and, based on the measurement, a new model for the temperature dependence of TaSiN thin film conductivity was proposed. TaSiN thin films were deposited on thermally oxidized Si wafers using reactive RF cosputtering. Resistivities of the films were measured from room temperature to 900°C by the four-contact probe method. All the films showed decreases in resistivity as temperature increased. The temperature dependence of conductivity at high temperature was described by a model with two conductors connected in parallel, one proportional to 1/T, another proportional to the Arrhenius-type thermal activation term (exp (-E/kT)).

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