Characterization of contact resistance between electrode and TaN_x thin‐film resistor prepared by reactive sputtering

Abstract

SUMMARYThe design of thin-film resistors is an important element in forming the circuits of high-precision thin-film submount substrates. In this paper, we studied the effect of the contact resistance of the electrode on the precision of a tantalum nitride (TaN x ) thin-film resistor formed by reactive sputtering. By changing the length of the resistor while maintaining a constant electrode shape, we independently evaluated the resistance of the electrode and the resistance of the resistor itself. We used the Transmission Line Model (TLM) to determine the specific contact resistivity between the TaN x thin film and the electrode and the temperature coefficient of resistance (TCR), and studied the relationship to the deposition conditions of the TaN x thin film. The resistance of the electrode had about 1/10 of the sheet resistance of the resistor and must be considered during design when fabricating a high-precision thin-film resistor. The specific contact resistivity depended on the concentration of nitrogen in the TaN x thin film and was on the order of 10 -8 Ωm 2.