In this study, the thermal stability of polysilicon lines with various widths and different dopant types in 90-nm processes is investigated. The thermal behavior of silicides formed on N+ polyresistors and P+ polyresistors is very different. The worst thermal stability is found on the narrower N+ polyresistors, while an abnormal thermal behavior is observed on P+ polyresistors. This anomalous thermal-stability change with different drawn linewidths of P+ polyresistors is related to the C Grain-size distribution and the actual polyresistor linewidth. Also, it is interesting to find that the voids formed in P+ polyresistors lead to a stepped increase in sheet resistance. (c) 2006 American Vactatin Society.