Combined TiN- and TaN temperature compensated thin film resistors

The opposite signs of the temperature coefficient of resistance (TCR) of two thin film materials, titanium nitride (TiN) and tantalum nitride (TaN), were used to form temperature compensated thin film resistors (TFRs). The principle of designing temperature compensated TFRs by connecting TFRs of each compound in series or in parallel was demonstrated. TiN, TaN, and combined TiN and TaN TFRs for monolithic microwave integrated circuits (MMICs) were fabricated by reactive sputtering. DC characterization was performed over the temperature range of 30-200 degrees C. The TiN TFRs exhibited an increase in resistivity with temperature with TCRs of 540 and 750 ppm/degrees C. The TaN TFR on the other hand exhibited a negative TCR of -470 ppm/degrees C. The shunted TFRs were fabricated by serial deposition of TiN and TaN to form a bilayer component. The TCRs of the series- and shunt configurations were experimentally reduced to -60 and 100 ppm/degrees C, respectively. The concept of temperature compensation was used to build a Wheatstone bridge with an application in on-chip temperature sensing. (C) 2011 Elsevier B.V. All rights reserved.