Temperature-dependent characteristics of diffused and polysilicon resistors for ULSI applications

The temperature-dependent characteristics of polysilicon and diffused resistors have been studied. By using the 0.18 /spl mu/m CMOS technology, cobalt salicide process is employed and silicide is formed at the ends of resistors. Based on a simple and useful model, some important parameters of resistors including bulk sheet resistance (R/sub bulk/) and interface resistance (R/sub interface/) are obtained at different temperature. For diffused resistors, the R/sub bulk/ and R/sub interface/, values are increased and decreased with the increase of temperature, respectively. Positive values of temperature coefficient of resistance (TCR) are observed. Furthermore, TCR values are decreased with the decrease of resistor size. For polysilicon resistors, the Rinterface values are decreased with the increase of temperature. In addition, negative and positive TCR values of RNA are found in n/sup +/ and p/sup +/ polysilicon resistors, respectively. In conclusion, by comparing the studied diffused and polysilicon resistors, the negative trends of TCR are observed when the resistor sizes are decreased.