Paper TF-ThP1
Ultra Thin Cermet Resistor Films Deposited by DC Magnetron Sputtering
Thursday, November 12, 2009, 6:00 pm, Room Hall 3
Technological solutions for producing nanoscale cermet resistor films with sheet resistances above 1000 Ω /□ (Ohm per square) and low temperature coefficients of resistance (TCR) have been investigated. 2 to 40 nm thick films were sputter deposited from CrSi2-Cr-SiC targets by a dual cathode dc S-Gun magnetron. In addition to studying film resistance versus temperature using four point probe measurements, scanning electron microscopy and atomic force microscopy were also employed for analysis of the nanofilm structure features. This study has revealed that the cermet film TCR displays a significant increase when the deposited film thickness is reduced below 2.5 nm. An optimized sputter process consisting of wafer degassing, cermet film deposition at elevated temperature with rf substrate bias, and a double annealing in vacuum consisting of an in situ annealing following the film sputtering and an additional annealing following the exposure of the wafers to air has been found to be very effective for the film thermal stabilization and for fine tuning the film TCR. Cermet films with thicknesses in the range of 2.5 - 4 nm deposited using this process had sheet resistance ranging from 1800 to 1200 Ω /□ and TCR from – 50 ppm/˚C to near zero, respectively. A possible mechanism responsible for the high efficiency of annealing the cermet films in vacuum (after preliminary exposure the films to air) resulting in resistance stabilization and TCR reduction is discussed.