Processing factor dependence of resistivity parameters of ruthenate-based thick film resistors with low temperature coefficients

Abstract

Many analog sensor and control circuits take advantage of the low (<100ppm/°C) temperature coefficient of resistance (TCR) of thick film resistors which are based on fired ruthenate-glass nanocomposites. To manufacture resistors with even smaller TCRs, a knowledge of the effects of processing on conduction mechanism parameters is of particular importance, because TCR is fixed in firing and cannot be trimmed later to a target value, as resistance can be. The peak firing temperature and time were varied, and a special four-probe dc design was used to minimize contact and printing nonuniformities. Corresponding to a greater energy level degeneracy in larger particles, the electrostatic charging energy decreased with the observed coarsening of the resistor microstructure. For the primary data set, the charging energy decreased (at >95% confidence) from 1.56 to 1.15 meV with increasing firing temperature (from 845 to 855 °C) and time (from 8 to 11 min). Model-based estimation of parameters is a means to provide quantitative understanding of how TCR and underlying conduction are controlled by process factors.