Decay of magnetoresistance in a low-k dielectric upon application of electrical bias and temperature stress

The magnitude of the negative magnetoresistance (MR) effect found in the low-k dielectric SiCOH is found to decrease with time on electrical bias and temperature stress (BTS). The MR decay fits an exponential function reasonably well such that the time constant of the fit can be used to compare decays due to different BTS conditions. Higher voltages and higher temperatures are observed to decay more rapidly than relatively lower voltages and temperatures. The time constant of the decay varies with voltage such that it fits a power law with an exponent of about 30 which bears resemblance to the voltage dependence of TDDB time to failure experiments conducted with SiCOH. Assuming an Arrhenius temperature relation, the decay has an activation energy of about 0.3 eV. The apparent activation energy displays a weak dependence on the electric field applied to the device.