Ti/Ni(80%)Cr(20%) Thin-Film Resistor With a Nearly Zero Temperature Coefficient of Resistance for Integration in a Standard CMOS Process
A thin-film resistor out of Ni(80%)Cr(20%) for integration in a standard complementary metal-oxide-semiconductor process with a temperature coefficient of resistance (TCR) below 10 ppm/K was realized by applying a thin Ti layer underneath. The Ti-layer thickness and the temperature and duration of furnace annealing after deposition were optimized in different experiments. The combination of 5-nm Ti + 10-nm NiCr and a 30-min heat treatment at 350degC in a forming gas ambient was found to yield a sheet resistance of about 140 Omega/sq and a TCR of below 10 ppm/K. The long-term drift of the sheet resistance after 1000 h at 200degC was about 0.3%. A transmission electron microscopy analysis was conducted to investigate the structure of the film and a possible change during annealing. An Auger analysis was conducted for film surface analysis.
Electrical properties of micro-heaters using sputtered NiCr thin film
NiCr (80/20 at.%) thin films were deposited on SiO2/Si substrates as a cryonetic heater by DC magnetron sputtering technique. After a series of annealing treatments under various conditions, the electrical properties and microstructure of the films were investigated. The crystallinity and composition of the films were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The films are changed from crystalline to amorphous phase after annealing at 250°C in nitrogen ambient and the annealing conditions have a significant effect on the resistivity and temperature coefficient of resistance (TCR) of the films. TCR of the samples annealed at 250°C for 9 minutes in N2 shows 9.23 ppm/K at 20K which is finally confirmed as the optimal result.
The Homogeneous Distribution of Non-Metallic Bonds in As-Deposited NiCrO Resistive Films
It is shown that the usual assumption of a macroscopic two phase model for the as-deposited NiCrO resistive films results in serious contradictions to experimentally well-established facts concerning both the structural and electrical properties. Therefore, the CrO bonds formed by the preferential oxidation of chromium during the film growth must be homogeneously dispersed with respect to a macroscopic length scale. Considering structural studies by transmission electron diffraction a qualitative explanation for the establishment of such a homogeneous structure during the film growth is proposed. 
 
 
 
Es wird gezeigt, das die ubliche Annahme eines makroskopischen Zweiphasenmodells fur NiCrO-Widerstandsschichten im Widerspruch zu experimentell gesicherten strukturellen und elektrischen Eigenschaften der Schichten steht. Die CrO-Bindungen, die wahrend des Schichtwachstums durch die bevorzugte Chromoxidation gebildet werden, liegen vielmehr bzgl. einer makroskopischen Langenskala homogen verteilt vor. Anhand von Strukturuntersuchungen mittels Transmissions-elektronenbeugung wird eine qualitative Erklarung fur die Ausbildung eines solchen homogenen Strukturzustandes wahrend des Schichtwachstums vorgeschlagen.