Influence of room-temperature oxidation on stability and performance of reactively sputtered TaN thin films for high-precision sheet resistors

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Department of Computer Science


Reactively sputtered tantalum nitride (TaN) thin films are used extensively in high-precision chip resistors because of their near-zero temperature coefficients of resistance (TCR). Passivation is usually necessary to ensure the long-term stability of the films. However, the inevitable room-temperature oxidation of TaN films before resistor device passivation poses a challenge. The impact of room-temperature oxidation on the stability and properties of TaN thin films intended for use in resistors remains unclear. This work systematically studies the room-temperature oxidation of reactively sputtered TaN thin films with varying nitrogen contents, represented by nitrogen flow ratios during film deposition. Results suggest that among different nitrogen flow ratios of 2%, 3%, 5%, and 7%, the films sputtered with a 3% N2 flow ratio are predominantly composed of the Ta2N phase, exhibiting the most stable structure and properties. These films demonstrate unaffected TCR, resistance, and thermal conductivity even upon exposure to air. In contrast, films prepared with other N2 contents are prone to room-temperature oxidation, leading to noticeable degradation in TCR and a reduction in lattice thermal conductivities. Notably, the electrical resistances of different films show little susceptibility to room-temperature oxidation. This work contributes essential insights into the effects of short-term room-temperature oxidation on the properties of TaN films and can have a great impact on their applications in high-precision sheet resistors.

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Surfaces and Interfaces