Assessing the degradation mechanisms and current limitation design rules of SiCr-based thin-film resistors in integrated circuits

Abstract

The degradation of SiCr-based thin-film resistors under current and temperature stress and the Joule heating in the resistors are experimentally investigated to set current limitation design rules. Degradation mechanisms, the failure modes, and the impact of the stress test on Temperature Coefficient of Resistance (TCR), are studied with the use of various test structures stressed under different conditions (temperature, current density and direction), followed by optical inspections, Infra-Red imaging and SEM/TEM cross-sections. Electromigration (EM) is found to be the dominating degradation mechanism, but the EM process differs from that in commonly used interconnects. Current accelerating factor and the equivalent activation energy are determined for data extrapolation. To avoid errors in Joule-heating determination from TCR, integrated temperature sensors are employed. Current limitation design rules are deduced based on the EM and Joule heating results.

Process Optimization of Integrated SiCr Thin-Film Resistor for High-Performance Analog Circuits

“…Secondly, the integrated thin-film resistor (TFR), which has been widely researched [8]- [22] because of its various advantages such as near-zero TCR [8]- [11], low noise [12], [13], good matching property [13]- [15], and the ability to be electrically trimmed [16], although additional masks are required to form TFRs. However, previous research has focused only on the electrical properties [8]- [16] and the reliability issues [17]- [22] according to the mixing ratio of resistor materials. Therefore, the enough information about the electrical properties of TFR according to process conditions should be required to find the electrical characteristic variations of TFR for the process optimization.…”