Pulsed Overload Tolerance of Si/Cr, Ni/Cr and Mo/Si Thin Film Resistors on Integrated Circuits

The maximum Fusing Voltage (FV) (for 0.1-10 ¿s pulses) of Mo/Si, Ni/Cr, and Si/Cr resistors formed on oxidized Si substrates has been experimentally shown to be essentially independent of the following parameters: 1) resistive film material, 2) passivation film material (but a crack-free film is important for Ni/Cr resistors) and 3) the thickness of the oxide fim between the resistor and silicon substrate (0.5-1.5 ¿m). The FV depends on the resistor geometry, substrate material, and post fabrication annealing of the resistors. The most commonly used resistor geometry is adequate for use on ICs. The most dramatic change in FV obtained in the study was for resistors formed on glass substrates. The FV was reduced by almost a factor of 2 for 0.1 ¿s pulses over that of resistors on Si substrates. Post fabrication annealing resulted in marked increases in FV for each material for the 0.1 ¿s pulses but had diminishing effects for 1.0 and 10 ¿s. Annealing for times greater than 60 minutes or temperatures greater than 470° didn´t result in important further increases.