Michihiro Watanabe

Analysis of resistance change of thick‐film resistor by electric pulse loading

An analysis of the electrical conduction mechanism in a thick-film resistor is carried out by numerical calculations. In thick-film resistors, the resistance value tends to decrease when a high-voltage short-term pulse signal is applied. In order to elucidate this mechanism, a numerical model of the thick-film resistor is analyzed and is compared with the experimental results. The model used in the analysis consists of conductive particles and the conductive paths connecting the conductive particles. The resistance value of the conductive path is assumed to shift to a low-resistance state when the electric field intensity of the applied pulse signal in the conductive path exceeds the threshold value. From the results of the analysis, it is found that the above model coincides with the experimental results of the thick-film resistor on the variation of the resistance value under a high-voltage pulse signal application.

Failure mechanism of chromium-silicon-oxide resistive films stressed by electric pulse loading

The failure mechanism of chromium-silicon-oxide (Cr-Si-O) resistive films stressed by electric pulse loading has been investigated. Cr-Si-O resistive films were deposited with the Cr-Si target in an oxygen partial pressure of 0.05 Pa by reactive sputtering. The composition was 26 at % Cr, 48 at % Si, and 26 at % O with a microstructure of CrSi2 small crystallites and an amorphous SiO2 matrix. Resistance increased and flow patterns on the film surfaces were observed during the load-life tests to stress the resistive films at high-power electric pulses. The temperature increase in the film during the load-life tests was obtained numerically by using a finite element method (FEM), due to the difficulty of experimentally measuring the temperature increase. It reaches 400°C, for example, when supplied with a 0.5 W electric pulse of 1 ms pulse width. Film lifetimes and peak temperatures have a linear relation in the Arrhenius plots. Structurally, a decrease of chromium concentration was observed near the cathode region after electric pulse loading. These results indicate that the CrSi2 particles move in the Cr-Si-O film during the load-life tests. This movement induces the resistance increase and the final failure of the film as the electromigration phenomenon in pure aluminium or aluminium alloy films induces film failure. The activation energy for the electromigration of CrSi2 particles in the Cr-Si-O film was found to be 1.53 eV from the slopes in the Arrhenius plots.