Reactive sputter deposition and properties of Ta sub(x)N thin films

The aim of this work was to evaluate tantalum nitride thin films fabricated using reactive sputtering with adjusted deposition parameters. Thin Ta sub(x)N films were deposited reactively on Si wafers using reactive RF magnetron sputtering at various N sub(2)/Ar gas ratios. The films were investigated by four-point probe sheet resistance measurement, profilometry, X-ray diffraction, scanning electron microscope, 2 MeV super(4)He super(+) backscattering spectroscopy, and atomic force microscopy. As the amount of nitrogen was increased, the phases in the as-deposited films were identified as beta -Ta, Ta sub(2)N (5% N sub(2)-flow), hexagonal TaN (10% N sub(2)-flow) and f.c.c.-TaN (15% N sub(2)-flow) with resistivities of 166 mu Omega cm, 234 mu Omega cm, 505 mu Omega cm and 531 mu Omega cm, respectively. Only the phase obtained at 5% N sub(2)-flow showed a reasonable uniformity over the wafer suggesting suitability as thin film resistors. The value of temperature coefficient of resistance (TCR) determined for the Ta sub(2)N thin film resistor was - 103 ppm/ degree C. copyright 2002 Elsevier Science B.V. All rights reserved.