Electrical properties of TaN-Cu nanocomposite thin films

TaN-Cu nanocomposite thin films used as materials for TFR (thin film resistor) were prepared by reactive co-sputtering of Ta and Cu in the plasma of N₂ and Ar. After deposition, the films were annealed using rapid thermal processing (RTP) at 400°C for 2, 4, 8min, respectively to induce the nucleation and grain growth of Cu. The results reveal that temperature coefficient of resistivity (TCR) values will increase with the increase of Cu content for both the as-deposited and annealed films. The increase of nitrogen will result in higher resistivity and more negative TCR. At a constant nitrogen flow rate, the resistivity and TCR may increase or decrease with the increase of annealing time depending on the Cu content. In general, to reach near-zero TCR value, more copper is needed to compensate the negative effect caused by Ta-N. Thus, electrical properties of thin films can be characterized as functions of N₂ flow rate, Cu concentration and annealing time.